45 lines · cpp
1//===--- Cancellation.cpp -----------------------------------------*-C++-*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "support/Cancellation.h"10#include <atomic>11 12namespace clang {13namespace clangd {14 15char CancelledError::ID = 0;16 17// We don't want a cancelable scope to "shadow" an enclosing one.18struct CancelState {19 std::shared_ptr<std::atomic<int>> Cancelled;20 const CancelState *Parent;21};22static Key<CancelState> StateKey;23 24std::pair<Context, Canceler> cancelableTask(int Reason) {25 assert(Reason != 0 && "Can't detect cancellation if Reason is zero");26 CancelState State;27 State.Cancelled = std::make_shared<std::atomic<int>>();28 State.Parent = Context::current().get(StateKey);29 return {30 Context::current().derive(StateKey, State),31 [Reason, Flag(State.Cancelled)] { *Flag = Reason; },32 };33}34 35int isCancelled(const Context &Ctx) {36 for (const CancelState *State = Ctx.get(StateKey); State != nullptr;37 State = State->Parent)38 if (int Reason = State->Cancelled->load())39 return Reason;40 return 0;41}42 43} // namespace clangd44} // namespace clang45