| 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-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | |
| 9 | #include "support/Cancellation.h" |
| 10 | #include <atomic> |
| 11 | |
| 12 | namespace clang { |
| 13 | namespace clangd { |
| 14 | |
| 15 | char CancelledError::ID = 0; |
| 16 | |
| 17 | // We don't want a cancelable scope to "shadow" an enclosing one. |
| 18 | struct CancelState { |
| 19 | std::shared_ptr<std::atomic<int>> Cancelled; |
| 20 | const CancelState *Parent; |
| 21 | }; |
| 22 | static Key<CancelState> StateKey; |
| 23 | |
| 24 | std::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(Key: StateKey); |
| 29 | return { |
| 30 | Context::current().derive(Key: StateKey, Value: State), |
| 31 | [Reason, Flag(State.Cancelled)] { *Flag = Reason; }, |
| 32 | }; |
| 33 | } |
| 34 | |
| 35 | int isCancelled(const Context &Ctx) { |
| 36 | for (const CancelState *State = Ctx.get(Key: StateKey); State != nullptr; |
| 37 | State = State->Parent) |
| 38 | if (int Reason = State->Cancelled->load()) |
| 39 | return Reason; |
| 40 | return 0; |
| 41 | } |
| 42 | |
| 43 | } // namespace clangd |
| 44 | } // namespace clang |
| 45 |