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TeeSink: Pre-reserve string space

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When receiving a very large file, this can prevent the string from
having tobe copied, which temporarily doubles memory consumption.
This commit is contained in:
Eelco Dolstra 2017-03-01 16:16:04 +01:00
parent f61f67ddee
commit fa125b9b28
No known key found for this signature in database
GPG key ID: 8170B4726D7198DE
3 changed files with 21 additions and 10 deletions
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11
src/libstore/export-import.cc
View file

@ -70,9 +70,8 @@ Paths Store::importPaths(Source & source, std::shared_ptr<FSAccessor> accessor,
if (n != 1) throw Error("input doesn't look like something created by ‘nix-store --export’");
/* Extract the NAR from the source. */
TeeSource tee(source);
ParseSink sink;
parseDump(sink, tee);
TeeSink tee(source);
parseDump(tee, tee.source);
uint32_t magic = readInt(source);
if (magic != exportMagic)
@ -89,14 +88,14 @@ Paths Store::importPaths(Source & source, std::shared_ptr<FSAccessor> accessor,
info.deriver = readString(source);
if (info.deriver != "") assertStorePath(info.deriver);
info.narHash = hashString(htSHA256, *tee.data);
info.narSize = tee.data->size();
info.narHash = hashString(htSHA256, *tee.source.data);
info.narSize = tee.source.data->size();
// Ignore optional legacy signature.
if (readInt(source) == 1)
readString(source);
addToStore(info, tee.data, false, dontCheckSigs, accessor);
addToStore(info, tee.source.data, false, dontCheckSigs, accessor);
res.push_back(info.path);
}

13
src/libutil/archive.hh
View file

@ -70,6 +70,19 @@ struct ParseSink
virtual void createSymlink(const Path & path, const string & target) { };
};
struct TeeSink : ParseSink
{
TeeSource source;
TeeSink(Source & source) : source(source) { }
void preallocateContents(unsigned long long size) override
{
source.data->reserve(source.data->size() + size + 1024);
};
};
void parseDump(ParseSink & sink, Source & source);
void restorePath(const Path & path, Source & source);

7
src/nix-daemon/nix-daemon.cc
View file

@ -583,12 +583,11 @@ static void performOp(ref<LocalStore> store, bool trusted, unsigned int clientVe
if (!trusted && dontCheckSigs)
dontCheckSigs = false;
TeeSource tee(from);
ParseSink sink;
parseDump(sink, tee);
TeeSink tee(from);
parseDump(tee, tee.source);
startWork();
store->addToStore(info, tee.data, repair, dontCheckSigs, nullptr);
store->addToStore(info, tee.source.data, repair, dontCheckSigs, nullptr);
stopWork();
break;
}