chore: change default for run_binary#stamp

Greg convinced me that users will get really slow stamped builds because most run_binary tools don't actually read the status files, but will be cache-invalidated.
publish-to-bcr-dev · Jul 15, 2022 · 8a11a10 · 8a11a10
1 parent 56bc408
commit 8a11a10
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Showing 3 changed files with 9 additions and 4 deletions.
diff --git a/docs/run_binary.md b/docs/run_binary.md
diff --git a/lib/private/run_binary.bzl b/lib/private/run_binary.bzl
@@ -117,7 +117,7 @@ def run_binary(
         mnemonic = "RunBinary",
         progress_message = None,
         execution_requirements = None,
-        stamp = -1,
+        stamp = 0,
         # TODO: remove output_dir in 2.x release
         output_dir = False,
         **kwargs):
@@ -187,13 +187,16 @@ def run_binary(
 
         stamp: Whether to include build status files as inputs to the tool. Possible values:
 
+            - `stamp = 0` (default): Never include build status files as inputs to the tool.
+                This gives good build result caching.
+                Most tools don't use the status files, so including them in `--stamp` builds makes those
+                builds have many needless cache misses.
+                (Note: this default is different from most rules with an integer-typed `stamp` attribute.)
             - `stamp = 1`: Always include build status files as inputs to the tool, even in
                 [--nostamp](https://docs.bazel.build/versions/main/user-manual.html#flag--stamp) builds.
                 This setting should be avoided, since it is non-deterministic.
                 It potentially causes remote cache misses for the target and
                 any downstream actions that depend on the result.
-            - `stamp = 0`: Never include build status files as inputs to the tool.
-                This gives good build result caching.
             - `stamp = -1`: Inclusion of build status files as inputs is controlled by the
                 [--[no]stamp](https://docs.bazel.build/versions/main/user-manual.html#flag--stamp) flag.
                 Stamped targets are not rebuilt unless their dependencies change.

diff --git a/lib/tests/stamping/BUILD.bazel b/lib/tests/stamping/BUILD.bazel
@@ -28,5 +28,7 @@ run_binary(
     name = "run_stamper",
     outs = ["stamped"],
     args = ["$(location stamped)"],
+    # Include status files as inputs when --stamp is set.
+    stamp = -1,
     tool = "stamper",
 )