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NarAccessor: Run in constant memory

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This commit is contained in:
Eelco Dolstra 2020-07-13 17:30:42 +02:00
parent fc84c358d9
commit 0a9da00a10
7 changed files with 57 additions and 37 deletions
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16
src/libstore/binary-cache-store.cc
View file

@ -155,13 +155,17 @@ void BinaryCacheStore::addToStore(const ValidPathInfo & info, Source & narSource
auto now1 = std::chrono::steady_clock::now();
/* Read the NAR simultaneously into a CompressionSink+FileSink (to
write the compressed NAR to disk), into a HashSink (to get the
NAR hash), and into a NarAccessor (to get the NAR listing). */
HashSink fileHashSink(htSHA256);
std::shared_ptr<FSAccessor> narAccessor;
{
FdSink fileSink(fdTemp.get());
TeeSink teeSink(fileSink, fileHashSink);
auto compressionSink = makeCompressionSink(compression, teeSink);
copyNAR(narSource, *compressionSink);
TeeSource teeSource(narSource, *compressionSink);
narAccessor = makeNarAccessor(teeSource);
compressionSink->finish();
}
@ -200,10 +204,9 @@ void BinaryCacheStore::addToStore(const ValidPathInfo & info, Source & narSource
#if 0
auto accessor_ = std::dynamic_pointer_cast<RemoteFSAccessor>(accessor);
auto narAccessor = makeNarAccessor(nar);
if (accessor_)
accessor_->addToCache(printStorePath(info.path), *nar, narAccessor);
#endif
/* Optionally write a JSON file containing a listing of the
contents of the NAR. */
@ -216,15 +219,13 @@ void BinaryCacheStore::addToStore(const ValidPathInfo & info, Source & narSource
{
auto res = jsonRoot.placeholder("root");
listNar(res, narAccessor, "", true);
listNar(res, ref<FSAccessor>(narAccessor), "", true);
}
}
upsertFile(std::string(info.path.to_string()) + ".ls", jsonOut.str(), "application/json");
}
#endif
#if 0
/* Optionally maintain an index of DWARF debug info files
consisting of JSON files named 'debuginfo/<build-id>' that
specify the NAR file and member containing the debug info. */
@ -281,7 +282,6 @@ void BinaryCacheStore::addToStore(const ValidPathInfo & info, Source & narSource
threadPool.process();
}
}
#endif
/* Atomically write the NAR file. */
if (repair || !fileExists(narInfo->url)) {

9
src/libstore/daemon.cc
View file

@ -391,7 +391,8 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
}
HashType hashAlgo = parseHashType(s);
TeeSource savedNAR(from);
StringSink savedNAR;
TeeSource savedNARSource(from, savedNAR);
RetrieveRegularNARSink savedRegular;
if (method == FileIngestionMethod::Recursive) {
@ -399,7 +400,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
a string so that we can pass it to
addToStoreFromDump(). */
ParseSink sink; /* null sink; just parse the NAR */
parseDump(sink, savedNAR);
parseDump(sink, savedNARSource);
} else
parseDump(savedRegular, from);
@ -407,7 +408,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
if (!savedRegular.regular) throw Error("regular file expected");
auto path = store->addToStoreFromDump(
method == FileIngestionMethod::Recursive ? *savedNAR.data : savedRegular.s,
method == FileIngestionMethod::Recursive ? *savedNAR.s : savedRegular.s,
baseName,
method,
hashAlgo);
@ -733,7 +734,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
else {
TeeParseSink tee(from);
parseDump(tee, tee.source);
saved = std::move(*tee.source.data);
saved = std::move(*tee.saved.s);
source = std::make_unique<StringSource>(saved);
}

6
src/libstore/export-import.cc
View file

@ -77,15 +77,15 @@ StorePaths Store::importPaths(Source & source, std::shared_ptr<FSAccessor> acces
if (deriver != "")
info.deriver = parseStorePath(deriver);
info.narHash = hashString(htSHA256, *tee.source.data);
info.narSize = tee.source.data->size();
info.narHash = hashString(htSHA256, *tee.saved.s);
info.narSize = tee.saved.s->size();
// Ignore optional legacy signature.
if (readInt(source) == 1)
readString(source);
// Can't use underlying source, which would have been exhausted
auto source = StringSource { *tee.source.data };
auto source = StringSource { *tee.saved.s };
addToStore(info, source, NoRepair, checkSigs, accessor);
res.push_back(info.path);

46
src/libstore/nar-accessor.cc
View file

@ -18,7 +18,7 @@ struct NarMember
/* If this is a regular file, position of the contents of this
file in the NAR. */
size_t start = 0, size = 0;
uint64_t start = 0, size = 0;
std::string target;
@ -34,17 +34,19 @@ struct NarAccessor : public FSAccessor
NarMember root;
struct NarIndexer : ParseSink, StringSource
struct NarIndexer : ParseSink, Source
{
NarAccessor & acc;
Source & source;
std::stack<NarMember *> parents;
std::string currentStart;
bool isExec = false;
NarIndexer(NarAccessor & acc, const std::string & nar)
: StringSource(nar), acc(acc)
uint64_t pos = 0;
NarIndexer(NarAccessor & acc, Source & source)
: acc(acc), source(source)
{ }
void createMember(const Path & path, NarMember member) {
@ -79,31 +81,38 @@ struct NarAccessor : public FSAccessor
void preallocateContents(unsigned long long size) override
{
currentStart = string(s, pos, 16);
assert(size <= std::numeric_limits<size_t>::max());
parents.top()->size = (size_t)size;
assert(size <= std::numeric_limits<uint64_t>::max());
parents.top()->size = (uint64_t) size;
parents.top()->start = pos;
}
void receiveContents(unsigned char * data, unsigned int len) override
{
// Sanity check
if (!currentStart.empty()) {
assert(len < 16 || currentStart == string((char *) data, 16));
currentStart.clear();
}
}
{ }
void createSymlink(const Path & path, const string & target) override
{
createMember(path,
NarMember{FSAccessor::Type::tSymlink, false, 0, 0, target});
}
size_t read(unsigned char * data, size_t len) override
{
auto n = source.read(data, len);
pos += n;
return n;
}
};
NarAccessor(ref<const std::string> nar) : nar(nar)
{
NarIndexer indexer(*this, *nar);
StringSource source(*nar);
NarIndexer indexer(*this, source);
parseDump(indexer, indexer);
}
NarAccessor(Source & source)
{
NarIndexer indexer(*this, source);
parseDump(indexer, indexer);
}
@ -219,6 +228,11 @@ ref<FSAccessor> makeNarAccessor(ref<const std::string> nar)
return make_ref<NarAccessor>(nar);
}
ref<FSAccessor> makeNarAccessor(Source & source)
{
return make_ref<NarAccessor>(source);
}
ref<FSAccessor> makeLazyNarAccessor(const std::string & listing,
GetNarBytes getNarBytes)
{

4
src/libstore/nar-accessor.hh
View file

@ -6,10 +6,14 @@
namespace nix {
struct Source;
/* Return an object that provides access to the contents of a NAR
file. */
ref<FSAccessor> makeNarAccessor(ref<const std::string> nar);
ref<FSAccessor> makeNarAccessor(Source & source);
/* Create a NAR accessor from a NAR listing (in the format produced by
listNar()). The callback getNarBytes(offset, length) is used by the
readFile() method of the accessor to get the contents of files

3
src/libutil/archive.hh
View file

@ -65,9 +65,10 @@ struct ParseSink
struct TeeParseSink : ParseSink
{
StringSink saved;
TeeSource source;
TeeParseSink(Source & source) : source(source) { }
TeeParseSink(Source & source) : source(source, saved) { }
};
void parseDump(ParseSink & sink, Source & source);

10
src/libutil/serialise.hh
View file

@ -179,17 +179,17 @@ struct TeeSink : Sink
};
/* Adapter class of a Source that saves all data read to `s'. */
/* Adapter class of a Source that saves all data read to a sink. */
struct TeeSource : Source
{
Source & orig;
ref<std::string> data;
TeeSource(Source & orig)
: orig(orig), data(make_ref<std::string>()) { }
Sink & sink;
TeeSource(Source & orig, Sink & sink)
: orig(orig), sink(sink) { }
size_t read(unsigned char * data, size_t len)
{
size_t n = orig.read(data, len);
this->data->append((const char *) data, n);
sink(data, len);
return n;
}
};