[llvm] 5039d36 - [Support] Remove TaskQueue
Alexandre Ganea via llvm-commits
llvm-commits at lists.llvm.org
Tue Jun 13 07:19:50 PDT 2023
Author: Raphael Isemann
Date: 2023-06-13T10:19:42-04:00
New Revision: 5039d364547c33ca69c5289894a09c48bc91e10b
URL: https://github.com/llvm/llvm-project/commit/5039d364547c33ca69c5289894a09c48bc91e10b
DIFF: https://github.com/llvm/llvm-project/commit/5039d364547c33ca69c5289894a09c48bc91e10b.diff
LOG: [Support] Remove TaskQueue
TaskQueue was added several years ago as part of D48240.
There are currently no uses of this class anywhere in LLVM and I don't see
any patch that plans to use this class, so it doesn't seem useful to keep
compiling and testing this class at the moment.
The code itself is fine, so if we actually end up having a use for this code,
then I think it's perfectly fine to just re-commit this class then.
Differential revision: https://reviews.llvm.org/D86338
Added:
Modified:
llvm/unittests/Support/CMakeLists.txt
llvm/utils/gn/secondary/llvm/unittests/Support/BUILD.gn
Removed:
llvm/include/llvm/Support/TaskQueue.h
llvm/unittests/Support/TaskQueueTest.cpp
################################################################################
diff --git a/llvm/include/llvm/Support/TaskQueue.h b/llvm/include/llvm/Support/TaskQueue.h
deleted file mode 100644
index 1b44a163568af..0000000000000
--- a/llvm/include/llvm/Support/TaskQueue.h
+++ /dev/null
@@ -1,138 +0,0 @@
-//===-- llvm/Support/TaskQueue.h - A TaskQueue implementation ---*- C++ -*-===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This file defines a crude C++11 based task queue.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_SUPPORT_TASKQUEUE_H
-#define LLVM_SUPPORT_TASKQUEUE_H
-
-#include "llvm/Config/llvm-config.h"
-#include "llvm/Support/ThreadPool.h"
-#include "llvm/Support/thread.h"
-
-#include <atomic>
-#include <cassert>
-#include <condition_variable>
-#include <deque>
-#include <functional>
-#include <future>
-#include <memory>
-#include <mutex>
-#include <utility>
-
-namespace llvm {
-/// TaskQueue executes serialized work on a user-defined Thread Pool. It
-/// guarantees that if task B is enqueued after task A, task B begins after
-/// task A completes and there is no overlap between the two.
-class TaskQueue {
- // Because we don't have init capture to use move-only local variables that
- // are captured into a lambda, we create the promise inside an explicit
- // callable struct. We want to do as much of the wrapping in the
- // type-specialized domain (before type erasure) and then erase this into a
- // std::function.
- template <typename Callable> struct Task {
- using ResultTy = std::invoke_result_t<Callable>;
- explicit Task(Callable C, TaskQueue &Parent)
- : C(std::move(C)), P(std::make_shared<std::promise<ResultTy>>()),
- Parent(&Parent) {}
-
- template<typename T>
- void invokeCallbackAndSetPromise(T*) {
- P->set_value(C());
- }
-
- void invokeCallbackAndSetPromise(void*) {
- C();
- P->set_value();
- }
-
- void operator()() noexcept {
- ResultTy *Dummy = nullptr;
- invokeCallbackAndSetPromise(Dummy);
- Parent->completeTask();
- }
-
- Callable C;
- std::shared_ptr<std::promise<ResultTy>> P;
- TaskQueue *Parent;
- };
-
-public:
- /// Construct a task queue with no work.
- TaskQueue(ThreadPool &Scheduler) : Scheduler(Scheduler) { (void)Scheduler; }
-
- /// Blocking destructor: the queue will wait for all work to complete.
- ~TaskQueue() {
- Scheduler.wait();
- assert(Tasks.empty());
- }
-
- /// Asynchronous submission of a task to the queue. The returned future can be
- /// used to wait for the task (and all previous tasks that have not yet
- /// completed) to finish.
- template <typename Callable>
- std::future<std::invoke_result_t<Callable>> async(Callable &&C) {
-#if !LLVM_ENABLE_THREADS
- static_assert(false,
- "TaskQueue requires building with LLVM_ENABLE_THREADS!");
-#endif
- Task<Callable> T{std::move(C), *this};
- using ResultTy = std::invoke_result_t<Callable>;
- std::future<ResultTy> F = T.P->get_future();
- {
- std::lock_guard<std::mutex> Lock(QueueLock);
- // If there's already a task in flight, just queue this one up. If
- // there is not a task in flight, bypass the queue and schedule this
- // task immediately.
- if (IsTaskInFlight)
- Tasks.push_back(std::move(T));
- else {
- Scheduler.async(std::move(T));
- IsTaskInFlight = true;
- }
- }
- return F;
- }
-
-private:
- void completeTask() {
- // We just completed a task. If there are no more tasks in the queue,
- // update IsTaskInFlight to false and stop doing work. Otherwise
- // schedule the next task (while not holding the lock).
- std::function<void()> Continuation;
- {
- std::lock_guard<std::mutex> Lock(QueueLock);
- if (Tasks.empty()) {
- IsTaskInFlight = false;
- return;
- }
-
- Continuation = std::move(Tasks.front());
- Tasks.pop_front();
- }
- Scheduler.async(std::move(Continuation));
- }
-
- /// The thread pool on which to run the work.
- ThreadPool &Scheduler;
-
- /// State which indicates whether the queue currently is currently processing
- /// any work.
- bool IsTaskInFlight = false;
-
- /// Mutex for synchronizing access to the Tasks array.
- std::mutex QueueLock;
-
- /// Tasks waiting for execution in the queue.
- std::deque<std::function<void()>> Tasks;
-};
-} // namespace llvm
-
-#endif // LLVM_SUPPORT_TASKQUEUE_H
diff --git a/llvm/unittests/Support/CMakeLists.txt b/llvm/unittests/Support/CMakeLists.txt
index 9b550b9b31112..016f5e19689e1 100644
--- a/llvm/unittests/Support/CMakeLists.txt
+++ b/llvm/unittests/Support/CMakeLists.txt
@@ -80,7 +80,6 @@ add_llvm_unittest(SupportTests
SuffixTreeTest.cpp
SwapByteOrderTest.cpp
TarWriterTest.cpp
- TaskQueueTest.cpp
ThreadPool.cpp
Threading.cpp
TimerTest.cpp
diff --git a/llvm/unittests/Support/TaskQueueTest.cpp b/llvm/unittests/Support/TaskQueueTest.cpp
deleted file mode 100644
index 4d8c3e4064b49..0000000000000
--- a/llvm/unittests/Support/TaskQueueTest.cpp
+++ /dev/null
@@ -1,107 +0,0 @@
-//========- unittests/Support/TaskQueue.cpp - TaskQueue.h tests ------========//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Config/llvm-config.h"
-
-#if LLVM_ENABLE_THREADS
-
-#include "llvm/Support/TaskQueue.h"
-
-#include "gtest/gtest.h"
-
-using namespace llvm;
-
-class TaskQueueTest : public testing::Test {
-protected:
- TaskQueueTest() {}
-};
-
-TEST_F(TaskQueueTest, OrderedFutures) {
- ThreadPool TP(hardware_concurrency(1));
- TaskQueue TQ(TP);
- std::atomic<int> X{ 0 };
- std::atomic<int> Y{ 0 };
- std::atomic<int> Z{ 0 };
-
- std::mutex M1, M2, M3;
- std::unique_lock<std::mutex> L1(M1);
- std::unique_lock<std::mutex> L2(M2);
- std::unique_lock<std::mutex> L3(M3);
-
- std::future<void> F1 = TQ.async([&] {
- std::unique_lock<std::mutex> Lock(M1);
- ++X;
- });
- std::future<void> F2 = TQ.async([&] {
- std::unique_lock<std::mutex> Lock(M2);
- ++Y;
- });
- std::future<void> F3 = TQ.async([&] {
- std::unique_lock<std::mutex> Lock(M3);
- ++Z;
- });
-
- L1.unlock();
- F1.wait();
- ASSERT_EQ(1, X);
- ASSERT_EQ(0, Y);
- ASSERT_EQ(0, Z);
-
- L2.unlock();
- F2.wait();
- ASSERT_EQ(1, X);
- ASSERT_EQ(1, Y);
- ASSERT_EQ(0, Z);
-
- L3.unlock();
- F3.wait();
- ASSERT_EQ(1, X);
- ASSERT_EQ(1, Y);
- ASSERT_EQ(1, Z);
-}
-
-TEST_F(TaskQueueTest, UnOrderedFutures) {
- ThreadPool TP(hardware_concurrency(1));
- TaskQueue TQ(TP);
- std::atomic<int> X{ 0 };
- std::atomic<int> Y{ 0 };
- std::atomic<int> Z{ 0 };
- std::mutex M;
-
- std::unique_lock<std::mutex> Lock(M);
-
- std::future<void> F1 = TQ.async([&] { ++X; });
- std::future<void> F2 = TQ.async([&] { ++Y; });
- std::future<void> F3 = TQ.async([&M, &Z] {
- std::unique_lock<std::mutex> Lock(M);
- ++Z;
- });
-
- F2.wait();
- ASSERT_EQ(1, X);
- ASSERT_EQ(1, Y);
- ASSERT_EQ(0, Z);
-
- Lock.unlock();
-
- F3.wait();
- ASSERT_EQ(1, X);
- ASSERT_EQ(1, Y);
- ASSERT_EQ(1, Z);
-}
-
-TEST_F(TaskQueueTest, FutureWithReturnValue) {
- ThreadPool TP(hardware_concurrency(1));
- TaskQueue TQ(TP);
- std::future<std::string> F1 = TQ.async([&] { return std::string("Hello"); });
- std::future<int> F2 = TQ.async([&] { return 42; });
-
- ASSERT_EQ(42, F2.get());
- ASSERT_EQ("Hello", F1.get());
-}
-#endif
diff --git a/llvm/utils/gn/secondary/llvm/unittests/Support/BUILD.gn b/llvm/utils/gn/secondary/llvm/unittests/Support/BUILD.gn
index e8ab17ce6c50f..7f17a69db3d3d 100644
--- a/llvm/utils/gn/secondary/llvm/unittests/Support/BUILD.gn
+++ b/llvm/utils/gn/secondary/llvm/unittests/Support/BUILD.gn
@@ -83,7 +83,6 @@ unittest("SupportTests") {
"SuffixTreeTest.cpp",
"SwapByteOrderTest.cpp",
"TarWriterTest.cpp",
- "TaskQueueTest.cpp",
"ThreadPool.cpp",
"Threading.cpp",
"TimeProfilerTest.cpp",
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