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Revert "Revert "Use template structs instead of phantoms""

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This is the more typically way to do [Argument-dependent
lookup](https://en.cppreference.com/w/cpp/language/adl)-leveraging
generic serializers in C++. It makes the relationship between the `read`
and `write` methods more clear and rigorous, and also looks more
familiar to users coming from other languages that do not have C++'s
libertine ad-hoc overloading.

I am returning to this because during the review in
https://github.com/NixOS/nix/pull/6223, it came up as something that
would make the code easier to read --- easier today hopefully already,
but definitely easier if we were have multiple codified protocols with
code sharing between them as that PR seeks to accomplish.

If I recall correctly, the main criticism of this the first time around
(in 2020) was that having to specify the type when writing, e.g.
`WorkerProto<MyType>::write`, was too verbose and cumbersome. This is
now addressed with the `workerProtoWrite` wrapper function.

This method is also the way `nlohmann::json`, which we have used for a
number of years now, does its serializers, for what its worth.

This reverts commit 45a0ed82f0. That
commit in turn reverted 9ab07e99f5.
This commit is contained in:
John Ericson 2023-05-17 22:04:59 -04:00
parent 684e9be8b9
commit cb5052d98f
10 changed files with 182 additions and 151 deletions
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62
src/libstore/remote-store.cc
View file

@ -100,7 +100,7 @@ void RemoteStore::initConnection(Connection & conn)
}
if (GET_PROTOCOL_MINOR(conn.daemonVersion) >= 35) {
conn.remoteTrustsUs = worker_proto::read(*this, conn.from, Phantom<std::optional<TrustedFlag>> {});
conn.remoteTrustsUs = WorkerProto<std::optional<TrustedFlag>>::read(*this, conn.from);
} else {
// We don't know the answer; protocol to old.
conn.remoteTrustsUs = std::nullopt;
@ -227,12 +227,12 @@ StorePathSet RemoteStore::queryValidPaths(const StorePathSet & paths, Substitute
return res;
} else {
conn->to << wopQueryValidPaths;
worker_proto::write(*this, conn->to, paths);
workerProtoWrite(*this, conn->to, paths);
if (GET_PROTOCOL_MINOR(conn->daemonVersion) >= 27) {
conn->to << (settings.buildersUseSubstitutes ? 1 : 0);
}
conn.processStderr();
return worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
return WorkerProto<StorePathSet>::read(*this, conn->from);
}
}
@ -242,7 +242,7 @@ StorePathSet RemoteStore::queryAllValidPaths()
auto conn(getConnection());
conn->to << wopQueryAllValidPaths;
conn.processStderr();
return worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
return WorkerProto<StorePathSet>::read(*this, conn->from);
}
@ -259,9 +259,9 @@ StorePathSet RemoteStore::querySubstitutablePaths(const StorePathSet & paths)
return res;
} else {
conn->to << wopQuerySubstitutablePaths;
worker_proto::write(*this, conn->to, paths);
workerProtoWrite(*this, conn->to, paths);
conn.processStderr();
return worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
return WorkerProto<StorePathSet>::read(*this, conn->from);
}
}
@ -283,7 +283,7 @@ void RemoteStore::querySubstitutablePathInfos(const StorePathCAMap & pathsMap, S
auto deriver = readString(conn->from);
if (deriver != "")
info.deriver = parseStorePath(deriver);
info.references = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
info.references = WorkerProto<StorePathSet>::read(*this, conn->from);
info.downloadSize = readLongLong(conn->from);
info.narSize = readLongLong(conn->from);
infos.insert_or_assign(i.first, std::move(info));
@ -296,9 +296,9 @@ void RemoteStore::querySubstitutablePathInfos(const StorePathCAMap & pathsMap, S
StorePathSet paths;
for (auto & path : pathsMap)
paths.insert(path.first);
worker_proto::write(*this, conn->to, paths);
workerProtoWrite(*this, conn->to, paths);
} else
worker_proto::write(*this, conn->to, pathsMap);
workerProtoWrite(*this, conn->to, pathsMap);
conn.processStderr();
size_t count = readNum<size_t>(conn->from);
for (size_t n = 0; n < count; n++) {
@ -306,7 +306,7 @@ void RemoteStore::querySubstitutablePathInfos(const StorePathCAMap & pathsMap, S
auto deriver = readString(conn->from);
if (deriver != "")
info.deriver = parseStorePath(deriver);
info.references = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
info.references = WorkerProto<StorePathSet>::read(*this, conn->from);
info.downloadSize = readLongLong(conn->from);
info.narSize = readLongLong(conn->from);
}
@ -349,7 +349,7 @@ void RemoteStore::queryReferrers(const StorePath & path,
auto conn(getConnection());
conn->to << wopQueryReferrers << printStorePath(path);
conn.processStderr();
for (auto & i : worker_proto::read(*this, conn->from, Phantom<StorePathSet> {}))
for (auto & i : WorkerProto<StorePathSet>::read(*this, conn->from))
referrers.insert(i);
}
@ -359,7 +359,7 @@ StorePathSet RemoteStore::queryValidDerivers(const StorePath & path)
auto conn(getConnection());
conn->to << wopQueryValidDerivers << printStorePath(path);
conn.processStderr();
return worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
return WorkerProto<StorePathSet>::read(*this, conn->from);
}
@ -371,7 +371,7 @@ StorePathSet RemoteStore::queryDerivationOutputs(const StorePath & path)
auto conn(getConnection());
conn->to << wopQueryDerivationOutputs << printStorePath(path);
conn.processStderr();
return worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
return WorkerProto<StorePathSet>::read(*this, conn->from);
}
@ -381,7 +381,7 @@ std::map<std::string, std::optional<StorePath>> RemoteStore::queryPartialDerivat
auto conn(getConnection());
conn->to << wopQueryDerivationOutputMap << printStorePath(path);
conn.processStderr();
return worker_proto::read(*this, conn->from, Phantom<std::map<std::string, std::optional<StorePath>>> {});
return WorkerProto<std::map<std::string, std::optional<StorePath>>>::read(*this, conn->from);
} else {
// Fallback for old daemon versions.
// For floating-CA derivations (and their co-dependencies) this is an
@ -427,7 +427,7 @@ ref<const ValidPathInfo> RemoteStore::addCAToStore(
<< wopAddToStore
<< name
<< caMethod.render(hashType);
worker_proto::write(*this, conn->to, references);
workerProtoWrite(*this, conn->to, references);
conn->to << repair;
// The dump source may invoke the store, so we need to make some room.
@ -452,7 +452,7 @@ ref<const ValidPathInfo> RemoteStore::addCAToStore(
name, printHashType(hashType));
std::string s = dump.drain();
conn->to << wopAddTextToStore << name << s;
worker_proto::write(*this, conn->to, references);
workerProtoWrite(*this, conn->to, references);
conn.processStderr();
},
[&](const FileIngestionMethod & fim) -> void {
@ -518,7 +518,7 @@ void RemoteStore::addToStore(const ValidPathInfo & info, Source & source,
sink
<< exportMagic
<< printStorePath(info.path);
worker_proto::write(*this, sink, info.references);
workerProtoWrite(*this, sink, info.references);
sink
<< (info.deriver ? printStorePath(*info.deriver) : "")
<< 0 // == no legacy signature
@ -528,7 +528,7 @@ void RemoteStore::addToStore(const ValidPathInfo & info, Source & source,
conn.processStderr(0, source2.get());
auto importedPaths = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
auto importedPaths = WorkerProto<StorePathSet>::read(*this, conn->from);
assert(importedPaths.size() <= 1);
}
@ -537,7 +537,7 @@ void RemoteStore::addToStore(const ValidPathInfo & info, Source & source,
<< printStorePath(info.path)
<< (info.deriver ? printStorePath(*info.deriver) : "")
<< info.narHash.to_string(Base16, false);
worker_proto::write(*this, conn->to, info.references);
workerProtoWrite(*this, conn->to, info.references);
conn->to << info.registrationTime << info.narSize
<< info.ultimate << info.sigs << renderContentAddress(info.ca)
<< repair << !checkSigs;
@ -610,7 +610,7 @@ void RemoteStore::registerDrvOutput(const Realisation & info)
conn->to << info.id.to_string();
conn->to << std::string(info.outPath.to_string());
} else {
worker_proto::write(*this, conn->to, info);
workerProtoWrite(*this, conn->to, info);
}
conn.processStderr();
}
@ -632,14 +632,14 @@ void RemoteStore::queryRealisationUncached(const DrvOutput & id,
auto real = [&]() -> std::shared_ptr<const Realisation> {
if (GET_PROTOCOL_MINOR(conn->daemonVersion) < 31) {
auto outPaths = worker_proto::read(
*this, conn->from, Phantom<std::set<StorePath>> {});
auto outPaths = WorkerProto<std::set<StorePath>>::read(
*this, conn->from);
if (outPaths.empty())
return nullptr;
return std::make_shared<const Realisation>(Realisation { .id = id, .outPath = *outPaths.begin() });
} else {
auto realisations = worker_proto::read(
*this, conn->from, Phantom<std::set<Realisation>> {});
auto realisations = WorkerProto<std::set<Realisation>>::read(
*this, conn->from);
if (realisations.empty())
return nullptr;
return std::make_shared<const Realisation>(*realisations.begin());
@ -653,7 +653,7 @@ void RemoteStore::queryRealisationUncached(const DrvOutput & id,
static void writeDerivedPaths(RemoteStore & store, ConnectionHandle & conn, const std::vector<DerivedPath> & reqs)
{
if (GET_PROTOCOL_MINOR(conn->daemonVersion) >= 30) {
worker_proto::write(store, conn->to, reqs);
workerProtoWrite(store, conn->to, reqs);
} else {
Strings ss;
for (auto & p : reqs) {
@ -723,7 +723,7 @@ std::vector<KeyedBuildResult> RemoteStore::buildPathsWithResults(
writeDerivedPaths(*this, conn, paths);
conn->to << buildMode;
conn.processStderr();
return worker_proto::read(*this, conn->from, Phantom<std::vector<KeyedBuildResult>> {});
return WorkerProto<std::vector<KeyedBuildResult>>::read(*this, conn->from);
} else {
// Avoid deadlock.
conn_.reset();
@ -806,7 +806,7 @@ BuildResult RemoteStore::buildDerivation(const StorePath & drvPath, const BasicD
conn->from >> res.timesBuilt >> res.isNonDeterministic >> res.startTime >> res.stopTime;
}
if (GET_PROTOCOL_MINOR(conn->daemonVersion) >= 28) {
auto builtOutputs = worker_proto::read(*this, conn->from, Phantom<DrvOutputs> {});
auto builtOutputs = WorkerProto<DrvOutputs>::read(*this, conn->from);
for (auto && [output, realisation] : builtOutputs)
res.builtOutputs.insert_or_assign(
std::move(output.outputName),
@ -865,7 +865,7 @@ void RemoteStore::collectGarbage(const GCOptions & options, GCResults & results)
conn->to
<< wopCollectGarbage << options.action;
worker_proto::write(*this, conn->to, options.pathsToDelete);
workerProtoWrite(*this, conn->to, options.pathsToDelete);
conn->to << options.ignoreLiveness
<< options.maxFreed
/* removed options */
@ -924,9 +924,9 @@ void RemoteStore::queryMissing(const std::vector<DerivedPath> & targets,
conn->to << wopQueryMissing;
writeDerivedPaths(*this, conn, targets);
conn.processStderr();
willBuild = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
willSubstitute = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
unknown = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
willBuild = WorkerProto<StorePathSet>::read(*this, conn->from);
willSubstitute = WorkerProto<StorePathSet>::read(*this, conn->from);
unknown = WorkerProto<StorePathSet>::read(*this, conn->from);
conn->from >> downloadSize >> narSize;
return;
}