forked from lix-project/lix
Make LocalStore::addToStore(srcPath) run in constant memory
This reduces memory consumption of nix-instantiate \ -E 'with import <nixpkgs> {}; runCommand "foo" { src = ./blender; } "echo foo"' \ --option nar-buffer-size 10000 (where ./blender is a 1.1 GiB tree) from 1716 to 36 MiB, while still ensuring that we don't do any write I/O for small source paths (up to 'nar-buffer-size' bytes). The downside is that large paths are now always written to a temporary location in the store, even if they produce an already valid store path. Thus, adding large paths might be slower and run out of disk space. ¯\_(ツ)_/¯ Of course, you can always restore the old behaviour by setting 'nar-buffer-size' to a very high value.
This commit is contained in:
parent
7d8d78f06a
commit
34f25124ba
|
@ -365,6 +365,9 @@ public:
|
|||
|
||||
Setting<bool> warnDirty{this, true, "warn-dirty",
|
||||
"Whether to warn about dirty Git/Mercurial trees."};
|
||||
|
||||
Setting<size_t> narBufferSize{this, 32 * 1024 * 1024, "nar-buffer-size",
|
||||
"Maximum size of NARs before spilling them to disk."};
|
||||
};
|
||||
|
||||
|
||||
|
|
|
@ -1098,16 +1098,119 @@ StorePath LocalStore::addToStore(const string & name, const Path & _srcPath,
|
|||
{
|
||||
Path srcPath(absPath(_srcPath));
|
||||
|
||||
/* Read the whole path into memory. This is not a very scalable
|
||||
method for very large paths, but `copyPath' is mainly used for
|
||||
small files. */
|
||||
StringSink sink;
|
||||
if (method == FileIngestionMethod::Recursive)
|
||||
dumpPath(srcPath, sink, filter);
|
||||
else
|
||||
sink.s = make_ref<std::string>(readFile(srcPath));
|
||||
if (method != FileIngestionMethod::Recursive)
|
||||
return addToStoreFromDump(readFile(srcPath), name, method, hashAlgo, repair);
|
||||
|
||||
return addToStoreFromDump(*sink.s, name, method, hashAlgo, repair);
|
||||
/* For computing the NAR hash. */
|
||||
auto sha256Sink = std::make_unique<HashSink>(htSHA256);
|
||||
|
||||
/* For computing the store path. In recursive SHA-256 mode, this
|
||||
is the same as the NAR hash, so no need to do it again. */
|
||||
std::unique_ptr<HashSink> hashSink =
|
||||
hashAlgo == htSHA256
|
||||
? nullptr
|
||||
: std::make_unique<HashSink>(hashAlgo);
|
||||
|
||||
/* Read the source path into memory, but only if it's up to
|
||||
narBufferSize bytes. If it's larger, write it to a temporary
|
||||
location in the Nix store. If the subsequently computed
|
||||
destination store path is already valid, we just delete the
|
||||
temporary path. Otherwise, we move it to the destination store
|
||||
path. */
|
||||
bool inMemory = true;
|
||||
std::string nar;
|
||||
|
||||
auto source = sinkToSource([&](Sink & sink) {
|
||||
|
||||
LambdaSink sink2([&](const unsigned char * buf, size_t len) {
|
||||
(*sha256Sink)(buf, len);
|
||||
if (hashSink) (*hashSink)(buf, len);
|
||||
|
||||
if (inMemory) {
|
||||
if (nar.size() + len > settings.narBufferSize) {
|
||||
inMemory = false;
|
||||
sink << 1;
|
||||
sink((const unsigned char *) nar.data(), nar.size());
|
||||
nar.clear();
|
||||
} else {
|
||||
nar.append((const char *) buf, len);
|
||||
}
|
||||
}
|
||||
|
||||
if (!inMemory) sink(buf, len);
|
||||
});
|
||||
|
||||
dumpPath(srcPath, sink2, filter);
|
||||
});
|
||||
|
||||
std::unique_ptr<AutoDelete> delTempDir;
|
||||
Path tempPath;
|
||||
|
||||
try {
|
||||
/* Wait for the source coroutine to give us some dummy
|
||||
data. This is so that we don't create the temporary
|
||||
directory if the NAR fits in memory. */
|
||||
readInt(*source);
|
||||
|
||||
auto tempDir = createTempDir(realStoreDir, "add");
|
||||
delTempDir = std::make_unique<AutoDelete>(tempDir);
|
||||
tempPath = tempDir + "/x";
|
||||
|
||||
restorePath(tempPath, *source);
|
||||
|
||||
} catch (EndOfFile &) {
|
||||
if (!inMemory) throw;
|
||||
/* The NAR fits in memory, so we didn't do restorePath(). */
|
||||
}
|
||||
|
||||
auto sha256 = sha256Sink->finish();
|
||||
|
||||
Hash hash = hashSink ? hashSink->finish().first : sha256.first;
|
||||
|
||||
Path dstPath = makeFixedOutputPath(method, hash, name);
|
||||
|
||||
addTempRoot(dstPath);
|
||||
|
||||
if (repair || !isValidPath(dstPath)) {
|
||||
|
||||
/* The first check above is an optimisation to prevent
|
||||
unnecessary lock acquisition. */
|
||||
|
||||
Path realPath = realStoreDir + "/" + baseNameOf(dstPath);
|
||||
|
||||
PathLocks outputLock({realPath});
|
||||
|
||||
if (repair || !isValidPath(dstPath)) {
|
||||
|
||||
deletePath(realPath);
|
||||
|
||||
autoGC();
|
||||
|
||||
if (inMemory) {
|
||||
/* Restore from the NAR in memory. */
|
||||
StringSource source(nar);
|
||||
restorePath(realPath, source);
|
||||
} else {
|
||||
/* Move the temporary path we restored above. */
|
||||
if (rename(tempPath.c_str(), realPath.c_str()))
|
||||
throw Error("renaming '%s' to '%s'", tempPath, realPath);
|
||||
}
|
||||
|
||||
canonicalisePathMetaData(realPath, -1); // FIXME: merge into restorePath
|
||||
|
||||
optimisePath(realPath);
|
||||
|
||||
ValidPathInfo info(dstPath);
|
||||
info.narHash = sha256.first;
|
||||
info.narSize = sha256.second;
|
||||
info.ca = FixedOutputHash { .method = method, .hash = hash };
|
||||
registerValidPath(info);
|
||||
}
|
||||
|
||||
outputLock.setDeletion(true);
|
||||
}
|
||||
|
||||
return dstPath;
|
||||
}
|
||||
|
||||
|
||||
|
|
Loading…
Reference in a new issue