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[stable/20221013] Proper fix for race in ClangdServer shutdown #5938

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Merged
merged 2 commits into from
Jan 9, 2023
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[stable/20221013] Proper fix for race in ClangdServer shutdown #5938

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eeb1938
Revert "[clangd] Wait for stdlib indexing to finish before destroying…
bnbarham Jan 9, 2023
8a93c5b
[clangd] Fix crashing race in ClangdServer shutdown with stdlib indexing
sam-mccall Dec 21, 2022
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26 changes: 16 additions & 10 deletions clang-tools-extra/clangd/ClangdServer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -63,27 +63,36 @@ struct UpdateIndexCallbacks : public ParsingCallbacks {
ClangdServer::Callbacks *ServerCallbacks,
const ThreadsafeFS &TFS, AsyncTaskRunner *Tasks)
: FIndex(FIndex), ServerCallbacks(ServerCallbacks), TFS(TFS),
Tasks(Tasks) {}
Stdlib{std::make_shared<StdLibSet>()}, Tasks(Tasks) {}

void onPreambleAST(PathRef Path, llvm::StringRef Version,
const CompilerInvocation &CI, ASTContext &Ctx,
Preprocessor &PP,
const CanonicalIncludes &CanonIncludes) override {
// If this preamble uses a standard library we haven't seen yet, index it.
if (FIndex)
if (auto Loc = Stdlib.add(*CI.getLangOpts(), PP.getHeaderSearchInfo()))
if (auto Loc = Stdlib->add(*CI.getLangOpts(), PP.getHeaderSearchInfo()))
indexStdlib(CI, std::move(*Loc));

if (FIndex)
FIndex->updatePreamble(Path, Version, Ctx, PP, CanonIncludes);
}

void indexStdlib(const CompilerInvocation &CI, StdLibLocation Loc) {
auto Task = [this, LO(*CI.getLangOpts()), Loc(std::move(Loc)),
CI(std::make_unique<CompilerInvocation>(CI))]() mutable {
// This task is owned by Tasks, which outlives the TUScheduler and
// therefore the UpdateIndexCallbacks.
// We must be careful that the references we capture outlive TUScheduler.
auto Task = [LO(*CI.getLangOpts()), Loc(std::move(Loc)),
CI(std::make_unique<CompilerInvocation>(CI)),
// External values that outlive ClangdServer
TFS(&TFS),
// Index outlives TUScheduler (declared first)
FIndex(FIndex),
// shared_ptr extends lifetime
Stdlib(Stdlib)]() mutable {
IndexFileIn IF;
IF.Symbols = indexStandardLibrary(std::move(CI), Loc, TFS);
if (Stdlib.isBest(LO))
IF.Symbols = indexStandardLibrary(std::move(CI), Loc, *TFS);
if (Stdlib->isBest(LO))
FIndex->updatePreamble(std::move(IF));
};
if (Tasks)
Expand Down Expand Up @@ -128,7 +137,7 @@ struct UpdateIndexCallbacks : public ParsingCallbacks {
FileIndex *FIndex;
ClangdServer::Callbacks *ServerCallbacks;
const ThreadsafeFS &TFS;
StdLibSet Stdlib;
std::shared_ptr<StdLibSet> Stdlib;
AsyncTaskRunner *Tasks;
};

Expand Down Expand Up @@ -233,9 +242,6 @@ ClangdServer::ClangdServer(const GlobalCompilationDatabase &CDB,
}

ClangdServer::~ClangdServer() {
// Wait for stdlib indexing to finish.
if (IndexTasks)
IndexTasks->wait();
// Destroying TUScheduler first shuts down request threads that might
// otherwise access members concurrently.
// (Nobody can be using TUScheduler because we're on the main thread).
Expand Down