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author | vitalyisaev <vitalyisaev@yandex-team.com> | 2023-06-29 10:00:50 +0300 |
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committer | vitalyisaev <vitalyisaev@yandex-team.com> | 2023-06-29 10:00:50 +0300 |
commit | 6ffe9e53658409f212834330e13564e4952558f6 (patch) | |
tree | 85b1e00183517648b228aafa7c8fb07f5276f419 /contrib/libs/llvm14/lib/Support/Parallel.cpp | |
parent | 726057070f9c5a91fc10fde0d5024913d10f1ab9 (diff) | |
download | ydb-6ffe9e53658409f212834330e13564e4952558f6.tar.gz |
YQ Connector: support managed ClickHouse
Со стороны dqrun можно обратиться к инстансу коннектора, который работает на streaming стенде, и извлечь данные из облачного CH.
Diffstat (limited to 'contrib/libs/llvm14/lib/Support/Parallel.cpp')
-rw-r--r-- | contrib/libs/llvm14/lib/Support/Parallel.cpp | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/contrib/libs/llvm14/lib/Support/Parallel.cpp b/contrib/libs/llvm14/lib/Support/Parallel.cpp new file mode 100644 index 0000000000..4977c188f9 --- /dev/null +++ b/contrib/libs/llvm14/lib/Support/Parallel.cpp @@ -0,0 +1,208 @@ +//===- llvm/Support/Parallel.cpp - Parallel algorithms --------------------===// +// +// 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/Support/Parallel.h" +#include "llvm/Config/llvm-config.h" +#include "llvm/Support/ManagedStatic.h" +#include "llvm/Support/Threading.h" + +#include <atomic> +#include <future> +#include <stack> +#include <thread> +#include <vector> + +llvm::ThreadPoolStrategy llvm::parallel::strategy; + +#if LLVM_ENABLE_THREADS + +namespace llvm { +namespace parallel { +namespace detail { + +namespace { + +/// An abstract class that takes closures and runs them asynchronously. +class Executor { +public: + virtual ~Executor() = default; + virtual void add(std::function<void()> func) = 0; + + static Executor *getDefaultExecutor(); +}; + +/// An implementation of an Executor that runs closures on a thread pool +/// in filo order. +class ThreadPoolExecutor : public Executor { +public: + explicit ThreadPoolExecutor(ThreadPoolStrategy S = hardware_concurrency()) { + unsigned ThreadCount = S.compute_thread_count(); + // Spawn all but one of the threads in another thread as spawning threads + // can take a while. + Threads.reserve(ThreadCount); + Threads.resize(1); + std::lock_guard<std::mutex> Lock(Mutex); + Threads[0] = std::thread([this, ThreadCount, S] { + for (unsigned I = 1; I < ThreadCount; ++I) { + Threads.emplace_back([=] { work(S, I); }); + if (Stop) + break; + } + ThreadsCreated.set_value(); + work(S, 0); + }); + } + + void stop() { + { + std::lock_guard<std::mutex> Lock(Mutex); + if (Stop) + return; + Stop = true; + } + Cond.notify_all(); + ThreadsCreated.get_future().wait(); + } + + ~ThreadPoolExecutor() override { + stop(); + std::thread::id CurrentThreadId = std::this_thread::get_id(); + for (std::thread &T : Threads) + if (T.get_id() == CurrentThreadId) + T.detach(); + else + T.join(); + } + + struct Creator { + static void *call() { return new ThreadPoolExecutor(strategy); } + }; + struct Deleter { + static void call(void *Ptr) { ((ThreadPoolExecutor *)Ptr)->stop(); } + }; + + void add(std::function<void()> F) override { + { + std::lock_guard<std::mutex> Lock(Mutex); + WorkStack.push(F); + } + Cond.notify_one(); + } + +private: + void work(ThreadPoolStrategy S, unsigned ThreadID) { + S.apply_thread_strategy(ThreadID); + while (true) { + std::unique_lock<std::mutex> Lock(Mutex); + Cond.wait(Lock, [&] { return Stop || !WorkStack.empty(); }); + if (Stop) + break; + auto Task = WorkStack.top(); + WorkStack.pop(); + Lock.unlock(); + Task(); + } + } + + std::atomic<bool> Stop{false}; + std::stack<std::function<void()>> WorkStack; + std::mutex Mutex; + std::condition_variable Cond; + std::promise<void> ThreadsCreated; + std::vector<std::thread> Threads; +}; + +Executor *Executor::getDefaultExecutor() { + // The ManagedStatic enables the ThreadPoolExecutor to be stopped via + // llvm_shutdown() which allows a "clean" fast exit, e.g. via _exit(). This + // stops the thread pool and waits for any worker thread creation to complete + // but does not wait for the threads to finish. The wait for worker thread + // creation to complete is important as it prevents intermittent crashes on + // Windows due to a race condition between thread creation and process exit. + // + // The ThreadPoolExecutor will only be destroyed when the static unique_ptr to + // it is destroyed, i.e. in a normal full exit. The ThreadPoolExecutor + // destructor ensures it has been stopped and waits for worker threads to + // finish. The wait is important as it prevents intermittent crashes on + // Windows when the process is doing a full exit. + // + // The Windows crashes appear to only occur with the MSVC static runtimes and + // are more frequent with the debug static runtime. + // + // This also prevents intermittent deadlocks on exit with the MinGW runtime. + + static ManagedStatic<ThreadPoolExecutor, ThreadPoolExecutor::Creator, + ThreadPoolExecutor::Deleter> + ManagedExec; + static std::unique_ptr<ThreadPoolExecutor> Exec(&(*ManagedExec)); + return Exec.get(); +} +} // namespace + +static std::atomic<int> TaskGroupInstances; + +// Latch::sync() called by the dtor may cause one thread to block. If is a dead +// lock if all threads in the default executor are blocked. To prevent the dead +// lock, only allow the first TaskGroup to run tasks parallelly. In the scenario +// of nested parallel_for_each(), only the outermost one runs parallelly. +TaskGroup::TaskGroup() : Parallel(TaskGroupInstances++ == 0) {} +TaskGroup::~TaskGroup() { + // We must ensure that all the workloads have finished before decrementing the + // instances count. + L.sync(); + --TaskGroupInstances; +} + +void TaskGroup::spawn(std::function<void()> F) { + if (Parallel) { + L.inc(); + Executor::getDefaultExecutor()->add([&, F] { + F(); + L.dec(); + }); + } else { + F(); + } +} + +} // namespace detail +} // namespace parallel +} // namespace llvm +#endif // LLVM_ENABLE_THREADS + +void llvm::parallelForEachN(size_t Begin, size_t End, + llvm::function_ref<void(size_t)> Fn) { + // If we have zero or one items, then do not incur the overhead of spinning up + // a task group. They are surprisingly expensive, and because they do not + // support nested parallelism, a single entry task group can block parallel + // execution underneath them. +#if LLVM_ENABLE_THREADS + auto NumItems = End - Begin; + if (NumItems > 1 && parallel::strategy.ThreadsRequested != 1) { + // Limit the number of tasks to MaxTasksPerGroup to limit job scheduling + // overhead on large inputs. + auto TaskSize = NumItems / parallel::detail::MaxTasksPerGroup; + if (TaskSize == 0) + TaskSize = 1; + + parallel::detail::TaskGroup TG; + for (; Begin + TaskSize < End; Begin += TaskSize) { + TG.spawn([=, &Fn] { + for (size_t I = Begin, E = Begin + TaskSize; I != E; ++I) + Fn(I); + }); + } + for (; Begin != End; ++Begin) + Fn(Begin); + return; + } +#endif + + for (; Begin != End; ++Begin) + Fn(Begin); +} |