module: do not split a portable compile cache by uid · nodejs/node@5821362 · GitHub
Skip to content

Commit 5821362

Browse files
codebytereaduh95
codebytere
authored and
aduh95
committed
module: do not split a portable compile cache by uid
A portable compile cache is meant to be reused wherever the same module layout is found, which includes being generated once (at build time, say) and shipped read-only with an application for whoever runs it. On platforms with uids the cache subdirectory is suffixed with the uid of the user who created it, so such a cache is only ever found by that one user. Omit the suffix in portable mode: a user who cannot write to the directory still reads it, and a failed write is only a cache miss. Signed-off-by: Shelley Vohr <shelley.vohr@gmail.com> PR-URL: #65293 Reviewed-By: James M Snell <jasnell@gmail.com>
1 parent 797ef40 commit 5821362

5 files changed

Lines changed: 36 additions & 10 deletions

File tree

‎doc/api/cli.md‎

Lines changed: 3 additions & 2 deletions

‎doc/api/module.md‎

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -405,6 +405,14 @@ to the cache directory remains the same. This would be done on a best-effort bas
405405
Node.js cannot compute the location of a module relative to the cache directory, the module
406406
will not be cached.
407407
408+
A portable cache is also not split by user: on platforms with uids the
409+
cache subdirectory of a non-portable cache is suffixed with the uid of the
410+
user who created it, so it is only found by that user, while a portable
411+
cache uses the same subdirectory for every user. This lets a cache generated
412+
once (for example at build time, then shipped read-only with an application)
413+
be read by whoever runs the code; a user who cannot write to the directory
414+
still reads it, and a failed write only means the module is compiled again.
415+
408416
There are two ways to enable the portable mode:
409417
410418
1. Using the portable option in [`module.enableCompileCache()`][]:

‎doc/node.1‎

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1858,8 +1858,9 @@ Enable the module compile cache for the Node.js instance. See the documentation
18581858
module compile cache for details.
18591859
.
18601860
.It Ev NODE_COMPILE_CACHE_PORTABLE Ar 1
1861-
When set to 1, the module compile cache can be reused across different directory
1862-
locations as long as the module layout relative to the cache directory remains the same.
1861+
When set to 1, the module compile cache can be reused across different directory
1862+
locations as long as the module layout relative to the cache directory remains the same,
1863+
and by any user (the cache subdirectory is not suffixed with the creating user's uid).
18631864
.
18641865
.It Ev NODE_DEBUG Ar module[,…]
18651866
\fB','\fR-separated list of core modules that should print debug information.

‎src/compile_cache.cc‎

Lines changed: 14 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -44,16 +44,23 @@ uint32_t GetHash(const char* data, size_t size) {
4444
return crc32(crc, reinterpret_cast<const Bytef*>(data), size);
4545
}
4646

47-
std::string GetCacheVersionTag() {
47+
std::string GetCacheVersionTag(EnableOption option) {
48+
std::string tag = std::string(NODE_VERSION) + '-' + std::string(NODE_ARCH) +
49+
'-' + Uint32ToHex(ScriptCompiler::CachedDataVersionTag());
50+
#ifdef NODE_IMPLEMENTS_POSIX_CREDENTIALS
4851
// On platforms where uids are available, use different folders for
4952
// different users to avoid cache miss due to permission incompatibility.
5053
// On platforms where uids are not available, bare with the cache miss.
5154
// This should be fine on Windows, as there local directories tend to be
5255
// user-specific.
53-
std::string tag = std::string(NODE_VERSION) + '-' + std::string(NODE_ARCH) +
54-
'-' + Uint32ToHex(ScriptCompiler::CachedDataVersionTag());
55-
#ifdef NODE_IMPLEMENTS_POSIX_CREDENTIALS
56-
tag += '-' + std::to_string(getuid());
56+
// A portable cache is meant to be reused wherever the same layout is
57+
// found, including by other users (e.g. a cache generated at build time
58+
// and shipped read-only with an application), so it is not split by uid:
59+
// a user who cannot write to it still reads it, and a failed write is
60+
// only a cache miss.
61+
if (option != EnableOption::PORTABLE) {
62+
tag += '-' + std::to_string(getuid());
63+
}
5764
#endif
5865
return tag;
5966
}
@@ -532,11 +539,12 @@ CompileCacheHandler::CompileCacheHandler(Environment* env)
532539
// Directory structure:
533540
// - Compile cache directory (from NODE_COMPILE_CACHE)
534541
// - $NODE_VERSION-$ARCH-$CACHE_DATA_VERSION_TAG-$UID
542+
// ($UID is omitted for a portable cache)
535543
// - $FILENAME_AND_MODULE_TYPE_HASH.cache: a hash of filename + module type
536544
CompileCacheEnableResult CompileCacheHandler::Enable(Environment* env,
537545
const std::string& dir,
538546
EnableOption option) {
539-
std::string cache_tag = GetCacheVersionTag();
547+
std::string cache_tag = GetCacheVersionTag(option);
540548
std::string absolute_cache_dir_base = PathResolve(env, {dir});
541549
std::string cache_dir_with_tag =
542550
absolute_cache_dir_base + kPathSeparator + cache_tag;

‎test/parallel/test-compile-cache-api-portable.js‎

Lines changed: 8 additions & 0 deletions

0 commit comments

Comments
 (0)