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memcached.c
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memcached.c
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/* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
* memcached - memory caching daemon
*
* http://www.memcached.org/
*
* Copyright 2003 Danga Interactive, Inc. All rights reserved.
*
* Use and distribution licensed under the BSD license. See
* the LICENSE file for full text.
*
* Authors:
* Anatoly Vorobey <[email protected]>
* Brad Fitzpatrick <[email protected]>
*/
/*
* Copyright 2018 Lenovo
*
* Licensed under the BSD-3 license. see LICENSE.Lenovo.txt for full text
*/
/*
* Note:
* Codes enclosed in `#ifdef PSLAB' and `#endif' are added by Lenovo for
* persistent memory support
*/
#include "memcached.h"
#ifdef EXTSTORE
#include "storage.h"
#endif
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <signal.h>
#include <sys/param.h>
#include <sys/resource.h>
#include <sys/uio.h>
#include <ctype.h>
#include <stdarg.h>
/* some POSIX systems need the following definition
* to get mlockall flags out of sys/mman.h. */
#ifndef _P1003_1B_VISIBLE
#define _P1003_1B_VISIBLE
#endif
/* need this to get IOV_MAX on some platforms. */
#ifndef __need_IOV_MAX
#define __need_IOV_MAX
#endif
#include <pwd.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <assert.h>
#include <limits.h>
#include <sysexits.h>
#include <stddef.h>
#ifdef HAVE_GETOPT_LONG
#include <getopt.h>
#endif
/* FreeBSD 4.x doesn't have IOV_MAX exposed. */
#ifndef IOV_MAX
#if defined(__FreeBSD__) || defined(__APPLE__) || defined(__GNU__)
# define IOV_MAX 1024
/* GNU/Hurd don't set MAXPATHLEN
* http://www.gnu.org/software/hurd/hurd/porting/guidelines.html#PATH_MAX_tt_MAX_PATH_tt_MAXPATHL */
#ifndef MAXPATHLEN
#define MAXPATHLEN 4096
#endif
#endif
#endif
/*
* forward declarations
*/
static void drive_machine(conn *c);
static int new_socket(struct addrinfo *ai);
static int try_read_command(conn *c);
enum try_read_result {
READ_DATA_RECEIVED,
READ_NO_DATA_RECEIVED,
READ_ERROR, /** an error occurred (on the socket) (or client closed connection) */
READ_MEMORY_ERROR /** failed to allocate more memory */
};
static enum try_read_result try_read_network(conn *c);
static enum try_read_result try_read_udp(conn *c);
static void conn_set_state(conn *c, enum conn_states state);
static int start_conn_timeout_thread();
/* stats */
static void stats_init(void);
static void server_stats(ADD_STAT add_stats, conn *c);
static void process_stat_settings(ADD_STAT add_stats, void *c);
static void conn_to_str(const conn *c, char *buf);
/* defaults */
static void settings_init(void);
/* event handling, network IO */
static void event_handler(const int fd, const short which, void *arg);
static void conn_close(conn *c);
static void conn_init(void);
static bool update_event(conn *c, const int new_flags);
static void complete_nread(conn *c);
static void process_command(conn *c, char *command);
static void write_and_free(conn *c, char *buf, int bytes);
static int ensure_iov_space(conn *c);
static int add_iov(conn *c, const void *buf, int len);
static int add_chunked_item_iovs(conn *c, item *it, int len);
static int add_msghdr(conn *c);
static void write_bin_error(conn *c, protocol_binary_response_status err,
const char *errstr, int swallow);
static void write_bin_miss_response(conn *c, char *key, size_t nkey);
#ifdef EXTSTORE
static void _get_extstore_cb(void *e, obj_io *io, int ret);
static inline int _get_extstore(conn *c, item *it, int iovst, int iovcnt);
#endif
static void conn_free(conn *c);
/** exported globals **/
struct stats stats;
struct stats_state stats_state;
struct settings settings;
time_t process_started; /* when the process was started */
conn **conns;
struct slab_rebalance slab_rebal;
volatile int slab_rebalance_signal;
#ifdef EXTSTORE
/* hoping this is temporary; I'd prefer to cut globals, but will complete this
* battle another day.
*/
void *ext_storage;
#endif
/** file scope variables **/
static conn *listen_conn = NULL;
static int max_fds;
static struct event_base *main_base;
enum transmit_result {
TRANSMIT_COMPLETE, /** All done writing. */
TRANSMIT_INCOMPLETE, /** More data remaining to write. */
TRANSMIT_SOFT_ERROR, /** Can't write any more right now. */
TRANSMIT_HARD_ERROR /** Can't write (c->state is set to conn_closing) */
};
static enum transmit_result transmit(conn *c);
/* This reduces the latency without adding lots of extra wiring to be able to
* notify the listener thread of when to listen again.
* Also, the clock timer could be broken out into its own thread and we
* can block the listener via a condition.
*/
static volatile bool allow_new_conns = true;
static struct event maxconnsevent;
static void maxconns_handler(const int fd, const short which, void *arg) {
struct timeval t = {.tv_sec = 0, .tv_usec = 10000};
if (fd == -42 || allow_new_conns == false) {
/* reschedule in 10ms if we need to keep polling */
evtimer_set(&maxconnsevent, maxconns_handler, 0);
event_base_set(main_base, &maxconnsevent);
evtimer_add(&maxconnsevent, &t);
} else {
evtimer_del(&maxconnsevent);
accept_new_conns(true);
}
}
#define REALTIME_MAXDELTA 60*60*24*30
/*
* given time value that's either unix time or delta from current unix time, return
* unix time. Use the fact that delta can't exceed one month (and real time value can't
* be that low).
*/
static rel_time_t realtime(const time_t exptime) {
/* no. of seconds in 30 days - largest possible delta exptime */
if (exptime == 0) return 0; /* 0 means never expire */
if (exptime > REALTIME_MAXDELTA) {
/* if item expiration is at/before the server started, give it an
expiration time of 1 second after the server started.
(because 0 means don't expire). without this, we'd
underflow and wrap around to some large value way in the
future, effectively making items expiring in the past
really expiring never */
if (exptime <= process_started)
return (rel_time_t)1;
return (rel_time_t)(exptime - process_started);
} else {
return (rel_time_t)(exptime + current_time);
}
}
static void stats_init(void) {
memset(&stats, 0, sizeof(struct stats));
memset(&stats_state, 0, sizeof(struct stats_state));
stats_state.accepting_conns = true; /* assuming we start in this state. */
/* make the time we started always be 2 seconds before we really
did, so time(0) - time.started is never zero. if so, things
like 'settings.oldest_live' which act as booleans as well as
values are now false in boolean context... */
process_started = time(0) - ITEM_UPDATE_INTERVAL - 2;
#ifdef PSLAB
if (settings.pslab_recover == true)
process_started = pslab_process_started(process_started);
#endif
stats_prefix_init();
}
static void stats_reset(void) {
STATS_LOCK();
memset(&stats, 0, sizeof(struct stats));
stats_prefix_clear();
STATS_UNLOCK();
threadlocal_stats_reset();
item_stats_reset();
}
static void settings_init(void) {
settings.use_cas = true;
settings.access = 0700;
settings.port = 11211;
settings.udpport = 11211;
/* By default this string should be NULL for getaddrinfo() */
settings.inter = NULL;
settings.maxbytes = 64 * 1024 * 1024; /* default is 64MB */
settings.maxconns = 1024; /* to limit connections-related memory to about 5MB */
settings.verbose = 0;
settings.oldest_live = 0;
settings.oldest_cas = 0; /* supplements accuracy of oldest_live */
settings.evict_to_free = 1; /* push old items out of cache when memory runs out */
settings.socketpath = NULL; /* by default, not using a unix socket */
settings.factor = 1.25;
settings.chunk_size = 48; /* space for a modest key and value */
settings.num_threads = 4; /* N workers */
settings.num_threads_per_udp = 0;
settings.prefix_delimiter = ':';
settings.detail_enabled = 0;
settings.reqs_per_event = 20;
settings.backlog = 1024;
settings.binding_protocol = negotiating_prot;
settings.item_size_max = 1024 * 1024; /* The famous 1MB upper limit. */
settings.slab_page_size = 1024 * 1024; /* chunks are split from 1MB pages. */
settings.slab_chunk_size_max = settings.slab_page_size / 2;
settings.sasl = false;
settings.maxconns_fast = true;
settings.lru_crawler = false;
settings.lru_crawler_sleep = 100;
settings.lru_crawler_tocrawl = 0;
settings.lru_maintainer_thread = false;
settings.lru_segmented = true;
settings.hot_lru_pct = 20;
settings.warm_lru_pct = 40;
settings.hot_max_factor = 0.2;
settings.warm_max_factor = 2.0;
settings.inline_ascii_response = false;
settings.temp_lru = false;
settings.temporary_ttl = 61;
settings.idle_timeout = 0; /* disabled */
settings.hashpower_init = 0;
settings.slab_reassign = true;
settings.slab_automove = 1;
settings.slab_automove_ratio = 0.8;
settings.slab_automove_window = 30;
settings.shutdown_command = false;
settings.tail_repair_time = TAIL_REPAIR_TIME_DEFAULT;
settings.flush_enabled = true;
settings.dump_enabled = true;
settings.crawls_persleep = 1000;
settings.logger_watcher_buf_size = LOGGER_WATCHER_BUF_SIZE;
settings.logger_buf_size = LOGGER_BUF_SIZE;
settings.drop_privileges = true;
#ifdef MEMCACHED_DEBUG
settings.relaxed_privileges = false;
#endif
}
/*
* Adds a message header to a connection.
*
* Returns 0 on success, -1 on out-of-memory.
*/
static int add_msghdr(conn *c)
{
struct msghdr *msg;
assert(c != NULL);
if (c->msgsize == c->msgused) {
msg = realloc(c->msglist, c->msgsize * 2 * sizeof(struct msghdr));
if (! msg) {
STATS_LOCK();
stats.malloc_fails++;
STATS_UNLOCK();
return -1;
}
c->msglist = msg;
c->msgsize *= 2;
}
msg = c->msglist + c->msgused;
/* this wipes msg_iovlen, msg_control, msg_controllen, and
msg_flags, the last 3 of which aren't defined on solaris: */
memset(msg, 0, sizeof(struct msghdr));
msg->msg_iov = &c->iov[c->iovused];
if (IS_UDP(c->transport) && c->request_addr_size > 0) {
msg->msg_name = &c->request_addr;
msg->msg_namelen = c->request_addr_size;
}
c->msgbytes = 0;
c->msgused++;
if (IS_UDP(c->transport)) {
/* Leave room for the UDP header, which we'll fill in later. */
return add_iov(c, NULL, UDP_HEADER_SIZE);
}
return 0;
}
extern pthread_mutex_t conn_lock;
/* Connection timeout thread bits */
static pthread_t conn_timeout_tid;
#define CONNS_PER_SLICE 100
#define TIMEOUT_MSG_SIZE (1 + sizeof(int))
static void *conn_timeout_thread(void *arg) {
int i;
conn *c;
char buf[TIMEOUT_MSG_SIZE];
rel_time_t oldest_last_cmd;
int sleep_time;
useconds_t timeslice = 1000000 / (max_fds / CONNS_PER_SLICE);
while(1) {
if (settings.verbose > 2)
fprintf(stderr, "idle timeout thread at top of connection list\n");
oldest_last_cmd = current_time;
for (i = 0; i < max_fds; i++) {
if ((i % CONNS_PER_SLICE) == 0) {
if (settings.verbose > 2)
fprintf(stderr, "idle timeout thread sleeping for %ulus\n",
(unsigned int)timeslice);
usleep(timeslice);
}
if (!conns[i])
continue;
c = conns[i];
if (!IS_TCP(c->transport))
continue;
if (c->state != conn_new_cmd && c->state != conn_read)
continue;
if ((current_time - c->last_cmd_time) > settings.idle_timeout) {
buf[0] = 't';
memcpy(&buf[1], &i, sizeof(int));
if (write(c->thread->notify_send_fd, buf, TIMEOUT_MSG_SIZE)
!= TIMEOUT_MSG_SIZE)
perror("Failed to write timeout to notify pipe");
} else {
if (c->last_cmd_time < oldest_last_cmd)
oldest_last_cmd = c->last_cmd_time;
}
}
/* This is the soonest we could have another connection time out */
sleep_time = settings.idle_timeout - (current_time - oldest_last_cmd) + 1;
if (sleep_time <= 0)
sleep_time = 1;
if (settings.verbose > 2)
fprintf(stderr,
"idle timeout thread finished pass, sleeping for %ds\n",
sleep_time);
usleep((useconds_t) sleep_time * 1000000);
}
return NULL;
}
static int start_conn_timeout_thread() {
int ret;
if (settings.idle_timeout == 0)
return -1;
if ((ret = pthread_create(&conn_timeout_tid, NULL,
conn_timeout_thread, NULL)) != 0) {
fprintf(stderr, "Can't create idle connection timeout thread: %s\n",
strerror(ret));
return -1;
}
return 0;
}
/*
* Initializes the connections array. We don't actually allocate connection
* structures until they're needed, so as to avoid wasting memory when the
* maximum connection count is much higher than the actual number of
* connections.
*
* This does end up wasting a few pointers' worth of memory for FDs that are
* used for things other than connections, but that's worth it in exchange for
* being able to directly index the conns array by FD.
*/
static void conn_init(void) {
/* We're unlikely to see an FD much higher than maxconns. */
int next_fd = dup(1);
int headroom = 10; /* account for extra unexpected open FDs */
struct rlimit rl;
max_fds = settings.maxconns + headroom + next_fd;
/* But if possible, get the actual highest FD we can possibly ever see. */
if (getrlimit(RLIMIT_NOFILE, &rl) == 0) {
max_fds = rl.rlim_max;
} else {
fprintf(stderr, "Failed to query maximum file descriptor; "
"falling back to maxconns\n");
}
close(next_fd);
if ((conns = calloc(max_fds, sizeof(conn *))) == NULL) {
fprintf(stderr, "Failed to allocate connection structures\n");
/* This is unrecoverable so bail out early. */
exit(1);
}
}
static const char *prot_text(enum protocol prot) {
char *rv = "unknown";
switch(prot) {
case ascii_prot:
rv = "ascii";
break;
case binary_prot:
rv = "binary";
break;
case negotiating_prot:
rv = "auto-negotiate";
break;
}
return rv;
}
void conn_close_idle(conn *c) {
if (settings.idle_timeout > 0 &&
(current_time - c->last_cmd_time) > settings.idle_timeout) {
if (c->state != conn_new_cmd && c->state != conn_read) {
if (settings.verbose > 1)
fprintf(stderr,
"fd %d wants to timeout, but isn't in read state", c->sfd);
return;
}
if (settings.verbose > 1)
fprintf(stderr, "Closing idle fd %d\n", c->sfd);
c->thread->stats.idle_kicks++;
conn_set_state(c, conn_closing);
drive_machine(c);
}
}
/* bring conn back from a sidethread. could have had its event base moved. */
void conn_worker_readd(conn *c) {
c->ev_flags = EV_READ | EV_PERSIST;
event_set(&c->event, c->sfd, c->ev_flags, event_handler, (void *)c);
event_base_set(c->thread->base, &c->event);
c->state = conn_new_cmd;
// TODO: call conn_cleanup/fail/etc
if (event_add(&c->event, 0) == -1) {
perror("event_add");
}
#ifdef EXTSTORE
// If we had IO objects, process
if (c->io_wraplist) {
//assert(c->io_wrapleft == 0); // assert no more to process
conn_set_state(c, conn_mwrite);
drive_machine(c);
}
#endif
}
conn *conn_new(const int sfd, enum conn_states init_state,
const int event_flags,
const int read_buffer_size, enum network_transport transport,
struct event_base *base) {
conn *c;
assert(sfd >= 0 && sfd < max_fds);
c = conns[sfd];
if (NULL == c) {
if (!(c = (conn *)calloc(1, sizeof(conn)))) {
STATS_LOCK();
stats.malloc_fails++;
STATS_UNLOCK();
fprintf(stderr, "Failed to allocate connection object\n");
return NULL;
}
MEMCACHED_CONN_CREATE(c);
c->rbuf = c->wbuf = 0;
c->ilist = 0;
c->suffixlist = 0;
c->iov = 0;
c->msglist = 0;
c->hdrbuf = 0;
c->rsize = read_buffer_size;
c->wsize = DATA_BUFFER_SIZE;
c->isize = ITEM_LIST_INITIAL;
c->suffixsize = SUFFIX_LIST_INITIAL;
c->iovsize = IOV_LIST_INITIAL;
c->msgsize = MSG_LIST_INITIAL;
c->hdrsize = 0;
c->rbuf = (char *)malloc((size_t)c->rsize);
c->wbuf = (char *)malloc((size_t)c->wsize);
c->ilist = (item **)malloc(sizeof(item *) * c->isize);
c->suffixlist = (char **)malloc(sizeof(char *) * c->suffixsize);
c->iov = (struct iovec *)malloc(sizeof(struct iovec) * c->iovsize);
c->msglist = (struct msghdr *)malloc(sizeof(struct msghdr) * c->msgsize);
if (c->rbuf == 0 || c->wbuf == 0 || c->ilist == 0 || c->iov == 0 ||
c->msglist == 0 || c->suffixlist == 0) {
conn_free(c);
STATS_LOCK();
stats.malloc_fails++;
STATS_UNLOCK();
fprintf(stderr, "Failed to allocate buffers for connection\n");
return NULL;
}
STATS_LOCK();
stats_state.conn_structs++;
STATS_UNLOCK();
c->sfd = sfd;
conns[sfd] = c;
}
c->transport = transport;
c->protocol = settings.binding_protocol;
/* unix socket mode doesn't need this, so zeroed out. but why
* is this done for every command? presumably for UDP
* mode. */
if (!settings.socketpath) {
c->request_addr_size = sizeof(c->request_addr);
} else {
c->request_addr_size = 0;
}
if (transport == tcp_transport && init_state == conn_new_cmd) {
if (getpeername(sfd, (struct sockaddr *) &c->request_addr,
&c->request_addr_size)) {
perror("getpeername");
memset(&c->request_addr, 0, sizeof(c->request_addr));
}
}
if (settings.verbose > 1) {
if (init_state == conn_listening) {
fprintf(stderr, "<%d server listening (%s)\n", sfd,
prot_text(c->protocol));
} else if (IS_UDP(transport)) {
fprintf(stderr, "<%d server listening (udp)\n", sfd);
} else if (c->protocol == negotiating_prot) {
fprintf(stderr, "<%d new auto-negotiating client connection\n",
sfd);
} else if (c->protocol == ascii_prot) {
fprintf(stderr, "<%d new ascii client connection.\n", sfd);
} else if (c->protocol == binary_prot) {
fprintf(stderr, "<%d new binary client connection.\n", sfd);
} else {
fprintf(stderr, "<%d new unknown (%d) client connection\n",
sfd, c->protocol);
assert(false);
}
}
c->state = init_state;
c->rlbytes = 0;
c->cmd = -1;
c->rbytes = c->wbytes = 0;
c->wcurr = c->wbuf;
c->rcurr = c->rbuf;
c->ritem = 0;
c->icurr = c->ilist;
c->suffixcurr = c->suffixlist;
c->ileft = 0;
c->suffixleft = 0;
c->iovused = 0;
c->msgcurr = 0;
c->msgused = 0;
c->authenticated = false;
c->last_cmd_time = current_time; /* initialize for idle kicker */
#ifdef EXTSTORE
c->io_wraplist = NULL;
c->io_wrapleft = 0;
#endif
c->write_and_go = init_state;
c->write_and_free = 0;
c->item = 0;
c->noreply = false;
event_set(&c->event, sfd, event_flags, event_handler, (void *)c);
event_base_set(base, &c->event);
c->ev_flags = event_flags;
if (event_add(&c->event, 0) == -1) {
perror("event_add");
return NULL;
}
STATS_LOCK();
stats_state.curr_conns++;
stats.total_conns++;
STATS_UNLOCK();
MEMCACHED_CONN_ALLOCATE(c->sfd);
return c;
}
#ifdef EXTSTORE
static void recache_or_free(conn *c, io_wrap *wrap) {
item *it;
it = (item *)wrap->io.buf;
bool do_free = true;
// If request was ultimately a miss, unlink the header.
if (wrap->miss) {
do_free = false;
size_t ntotal = ITEM_ntotal(wrap->hdr_it);
item_unlink(wrap->hdr_it);
slabs_free(it, ntotal, slabs_clsid(ntotal));
pthread_mutex_lock(&c->thread->stats.mutex);
c->thread->stats.miss_from_extstore++;
if (wrap->badcrc)
c->thread->stats.badcrc_from_extstore++;
pthread_mutex_unlock(&c->thread->stats.mutex);
} else if (settings.ext_recache_rate) {
// hashvalue is cuddled during store
uint32_t hv = (uint32_t)it->time;
// opt to throw away rather than wait on a lock.
void *hold_lock = item_trylock(hv);
if (hold_lock != NULL) {
item *h_it = wrap->hdr_it;
uint8_t flags = ITEM_LINKED|ITEM_FETCHED|ITEM_ACTIVE;
// Item must be recently hit at least twice to recache.
if (((h_it->it_flags & flags) == flags) &&
h_it->time > current_time - ITEM_UPDATE_INTERVAL &&
c->recache_counter++ % settings.ext_recache_rate == 0) {
do_free = false;
// In case it's been updated.
it->exptime = h_it->exptime;
it->it_flags &= ~ITEM_LINKED;
it->refcount = 0;
it->h_next = NULL; // might not be necessary.
STORAGE_delete(c->thread->storage, h_it);
item_replace(h_it, it, hv);
pthread_mutex_lock(&c->thread->stats.mutex);
c->thread->stats.recache_from_extstore++;
pthread_mutex_unlock(&c->thread->stats.mutex);
}
}
if (hold_lock)
item_trylock_unlock(hold_lock);
}
if (do_free)
slabs_free(it, ITEM_ntotal(it), ITEM_clsid(it));
wrap->io.buf = NULL; // sanity.
wrap->io.next = NULL;
wrap->next = NULL;
wrap->active = false;
// TODO: reuse lock and/or hv.
item_remove(wrap->hdr_it);
}
#endif
static void conn_release_items(conn *c) {
assert(c != NULL);
if (c->item) {
item_remove(c->item);
c->item = 0;
}
while (c->ileft > 0) {
item *it = *(c->icurr);
assert((it->it_flags & ITEM_SLABBED) == 0);
item_remove(it);
c->icurr++;
c->ileft--;
}
if (c->suffixleft != 0) {
for (; c->suffixleft > 0; c->suffixleft--, c->suffixcurr++) {
do_cache_free(c->thread->suffix_cache, *(c->suffixcurr));
}
}
#ifdef EXTSTORE
if (c->io_wraplist) {
io_wrap *tmp = c->io_wraplist;
while (tmp) {
io_wrap *next = tmp->next;
recache_or_free(c, tmp);
do_cache_free(c->thread->io_cache, tmp); // lockless
tmp = next;
}
c->io_wraplist = NULL;
}
#endif
c->icurr = c->ilist;
c->suffixcurr = c->suffixlist;
}
static void conn_cleanup(conn *c) {
assert(c != NULL);
conn_release_items(c);
if (c->write_and_free) {
free(c->write_and_free);
c->write_and_free = 0;
}
if (c->sasl_conn) {
assert(settings.sasl);
sasl_dispose(&c->sasl_conn);
c->sasl_conn = NULL;
}
if (IS_UDP(c->transport)) {
conn_set_state(c, conn_read);
}
}
/*
* Frees a connection.
*/
void conn_free(conn *c) {
if (c) {
assert(c != NULL);
assert(c->sfd >= 0 && c->sfd < max_fds);
MEMCACHED_CONN_DESTROY(c);
conns[c->sfd] = NULL;
if (c->hdrbuf)
free(c->hdrbuf);
if (c->msglist)
free(c->msglist);
if (c->rbuf)
free(c->rbuf);
if (c->wbuf)
free(c->wbuf);
if (c->ilist)
free(c->ilist);
if (c->suffixlist)
free(c->suffixlist);
if (c->iov)
free(c->iov);
free(c);
}
}
static void conn_close(conn *c) {
assert(c != NULL);
/* delete the event, the socket and the conn */
event_del(&c->event);
if (settings.verbose > 1)
fprintf(stderr, "<%d connection closed.\n", c->sfd);
conn_cleanup(c);
MEMCACHED_CONN_RELEASE(c->sfd);
conn_set_state(c, conn_closed);
close(c->sfd);
pthread_mutex_lock(&conn_lock);
allow_new_conns = true;
pthread_mutex_unlock(&conn_lock);
STATS_LOCK();
stats_state.curr_conns--;
STATS_UNLOCK();
return;
}
/*
* Shrinks a connection's buffers if they're too big. This prevents
* periodic large "get" requests from permanently chewing lots of server
* memory.
*
* This should only be called in between requests since it can wipe output
* buffers!
*/
static void conn_shrink(conn *c) {
assert(c != NULL);
if (IS_UDP(c->transport))
return;
if (c->rsize > READ_BUFFER_HIGHWAT && c->rbytes < DATA_BUFFER_SIZE) {
char *newbuf;
if (c->rcurr != c->rbuf)
memmove(c->rbuf, c->rcurr, (size_t)c->rbytes);
newbuf = (char *)realloc((void *)c->rbuf, DATA_BUFFER_SIZE);
if (newbuf) {
c->rbuf = newbuf;
c->rsize = DATA_BUFFER_SIZE;
}
/* TODO check other branch... */
c->rcurr = c->rbuf;
}
if (c->isize > ITEM_LIST_HIGHWAT) {
item **newbuf = (item**) realloc((void *)c->ilist, ITEM_LIST_INITIAL * sizeof(c->ilist[0]));
if (newbuf) {
c->ilist = newbuf;
c->isize = ITEM_LIST_INITIAL;
}
/* TODO check error condition? */
}
if (c->msgsize > MSG_LIST_HIGHWAT) {
struct msghdr *newbuf = (struct msghdr *) realloc((void *)c->msglist, MSG_LIST_INITIAL * sizeof(c->msglist[0]));
if (newbuf) {
c->msglist = newbuf;
c->msgsize = MSG_LIST_INITIAL;
}
/* TODO check error condition? */
}
if (c->iovsize > IOV_LIST_HIGHWAT) {
struct iovec *newbuf = (struct iovec *) realloc((void *)c->iov, IOV_LIST_INITIAL * sizeof(c->iov[0]));
if (newbuf) {
c->iov = newbuf;
c->iovsize = IOV_LIST_INITIAL;
}
/* TODO check return value */
}
}
/**
* Convert a state name to a human readable form.
*/
static const char *state_text(enum conn_states state) {
const char* const statenames[] = { "conn_listening",
"conn_new_cmd",
"conn_waiting",
"conn_read",
"conn_parse_cmd",
"conn_write",
"conn_nread",
"conn_swallow",
"conn_closing",
"conn_mwrite",
"conn_closed",
"conn_watch" };
return statenames[state];
}
/*
* Sets a connection's current state in the state machine. Any special
* processing that needs to happen on certain state transitions can
* happen here.
*/
static void conn_set_state(conn *c, enum conn_states state) {
assert(c != NULL);
assert(state >= conn_listening && state < conn_max_state);
if (state != c->state) {
if (settings.verbose > 2) {
fprintf(stderr, "%d: going from %s to %s\n",
c->sfd, state_text(c->state),
state_text(state));
}
if (state == conn_write || state == conn_mwrite) {
MEMCACHED_PROCESS_COMMAND_END(c->sfd, c->wbuf, c->wbytes);
}
c->state = state;
}
}
/*
* Ensures that there is room for another struct iovec in a connection's
* iov list.
*
* Returns 0 on success, -1 on out-of-memory.
*/
static int ensure_iov_space(conn *c) {
assert(c != NULL);
if (c->iovused >= c->iovsize) {
int i, iovnum;
struct iovec *new_iov = (struct iovec *)realloc(c->iov,
(c->iovsize * 2) * sizeof(struct iovec));
if (! new_iov) {
STATS_LOCK();
stats.malloc_fails++;
STATS_UNLOCK();
return -1;
}
c->iov = new_iov;
c->iovsize *= 2;
/* Point all the msghdr structures at the new list. */
for (i = 0, iovnum = 0; i < c->msgused; i++) {
c->msglist[i].msg_iov = &c->iov[iovnum];
iovnum += c->msglist[i].msg_iovlen;
}
}
return 0;
}
/*
* Adds data to the list of pending data that will be written out to a
* connection.
*
* Returns 0 on success, -1 on out-of-memory.
* Note: This is a hot path for at least ASCII protocol. While there is
* redundant code in splitting TCP/UDP handling, any reduction in steps has a
* large impact for TCP connections.
*/
static int add_iov(conn *c, const void *buf, int len) {
struct msghdr *m;
int leftover;
assert(c != NULL);
if (IS_UDP(c->transport)) {
do {
m = &c->msglist[c->msgused - 1];
/*
* Limit UDP packets to UDP_MAX_PAYLOAD_SIZE bytes.
*/
/* We may need to start a new msghdr if this one is full. */
if (m->msg_iovlen == IOV_MAX ||
(c->msgbytes >= UDP_MAX_PAYLOAD_SIZE)) {
add_msghdr(c);
m = &c->msglist[c->msgused - 1];
}
if (ensure_iov_space(c) != 0)
return -1;
/* If the fragment is too big to fit in the datagram, split it up */
if (len + c->msgbytes > UDP_MAX_PAYLOAD_SIZE) {
leftover = len + c->msgbytes - UDP_MAX_PAYLOAD_SIZE;
len -= leftover;
} else {
leftover = 0;