forked from OSchip/llvm-project
258 lines
10 KiB
C++
258 lines
10 KiB
C++
//===--- TUScheduler.h -------------------------------------------*-C++-*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_TUSCHEDULER_H
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#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_TUSCHEDULER_H
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#include "ClangdUnit.h"
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#include "Function.h"
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#include "GlobalCompilationDatabase.h"
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#include "Threading.h"
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#include "index/CanonicalIncludes.h"
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#include "llvm/ADT/Optional.h"
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#include "llvm/ADT/StringMap.h"
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#include "llvm/ADT/StringRef.h"
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#include <future>
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namespace clang {
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namespace clangd {
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/// Returns a number of a default async threads to use for TUScheduler.
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/// Returned value is always >= 1 (i.e. will not cause requests to be processed
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/// synchronously).
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unsigned getDefaultAsyncThreadsCount();
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struct InputsAndAST {
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const ParseInputs &Inputs;
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ParsedAST &AST;
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};
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struct InputsAndPreamble {
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llvm::StringRef Contents;
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const tooling::CompileCommand &Command;
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// This can be nullptr if no preamble is availble.
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const PreambleData *Preamble;
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};
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/// Determines whether diagnostics should be generated for a file snapshot.
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enum class WantDiagnostics {
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Yes, /// Diagnostics must be generated for this snapshot.
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No, /// Diagnostics must not be generated for this snapshot.
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Auto, /// Diagnostics must be generated for this snapshot or a subsequent one,
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/// within a bounded amount of time.
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};
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/// Configuration of the AST retention policy. This only covers retention of
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/// *idle* ASTs. If queue has operations requiring the AST, they might be
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/// kept in memory.
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struct ASTRetentionPolicy {
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/// Maximum number of ASTs to be retained in memory when there are no pending
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/// requests for them.
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unsigned MaxRetainedASTs = 3;
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};
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struct TUAction {
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enum State {
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Queued, // The TU is pending in the thread task queue to be built.
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RunningAction, // Starting running actions on the TU.
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BuildingPreamble, // The preamble of the TU is being built.
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BuildingFile, // The TU is being built. It is only emitted when building
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// the AST for diagnostics in write action (update).
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Idle, // Indicates the worker thread is idle, and ready to run any upcoming
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// actions.
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};
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TUAction(State S, llvm::StringRef Name) : S(S), Name(Name) {}
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State S;
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/// The name of the action currently running, e.g. Update, GoToDef, Hover.
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/// Empty if we are in the idle state.
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std::string Name;
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};
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// Internal status of the TU in TUScheduler.
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struct TUStatus {
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struct BuildDetails {
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/// Indicates whether clang failed to build the TU.
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bool BuildFailed = false;
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/// Indicates whether we reused the prebuilt AST.
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bool ReuseAST = false;
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};
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/// Serialize this to an LSP file status item.
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FileStatus render(PathRef File) const;
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TUAction Action;
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BuildDetails Details;
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};
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class ParsingCallbacks {
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public:
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virtual ~ParsingCallbacks() = default;
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/// Called on the AST that was built for emitting the preamble. The built AST
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/// contains only AST nodes from the #include directives at the start of the
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/// file. AST node in the current file should be observed on onMainAST call.
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virtual void onPreambleAST(PathRef Path, ASTContext &Ctx,
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std::shared_ptr<clang::Preprocessor> PP,
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const CanonicalIncludes &) {}
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/// Called on the AST built for the file itself. Note that preamble AST nodes
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/// are not deserialized and should be processed in the onPreambleAST call
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/// instead.
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/// The \p AST always contains all AST nodes for the main file itself, and
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/// only a portion of the AST nodes deserialized from the preamble. Note that
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/// some nodes from the preamble may have been deserialized and may also be
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/// accessed from the main file AST, e.g. redecls of functions from preamble,
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/// etc. Clients are expected to process only the AST nodes from the main file
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/// in this callback (obtained via ParsedAST::getLocalTopLevelDecls) to obtain
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/// optimal performance.
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virtual void onMainAST(PathRef Path, ParsedAST &AST) {}
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/// Called whenever the diagnostics for \p File are produced.
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virtual void onDiagnostics(PathRef File, std::vector<Diag> Diags) {}
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/// Called whenever the TU status is updated.
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virtual void onFileUpdated(PathRef File, const TUStatus &Status) {}
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};
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/// Handles running tasks for ClangdServer and managing the resources (e.g.,
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/// preambles and ASTs) for opened files.
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/// TUScheduler is not thread-safe, only one thread should be providing updates
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/// and scheduling tasks.
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/// Callbacks are run on a threadpool and it's appropriate to do slow work in
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/// them. Each task has a name, used for tracing (should be UpperCamelCase).
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/// FIXME(sammccall): pull out a scheduler options struct.
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class TUScheduler {
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public:
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TUScheduler(const GlobalCompilationDatabase &CDB, unsigned AsyncThreadsCount,
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bool StorePreamblesInMemory,
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std::unique_ptr<ParsingCallbacks> ASTCallbacks,
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std::chrono::steady_clock::duration UpdateDebounce,
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ASTRetentionPolicy RetentionPolicy);
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~TUScheduler();
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/// Returns estimated memory usage for each of the currently open files.
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/// The order of results is unspecified.
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std::vector<std::pair<Path, std::size_t>> getUsedBytesPerFile() const;
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/// Returns a list of files with ASTs currently stored in memory. This method
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/// is not very reliable and is only used for test. E.g., the results will not
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/// contain files that currently run something over their AST.
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std::vector<Path> getFilesWithCachedAST() const;
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/// Schedule an update for \p File.
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/// The compile command in \p Inputs is ignored; worker queries CDB to get
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/// the actual compile command.
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/// If diagnostics are requested (Yes), and the context is cancelled
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/// before they are prepared, they may be skipped if eventual-consistency
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/// permits it (i.e. WantDiagnostics is downgraded to Auto).
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/// Returns true if the file was not previously tracked.
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bool update(PathRef File, ParseInputs Inputs, WantDiagnostics WD);
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/// Remove \p File from the list of tracked files and schedule removal of its
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/// resources. Pending diagnostics for closed files may not be delivered, even
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/// if requested with WantDiags::Auto or WantDiags::Yes.
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void remove(PathRef File);
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/// Returns the current contents of the buffer for File, per last update().
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/// The returned StringRef may be invalidated by any write to TUScheduler.
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llvm::StringRef getContents(PathRef File) const;
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/// Schedule an async task with no dependencies.
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void run(llvm::StringRef Name, llvm::unique_function<void()> Action);
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/// Schedule an async read of the AST. \p Action will be called when AST is
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/// ready. The AST passed to \p Action refers to the version of \p File
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/// tracked at the time of the call, even if new updates are received before
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/// \p Action is executed.
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/// If an error occurs during processing, it is forwarded to the \p Action
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/// callback.
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/// If the context is cancelled before the AST is ready, the callback will
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/// receive a CancelledError.
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void runWithAST(llvm::StringRef Name, PathRef File,
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Callback<InputsAndAST> Action);
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/// Controls whether preamble reads wait for the preamble to be up-to-date.
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enum PreambleConsistency {
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/// The preamble is generated from the current version of the file.
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/// If the content was recently updated, we will wait until we have a
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/// preamble that reflects that update.
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/// This is the slowest option, and may be delayed by other tasks.
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Consistent,
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/// The preamble may be generated from an older version of the file.
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/// Reading from locations in the preamble may cause files to be re-read.
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/// This gives callers two options:
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/// - validate that the preamble is still valid, and only use it if so
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/// - accept that the preamble contents may be outdated, and try to avoid
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/// reading source code from headers.
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/// This is the fastest option, usually a preamble is available immediately.
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Stale,
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/// Besides accepting stale preamble, this also allow preamble to be absent
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/// (not ready or failed to build).
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StaleOrAbsent,
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};
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/// Schedule an async read of the preamble.
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/// If there's no up-to-date preamble, we follow the PreambleConsistency
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/// policy.
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/// If an error occurs, it is forwarded to the \p Action callback.
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/// Context cancellation is ignored and should be handled by the Action.
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/// (In practice, the Action is almost always executed immediately).
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void runWithPreamble(llvm::StringRef Name, PathRef File,
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PreambleConsistency Consistency,
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Callback<InputsAndPreamble> Action);
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/// Wait until there are no scheduled or running tasks.
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/// Mostly useful for synchronizing tests.
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bool blockUntilIdle(Deadline D) const;
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private:
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/// This class stores per-file data in the Files map.
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struct FileData;
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public:
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/// Responsible for retaining and rebuilding idle ASTs. An implementation is
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/// an LRU cache.
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class ASTCache;
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// The file being built/processed in the current thread. This is a hack in
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// order to get the file name into the index implementations. Do not depend on
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// this inside clangd.
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// FIXME: remove this when there is proper index support via build system
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// integration.
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static llvm::Optional<llvm::StringRef> getFileBeingProcessedInContext();
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private:
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const GlobalCompilationDatabase &CDB;
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const bool StorePreamblesInMemory;
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std::unique_ptr<ParsingCallbacks> Callbacks; // not nullptr
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Semaphore Barrier;
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llvm::StringMap<std::unique_ptr<FileData>> Files;
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std::unique_ptr<ASTCache> IdleASTs;
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// None when running tasks synchronously and non-None when running tasks
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// asynchronously.
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llvm::Optional<AsyncTaskRunner> PreambleTasks;
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llvm::Optional<AsyncTaskRunner> WorkerThreads;
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std::chrono::steady_clock::duration UpdateDebounce;
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};
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/// Runs \p Action asynchronously with a new std::thread. The context will be
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/// propagated.
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template <typename T>
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std::future<T> runAsync(llvm::unique_function<T()> Action) {
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return std::async(
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std::launch::async,
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[](llvm::unique_function<T()> &&Action, Context Ctx) {
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WithContext WithCtx(std::move(Ctx));
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return Action();
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},
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std::move(Action), Context::current().clone());
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}
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} // namespace clangd
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} // namespace clang
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#endif
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