[clangd] Allow CDBs to have background work to block on.

In preparation for moving DirectoryBasedCompilationDatabase broadcasting off
the main thread.

Differential Revision: https://reviews.llvm.org/D94603

Author: sam-mccall

clang-tools-extra/clangd/ClangdServer.cpp

@@ -139,7 +139,8 @@ ClangdServer::Options::operator TUScheduler::Options() const {
 ClangdServer::ClangdServer(const GlobalCompilationDatabase &CDB,
                            const ThreadsafeFS &TFS, const Options &Opts,
                            Callbacks *Callbacks)
-    : ConfigProvider(Opts.ConfigProvider), TFS(TFS), ServerCallbacks(Callbacks),
+    : ConfigProvider(Opts.ConfigProvider), CDB(CDB), TFS(TFS),
+      ServerCallbacks(Callbacks),
       DynamicIdx(Opts.BuildDynamicSymbolIndex
                      ? new FileIndex(Opts.HeavyweightDynamicSymbolIndex,
                                      Opts.CollectMainFileRefs)
@@ -870,6 +871,7 @@ Context ClangdServer::createProcessingContext(PathRef File) const {
 LLVM_NODISCARD bool
 ClangdServer::blockUntilIdleForTest(llvm::Optional<double> TimeoutSeconds) {
   return WorkScheduler.blockUntilIdle(timeoutSeconds(TimeoutSeconds)) &&
+         CDB.blockUntilIdle(timeoutSeconds(TimeoutSeconds)) &&
          (!BackgroundIdx ||
           BackgroundIdx->blockUntilIdleForTest(TimeoutSeconds));
 }

clang-tools-extra/clangd/ClangdServer.h

@@ -362,6 +362,7 @@ class ClangdServer {
   Context createProcessingContext(PathRef) const;
   config::Provider *ConfigProvider = nullptr;
 
+  const GlobalCompilationDatabase &CDB;
   const ThreadsafeFS &TFS;
   Callbacks *ServerCallbacks = nullptr;
   mutable std::mutex ConfigDiagnosticsMu;

clang-tools-extra/clangd/GlobalCompilationDatabase.cpp

@@ -636,5 +636,11 @@ tooling::CompileCommand DelegatingCDB::getFallbackCommand(PathRef File) const {
   return Base->getFallbackCommand(File);
 }
 
+bool DelegatingCDB::blockUntilIdle(Deadline D) const {
+  if (!Base)
+    return true;
+  return Base->blockUntilIdle(D);
+}
+
 } // namespace clangd
 } // namespace clang

clang-tools-extra/clangd/GlobalCompilationDatabase.h

@@ -51,6 +51,10 @@ class GlobalCompilationDatabase {
   /// Clangd should treat the results as unreliable.
   virtual tooling::CompileCommand getFallbackCommand(PathRef File) const;
 
+  /// If the CDB does any asynchronous work, wait for it to complete.
+  /// For use in tests.
+  virtual bool blockUntilIdle(Deadline D) const { return true; }
+
   using CommandChanged = Event<std::vector<std::string>>;
   /// The callback is notified when files may have new compile commands.
   /// The argument is a list of full file paths.
@@ -75,6 +79,8 @@ class DelegatingCDB : public GlobalCompilationDatabase {
 
   tooling::CompileCommand getFallbackCommand(PathRef File) const override;
 
+  bool blockUntilIdle(Deadline D) const override;
+
 private:
   const GlobalCompilationDatabase *Base;
   std::unique_ptr<GlobalCompilationDatabase> BaseOwner;