From c64a77fb14ff5274e6932fe66dc15a7e0e5b7865 Mon Sep 17 00:00:00 2001
From: Eddie Kohler <ekohler@gmail.com>
Date: Sun, 14 Jun 2020 09:45:37 -0400
Subject: [PATCH] Deprecate global $Now in favor of Conf::$now.

---
 api.php                                  | 11 +--
 batch/cleandocstore.php                  |  8 +-
 buzzer.php                               | 11 ++-
 deadlines.php                            |  6 +-
 doc.php                                  |  3 +-
 lib/csv.php                              |  3 +-
 lib/filer.php                            |  9 +--
 lib/mincostmaxflow.php                   |  7 +-
 lib/redirect.php                         | 11 ++-
 lib/s3client.php                         |  5 +-
 lib/zipdocument.php                      |  4 +-
 manualassign.php                         |  2 +-
 profile.php                              |  6 +-
 review.php                               |  2 +-
 src/api/api_requestreview.php            | 11 +--
 src/api/api_searchconfig.php             |  6 +-
 src/api/api_user.php                     |  3 +-
 src/assigners/a_decision.php             |  4 +-
 src/assigners/a_status.php               |  8 +-
 src/assignmentset.php                    |  4 +-
 src/capabilities/cap_reviewaccept.php    |  7 +-
 src/checkformat.php                      |  3 +-
 src/commentinfo.php                      | 17 ++---
 src/conference.php                       | 94 ++++++++++++------------
 src/contact.php                          | 91 ++++++++++-------------
 src/formula.php                          |  5 +-
 src/helpers.php                          |  6 +-
 src/init.php                             |  2 +-
 src/initweb.php                          |  4 +-
 src/mailclasses.php                      |  3 +-
 src/meetingtracker.php                   | 27 ++-----
 src/papercolumns/pc_reviewdelegation.php |  1 -
 src/paperstatus.php                      | 16 ++--
 src/papertable.php                       | 10 +--
 src/partials/p_signin.php                |  8 +-
 src/review.php                           |  3 +-
 src/reviewinfo.php                       |  3 +-
 src/sessionlist.php                      |  3 +-
 src/settings/s_decisionvisibility.php    |  4 +-
 src/settings/s_finalversions.php         |  3 +-
 src/settings/s_reviewform.php            |  3 +-
 src/settings/s_reviews.php               |  5 +-
 src/settings/s_subform.php               |  3 +-
 src/settings/s_submissions.php           |  3 +-
 src/settingvalues.php                    |  4 -
 src/userstatus.php                       |  3 +-
 test/setup.php                           |  1 -
 test/test01.php                          | 20 ++---
 test/test02.php                          |  3 +-
 test/test04.php                          | 10 +--
 test/test05.php                          |  4 +-
 51 files changed, 205 insertions(+), 288 deletions(-)

diff --git a/api.php b/api.php
index c358dfa73..0ab321211 100644
--- a/api.php
+++ b/api.php
@@ -49,9 +49,9 @@
 if (!$Me->has_account_here()
     && ($key = $Me->capability("tracker_kiosk"))) {
     $kiosks = $Conf->setting_json("__tracker_kiosk") ? : (object) array();
-    if (isset($kiosks->$key) && $kiosks->$key->update_at >= $Now - 172800) {
-        if ($kiosks->$key->update_at < $Now - 3600) {
-            $kiosks->$key->update_at = $Now;
+    if (isset($kiosks->$key) && $kiosks->$key->update_at >= Conf::$now - 172800) {
+        if ($kiosks->$key->update_at < Conf::$now - 3600) {
+            $kiosks->$key->update_at = Conf::$now;
             $Conf->save_setting("__tracker_kiosk", 1, $kiosks);
         }
         $Me->tracker_kiosk_state = $kiosks->$key->show_papers ? 2 : 1;
@@ -70,8 +70,9 @@
     if (!$Me->is_reviewer())
         json_exit(403, ["ok" => false]);
     $from = $Qreq->from;
-    if (!$from || !ctype_digit($from))
-        $from = $Now;
+    if (!$from || !ctype_digit($from)) {
+        $from = Conf::$now;
+    }
     $when = $from;
     $rf = $Conf->review_form();
     $events = new PaperEvents($Me);
diff --git a/batch/cleandocstore.php b/batch/cleandocstore.php
index 0777fb73a..7bdf088db 100644
--- a/batch/cleandocstore.php
+++ b/batch/cleandocstore.php
@@ -31,7 +31,6 @@ class Batch_CleanDocstore {
     public $ftrees = [];
 
     function fparts_random_match() {
-        global $Now;
         $fmatches = [];
         for ($i = 0; $i !== count($this->ftrees); ++$i) {
             if (!($ftree = $this->ftrees[$i])) {
@@ -44,7 +43,7 @@ function fparts_random_match() {
                 $fm = $ftree->random_match();
                 if ($fm->is_complete()
                     && (($fm->treeid & 1) === 0
-                        || max($fm->atime(), $fm->mtime()) < $Now - 86400)) {
+                        || max($fm->atime(), $fm->mtime()) < Conf::$now - 86400)) {
                     ++$n;
                     $fmatches[] = $fm;
                 } else {
@@ -56,14 +55,13 @@ function fparts_random_match() {
             }
         }
         usort($fmatches, function ($a, $b) {
-            global $Now;
             // week-old temporary files should be removed first
             $at = $a->atime();
-            if (($a->treeid & 1) && $at < $Now - 604800) {
+            if (($a->treeid & 1) && $at < Conf::$now - 604800) {
                 $at = 1;
             }
             $bt = $b->atime();
-            if (($b->treeid & 1) && $bt < $Now - 604800) {
+            if (($b->treeid & 1) && $bt < Conf::$now - 604800) {
                 $bt = 1;
             }
             if ($at !== false && $bt !== false) {
diff --git a/buzzer.php b/buzzer.php
index 04550ce7c..f59fefc74 100644
--- a/buzzer.php
+++ b/buzzer.php
@@ -6,7 +6,6 @@
 require_once("src/initweb.php");
 
 function kiosk_manager(Contact $user, Qrequest $qreq) {
-    global $Now;
     $kiosks = (array) ($user->conf->setting_json("__tracker_kiosk") ? : array());
     uasort($kiosks, function ($a, $b) {
         return $a->update_at - $b->update_at;
@@ -14,7 +13,7 @@ function kiosk_manager(Contact $user, Qrequest $qreq) {
     $kchange = false;
     // delete old kiosks
     while (!empty($kiosks)
-           && (count($kiosks) > 12 || current($kiosks)->update_at <= $Now - 172800)) {
+           && (count($kiosks) > 12 || current($kiosks)->update_at <= Conf::$now - 172800)) {
         array_shift($kiosks);
         $kchange = true;
         reset($kiosks);
@@ -22,13 +21,13 @@ function kiosk_manager(Contact $user, Qrequest $qreq) {
     // look for new kiosks
     $kiosk_keys = [null, null];
     foreach ($kiosks as $k => $kj) {
-        if ($kj->update_at >= $Now - 7200)
+        if ($kj->update_at >= Conf::$now - 7200)
             $kiosk_keys[$kj->show_papers ? 1 : 0] = $k;
     }
     for ($i = 0; $i <= 1; ++$i) {
         if (!$kiosk_keys[$i]) {
             $key = hotcrp_random_password();
-            $kiosks[$key] = (object) ["update_at" => $Now, "show_papers" => !!$i];
+            $kiosks[$key] = (object) ["update_at" => Conf::$now, "show_papers" => !!$i];
             $kiosk_keys[$i] = $kchange = $key;
         }
     }
@@ -50,9 +49,9 @@ function kiosk_manager(Contact $user, Qrequest $qreq) {
 }
 
 function kiosk_lookup($key) {
-    global $Conf, $Now;
+    global $Conf;
     $kiosks = (array) ($Conf->setting_json("__tracker_kiosk") ? : []);
-    if (isset($kiosks[$key]) && $kiosks[$key]->update_at >= $Now - 604800) {
+    if (isset($kiosks[$key]) && $kiosks[$key]->update_at >= Conf::$now - 604800) {
         return $kiosks[$key];
     } else {
         return null;
diff --git a/deadlines.php b/deadlines.php
index 28de01bb5..25a71f9b7 100644
--- a/deadlines.php
+++ b/deadlines.php
@@ -49,7 +49,7 @@ function printDeadline($time, $phrase, $description) {
 if ($dl->resps ?? false) {
     foreach ($dl->resps as $rname => $dlr) {
         if (($dlr->open ?? false)
-            && $dlr->open <= $Now
+            && $dlr->open <= Conf::$now
             && ($dlr->done ?? false)) {
             if ($rname == 1) {
                 printDeadline($dlr->done, $Conf->_("Response deadline"),
@@ -75,14 +75,14 @@ function printDeadline($time, $phrase, $description) {
         if ($Viewer->isPC) {
             $ps = +$Conf->setting("pcrev_soft$isuf");
             $ph = +$Conf->setting("pcrev_hard$isuf");
-            if ($ph && ($ph < $Now || $ps < $Now)) {
+            if ($ph && ($ph < Conf::$now || $ps < Conf::$now)) {
                 $thisdl[] = "PH" . $ph;
             } else if ($ps) {
                 $thisdl[] = "PS" . $ps;
             }
         }
         if ($es != $ps || $eh != $ph) {
-            if ($eh && ($eh < $Now || $es < $Now)) {
+            if ($eh && ($eh < Conf::$now || $es < Conf::$now)) {
                 $thisdl[] = "EH" . $eh;
             } else if ($es) {
                 $thisdl[] = "ES" . $es;
diff --git a/doc.php b/doc.php
index 0e9fa82a2..429decc92 100644
--- a/doc.php
+++ b/doc.php
@@ -63,7 +63,6 @@ function document_history(Contact $user, PaperInfo $prow, $dtype) {
 }
 
 function document_download(Contact $user, $qreq) {
-    global $Now;
     try {
         $dr = new DocumentRequest($qreq, $qreq->path(), $user);
     } catch (Exception $e) {
@@ -90,7 +89,7 @@ function document_download(Contact $user, $qreq) {
         if (ctype_digit($qreq->at)) {
             $time = intval($qreq->at);
         } else if (!($time = $user->conf->parse_time($qreq->at))) {
-            $time = $Now;
+            $time = Conf::$now;
         }
         $want_pj = null;
         foreach (document_history($user, $prow, $dr->dtype) as $pj) {
diff --git a/lib/csv.php b/lib/csv.php
index 9d5843848..e26d6da58 100644
--- a/lib/csv.php
+++ b/lib/csv.php
@@ -649,7 +649,6 @@ function add_string($text) {
     }
 
     private function _flush_stream() {
-        global $Now;
         if ($this->stream === null) {
             $this->stream = false;
             if (($dir = Filer::docstore_tmpdir() ?? tempdir())) {
@@ -657,7 +656,7 @@ private function _flush_stream() {
                     $dir .= "/";
                 }
                 for ($i = 0; $i !== 100; ++$i) {
-                    $fn = $dir . "csvtmp-$Now-" . mt_rand(0, 99999999) . ".csv";
+                    $fn = $dir . "csvtmp-" . time() . "-" . mt_rand(0, 99999999) . ".csv";
                     if (($this->stream = @fopen($fn, "xb"))) {
                         $this->stream_filename = $fn;
                         break;
diff --git a/lib/filer.php b/lib/filer.php
index 4508a54d9..1588d3587 100644
--- a/lib/filer.php
+++ b/lib/filer.php
@@ -139,7 +139,7 @@ static function download_file($filename, $mimetype, $no_accel = false) {
     }
     /** @param DocumentInfo|list<DocumentInfo> $doc */
     static function multidownload($doc, $downloadname = null, $opts = null) {
-        global $Now, $zlib_output_compression;
+        global $zlib_output_compression;
         if (is_array($doc) && count($doc) == 1) {
             $doc = $doc[0];
             $downloadname = null;
@@ -182,7 +182,7 @@ static function multidownload($doc, $downloadname = null, $opts = null) {
         header("Content-Disposition: " . ($attachment ? "attachment" : "inline") . "; filename=" . mime_quote_string($downloadname));
         if (is_array($opts) && ($opts["cacheable"] ?? false)) {
             header("Cache-Control: max-age=315576000, private");
-            header("Expires: " . gmdate("D, d M Y H:i:s", $Now + 315576000) . " GMT");
+            header("Expires: " . gmdate("D, d M Y H:i:s", Conf::$now + 315576000) . " GMT");
         }
         // reduce likelihood of XSS attacks in IE
         header("X-Content-Type-Options: nosniff");
@@ -226,7 +226,6 @@ static function sha1_hash_as_text($str) {
     const FPATH_EXISTS = 1;
     const FPATH_MKDIR = 2;
     static function docstore_path(DocumentInfo $doc, $flags = 0) {
-        global $Now;
         if ($doc->error || !($pattern = $doc->conf->docstore())) {
             return null;
         }
@@ -245,8 +244,8 @@ static function docstore_path(DocumentInfo $doc, $flags = 0) {
                     return null;
                 }
             }
-            if (filemtime($path) < $Now - 172800 && !self::$no_touch) {
-                @touch($path, $Now);
+            if (filemtime($path) < Conf::$now - 172800 && !self::$no_touch) {
+                @touch($path, Conf::$now);
             }
         }
         if (($flags & self::FPATH_MKDIR)
diff --git a/lib/mincostmaxflow.php b/lib/mincostmaxflow.php
index a51d0ad90..a889b2cac 100644
--- a/lib/mincostmaxflow.php
+++ b/lib/mincostmaxflow.php
@@ -796,14 +796,13 @@ function shuffle() {
     }
 
     private function make_debug_file() {
-        global $Conf, $Now;
-        if (!($dir = $Conf->opt("minCostMaxFlowDebug"))) {
+        if (!($dir = Conf::$g->opt("minCostMaxFlowDebug"))) {
             return null;
         }
         $f = null;
         $time = time();
-        while (!$f && $time < $Now + 20) {
-            $f = @fopen($dir . "/mcmf-{$Conf->dbname}-{$time}.txt", "xb");
+        while (!$f && $time < Conf::$now + 20) {
+            $f = @fopen("$dir/mcmf-".Conf::$g->dbname."-{$time}.txt", "xb");
             ++$time;
         }
         return $f;
diff --git a/lib/redirect.php b/lib/redirect.php
index 9e282b9f1..7174e8bd5 100644
--- a/lib/redirect.php
+++ b/lib/redirect.php
@@ -91,7 +91,7 @@ function set_session_name(Conf $conf) {
 }
 
 function ensure_session($flags = 0) {
-    global $Conf, $Now;
+    global $Conf;
     if (session_id() !== ""
         && !($flags & ENSURE_SESSION_REGENERATE_ID)) {
         return;
@@ -111,13 +111,13 @@ function ensure_session($flags = 0) {
         }
         $session_data = $_SESSION ? : [];
         $new_sid = session_create_id();
-        $_SESSION["deletedat"] = $Now;
+        $_SESSION["deletedat"] = Conf::$now;
         session_commit();
 
         session_id($new_sid);
         if (!isset($_COOKIE[$sn]) || $_COOKIE[$sn] !== $new_sid) {
             $params = session_get_cookie_params();
-            $params["expires"] = $Now + $params["lifetime"];
+            $params["expires"] = Conf::$now + $params["lifetime"];
             unset($params["lifetime"]);
             hotcrp_setcookie($sn, $new_sid, $params);
         }
@@ -127,7 +127,7 @@ function ensure_session($flags = 0) {
 
     // maybe kill old session
     if (isset($_SESSION["deletedat"])
-        && $_SESSION["deletedat"] < $Now - 30) {
+        && $_SESSION["deletedat"] < Conf::$now - 30) {
         $_SESSION = [];
     }
 
@@ -167,14 +167,13 @@ function post_value($allow_empty = false) {
 }
 
 function kill_session() {
-    global $Now;
     if (($sn = session_name())
         && isset($_COOKIE[$sn])) {
         if (session_id() !== "") {
             session_commit();
         }
         $params = session_get_cookie_params();
-        $params["expires"] = $Now - 86400;
+        $params["expires"] = Conf::$now - 86400;
         unset($params["lifetime"]);
         hotcrp_setcookie($sn, "", $params);
         $_COOKIE[$sn] = "";
diff --git a/lib/s3client.php b/lib/s3client.php
index ba5baa671..5b9545107 100644
--- a/lib/s3client.php
+++ b/lib/s3client.php
@@ -56,7 +56,6 @@ function check_key_secret_bucket($key, $secret, $bucket) {
 
     /** @return array{string,string} */
     function scope_and_signing_key($time) {
-        global $Now;
         if ($this->s3_scope === null
             && $this->setting_cache) {
             $this->s3_scope = $this->setting_cache->setting_data($this->setting_cache_prefix . "_scope");
@@ -73,8 +72,8 @@ function scope_and_signing_key($time) {
             $service_key = hash_hmac("sha256", "s3", $region_key, true);
             $this->s3_signing_key = hash_hmac("sha256", "aws4_request", $service_key, true);
             if ($this->setting_cache) {
-                $this->setting_cache->__save_setting($this->setting_cache_prefix . "_scope", $Now, $this->s3_scope);
-                $this->setting_cache->__save_setting($this->setting_cache_prefix . "_signing_key", $Now, $this->s3_signing_key);
+                $this->setting_cache->__save_setting($this->setting_cache_prefix . "_scope", Conf::$now, $this->s3_scope);
+                $this->setting_cache->__save_setting($this->setting_cache_prefix . "_signing_key", Conf::$now, $this->s3_signing_key);
             }
         }
         return [$this->s3_scope, $this->s3_signing_key];
diff --git a/lib/zipdocument.php b/lib/zipdocument.php
index 65e19b801..57fb67c95 100644
--- a/lib/zipdocument.php
+++ b/lib/zipdocument.php
@@ -178,8 +178,6 @@ private function _make_document($error_html = false) {
 
     /** @return DocumentInfo */
     function create() {
-        global $Now;
-
         if (!empty($this->warnings)) {
             $this->add_as(join("\n", $this->warnings) . "\n", "README-warnings.txt");
         }
@@ -197,7 +195,7 @@ function create() {
             $this->filestore = $dstore_tmp . hash("sha256", $signature, false) . ".zip";
             // maybe zipfile with that signature already exists
             if (file_exists($this->filestore)) {
-                if (@filemtime($this->filestore) < $Now - 21600) {
+                if (@filemtime($this->filestore) < Conf::$now - 21600) {
                     @touch($this->filestore);
                 }
                 return $this->_make_document();
diff --git a/manualassign.php b/manualassign.php
index e61eba208..6fd144dbc 100644
--- a/manualassign.php
+++ b/manualassign.php
@@ -46,7 +46,7 @@
 
 
 function saveAssignments($qreq, $reviewer) {
-    global $Conf, $Me, $Now;
+    global $Conf, $Me;
     $round_number = null;
     $rcid = $reviewer->contactId;
 
diff --git a/profile.php b/profile.php
index 3bc4e51ef..c94f244c2 100644
--- a/profile.php
+++ b/profile.php
@@ -222,7 +222,7 @@ function change_email_by_capability($Qreq) {
 /** @param UserStatus $user_status
  * @param ?Contact $Acct */
 function save_user($cj, $user_status, $Acct, $allow_modification) {
-    global $Conf, $Me, $Now, $newProfile;
+    global $Conf, $Me, $newProfile;
     if ($newProfile) {
         $Acct = null;
     }
@@ -417,7 +417,7 @@ function parseBulkFile($text, $filename) {
         $success = parseBulkFile($Qreq->bulkentry, "");
     }
     if (!$success) {
-        $Me->save_session("profile_bulkentry", array($Now, $Qreq->bulkentry));
+        $Me->save_session("profile_bulkentry", array(Conf::$now, $Qreq->bulkentry));
     }
     $Conf->self_redirect($Qreq, ["anchor" => "bulk"]);
 } else if (isset($Qreq->save)) {
@@ -664,7 +664,7 @@ function parseBulkFile($text, $filename) {
     if ($Qreq->bulkentry === null
         && ($session_bulkentry = $Me->session("profile_bulkentry"))
         && is_array($session_bulkentry)
-        && $session_bulkentry[0] > $Now - 5) {
+        && $session_bulkentry[0] > Conf::$now - 5) {
         $Qreq->bulkentry = $session_bulkentry[1];
         $Me->save_session("profile_bulkentry", null);
     }
diff --git a/review.php b/review.php
index 8afb38fd5..31d31f41b 100644
--- a/review.php
+++ b/review.php
@@ -285,7 +285,7 @@ function download_one_text_review(ReviewInfo $rrow) {
         if ($rrow->reviewModified <= 0) {
             Dbl::qe("update PaperReview set reviewModified=1, timeRequestNotified=greatest(?,timeRequestNotified)
                 where paperId=? and reviewId=? and coalesce(reviewModified,0)<=0",
-                $Now, $prow->paperId, $rrow->reviewId);
+                Conf::$now, $prow->paperId, $rrow->reviewId);
             if ($Me->is_signed_in()) {
                 $rrow->delete_acceptor();
             }
diff --git a/src/api/api_requestreview.php b/src/api/api_requestreview.php
index d9fc1ddb9..c253ee0ae 100644
--- a/src/api/api_requestreview.php
+++ b/src/api/api_requestreview.php
@@ -7,7 +7,6 @@ class RequestReview_API {
      * @param Qrequest $qreq
      * @param PaperInfo $prow */
     static function requestreview($user, $qreq, $prow) {
-        global $Now;
         $round = null;
         if ((string) $qreq->round !== ""
             && ($rname = $user->conf->sanitize_round_name($qreq->round)) !== false) {
@@ -100,7 +99,7 @@ static function requestreview($user, $qreq, $prow) {
               || ($extrev_chairreq === 2 && $potconflict)) {
             $prow->conf->qe("insert into ReviewRequest set paperId=?, email=?, firstName=?, lastName=?, affiliation=?, requestedBy=?, timeRequested=?, reason=?, reviewRound=? on duplicate key update paperId=paperId",
                 $prow->paperId, $email, $xreviewer->firstName, $xreviewer->lastName,
-                $xreviewer->affiliation, $user->contactId, $Now, $reason, $round);
+                $xreviewer->affiliation, $user->contactId, Conf::$now, $reason, $round);
             if ($user->can_administer($prow)) {
                 $msg = "<p>" . $xreviewer->name_h(NAME_E) . " has a potential conflict with this submission, so you must approve this request for it to take effect.</p>"
                     . PaperInfo::potential_conflict_tooltip_html($potconflict);
@@ -178,7 +177,6 @@ static function requestreview_anonymous($user, $qreq, $prow) {
      * @param Qrequest $qreq
      * @param PaperInfo $prow */
     static function denyreview($user, $qreq, $prow) {
-        global $Now;
         if (!$user->allow_administer($prow)) {
             return new JsonResult(403, "Permission error.");
         }
@@ -201,7 +199,7 @@ static function denyreview($user, $qreq, $prow) {
                 $prow->paperId, $email, $reviewer ? $reviewer->contactId : 0,
                 $request->firstName, $request->lastName, $request->affiliation,
                 $request->requestedBy, $request->timeRequested,
-                $user->contactId, $Now, $reason, REVIEW_EXTERNAL,
+                $user->contactId, Conf::$now, $reason, REVIEW_EXTERNAL,
                 $request->reviewRound);
             Dbl::qx_raw("unlock tables");
 
@@ -228,7 +226,6 @@ static function denyreview($user, $qreq, $prow) {
      * @param Qrequest $qreq
      * @param PaperInfo $prow */
     static function declinereview($user, $qreq, $prow) {
-        global $Now;
         $xrrows = $refusals = [];
         $email = trim($qreq->email);
         if ($email === "" || $email === "me") {
@@ -290,7 +287,7 @@ static function declinereview($user, $qreq, $prow) {
                 on duplicate key update reason=coalesce(values(reason),reason)",
                 $prow->paperId, $rrow->email, $rrow->contactId,
                 $rrow->requestedBy, $rrow->timeRequested,
-                $user->contactId, $Now, $reason, $rrow->reviewType,
+                $user->contactId, Conf::$now, $reason, $rrow->reviewType,
                 $rrow->reviewRound, $rrow->data);
             $user->conf->qe("delete from PaperReview where paperId=? and reviewId=?",
                 $prow->paperId, $rrow->reviewId);
@@ -343,7 +340,6 @@ static function declinereview($user, $qreq, $prow) {
      * @param Qrequest $qreq
      * @param PaperInfo $prow */
     static function retractreview($user, $qreq, $prow) {
-        global $Now;
         $xrrows = $xrequests = [];
         $email = trim($qreq->email);
         if ($email === "") {
@@ -424,7 +420,6 @@ static function retractreview($user, $qreq, $prow) {
      * @param Qrequest $qreq
      * @param ?PaperInfo $prow */
     static function undeclinereview($user, $qreq, $prow) {
-        global $Now;
         $refusals = [];
         $email = trim($qreq->email);
         if ($email === "" || $email === "me") {
diff --git a/src/api/api_searchconfig.php b/src/api/api_searchconfig.php
index b50e88eff..956f7928e 100644
--- a/src/api/api_searchconfig.php
+++ b/src/api/api_searchconfig.php
@@ -60,8 +60,6 @@ static function namedformula(Contact $user, Qrequest $qreq) {
     }
 
     static function save_namedformula(Contact $user, Qrequest $qreq) {
-        global $Now;
-
         // capture current formula set
         $new_formula_by_id = $formula_by_id = $user->conf->named_formulas();
         $max_id = array_reduce($formula_by_id, function ($max, $f) {
@@ -161,10 +159,10 @@ static function save_namedformula(Contact $user, Qrequest $qreq) {
                 $fdef = $formula_by_id[$f->formulaId] ?? null;
                 if (!$fdef) {
                     $q[] = "insert into Formula set name=?, expression=?, createdBy=?, timeModified=?";
-                    array_push($qv, $f->name, $f->expression, $user->privChair ? -$user->contactId : $user->contactId, $Now);
+                    array_push($qv, $f->name, $f->expression, $user->privChair ? -$user->contactId : $user->contactId, Conf::$now);
                 } else if ($f->name !== $fdef->name || $f->expression !== $fdef->expression) {
                     $q[] = "update Formula set name=?, expression=?, timeModified=? where formulaId=?";
-                    array_push($qv, $f->name, $f->expression, $Now, $f->formulaId);
+                    array_push($qv, $f->name, $f->expression, Conf::$now, $f->formulaId);
                 }
             }
             if (empty($new_formula_by_id)) {
diff --git a/src/api/api_user.php b/src/api/api_user.php
index 35010dccc..c94f87795 100644
--- a/src/api/api_user.php
+++ b/src/api/api_user.php
@@ -56,7 +56,6 @@ static function user(Contact $user, Qrequest $qreq) {
     }
 
     static function clickthrough(Contact $user, Qrequest $qreq) {
-        global $Now;
         if ($qreq->accept
             && $qreq->clickthrough_id
             && ($hash = Filer::sha1_hash_as_text($qreq->clickthrough_id))) {
@@ -70,7 +69,7 @@ static function clickthrough(Contact $user, Qrequest $qreq) {
                 return new JsonResult(400, "No such user.");
             }
             $dest_user->activate_database_account();
-            $dest_user->merge_and_save_data(["clickthrough" => [$hash => $Now]]);
+            $dest_user->merge_and_save_data(["clickthrough" => [$hash => Conf::$now]]);
             $user->log_activity_for($dest_user, "Terms agreed " . substr($hash, 0, 10) . "...");
             return ["ok" => true];
         } else if ($qreq->clickthrough_accept) {
diff --git a/src/assigners/a_decision.php b/src/assigners/a_decision.php
index 58d1e603b..9d59d5e4e 100644
--- a/src/assigners/a_decision.php
+++ b/src/assigners/a_decision.php
@@ -55,12 +55,11 @@ function apply(PaperInfo $prow, Contact $contact, $req, AssignmentState $state)
             $decyes = 0;
             // accepted papers are always submitted
             if ($dec > 0) {
-                global $Now;
                 Status_AssignmentParser::load_status_state($state);
                 $sm = $state->remove(["type" => "status", "pid" => $prow->paperId]);
                 $sres = $sm[0];
                 if ($sres["_submitted"] === 0) {
-                    $sres["_submitted"] = ($sres["_withdrawn"] > 0 ? -$Now : $Now);
+                    $sres["_submitted"] = ($sres["_withdrawn"] > 0 ? -Conf::$now : Conf::$now);
                 }
                 $state->add($sres);
                 if ($sres["_submitted"] > 0) {
@@ -115,7 +114,6 @@ function add_locks(AssignmentSet $aset, &$locks) {
         $locks["Paper"] = "write";
     }
     function execute(AssignmentSet $aset) {
-        global $Now;
         $dec = $this->item->deleted() ? 0 : $this->item["_decision"];
         $aset->stage_qe("update Paper set outcome=? where paperId=?", $dec, $this->pid);
         if ($dec > 0 || $this->item->pre("_decision") > 0) {
diff --git a/src/assigners/a_status.php b/src/assigners/a_status.php
index a46d820ad..ba75e0d62 100644
--- a/src/assigners/a_status.php
+++ b/src/assigners/a_status.php
@@ -58,7 +58,6 @@ function load_state(AssignmentState $state) {
         Status_AssignmentParser::load_status_state($state);
     }
     function apply(PaperInfo $prow, Contact $contact, $req, AssignmentState $state) {
-        global $Now;
         $m = $state->remove(["type" => "status", "pid" => $prow->paperId]);
         $res = $m[0];
         $ch = false;
@@ -66,7 +65,7 @@ function apply(PaperInfo $prow, Contact $contact, $req, AssignmentState $state)
             if ($res["_submitted"] === 0) {
                 if (($whynot = $state->user->perm_finalize_paper($prow)))
                     return whyNotText($whynot);
-                $res["_submitted"] = ($res["_withdrawn"] > 0 ? -$Now : $Now);
+                $res["_submitted"] = ($res["_withdrawn"] > 0 ? -Conf::$now : Conf::$now);
             }
         } else if ($this->xtype === "unsubmit") {
             if ($res["_submitted"] !== 0) {
@@ -79,7 +78,7 @@ function apply(PaperInfo $prow, Contact $contact, $req, AssignmentState $state)
                 assert($res["_submitted"] >= 0);
                 if (($whynot = $state->user->perm_withdraw_paper($prow)))
                     return whyNotText($whynot);
-                $res["_withdrawn"] = $Now;
+                $res["_withdrawn"] = Conf::$now;
                 $res["_submitted"] = -$res["_submitted"];
                 if ($state->conf->tags()->has_votish) {
                     Tag_AssignmentParser::load_tag_state($state);
@@ -97,7 +96,7 @@ function apply(PaperInfo $prow, Contact $contact, $req, AssignmentState $state)
                     return whyNotText($whynot);
                 $res["_withdrawn"] = 0;
                 if ($res["_submitted"] === -100)
-                    $res["_submitted"] = $Now;
+                    $res["_submitted"] = Conf::$now;
                 else
                     $res["_submitted"] = -$res["_submitted"];
                 $res["_withdraw_reason"] = null;
@@ -147,7 +146,6 @@ function add_locks(AssignmentSet $aset, &$locks) {
         $locks["Paper"] = "write";
     }
     function execute(AssignmentSet $aset) {
-        global $Now;
         $submitted = $this->item["_submitted"];
         $old_submitted = $this->item->pre("_submitted");
         $withdrawn = $this->item["_withdrawn"];
diff --git a/src/assignmentset.php b/src/assignmentset.php
index 8b2307277..217d8d99c 100644
--- a/src/assignmentset.php
+++ b/src/assignmentset.php
@@ -1394,7 +1394,6 @@ private function collect_parser($req) {
     }
 
     private function expand_special_user($user, AssignmentParser $aparser, PaperInfo $prow, $req) {
-        global $Now;
         if ($user === "any") {
             $u = $aparser->expand_any_user($prow, $req, $this->astate);
         } else if ($user === "missing") {
@@ -1785,7 +1784,6 @@ function prow($pid) {
     }
 
     function execute($verbose = false) {
-        global $Now;
         if ($this->has_error() || empty($this->assigners)) {
             if ($verbose && $this->astate->has_messages()) {
                 $this->report_errors();
@@ -1830,7 +1828,7 @@ function execute($verbose = false) {
         $this->conf->qe("unlock tables");
 
         // confirmation message
-        if ($verbose && $this->conf->setting("pcrev_assigntime") == $Now) {
+        if ($verbose && $this->conf->setting("pcrev_assigntime") == Conf::$now) {
             $this->conf->confirmMsg("Assignments saved! You may want to " . $this->conf->hotlink("send mail about the new assignments", "mail", "template=newpcrev") . ".");
         } else if ($verbose) {
             $this->conf->confirmMsg("Assignments saved!");
diff --git a/src/capabilities/cap_reviewaccept.php b/src/capabilities/cap_reviewaccept.php
index a9f2be987..d483f0c4c 100644
--- a/src/capabilities/cap_reviewaccept.php
+++ b/src/capabilities/cap_reviewaccept.php
@@ -4,8 +4,7 @@
 
 class ReviewAccept_Capability {
     private static function make_review_acceptor($user, $at, $pid, $cid, $uf) {
-        global $Now;
-        if ($at && $at >= $Now - 2592000) {
+        if ($at && $at >= Conf::$now - 2592000) {
             $user->set_capability("@ra$pid", $cid);
             if ($user->is_activated()) {
                 ensure_session();
@@ -17,8 +16,6 @@ private static function make_review_acceptor($user, $at, $pid, $cid, $uf) {
     }
 
     static function apply_review_acceptor(Contact $user, $uf, $isadd) {
-        global $Now;
-
         $result = $user->conf->qe("select * from PaperReview where reviewId=?", $uf->match_data[1]);
         $rrow = ReviewInfo::fetch($result, $user->conf);
         Dbl::free($result);
@@ -27,7 +24,7 @@ static function apply_review_acceptor(Contact $user, $uf, $isadd) {
             return;
         }
 
-        $result = $user->conf->qe("select * from PaperReviewRefused where `data` is not null and timeRefused>=?", $Now - 604800);
+        $result = $user->conf->qe("select * from PaperReviewRefused where `data` is not null and timeRefused>=?", Conf::$now - 604800);
         while (($refusal = $result->fetch_object())) {
             $data = json_decode((string) $refusal->data);
             if ($data
diff --git a/src/checkformat.php b/src/checkformat.php
index 92c5c7f43..411c64734 100644
--- a/src/checkformat.php
+++ b/src/checkformat.php
@@ -338,7 +338,6 @@ private function compress_bj($bj) {
     }
 
     function check(CheckFormat $cf, FormatSpec $spec, PaperInfo $prow, $doc) {
-        global $Now;
         $bj = null;
         if (($m = $doc->metadata()) && isset($m->banal)) {
             $bj = $m->banal;
@@ -347,7 +346,7 @@ function check(CheckFormat $cf, FormatSpec $spec, PaperInfo $prow, $doc) {
             && get($bj, "args") == self::$banal_args;
         if (!$bj_ok)
             ++$cf->need_run;
-        if (!$bj_ok || $bj->at < $Now - 86400) {
+        if (!$bj_ok || $bj->at < Conf::$now - 86400) {
             $cf->possible_run = true;
             if ($cf->allow_run == CheckFormat::RUN_YES
                 || (!$bj_ok && $cf->allow_run == CheckFormat::RUN_PREFER_NO))
diff --git a/src/commentinfo.php b/src/commentinfo.php
index 9febb2738..dad9cb6e9 100644
--- a/src/commentinfo.php
+++ b/src/commentinfo.php
@@ -514,7 +514,6 @@ private function save_ordinal($cmtid, $ctype, $Table, $LinkTable, $LinkColumn) {
     }
 
     function save($req, Contact $acting_contact) {
-        global $Now;
         if (is_array($req)) {
             $req = (object) $req;
         }
@@ -622,7 +621,7 @@ function save($req, Contact $acting_contact) {
         } else if (!$this->commentId) {
             $change = true;
             $qa = ["contactId, $LinkColumn, commentType, comment, commentOverflow, timeModified, replyTo"];
-            $qb = [$contact->contactId, $this->prow->$LinkColumn, $ctype, "?", "?", $Now, 0];
+            $qb = [$contact->contactId, $this->prow->$LinkColumn, $ctype, "?", "?", Conf::$now, 0];
             if (strlen($text) <= 32000) {
                 array_push($qv, $text, null);
             } else {
@@ -639,7 +638,7 @@ function save($req, Contact $acting_contact) {
             }
             if ($displayed) {
                 $qa[] = "timeDisplayed, timeNotified";
-                $qb[] = "$Now, $Now";
+                $qb[] = Conf::$now . ", " . Conf::$now;
             }
             $q = "insert into $Table (" . join(", ", $qa) . ") select " . join(", ", $qb) . "\n";
             if ($is_response) {
@@ -652,24 +651,24 @@ function save($req, Contact $acting_contact) {
             }
         } else {
             $change = ($this->commentType >= COMMENTTYPE_AUTHOR) != ($ctype >= COMMENTTYPE_AUTHOR);
-            if ($this->timeModified >= $Now) {
-                $Now = $this->timeModified + 1;
+            if ($this->timeModified >= Conf::$now) {
+                Conf::advance_current_time($this->timeModified);
             }
             // do not notify on updates within 3 hours
             $qa = "";
-            if ($this->timeNotified + 10800 < $Now
+            if ($this->timeNotified + 10800 < Conf::$now
                 || (($ctype & COMMENTTYPE_RESPONSE)
                     && !($ctype & COMMENTTYPE_DRAFT)
                     && ($this->commentType & COMMENTTYPE_DRAFT))) {
-                $qa .= ", timeNotified=$Now";
+                $qa .= ", timeNotified=" . Conf::$now;
             }
             // reset timeDisplayed if you change the comment type
             if ((!$this->timeDisplayed || $this->ordinal_missing($ctype))
                 && ($text !== "" || $docids)
                 && $displayed) {
-                $qa .= ", timeDisplayed=$Now";
+                $qa .= ", timeDisplayed=" . Conf::$now;
             }
-            $q = "update $Table set timeModified=$Now$qa, commentType=$ctype, comment=?, commentOverflow=?, commentTags=? where commentId=$this->commentId";
+            $q = "update $Table set timeModified=" . Conf::$now . $qa . ", commentType=$ctype, comment=?, commentOverflow=?, commentTags=? where commentId=$this->commentId";
             if (strlen($text) <= 32000) {
                 array_push($qv, $text, null);
             } else {
diff --git a/src/conference.php b/src/conference.php
index 0602378ba..2441a303a 100644
--- a/src/conference.php
+++ b/src/conference.php
@@ -50,7 +50,6 @@ class ResponseRound {
     /** @var ?PaperSearch */
     public $search;
     function relevant(Contact $user, PaperInfo $prow = null) {
-        global $Now;
         if ($user->allow_administer($prow)
             && ($this->done || $this->search || $this->name !== "1")) {
             return true;
@@ -58,20 +57,19 @@ function relevant(Contact $user, PaperInfo $prow = null) {
             return $this->open > 0;
         } else {
             return $this->open > 0
-                && $this->open < $Now
+                && $this->open < Conf::$now
                 && (!$this->search || $this->search->filter($prow ? [$prow] : $user->authored_papers()));
         }
     }
     function time_allowed($with_grace) {
-        global $Now;
-        if ($this->open === null || $this->open <= 0 || $this->open > $Now) {
+        if ($this->open === null || $this->open <= 0 || $this->open > Conf::$now) {
             return false;
         }
         $t = $this->done;
         if ($t !== null && $t > 0 && $with_grace && $this->grace) {
             $t += $this->grace;
         }
-        return $t === null || $t <= 0 || $t >= $Now;
+        return $t === null || $t <= 0 || $t >= Conf::$now;
     }
     function instructions(Conf $conf) {
         $m = $conf->_i("resp_instrux_$this->number", false, $this->words);
@@ -243,6 +241,10 @@ class Conf {
 
     /** @var Conf */
     static public $g;
+
+    /** @var int */
+    static public $now;
+
     static public $no_invalidate_caches = false;
     static public $next_xt_subposition = 0;
     static private $xt_require_resolved = [];
@@ -292,14 +294,23 @@ function __construct($options, $make_dsn) {
         }
     }
 
+    /** @param int $t */
+    static function set_current_time($t) {
+        global $Now;
+        $Now = Conf::$now = $t;
+    }
+
+    /** @param int $advance_past */
+    static function advance_current_time($advance_past) {
+        self::set_current_time(max(Conf::$now, $advance_past + 1));
+    }
+
 
     //
     // Initialization functions
     //
 
     function load_settings() {
-        global $Now;
-
         // load settings from database
         $this->settings = array();
         $this->settingTexts = array();
@@ -354,7 +365,7 @@ function load_settings() {
         }
 
         // GC old capabilities
-        if (($this->settings["__capability_gc"] ?? 0) < $Now - 86400) {
+        if (($this->settings["__capability_gc"] ?? 0) < Conf::$now - 86400) {
             $this->cleanup_capabilities();
         }
 
@@ -363,8 +374,6 @@ function load_settings() {
     }
 
     private function crosscheck_settings() {
-        global $Now;
-
         // enforce invariants
         foreach (["pcrev_any", "extrev_view"] as $x) {
             if (!isset($this->settings[$x])) {
@@ -438,9 +447,9 @@ private function crosscheck_settings() {
         $this->_pc_see_pdf = true;
         if (($this->settings["sub_freeze"] ?? 0) <= 0
             && ($so = $this->settings["sub_open"] ?? 0) > 0
-            && $so < $Now
+            && $so < Conf::$now
             && ($ss = $this->settings["sub_sub"] ?? 0) > 0
-            && $ss > $Now
+            && $ss > Conf::$now
             && (($this->settings["pc_seeallpdf"] ?? 0) <= 0
                 || !$this->can_pc_see_active_submissions())) {
             $this->_pc_see_pdf = false;
@@ -684,7 +693,6 @@ function crosscheck_options() {
     }
 
     private function cleanup_capabilities() {
-        global $Now;
         $ctmap = $this->capability_type_map();
         $ct_cleanups = [];
         foreach ($ctmap as $ctj) {
@@ -692,15 +700,15 @@ private function cleanup_capabilities() {
                 $ct_cleanups[] = $ctj->type;
         }
         if (!empty($ct_cleanups)) {
-            $result = $this->ql("select * from Capability where timeExpires>0 and timeExpires<$Now and capabilityType?a", $ct_cleanups);
+            $result = $this->ql("select * from Capability where timeExpires>0 and timeExpires<? and capabilityType?a", Conf::$now, $ct_cleanups);
             while (($cap = CapabilityInfo::fetch($result, $this, false))) {
                 call_user_func($ctmap[$cap->capabilityType]->cleanup_callback, $cap);
             }
             Dbl::free($result);
         }
-        $this->ql("delete from Capability where timeExpires>0 and timeExpires<$Now");
-        $this->ql("insert into Settings set name='__capability_gc', value=$Now on duplicate key update value=values(value)");
-        $this->settings["__capability_gc"] = $Now;
+        $this->ql("delete from Capability where timeExpires>0 and timeExpires<".Conf::$now);
+        $this->ql("insert into Settings set name='__capability_gc', value=".Conf::$now." on duplicate key update value=values(value)");
+        $this->settings["__capability_gc"] = Conf::$now;
     }
 
 
@@ -956,7 +964,6 @@ function docstore() {
 
     /** @return ?S3Client */
     function s3_docstore() {
-        global $Now;
         if ($this->_s3_client === false) {
             if ($this->setting_data("s3_bucket")) {
                 $opts = [
@@ -2844,10 +2851,7 @@ function parseableTime($value, $include_zone) {
         return $d;
     }
     function parse_time($d, $reference = null) {
-        global $Now;
-        if ($reference === null) {
-            $reference = $Now;
-        }
+        $reference = $reference ?? Conf::$now;
         if (!isset($this->opt["dateFormatTimezoneRemover"])) {
             $x = array();
             if (function_exists("timezone_abbreviations_list")) {
@@ -2949,8 +2953,7 @@ function unparse_time_log($timestamp) {
     /** @param int $timestamp
      * @param int $now */
     function unparse_time_relative($timestamp, $now = 0, $format = 0) {
-        global $Now;
-        $d = abs($timestamp - ($now ? : $Now));
+        $d = abs($timestamp - ($now ? : Conf::$now));
         if ($d >= 5227200) {
             if (!($format & 1)) {
                 return ($format & 8 ? "on " : "") . date($this->_dateFormat("obscure"), $timestamp);
@@ -2984,7 +2987,7 @@ function unparse_time_relative($timestamp, $now = 0, $format = 0) {
         if ($format & 2) {
             return $d;
         } else {
-            return $timestamp < ($now ? : $Now) ? $d . " ago" : "in " . $d;
+            return $timestamp < ($now ? : Conf::$now) ? $d . " ago" : "in " . $d;
         }
     }
 
@@ -3000,24 +3003,21 @@ function printableDeadlineSetting($what, $useradjust = false, $preadjust = null)
     }
 
     function settingsAfter($name) {
-        global $Now;
         $t = $this->settings[$name] ?? null;
-        return $t !== null && $t > 0 && $t <= $Now;
+        return $t !== null && $t > 0 && $t <= Conf::$now;
     }
     function deadlinesAfter($name, $grace = null) {
-        global $Now;
         $t = $this->settings[$name] ?? null;
         if ($t !== null && $t > 0 && $grace
             && ($g = $this->settings[$grace] ?? null)) {
             $t += $g;
         }
-        return $t !== null && $t > 0 && $t <= $Now;
+        return $t !== null && $t > 0 && $t <= Conf::$now;
     }
     function deadlinesBetween($name1, $name2, $grace = null) {
         // see also ResponseRound::time_allowed
-        global $Now;
         $t = $this->settings[$name1] ?? null;
-        if (($t === null || $t <= 0 || $t > $Now) && $name1) {
+        if (($t === null || $t <= 0 || $t > Conf::$now) && $name1) {
             return false;
         }
         $t = $this->settings[$name2] ?? null;
@@ -3025,7 +3025,7 @@ function deadlinesBetween($name1, $name2, $grace = null) {
             && ($g = $this->settings[$grace] ?? null)) {
             $t += $g;
         }
-        return $t === null || $t <= 0 || $t >= $Now;
+        return $t === null || $t <= 0 || $t >= Conf::$now;
     }
 
     function timeStartPaper() {
@@ -3058,9 +3058,8 @@ function can_some_author_view_decision() {
         return $this->setting("seedec") == self::SEEDEC_ALL;
     }
     function time_review_open() {
-        global $Now;
         $rev_open = $this->settings["rev_open"] ?? 0;
-        return 0 < $rev_open && $rev_open <= $Now;
+        return 0 < $rev_open && $rev_open <= Conf::$now;
     }
     function review_deadline($round, $isPC, $hard) {
         if ($round === null) {
@@ -3072,14 +3071,13 @@ function review_deadline($round, $isPC, $hard) {
             . ($round ? "_$round" : "");
     }
     function missed_review_deadline($round, $isPC, $hard) {
-        global $Now;
         $rev_open = $this->settings["rev_open"] ?? 0;
-        if (!(0 < $rev_open && $rev_open <= $Now)) {
+        if (!(0 < $rev_open && $rev_open <= Conf::$now)) {
             return "rev_open";
         }
         $dn = $this->review_deadline($round, $isPC, $hard);
         $dv = $this->settings[$dn] ?? 0;
-        if ($dv > 0 && $dv < $Now) {
+        if ($dv > 0 && $dv < Conf::$now) {
             return $dn;
         }
         return false;
@@ -4010,11 +4008,11 @@ function set_cookie($name, $value, $expires_at) {
     }
 
     function header_head($title, $extra = []) {
-        global $Me, $Now, $ConfSitePATH;
+        global $Me;
         // clear session list cookies
         foreach ($_COOKIE as $k => $v) {
             if (str_starts_with($k, "hotlist-info"))
-                $this->set_cookie($k, "", $Now - 86400);
+                $this->set_cookie($k, "", Conf::$now - 86400);
         }
 
         echo "<!DOCTYPE html>
@@ -4159,17 +4157,16 @@ function header_head($title, $extra = []) {
 
     /** @return bool */
     function has_interesting_deadline($my_deadlines) {
-        global $Now;
         if ($my_deadlines->sub->open ?? false) {
             foreach (["reg", "update", "sub"] as $k) {
-                if ($Now <= get($my_deadlines->sub, $k, 0) || get($my_deadlines->sub, "{$k}_ingrace"))
+                if (Conf::$now <= get($my_deadlines->sub, $k, 0) || get($my_deadlines->sub, "{$k}_ingrace"))
                     return true;
             }
         }
         if (($my_deadlines->is_author ?? false)
             && ($my_deadlines->resps ?? false)) {
             foreach ($my_deadlines->resps as $r) {
-                if ($r->open && ($Now <= $r->done || ($r->ingrace ?? false)))
+                if ($r->open && (Conf::$now <= $r->done || ($r->ingrace ?? false)))
                     return true;
             }
         }
@@ -4177,7 +4174,7 @@ function has_interesting_deadline($my_deadlines) {
     }
 
     function header_body($title, $id, $extra = []) {
-        global $Me, $Now;
+        global $Me;
         echo "<body";
         if ($id) {
             echo ' id="body-', $id, '"';
@@ -4195,7 +4192,7 @@ function header_body($title, $id, $extra = []) {
         echo ">\n";
 
         // initial load (JS's timezone offsets are negative of PHP's)
-        Ht::stash_script("hotcrp_load.time(" . (-(int) date("Z", $Now) / 60) . "," . ($this->opt("time24hour") ? 1 : 0) . ")");
+        Ht::stash_script("hotcrp_load.time(" . (-(int) date("Z", Conf::$now) / 60) . "," . ($this->opt("time24hour") ? 1 : 0) . ")");
 
         // deadlines settings
         $my_deadlines = null;
@@ -4323,7 +4320,7 @@ function header_body($title, $id, $extra = []) {
                         $this->msg($t, $m[1]);
                     }
                 }
-                hotcrp_setcookie("hotcrpmessage", "", ["expires" => $Now - 3600]);
+                hotcrp_setcookie("hotcrpmessage", "", ["expires" => Conf::$now - 3600]);
             }
         }
         echo "</div></div>\n";
@@ -4339,7 +4336,7 @@ function header_body($title, $id, $extra = []) {
         if ($Me
             && $Me->privChair
             && (!isset($_SESSION["updatecheck"])
-                || $_SESSION["updatecheck"] + 3600 <= $Now)
+                || $_SESSION["updatecheck"] + 3600 <= Conf::$now)
             && (!isset($this->opt["updatesSite"]) || $this->opt["updatesSite"])) {
             $m = isset($this->opt["updatesSite"]) ? $this->opt["updatesSite"] : "//hotcrp.lcdf.org/updates";
             $m .= (strpos($m, "?") === false ? "?" : "&")
@@ -4360,7 +4357,7 @@ function header_body($title, $id, $extra = []) {
                 }
             }
             Ht::stash_script("check_version(\"$m\",\"$v\")");
-            $_SESSION["updatecheck"] = $Now;
+            $_SESSION["updatecheck"] = Conf::$now;
         }
     }
 
@@ -4598,7 +4595,6 @@ function log_for($user, $dest_user, $text, $pids = null) {
 
     /** @return list<list<string>> */
     private static function format_log_values($text, $user, $dest_user, $true_user, $pids) {
-        global $Now;
         if (empty($pids)) {
             $pids = [null];
         }
@@ -4638,7 +4634,7 @@ private static function format_log_values($text, $user, $dest_user, $true_user,
                 $pid = null;
                 $t = substr($t, 0, 4096);
             }
-            $result[] = [$addr, $user, $dest_user, $true_user, $pid, $Now, $t];
+            $result[] = [$addr, $user, $dest_user, $true_user, $pid, Conf::$now, $t];
             $l = $r;
         }
         return $result;
diff --git a/src/contact.php b/src/contact.php
index a24149317..a31db4c9a 100644
--- a/src/contact.php
+++ b/src/contact.php
@@ -529,7 +529,6 @@ private function actas_user($x) {
 
     /** @return Contact */
     function activate($qreq, $signin = false) {
-        global $Now;
         $this->_activated = true;
 
         // Handle actas requests
@@ -574,8 +573,8 @@ function activate($qreq, $signin = false) {
         if (!self::$true_user && $this->email) {
             $trueuser_aucheck = $this->session("trueuser_author_check", 0);
             if (!$this->has_account_here()
-                && $trueuser_aucheck + 600 < $Now) {
-                $this->save_session("trueuser_author_check", $Now);
+                && $trueuser_aucheck + 600 < Conf::$now) {
+                $this->save_session("trueuser_author_check", Conf::$now);
                 $aupapers = self::email_authored_papers($this->conf, $this->email, $this);
                 if (!empty($aupapers))
                     $this->activate_database_account();
@@ -585,7 +584,7 @@ function activate($qreq, $signin = false) {
                 foreach ($_SESSION as $k => $v) {
                     if (is_array($v)
                         && isset($v["trueuser_author_check"])
-                        && $v["trueuser_author_check"] + 600 < $Now)
+                        && $v["trueuser_author_check"] + 600 < Conf::$now)
                         unset($_SESSION[$k]["trueuser_author_check"]);
                 }
             }
@@ -670,9 +669,8 @@ function contactdb_user($refresh = false) {
     }
 
     private function _contactdb_save_roles($cdbur) {
-        global $Now;
         if (($roles = $this->contactdb_roles())) {
-            Dbl::ql($this->conf->contactdb(), "insert into Roles set contactDbId=?, confid=?, roles=?, activity_at=? on duplicate key update roles=values(roles), activity_at=values(activity_at)", $cdbur->contactDbId, $cdbur->confid, $roles, $Now);
+            Dbl::ql($this->conf->contactdb(), "insert into Roles set contactDbId=?, confid=?, roles=?, activity_at=? on duplicate key update roles=values(roles), activity_at=values(activity_at)", $cdbur->contactDbId, $cdbur->confid, $roles, Conf::$now);
         } else {
             Dbl::ql($this->conf->contactdb(), "delete from Roles where contactDbId=? and confid=? and roles=0", $cdbur->contactDbId, $cdbur->confid);
         }
@@ -1247,7 +1245,7 @@ function apply_capability_text($text) {
 
 
     function escape($qreq = null) {
-        global $Qreq, $Now;
+        global $Qreq;
         $qreq = $qreq ? : $Qreq;
 
         if ($qreq->ajax) {
@@ -1271,7 +1269,7 @@ function escape($qreq = null) {
                 $x["anchor"] = $qreq->anchor;
             }
             $url = $this->conf->selfurl($qreq, $x, Conf::HOTURL_RAW | Conf::HOTURL_SITE_RELATIVE);
-            $_SESSION["login_bounce"] = [$this->conf->dsn, $url, Navigation::page(), $_POST, $Now + 120];
+            $_SESSION["login_bounce"] = [$this->conf->dsn, $url, Navigation::page(), $_POST, Conf::$now + 120];
             if ($qreq->post_ok()) {
                 error_go(false, "You must sign in to access that page. Your changes were not saved; after signing in, you may submit them again.");
             } else {
@@ -1442,7 +1440,6 @@ private function _make_create_updater($reg, $is_cdb) {
     }
 
     function apply_updater($updater, $is_cdb) {
-        global $Now;
         if ($is_cdb) {
             $db = $this->conf->contactdb();
             $idk = "contactDbId";
@@ -1463,10 +1460,10 @@ function apply_updater($updater, $is_cdb) {
             assert(isset($updater["email"]));
             if (!isset($updater["password"])) {
                 $updater["password"] = validate_email($updater["email"]) ? " unset" : " nologin";
-                $updater["passwordTime"] = $Now;
+                $updater["passwordTime"] = Conf::$now;
             }
             if (!$is_cdb) {
-                $updater["creationTime"] = $Now;
+                $updater["creationTime"] = Conf::$now;
             }
             $result = Dbl::qe_apply($db, "insert into ContactInfo set " . join("=?, ", array_keys($updater)) . "=? on duplicate key update firstName=firstName", array_values($updater));
             if ($result->affected_rows) {
@@ -1698,7 +1695,6 @@ private function hash_password($input) {
     /** @param string $input
      * @return array{ok:bool} */
     function check_password_info($input, $options = []) {
-        global $Now;
         assert(!$this->conf->external_login());
         $cdbu = $this->contactdb_user();
 
@@ -1752,7 +1748,7 @@ function check_password_info($input, $options = []) {
                     $x["local_password"] = $this->password;
                 }
                 if ($this->passwordTime > 0) {
-                    $x["local_password_age"] = ceil(($Now - $this->passwordTime) / 8640) / 10;
+                    $x["local_password_age"] = ceil((Conf::$now - $this->passwordTime) / 8640) / 10;
                 }
             }
             if ($cdbu && $cdbu->password) {
@@ -1761,7 +1757,7 @@ function check_password_info($input, $options = []) {
                     $x["cdbu_password"] = $cdbu->password;
                 }
                 if ($cdbu->passwordTime > 0) {
-                    $x["cdb_password_age"] = ceil(($Now - $cdbu->passwordTime) / 8640) / 10;
+                    $x["cdb_password_age"] = ceil((Conf::$now - $cdbu->passwordTime) / 8640) / 10;
                 }
             }
             return $x;
@@ -1785,37 +1781,37 @@ function check_password_info($input, $options = []) {
         // update cdb password
         if ($cdb_ok
             || ($cdbu && (string) $cdbu->password === "")) {
-            $updater = ["passwordUseTime" => $Now];
+            $updater = ["passwordUseTime" => Conf::$now];
             if (!$cdb_ok || $this->password_needs_rehash($cdbu->password)) {
                 $updater["password"] = $this->hash_password($input);
             }
             if (!$cdb_ok || !$cdbu->passwordTime) {
-                $updater["passwordTime"] = $Now;
+                $updater["passwordTime"] = Conf::$now;
             }
             $cdbu->apply_updater($updater, true);
 
             // clear local password
             if ($this->contactId > 0 && (string) $this->password !== "") {
-                $this->apply_updater(["passwordUseTime" => $Now, "password" => "", "passwordTime" => $Now], false);
+                $this->apply_updater(["passwordUseTime" => Conf::$now, "password" => "", "passwordTime" => Conf::$now], false);
                 $local_ok = false;
             }
         }
 
         // update local password
         if ($local_ok) {
-            $updater = ["passwordUseTime" => $Now];
+            $updater = ["passwordUseTime" => Conf::$now];
             if ($this->password_needs_rehash($this->password)) {
                 $updater["password"] = $this->hash_password($input);
             }
             if (!$this->passwordTime) {
-                $updater["passwordTime"] = $Now;
+                $updater["passwordTime"] = Conf::$now;
             }
             $this->apply_updater($updater, false);
 
             // complain about local password use
             if ($cdbu) {
-                $t0 = $this->passwordTime ? ceil(($Now - $this->passwordTime) / 8640) / 10 : -1;
-                $t1 = $cdbu->passwordTime ? ceil(($Now - $cdbu->passwordTime) / 8640) / 10 : -1;
+                $t0 = $this->passwordTime ? ceil((Conf::$now - $this->passwordTime) / 8640) / 10 : -1;
+                $t1 = $cdbu->passwordTime ? ceil((Conf::$now - $cdbu->passwordTime) / 8640) / 10 : -1;
                 error_log("{$this->conf->dbname}: user {$this->email}: signing in with local password, which is " . ($this->passwordTime < $cdbu->passwordTime ? "older" : "newer") . " than cdb [{$t0}d/{$t1}d]");
             }
         }
@@ -1831,13 +1827,12 @@ function check_password($input) {
     }
 
     function change_password($new) {
-        global $Now;
         assert(!$this->conf->external_login());
         assert($new !== null);
 
         if ($new && $new[0] !== " ") {
             $hash = $this->hash_password($new);
-            $use_time = $Now;
+            $use_time = Conf::$now;
         } else {
             $hash = $new;
             $use_time = 0;
@@ -1845,12 +1840,12 @@ function change_password($new) {
 
         $cdbu = $this->contactdb_user();
         if ($cdbu) {
-            $cdbu->apply_updater(["passwordUseTime" => $use_time, "password" => $hash, "passwordTime" => $Now], true);
+            $cdbu->apply_updater(["passwordUseTime" => $use_time, "password" => $hash, "passwordTime" => Conf::$now], true);
             if ($this->contactId && (string) $this->password !== "") {
-                $this->apply_updater(["passwordUseTime" => $use_time, "password" => "", "passwordTime" => $Now], false);
+                $this->apply_updater(["passwordUseTime" => $use_time, "password" => "", "passwordTime" => Conf::$now], false);
             }
         } else if ($this->contactId) {
-            $this->apply_updater(["passwordUseTime" => $use_time, "password" => $hash, "passwordTime" => $Now], false);
+            $this->apply_updater(["passwordUseTime" => $use_time, "password" => $hash, "passwordTime" => Conf::$now], false);
         }
         return true;
     }
@@ -1870,26 +1865,24 @@ function send_mail($template, $rest = []) {
 
 
     function mark_login() {
-        global $Now;
         // at least one login every 30 days is marked as activity
-        if ((int) $this->activity_at <= $Now - 2592000
+        if ((int) $this->activity_at <= Conf::$now - 2592000
             || (($cdbu = $this->contactdb_user())
-                && ((int) $cdbu->activity_at <= $Now - 2592000))) {
+                && ((int) $cdbu->activity_at <= Conf::$now - 2592000))) {
             $this->mark_activity();
         }
     }
 
     function mark_activity() {
-        global $Now;
-        if ((!$this->activity_at || $this->activity_at < $Now)
+        if ((!$this->activity_at || $this->activity_at < Conf::$now)
             && !$this->is_anonymous_user()) {
-            $this->activity_at = $Now;
+            $this->activity_at = Conf::$now;
             if ($this->contactId) {
-                $this->conf->ql("update ContactInfo set lastLogin=$Now where contactId=$this->contactId");
+                $this->conf->ql("update ContactInfo set lastLogin=".Conf::$now." where contactId=$this->contactId");
             }
             if (($cdbu = $this->contactdb_user())
                 && $cdbu->confid
-                && (int) $cdbu->activity_at <= $Now - 604800) {
+                && (int) $cdbu->activity_at <= Conf::$now - 604800) {
                 $this->_contactdb_save_roles($cdbu);
             }
         }
@@ -3762,12 +3755,11 @@ function can_comment(PaperInfo $prow, $crow, $submit = false) {
 
     /** @param ?CommentInfo $crow */
     function can_finalize_comment(PaperInfo $prow, $crow) {
-        global $Now;
         return $crow
             && ($crow->commentType & (COMMENTTYPE_RESPONSE | COMMENTTYPE_DRAFT)) === (COMMENTTYPE_RESPONSE | COMMENTTYPE_DRAFT)
             && ($rrd = get($prow->conf->resp_rounds(), $crow->commentRound))
             && $rrd->open > 0
-            && $rrd->open < $Now
+            && $rrd->open < Conf::$now
             && $prow->conf->setting("resp_active") > 0;
     }
 
@@ -4287,8 +4279,7 @@ function following_reviews(PaperInfo $prow, $watch) {
 
     function my_deadlines($prows = null) {
         // Return cleaned deadline-relevant settings that this user can see.
-        global $Now;
-        $dl = (object) ["now" => $Now, "email" => $this->email ? : null];
+        $dl = (object) ["now" => Conf::$now, "email" => $this->email ? : null];
         if ($this->privChair) {
             $dl->is_admin = true;
         } else if ($this->is_track_manager()) {
@@ -4352,7 +4343,7 @@ function my_deadlines($prows = null) {
         if ($this->conf->setting("final_open") > 0) {
             $dl->final = (object) array("open" => true);
             $final_soft = +$this->conf->setting("final_soft");
-            if ($final_soft > $Now) {
+            if ($final_soft > Conf::$now) {
                 $dl->final->done = $final_soft;
             } else {
                 $dl->final->done = +$this->conf->setting("final_done");
@@ -4366,7 +4357,7 @@ function my_deadlines($prows = null) {
         // reviewer deadlines
         $revtypes = array();
         $rev_open = +$this->conf->setting("rev_open");
-        $rev_open = $rev_open > 0 && $rev_open <= $Now;
+        $rev_open = $rev_open > 0 && $rev_open <= Conf::$now;
         if ($this->is_reviewer() && $rev_open) {
             $dl->rev = (object) ["open" => true];
         } else if ($this->privChair) {
@@ -4383,7 +4374,7 @@ function my_deadlines($prows = null) {
                 if ($rev_open) {
                     $dlround->open = true;
                 }
-                if ($h && ($h < $Now || $s < $Now)) {
+                if ($h && ($h < Conf::$now || $s < Conf::$now)) {
                     $dlround->done = $h;
                     $dlround->ishard = true;
                 } else if ($s) {
@@ -4405,8 +4396,8 @@ function my_deadlines($prows = null) {
             $dlx = $graces[$i];
             foreach ($graces[$i + 2] as $k) {
                 if ($dlx->$k
-                    && $dlx->$k - 30 < $Now
-                    && $dlx->$k + $graces[$i + 1] >= $Now) {
+                    && $dlx->$k - 30 < Conf::$now
+                    && $dlx->$k + $graces[$i + 1] >= Conf::$now) {
                     $kgrace = "{$k}_ingrace";
                     $dlx->$kgrace = true;
                 }
@@ -4491,18 +4482,17 @@ function my_deadlines($prows = null) {
     }
 
     function has_reportable_deadline() {
-        global $Now;
         $dl = $this->my_deadlines();
         if (isset($dl->sub->reg) || isset($dl->sub->update) || isset($dl->sub->sub)) {
             return true;
         }
         if (isset($dl->resps)) {
             foreach ($dl->resps as $dlr) {
-                if (isset($dlr->open) && $dlr->open < $Now && ($dlr->done ?? null))
+                if (isset($dlr->open) && $dlr->open < Conf::$now && ($dlr->done ?? null))
                     return true;
             }
         }
-        if (isset($dl->rev) && isset($dl->rev->open) && $dl->rev->open < $Now) {
+        if (isset($dl->rev) && isset($dl->rev->open) && $dl->rev->open < Conf::$now) {
             foreach ($dl->revs as $dlr) {
                 if ($dlr->done ?? null)
                     return true;
@@ -4572,7 +4562,6 @@ private function assign_review_explanation($type, $round) {
      * @param int $reviewer_cid
      * @param int $type */
     function assign_review($pid, $reviewer_cid, $type, $extra = []) {
-        global $Now;
         $result = $this->conf->qe("select reviewId, reviewType, reviewRound, reviewModified, reviewToken, requestedBy, reviewSubmitted from PaperReview where paperId=? and contactId=?", $pid, $reviewer_cid);
         $rrow = $result->fetch_object();
         Dbl::free($result);
@@ -4603,7 +4592,7 @@ function assign_review($pid, $reviewer_cid, $type, $extra = []) {
         if ($type && !$oldtype) {
             $qa = "";
             if ($extra["mark_notify"] ?? null) {
-                $qa .= ", timeRequestNotified=$Now";
+                $qa .= ", timeRequestNotified=" . Conf::$now;
             }
             if ($extra["token"] ?? null) {
                 $qa .= $this->unassigned_review_token();
@@ -4611,7 +4600,7 @@ function assign_review($pid, $reviewer_cid, $type, $extra = []) {
             if (($new_requester = $extra["requester_contact"] ?? null)) {
                 $new_requester_cid = $new_requester->contactId;
             }
-            $q = "insert into PaperReview set paperId=$pid, contactId=$reviewer_cid, reviewType=$type, reviewRound=$round, timeRequested=$Now$qa, requestedBy=$new_requester_cid";
+            $q = "insert into PaperReview set paperId=$pid, contactId=$reviewer_cid, reviewType=$type, reviewRound=$round, timeRequested=".Conf::$now."$qa, requestedBy=$new_requester_cid";
         } else if ($type && ($oldtype != $type || $rrow->reviewRound != $round)) {
             $q = "update PaperReview set reviewType=$type, reviewRound=$round";
             if (!$rrow->reviewSubmitted)
@@ -4649,8 +4638,8 @@ function assign_review($pid, $reviewer_cid, $type, $extra = []) {
                 $this->update_review_delegation($pid, $new_requester_cid, 1);
             }
             if ($type >= REVIEW_PC
-                && $this->conf->setting("pcrev_assigntime", 0) < $Now) {
-                $this->conf->save_setting("pcrev_assigntime", $Now);
+                && $this->conf->setting("pcrev_assigntime", 0) < Conf::$now) {
+                $this->conf->save_setting("pcrev_assigntime", Conf::$now);
             }
         } else if (!$type) {
             if ($oldtype < REVIEW_SECONDARY && $rrow->requestedBy > 0) {
diff --git a/src/formula.php b/src/formula.php
index 4291438e1..76793bc5d 100644
--- a/src/formula.php
+++ b/src/formula.php
@@ -1050,10 +1050,7 @@ function _add_tags() {
         return '$tags';
     }
     function _add_now() {
-        if ($this->check_gvar('$now')) {
-            $this->gstmt[] = "global \$Now;";
-        }
-        return '$Now';
+        return 'Conf::$now';
     }
 
     function loop_cid($aggregate = false) {
diff --git a/src/helpers.php b/src/helpers.php
index e7a81c4ce..dd32b24c8 100644
--- a/src/helpers.php
+++ b/src/helpers.php
@@ -457,7 +457,7 @@ function filter_whynot($whyNot, $keys) {
 
 /** @param array{conf:Conf,paperId?:int,reviewId?:int,option?:PaperOption} $whyNot */
 function whyNotText($whyNot, $text_only = false) {
-    global $Conf, $Now;
+    global $Conf;
     if (is_string($whyNot)) {
         $whyNot = array($whyNot => 1);
     }
@@ -569,9 +569,9 @@ function whyNotText($whyNot, $text_only = false) {
             }
         } else if ($start <= 0 || $start == $end) {
             $ms[] = $conf->_c("etime", "Action not available.", $open_dname, $paperId);
-        } else if ($start > 0 && $Now < $start) {
+        } else if ($start > 0 && Conf::$now < $start) {
             $ms[] = $conf->_c("etime", "Action not available until %3\$s.", $open_dname, $paperId, $conf->unparse_time($start));
-        } else if ($end > 0 && $Now > $end) {
+        } else if ($end > 0 && Conf::$now > $end) {
             $ms[] = $conf->_c("etime", "Deadline passed.", $dname, $paperId, $conf->unparse_time($end));
         } else {
             $ms[] = $conf->_c("etime", "Action not available.", $dname, $paperId);
diff --git a/src/init.php b/src/init.php
index 0ce04e721..43e83ed9c 100644
--- a/src/init.php
+++ b/src/init.php
@@ -62,7 +62,6 @@
 define("TAG_INDEXBOUND", 2147483646);
 
 global $Now, $ConfSitePATH;
-$Now = time();
 
 require_once(SiteLoader::find("lib/navigation.php"));
 require_once(SiteLoader::find("lib/polyfills.php"));
@@ -72,6 +71,7 @@
 require_once(SiteLoader::find("src/helpers.php"));
 require_once(SiteLoader::find("src/conference.php"));
 require_once(SiteLoader::find("src/contact.php"));
+Conf::set_current_time(time());
 
 
 // Set locale to C (so that, e.g., strtolower() on UTF-8 data doesn't explode)
diff --git a/src/initweb.php b/src/initweb.php
index b5c621143..0a301e37c 100644
--- a/src/initweb.php
+++ b/src/initweb.php
@@ -69,7 +69,7 @@ function initialize_user_redirect($nav, $uindex, $nusers) {
 }
 
 function initialize_user() {
-    global $Conf, $Me, $Now, $Qreq;
+    global $Conf, $Me, $Qreq;
     $nav = Navigation::get();
 
     // set up session
@@ -155,7 +155,7 @@ function initialize_user() {
 
     // if bounced through login, add post data
     if (isset($_SESSION["login_bounce"][4])
-        && $_SESSION["login_bounce"][4] <= $Now) {
+        && $_SESSION["login_bounce"][4] <= Conf::$now) {
         unset($_SESSION["login_bounce"]);
     }
 
diff --git a/src/mailclasses.php b/src/mailclasses.php
index 29a733909..306072a19 100644
--- a/src/mailclasses.php
+++ b/src/mailclasses.php
@@ -25,7 +25,6 @@ private function defsel($name, $description, $flags = 0) {
     }
 
     function __construct($contact, $type, $papersel, $newrev_since) {
-        global $Now;
         $this->conf = $contact->conf;
         $this->contact = $contact;
         assert(!!$contact->isPC);
@@ -158,7 +157,7 @@ function __construct($contact, $type, $papersel, $newrev_since) {
             if (preg_match(',\A(?:|n/a|\(?all\)?|0)\z,i', $t)) {
                 $this->newrev_since = 0;
             } else if (($this->newrev_since = $this->conf->parse_time($t)) !== false) {
-                if ($this->newrev_since > $Now) {
+                if ($this->newrev_since > Conf::$now) {
                     $this->conf->warnMsg("That time is in the future.");
                 }
             } else {
diff --git a/src/meetingtracker.php b/src/meetingtracker.php
index d525c2034..989ec5630 100644
--- a/src/meetingtracker.php
+++ b/src/meetingtracker.php
@@ -4,10 +4,9 @@
 
 class MeetingTracker {
     static function lookup(Conf $conf) {
-        global $Now;
         $tracker = $conf->setting_json("tracker");
         if ($tracker
-            && (!$tracker->trackerid || $tracker->update_at >= $Now - 150)) {
+            && (!$tracker->trackerid || $tracker->update_at >= Conf::$now - 150)) {
             return $tracker;
         } else {
             $when = $tracker ? $tracker->update_at + 0.1 : 0;
@@ -16,11 +15,10 @@ static function lookup(Conf $conf) {
     }
 
     static function expand($tracker) {
-        global $Now;
         if (isset($tracker->ts)) {
             $ts = [];
             foreach ($tracker->ts as $tr) {
-                if ($tr->update_at >= $Now - 150)
+                if ($tr->update_at >= Conf::$now - 150)
                     $ts[] = $tr;
             }
             return $ts;
@@ -65,8 +63,6 @@ static function session_owns_tracker(Conf $conf) {
 
 
     static function contact_tracker_comet(Conf $conf, $pids = null) {
-        global $Now;
-
         $comet_dir = $conf->opt("trackerCometUpdateDirectory");
         $comet_url = $conf->opt("trackerCometSite");
         if (!$comet_dir && !$comet_url) {
@@ -90,7 +86,7 @@ static function contact_tracker_comet(Conf $conf, $pids = null) {
             }
             $suffix = "";
             $count = 0;
-            while (($f = @fopen($comet_dir . $Now . $suffix, "x")) === false
+            while (($f = @fopen($comet_dir . Conf::$now . $suffix, "x")) === false
                    && $count < 20) {
                 $suffix = "x" . mt_rand(0, 65535);
                 ++$count;
@@ -225,7 +221,6 @@ static private function compute_default_visibility(Contact $user, $admin_perm) {
 
     static private function tracker_new(Contact $user, $trackerid, $xlist,
                                         $start_at, $position, $position_at) {
-        global $Now;
         if ($xlist instanceof SessionList) {
             $url = $xlist->full_site_relative_url();
         } else {
@@ -239,7 +234,7 @@ static private function tracker_new(Contact $user, $trackerid, $xlist,
             "description" => $xlist->description,
             "start_at" => $start_at,
             "position_at" => $position_at,
-            "update_at" => max($Now, $position_at),
+            "update_at" => max(Conf::$now, $position_at),
             "owner" => $user->contactId,
             "sessionid" => session_id(),
             "position" => $position
@@ -247,7 +242,6 @@ static private function tracker_new(Contact $user, $trackerid, $xlist,
     }
 
     static private function tracker_save(Conf $conf, $trs, $tracker, $position_at) {
-        global $Now;
         if (empty($trs)) {
             $tracker = (object) [
                 "trackerid" => false,
@@ -263,7 +257,7 @@ static private function tracker_save(Conf $conf, $trs, $tracker, $position_at) {
             $tracker = (object) [
                 "trackerid" => $tracker->trackerid,
                 "position_at" => $position_at,
-                "update_at" => max($Now, $position_at),
+                "update_at" => max(Conf::$now, $position_at),
                 "ts" => $trs
             ];
         }
@@ -275,7 +269,6 @@ static function track_api(Contact $user, $qreq) {
         // NB: This is a special API function; it should either return nothing
         // (in which case the result of a `status` api call is returned),
         // or call `json_exit` on error.
-        global $Now;
 
         // track="IDENTIFIER POSITION" or track="IDENTIFIER stop" or track=stop
         if (!$user->is_track_manager() || !$qreq->post_ok()) {
@@ -378,7 +371,7 @@ static function track_api(Contact $user, $qreq) {
                     $position_at = $trs[$match]->position_at;
                 }
             } else {
-                $start_at = $Now;
+                $start_at = Conf::$now;
             }
 
             ensure_session();
@@ -414,8 +407,6 @@ static function track_api(Contact $user, $qreq) {
     }
 
     static function trackerconfig_api(Contact $user, $qreq) {
-        global $Now;
-
         if (!$user->is_track_manager() || !$qreq->post_ok()) {
             return json_exit(403, "Permission error.");
         }
@@ -514,7 +505,7 @@ static function trackerconfig_api(Contact $user, $qreq) {
                         $new_trackerid = mt_rand(1, 9999999);
                     } while (self::tracker_search($new_trackerid, $trs) !== false);
 
-                    $tr = self::tracker_new($user, $new_trackerid, $xlist, $Now, $position, $position_at);
+                    $tr = self::tracker_new($user, $new_trackerid, $xlist, Conf::$now, $position, $position_at);
                     if ($name !== "") {
                         $tr->name = $name;
                     }
@@ -595,7 +586,6 @@ static function trackerconfig_api(Contact $user, $qreq) {
 
 
     static private function trinfo($tr, Contact $user) {
-        global $Now;
         $ti = (object) [
             "trackerid" => $tr->trackerid,
             "listid" => $tr->listid,
@@ -603,7 +593,7 @@ static private function trinfo($tr, Contact $user) {
             "start_at" => $tr->start_at,
             "position_at" => $tr->position_at,
             "url" => $tr->url,
-            "calculated_at" => $Now,
+            "calculated_at" => Conf::$now,
             "listinfo" => json_encode_browser([
                 "listid" => $tr->listid,
                 "ids" => SessionList::encode_ids($tr->ids),
@@ -732,7 +722,6 @@ static private function trinfo_papers($tis, $trs, Contact $user) {
     }
 
     static function my_deadlines($dl, Contact $user) {
-        global $Now;
         $tracker = self::lookup($user->conf);
         if ($tracker->trackerid && $user->can_view_tracker()) {
             $tis = $trs = [];
diff --git a/src/papercolumns/pc_reviewdelegation.php b/src/papercolumns/pc_reviewdelegation.php
index a51a22d3e..abdb426b2 100644
--- a/src/papercolumns/pc_reviewdelegation.php
+++ b/src/papercolumns/pc_reviewdelegation.php
@@ -16,7 +16,6 @@ function prepare(PaperList $pl, $visible) {
         return true;
     }
     function content(PaperList $pl, PaperInfo $row) {
-        global $Now;
         $rx = [];
         $row->ensure_reviewer_names();
         $old_overrides = $pl->user->add_overrides(Contact::OVERRIDE_CONFLICT);
diff --git a/src/paperstatus.php b/src/paperstatus.php
index a23af723c..147970504 100644
--- a/src/paperstatus.php
+++ b/src/paperstatus.php
@@ -596,7 +596,6 @@ private function valid_contact($email) {
 
     private function normalize($pj) {
         // Errors prevent saving
-        global $Now;
 
         // Authors
         $au_by_lemail = [];
@@ -648,12 +647,12 @@ private function normalize($pj) {
                 if (is_numeric($pj->$k)) {
                     $pj->$k = (int) $pj->$k;
                 } else if (is_string($pj->$k)) {
-                    $pj->$k = $this->conf->parse_time($pj->$k, $Now);
+                    $pj->$k = $this->conf->parse_time($pj->$k, Conf::$now);
                 } else {
                     $pj->$k = false;
                 }
                 if ($pj->$k === false || $pj->$k < 0) {
-                    $pj->$k = $Now;
+                    $pj->$k = Conf::$now;
                 }
             }
         }
@@ -853,7 +852,6 @@ static function check_one_pdf(PaperOption $opt, PaperStatus $ps, $pj) {
     }
 
     static function check_status(PaperStatus $ps, $pj) {
-        global $Now;
         $pj_withdrawn = get($pj, "withdrawn");
         $pj_submitted = get($pj, "submitted");
         $pj_draft = get($pj, "draft");
@@ -883,7 +881,7 @@ static function check_status(PaperStatus $ps, $pj) {
                 $submitted_at = -$submitted_at;
             }
             if (!$ps->prow || $ps->prow->timeWithdrawn <= 0) {
-                $ps->save_paperf("timeWithdrawn", get($pj, "withdrawn_at") ? : $Now);
+                $ps->save_paperf("timeWithdrawn", get($pj, "withdrawn_at") ? : Conf::$now);
                 $ps->save_paperf("timeSubmitted", $submitted_at);
                 $ps->mark_diff("status");
             } else if (($ps->prow->submitted_at() > 0) !== $pj_submitted) {
@@ -894,7 +892,7 @@ static function check_status(PaperStatus $ps, $pj) {
             if (!$ps->prow || $ps->prow->timeSubmitted <= 0) {
                 if ($submitted_at <= 0
                     || $submitted_at === PaperInfo::SUBMITTED_AT_FOR_WITHDRAWN) {
-                    $submitted_at = $Now;
+                    $submitted_at = Conf::$now;
                 }
                 $ps->save_paperf("timeSubmitted", $submitted_at);
                 $ps->mark_diff("status");
@@ -912,10 +910,9 @@ static function check_status(PaperStatus $ps, $pj) {
     }
 
     static function check_final_status(PaperStatus $ps, $pj) {
-        global $Now;
         if (isset($pj->final_submitted)) {
             if ($pj->final_submitted) {
-                $time = get($pj, "final_submitted_at") ? : $Now;
+                $time = get($pj, "final_submitted_at") ? : Conf::$now;
             } else {
                 $time = 0;
             }
@@ -1371,7 +1368,6 @@ static function postexecute_check_required_options(PaperStatus $ps) {
     }
 
     function execute_save() {
-        global $Now;
         $dataOverflow = $this->prow ? $this->prow->dataOverflow : null;
         if (!empty($this->_paper_overflow_upd)) {
             $dataOverflow = $dataOverflow ?? [];
@@ -1436,7 +1432,7 @@ function execute_save() {
                 }
             }
 
-            $this->save_paperf("timeModified", $Now);
+            $this->save_paperf("timeModified", Conf::$now);
 
             if (!$need_insert) {
                 $qv = array_values($this->_paper_upd);
diff --git a/src/papertable.php b/src/papertable.php
index 1f47f1b6f..8f8592016 100644
--- a/src/papertable.php
+++ b/src/papertable.php
@@ -2014,11 +2014,10 @@ private function papstripWatch() {
     // Functions for editing
 
     function deadline_setting_is($dname, $dl = "deadline") {
-        global $Now;
         $deadline = $this->conf->printableTimeSetting($dname, "span");
         if ($deadline === "N/A") {
             return "";
-        } else if ($Now < $this->conf->setting($dname)) {
+        } else if (Conf::$now < $this->conf->setting($dname)) {
             return " The $dl is $deadline.";
         } else {
             return " The $dl was $deadline.";
@@ -2041,11 +2040,10 @@ private function _forceShow_message() {
     }
 
     private function _edit_message_new_paper() {
-        global $Now;
         $msg = "";
         if (!$this->conf->timeStartPaper()) {
             $sub_open = $this->conf->setting("sub_open");
-            if ($sub_open <= 0 || $sub_open > $Now) {
+            if ($sub_open <= 0 || $sub_open > Conf::$now) {
                 $msg = "The site is not open for submissions." . $this->_deadline_override_message();
             } else {
                 $msg = 'The <a href="' . $this->conf->hoturl("deadlines") . '">deadline</a> for registering submissions has passed.' . $this->deadline_setting_is("sub_reg") . $this->_deadline_override_message();
@@ -2382,13 +2380,13 @@ private function _paptabBeginKnown() {
     }
 
     static private function _echo_clickthrough($ctype) {
-        global $Conf, $Now;
+        global $Conf;
         $data = $Conf->_i("clickthrough_$ctype");
         $buttons = [Ht::submit("Agree", ["class" => "btnbig btn-success ui js-clickthrough"])];
         echo Ht::form("", ["class" => "ui"]), '<div>', $data,
             Ht::hidden("clickthrough_type", $ctype),
             Ht::hidden("clickthrough_id", sha1($data)),
-            Ht::hidden("clickthrough_time", $Now),
+            Ht::hidden("clickthrough_time", Conf::$now),
             Ht::actions($buttons, ["class" => "aab aabig aabr"]), "</div></form>";
     }
 
diff --git a/src/partials/p_signin.php b/src/partials/p_signin.php
index cc5156d1d..fd68fe4a2 100644
--- a/src/partials/p_signin.php
+++ b/src/partials/p_signin.php
@@ -96,10 +96,9 @@ static function render_signin_head(Contact $user, Qrequest $qreq, $gx) {
     }
 
     static function render_signin_form(Contact $user, Qrequest $qreq, $gx) {
-        global $Now;
         $conf = $user->conf;
         if (($password_reset = $user->session("password_reset"))) {
-            if ($password_reset->time < $Now - 900) {
+            if ($password_reset->time < Conf::$now - 900) {
                 $user->save_session("password_reset", null);
             } else if (!isset($qreq->email)) {
                 $qreq->email = $password_reset->email;
@@ -383,7 +382,6 @@ function render_forgot_form_actions() {
 
     // Password reset
     function reset_request(Contact $user, Qrequest $qreq) {
-        global $Now;
         ensure_session();
         $conf = $user->conf;
         if ($qreq->cancel) {
@@ -456,7 +454,9 @@ function reset_request(Contact $user, Qrequest $qreq) {
                 $conf->msg("Password changed. Use the new password to sign in below.", "xconfirm");
                 $this->_reset_capdata->delete();
                 $user->save_session("password_reset", (object) [
-                    "time" => $Now, "email" => $this->_reset_user->email, "password" => $p1
+                    "time" => Conf::$now,
+                    "email" => $this->_reset_user->email,
+                    "password" => $p1
                 ]);
                 Navigation::redirect($conf->hoturl("signin"));
             }
diff --git a/src/review.php b/src/review.php
index 4fd0683d3..1292cff9b 100644
--- a/src/review.php
+++ b/src/review.php
@@ -794,14 +794,13 @@ static function update_review_author_seen() {
 
     static private function check_review_author_seen($prow, $rrow, $contact,
                                                      $no_update = false) {
-        global $Now;
         if ($rrow
             && !$rrow->reviewAuthorSeen
             && $contact->act_author_view($prow)
             && !$contact->is_actas_user()) {
             // XXX combination of review tokens & authorship gets weird
             assert($rrow->reviewAuthorModified > 0);
-            $rrow->reviewAuthorSeen = $Now;
+            $rrow->reviewAuthorSeen = Conf::$now;
             if (!$no_update) {
                 if (!self::$review_author_seen) {
                     register_shutdown_function("ReviewForm::update_review_author_seen");
diff --git a/src/reviewinfo.php b/src/reviewinfo.php
index 34c96f1ce..a76b9d038 100644
--- a/src/reviewinfo.php
+++ b/src/reviewinfo.php
@@ -446,13 +446,12 @@ private function _save_data() {
     }
 
     function acceptor() {
-        global $Now;
         if ($this->_data === null) {
             $this->_load_data();
         }
         if (!isset($this->_data->acceptor)) {
             $text = base48_encode(random_bytes(10));
-            $this->_data->acceptor = (object) ["text" => $text, "at" => $Now];
+            $this->_data->acceptor = (object) ["text" => $text, "at" => Conf::$now];
             $this->_save_data();
         }
         return $this->_data->acceptor;
diff --git a/src/sessionlist.php b/src/sessionlist.php
index 9cf0c49bc..15a437423 100644
--- a/src/sessionlist.php
+++ b/src/sessionlist.php
@@ -318,9 +318,8 @@ static function load_cookie(Contact $user, $type) {
     }
 
     function set_cookie(Contact $user) {
-        global $Now;
         $t = round(microtime(true) * 1000);
-        $user->conf->set_cookie("hotlist-info-" . $t, $this->info_string(), $Now + 20);
+        $user->conf->set_cookie("hotlist-info-" . $t, $this->info_string(), Conf::$now + 20);
     }
 
     /** @param int $id */
diff --git a/src/settings/s_decisionvisibility.php b/src/settings/s_decisionvisibility.php
index ea56cf146..bd91e3f56 100644
--- a/src/settings/s_decisionvisibility.php
+++ b/src/settings/s_decisionvisibility.php
@@ -20,8 +20,6 @@ static function render(SettingValues $sv) {
     }
 
     static function crosscheck(SettingValues $sv) {
-        global $Now;
-
         if ($sv->has_interest("seedec")
             && $sv->newv("seedec") == Conf::SEEDEC_ALL
             && $sv->newv("au_seerev") == Conf::AUSEEREV_NO) {
@@ -30,7 +28,7 @@ static function crosscheck(SettingValues $sv) {
 
         if (($sv->has_interest("seedec") || $sv->has_interest("sub_sub"))
             && $sv->newv("sub_open")
-            && $sv->newv("sub_sub") > $Now
+            && $sv->newv("sub_sub") > Conf::$now
             && $sv->newv("seedec") != Conf::SEEDEC_ALL
             && $sv->conf->fetch_value("select paperId from Paper where outcome<0 limit 1") > 0) {
             $sv->warning_at(null, "Updates will not be allowed for rejected submissions. This exposes decision information that would otherwise be hidden from authors.");
diff --git a/src/settings/s_finalversions.php b/src/settings/s_finalversions.php
index b9d4ead92..180b49bf3 100644
--- a/src/settings/s_finalversions.php
+++ b/src/settings/s_finalversions.php
@@ -20,11 +20,10 @@ static function render(SettingValues $sv) {
     }
 
     static function crosscheck(SettingValues $sv) {
-        global $Now;
         if ($sv->has_interest("final_open")
             && $sv->newv("final_open")
             && ($sv->newv("final_soft") || $sv->newv("final_done"))
-            && (!$sv->newv("final_done") || $sv->newv("final_done") > $Now)
+            && (!$sv->newv("final_done") || $sv->newv("final_done") > Conf::$now)
             && $sv->newv("seedec") != Conf::SEEDEC_ALL) {
             $sv->warning_at(null, "The system is set to collect final versions, but authors cannot submit final versions until they can see decisions. You may want to update the " . $sv->setting_link("“Who can see decisions” setting", "seedec") . ".");
         }
diff --git a/src/settings/s_reviewform.php b/src/settings/s_reviewform.php
index 50f43d1a6..28cefc869 100644
--- a/src/settings/s_reviewform.php
+++ b/src/settings/s_reviewform.php
@@ -295,7 +295,6 @@ private function clear_nonexisting_options($fields, Conf $conf) {
     }
 
     function save(SettingValues $sv, Si $si) {
-        global $Now;
         if (!$sv->update("review_form", json_encode_db($this->nrfj))) {
             return;
         }
@@ -363,7 +362,7 @@ function save(SettingValues $sv, Si $si) {
                     }
                     $max_ordinal = $sv->conf->fetch_ivalue("select coalesce(max(reviewOrdinal), 0) from PaperReview where paperId=? group by paperId", $rrow->paperId);
                     if ($max_ordinal !== null) {
-                        $sv->conf->qe("update PaperReview set reviewOrdinal=?, timeDisplayed=? where paperId=? and reviewId=?", $max_ordinal + 1, $Now, $rrow->paperId, $rrow->reviewId);
+                        $sv->conf->qe("update PaperReview set reviewOrdinal=?, timeDisplayed=? where paperId=? and reviewId=?", $max_ordinal + 1, Conf::$now, $rrow->paperId, $rrow->reviewId);
                     }
                 }
             }
diff --git a/src/settings/s_reviews.php b/src/settings/s_reviews.php
index 3172f255b..0a0d321d6 100644
--- a/src/settings/s_reviews.php
+++ b/src/settings/s_reviews.php
@@ -266,13 +266,12 @@ static function render_ratings(SettingValues $sv) {
     }
 
     static function crosscheck(SettingValues $sv) {
-        global $Now;
         $errored = false;
         foreach ($sv->conf->round_list() as $i => $rname) {
             $suf = $i ? "_$i" : "";
             foreach (Conf::$review_deadlines as $deadline) {
                 if ($sv->has_interest($deadline . $suf)
-                    && $sv->newv($deadline . $suf) > $Now
+                    && $sv->newv($deadline . $suf) > Conf::$now
                     && $sv->newv("rev_open") <= 0
                     && !$errored) {
                     $sv->warning_at("rev_open", "A review deadline is set in the future, but the site is not open for reviewing. This is sometimes unintentional.");
@@ -286,7 +285,7 @@ static function crosscheck(SettingValues $sv) {
             && $sv->newv("au_seerev") != Conf::AUSEEREV_NO
             && $sv->newv("au_seerev") != Conf::AUSEEREV_TAGS
             && $sv->newv("pcrev_soft") > 0
-            && $Now < $sv->newv("pcrev_soft")
+            && Conf::$now < $sv->newv("pcrev_soft")
             && !$sv->has_error()) {
             $sv->warning_at(null, "Authors can see reviews and comments although it is before the review deadline. This is sometimes unintentional.");
         }
diff --git a/src/settings/s_subform.php b/src/settings/s_subform.php
index 6e37bc64a..95f61f8be 100644
--- a/src/settings/s_subform.php
+++ b/src/settings/s_subform.php
@@ -68,7 +68,6 @@ static private function check_banal($sv) {
         }
     }
     static function parse($suffix, $sv, $check) {
-        global $Now;
         if (!$sv->has_reqv("sub_banal$suffix")) {
             $fs = new FormatSpec($sv->newv("sub_banal_opt$suffix"));
             $sv->save("sub_banal$suffix", $fs->is_banal_empty() ? 0 : -1);
@@ -208,7 +207,7 @@ static function parse($suffix, $sv, $check) {
             $unparse = "";
         $sv->save("sub_banal_data$suffix", $unparse);
         if ($old_unparse !== $unparse || $sv->oldv("sub_banal$suffix") <= 0) {
-            $sv->save("sub_banal$suffix", $unparse !== "" ? $Now : 0);
+            $sv->save("sub_banal$suffix", $unparse !== "" ? Conf::$now : 0);
         } else {
             $sv->save("sub_banal$suffix", $unparse === "" ? 0 : $sv->oldv("sub_banal$suffix"));
         }
diff --git a/src/settings/s_submissions.php b/src/settings/s_submissions.php
index 74826a62f..ba8686f93 100644
--- a/src/settings/s_submissions.php
+++ b/src/settings/s_submissions.php
@@ -46,13 +46,12 @@ static function crosscheck(SettingValues $sv) {
 
 class Submissions_SettingParser extends SettingParser {
     function validate(SettingValues $sv, Si $si) {
-        global $Now;
         $d1 = $sv->newv($si->name);
         if ($si->name === "sub_open") {
             if ($d1 <= 0
                 && $sv->oldv("sub_open") > 0
                 && $sv->newv("sub_sub") <= 0) {
-                $sv->save("sub_close", $Now);
+                $sv->save("sub_close", Conf::$now);
             }
         } else if ($si->name === "sub_sub") {
             $sv->check_date_before("sub_reg", "sub_sub", true);
diff --git a/src/settingvalues.php b/src/settingvalues.php
index f8d7d6b78..4f748f33b 100644
--- a/src/settingvalues.php
+++ b/src/settingvalues.php
@@ -1204,8 +1204,6 @@ function setting_link($html, $si, $js = null) {
 
 
     function parse_value(Si $si) {
-        global $Now;
-
         $v = $this->reqv($si->name);
         if ($v === null) {
             if (in_array($si->type, ["cdate", "checkbox"]))
@@ -1350,8 +1348,6 @@ private function account(Si $si1) {
     }
 
     function execute() {
-        global $Now;
-
         // parse and validate settings
         foreach (Si::si_map($this->conf) as $si) {
             $this->account($si);
diff --git a/src/userstatus.php b/src/userstatus.php
index 2b255c003..fae9042ab 100644
--- a/src/userstatus.php
+++ b/src/userstatus.php
@@ -679,7 +679,6 @@ private function maybe_assign($user, $cj, $cu, $fields, $userval = true) {
     /** @param object $cj
      * @param ?Contact $old_user */
     function save($cj, $old_user = null) {
-        global $Now;
         assert(is_object($cj));
         assert(!$old_user || (!$this->no_create && !$this->no_modify));
         $msgcount = $this->message_count();
@@ -865,7 +864,7 @@ function save($cj, $old_user = null) {
         // Changes to the above fields also change the updateTime
         // (changes to the below fields do not).
         if (!empty($cu->qv)) {
-            $user->save_assign_field("updateTime", $Now, $cu);
+            $user->save_assign_field("updateTime", Conf::$now, $cu);
         }
 
         // Follow
diff --git a/test/setup.php b/test/setup.php
index d4496d50b..b8fddff10 100644
--- a/test/setup.php
+++ b/test/setup.php
@@ -545,4 +545,3 @@ function xassert_paper_status(PaperStatus $ps) {
 }
 
 MailChecker::clear();
-echo "* Tests initialized.\n";
diff --git a/test/test01.php b/test/test01.php
index 480be3991..0c2c4163d 100644
--- a/test/test01.php
+++ b/test/test01.php
@@ -6,8 +6,8 @@
 $Conf->check_invariants();
 
 $Conf->save_setting("sub_open", 1);
-$Conf->save_setting("sub_update", $Now + 10);
-$Conf->save_setting("sub_sub", $Now + 10);
+$Conf->save_setting("sub_update", Conf::$now + 10);
+$Conf->save_setting("sub_sub", Conf::$now + 10);
 
 // load users
 $user_chair = $Conf->checked_user_by_email("chair@_.com");
@@ -128,8 +128,8 @@ function check_paper1($paper1) {
 xassert_eq($Conf->setting("paperacc", 0), 0);
 
 // change submission date
-$Conf->save_setting("sub_update", $Now - 5);
-$Conf->save_setting("sub_sub", $Now - 5);
+$Conf->save_setting("sub_update", Conf::$now - 5);
+$Conf->save_setting("sub_sub", Conf::$now - 5);
 xassert($user_chair->can_update_paper($paper1));
 xassert(!$user_chair->call_with_overrides(Contact::OVERRIDE_CHECK_TIME, "can_update_paper", $paper1));
 xassert(!$user_estrin->can_update_paper($paper1));
@@ -816,8 +816,8 @@ function sorted_conflicts(PaperInfo $prow, $contacts) {
 xassert_eqq(sorted_conflicts($paper3, false), "mgbaker@cs.stanford.edu sclin@leland.stanford.edu");
 
 $user_sclin = $Conf->checked_user_by_email("sclin@leland.stanford.edu");
-$Conf->save_setting("sub_update", $Now + 10);
-$Conf->save_setting("sub_sub", $Now + 10);
+$Conf->save_setting("sub_update", Conf::$now + 10);
+$Conf->save_setting("sub_sub", Conf::$now + 10);
 xassert($user_sclin->can_update_paper($paper3));
 xassert_assign($user_sclin, "paper,action,user\n3,conflict,rguerin@ibm.com\n");
 $paper3 = $user_chair->checked_paper_by_id(3);
@@ -869,8 +869,8 @@ function sorted_conflicts(PaperInfo $prow, $contacts) {
 $paper3->load_conflicts(false);
 xassert_eqq($paper3->conflict_type($user_rguerin), 4);
 
-$Conf->save_setting("sub_update", $Now - 5);
-$Conf->save_setting("sub_sub", $Now - 5);
+$Conf->save_setting("sub_update", Conf::$now - 5);
+$Conf->save_setting("sub_sub", Conf::$now - 5);
 xassert_assign_fail($user_sclin, "paper,action,user\n3,clearconflict,rguerin@ibm.com\n");
 $paper3 = $user_chair->checked_paper_by_id(3);
 xassert_eqq(sorted_conflicts($paper3, false), "mgbaker@cs.stanford.edu rguerin@ibm.com sclin@leland.stanford.edu");
@@ -1126,7 +1126,7 @@ function sorted_conflicts(PaperInfo $prow, $contacts) {
 xassert(!$user_author2->can_view_review($paper2, $review2b));
 $Conf->save_setting("resp_active", 1);
 $Conf->save_setting("resp_open", 1);
-$Conf->save_setting("resp_done", $Now + 100);
+$Conf->save_setting("resp_done", Conf::$now + 100);
 xassert($user_author2->can_view_review($paper2, $review2b));
 $Conf->save_setting("au_seerev", Conf::AUSEEREV_NO);
 xassert($user_author2->can_view_review($paper2, $review2b));
@@ -1190,7 +1190,7 @@ function sorted_conflicts(PaperInfo $prow, $contacts) {
 xassert($paper16->timeWithdrawn > 0);
 xassert_eqq($paper16->withdrawReason, "Sucky");
 xassert_assign_fail($user_mogul, "paper,action,reason\n16,revive,Sucky\n");
-$Conf->save_setting("sub_sub", $Now + 5);
+$Conf->save_setting("sub_sub", Conf::$now + 5);
 xassert_assign($user_mogul, "paper,action,reason\n16,revive,Sucky\n");
 $paper16 = $user_mogul->checked_paper_by_id(16);
 xassert($paper16->timeSubmitted > 0);
diff --git a/test/test02.php b/test/test02.php
index fde38df6b..760a455e9 100644
--- a/test/test02.php
+++ b/test/test02.php
@@ -11,8 +11,7 @@
     "bucket" => null,
     "fixed_time" => gmmktime(0, 0, 0, 5, 24, 2013)
 ]);
-global $Now;
-$Now = gmmktime(0, 0, 0, 5, 24, 2013);
+Conf::set_current_time(gmmktime(0, 0, 0, 5, 24, 2013));
 
 $sig = $s3d->signature("GET",
                        "https://examplebucket.s3.amazonaws.com/test.txt",
diff --git a/test/test04.php b/test/test04.php
index f9d087d95..5a2356c48 100644
--- a/test/test04.php
+++ b/test/test04.php
@@ -19,10 +19,10 @@ function password($email, $iscdb = false) {
 }
 
 function save_password($email, $encoded_password, $iscdb = false) {
-    global $Conf, $Now;
+    global $Conf;
     $dblink = $iscdb ? $Conf->contactdb() : $Conf->dblink;
-    Dbl::qe($dblink, "update ContactInfo set password=?, passwordTime=?, passwordUseTime=? where email=?", $encoded_password, $Now + 1, $Now + 1, $email);
-    $Now += 2;
+    Dbl::qe($dblink, "update ContactInfo set password=?, passwordTime=?, passwordUseTime=? where email=?", $encoded_password, Conf::$now + 1, Conf::$now + 1, $email);
+    Conf::advance_current_time(Conf::$now + 2);
 }
 
 if (!$Conf->contactdb()) {
@@ -68,9 +68,9 @@ function save_password($email, $encoded_password, $iscdb = false) {
 xassert(user($marina)->check_password("ncurses"));
 
 // logging in with global password makes local password obsolete
-$Now += 3;
+Conf::advance_current_time(Conf::$now + 3);
 xassert(user($marina)->check_password("isdevitch"));
-$Now += 3;
+Conf::advance_current_time(Conf::$now + 3);
 xassert(!user($marina)->check_password("ncurses"));
 
 // null contactdb password => password is unset
diff --git a/test/test05.php b/test/test05.php
index 12ddd3625..ccff629fd 100644
--- a/test/test05.php
+++ b/test/test05.php
@@ -4,8 +4,8 @@
 
 require_once(preg_replace('/\/test\/[^\/]+/', '/test/setup.php', __FILE__));
 $Conf->save_setting("sub_open", 1);
-$Conf->save_setting("sub_update", $Now + 100);
-$Conf->save_setting("sub_sub", $Now + 100);
+$Conf->save_setting("sub_update", Conf::$now + 100);
+$Conf->save_setting("sub_sub", Conf::$now + 100);
 $Conf->save_setting("opt.contentHashMethod", 1, "sha1");
 
 // load users