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

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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

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Lines changed: 36 additions & 10 deletions

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‎doc/api/cli.md‎

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@@ -3704,8 +3704,9 @@ Enable the [module compile cache][] for the Node.js instance. See the documentat
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### `NODE_COMPILE_CACHE_PORTABLE=1`
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When set to 1, the [module compile cache][] can be reused across different directory
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locations as long as the module layout relative to the cache directory remains the same.
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When set to 1, the [module compile cache][] can be reused across different directory
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locations as long as the module layout relative to the cache directory remains the same,
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and by any user (the cache subdirectory is not suffixed with the creating user's uid).
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### `NODE_DEBUG=module[,…]`
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‎doc/api/module.md‎

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@@ -405,6 +405,14 @@ to the cache directory remains the same. This would be done on a best-effort bas
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Node.js cannot compute the location of a module relative to the cache directory, the module
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will not be cached.
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A portable cache is also not split by user: on platforms with uids the
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cache subdirectory of a non-portable cache is suffixed with the uid of the
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user who created it, so it is only found by that user, while a portable
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cache uses the same subdirectory for every user. This lets a cache generated
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once (for example at build time, then shipped read-only with an application)
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be read by whoever runs the code; a user who cannot write to the directory
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still reads it, and a failed write only means the module is compiled again.
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There are two ways to enable the portable mode:
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1. Using the portable option in [`module.enableCompileCache()`][]:

‎doc/node.1‎

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@@ -1858,8 +1858,9 @@ Enable the module compile cache for the Node.js instance. See the documentation
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module compile cache for details.
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.
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.It Ev NODE_COMPILE_CACHE_PORTABLE Ar 1
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When set to 1, the module compile cache can be reused across different directory
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locations as long as the module layout relative to the cache directory remains the same.
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When set to 1, the module compile cache can be reused across different directory
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locations as long as the module layout relative to the cache directory remains the same,
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and by any user (the cache subdirectory is not suffixed with the creating user's uid).
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.
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.It Ev NODE_DEBUG Ar module[,…]
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\fB','\fR-separated list of core modules that should print debug information.

‎src/compile_cache.cc‎

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Original file line numberDiff line numberDiff line change
@@ -44,16 +44,23 @@ uint32_t GetHash(const char* data, size_t size) {
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return crc32(crc, reinterpret_cast<const Bytef*>(data), size);
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}
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std::string GetCacheVersionTag() {
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std::string GetCacheVersionTag(EnableOption option) {
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std::string tag = std::string(NODE_VERSION) + '-' + std::string(NODE_ARCH) +
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'-' + Uint32ToHex(ScriptCompiler::CachedDataVersionTag());
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#ifdef NODE_IMPLEMENTS_POSIX_CREDENTIALS
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// On platforms where uids are available, use different folders for
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// different users to avoid cache miss due to permission incompatibility.
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// On platforms where uids are not available, bare with the cache miss.
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// This should be fine on Windows, as there local directories tend to be
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// user-specific.
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std::string tag = std::string(NODE_VERSION) + '-' + std::string(NODE_ARCH) +
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'-' + Uint32ToHex(ScriptCompiler::CachedDataVersionTag());
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#ifdef NODE_IMPLEMENTS_POSIX_CREDENTIALS
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tag += '-' + std::to_string(getuid());
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// A portable cache is meant to be reused wherever the same layout is
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// found, including by other users (e.g. a cache generated at build time
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// and shipped read-only with an application), so it is not split by uid:
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// a user who cannot write to it still reads it, and a failed write is
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// only a cache miss.
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if (option != EnableOption::PORTABLE) {
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tag += '-' + std::to_string(getuid());
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}
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#endif
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return tag;
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}
@@ -532,11 +539,12 @@ CompileCacheHandler::CompileCacheHandler(Environment* env)
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// Directory structure:
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// - Compile cache directory (from NODE_COMPILE_CACHE)
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// - $NODE_VERSION-$ARCH-$CACHE_DATA_VERSION_TAG-$UID
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// ($UID is omitted for a portable cache)
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// - $FILENAME_AND_MODULE_TYPE_HASH.cache: a hash of filename + module type
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CompileCacheEnableResult CompileCacheHandler::Enable(Environment* env,
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const std::string& dir,
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EnableOption option) {
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std::string cache_tag = GetCacheVersionTag();
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std::string cache_tag = GetCacheVersionTag(option);
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std::string absolute_cache_dir_base = PathResolve(env, {dir});
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std::string cache_dir_with_tag =
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absolute_cache_dir_base + kPathSeparator + cache_tag;

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

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@@ -57,6 +57,14 @@ const NODE_TEST_COMPILE_CACHE_OPTIONS = JSON.stringify({ directory: cacheRel, po
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);
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}
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// The cache subdirectory of a portable cache is not suffixed with the uid,
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// so a cache generated by one user is found by another.
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{
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const [tag] = fs.readdirSync(path.join(workDir, cacheRel));
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// $NODE_VERSION-$ARCH-$CACHE_DATA_VERSION_TAG, with no -$UID.
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assert.match(tag, new RegExp(`^${process.version}-${process.arch}-[0-9a-f]+$`));
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}
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// Second run — moved directory, but same relative cache path
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{
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const movedWorkDir = `${workDir}_moved`;

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