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66b9d21000
Read/write locks are not as good as you'd think; a simple mutex is better in almost all cases. rdar://90776105
90 lines
2.2 KiB
C++
90 lines
2.2 KiB
C++
//===--- MutexC11.h - Supports Mutex.h using C11 threading ------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Mutex, Read/Write lock, and Scoped lock implementations
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// using C11 threading primtives.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_RUNTIME_MUTEX_C11_H
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#define SWIFT_RUNTIME_MUTEX_C11_H
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#include <threads.h>
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namespace swift {
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namespace c11threads {
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class rwlock;
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static void fatalError(int errcode);
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static inline void handleError(int errcode) {
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if (SWIFT_LIKELY(errcode == thrd_success))
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return;
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fatalError(errcode);
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}
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}
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typedef ::mtx_t MutexHandle;
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#define SWIFT_MUTEX_SUPPORTS_CONSTEXPR 0
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/// C11 low-level implementation that supports Mutex
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/// found in Mutex.h
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///
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/// See Mutex
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class MutexPlatformHelper {
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public:
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static MutexHandle staticInit() {
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::mtx_t mutex;
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::mtx_init(&mutex, ::mtx_plain);
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return mutex;
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}
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static void init(MutexHandle &mutex, bool checked = false) {
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// C11 mutexes can't be checked
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c11threads::handleError(::mtx_init(&mutex, ::mtx_plain));
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}
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static void destroy(MutexHandle &mutex) {
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::mtx_destroy(&mutex);
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}
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static void lock(MutexHandle &mutex) {
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c11threads::handleError(::mtx_lock(&mutex));
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}
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static void unlock(MutexHandle &mutex) {
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c11threads::handleError(::mtx_unlock(&mutex));
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}
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static bool try_lock(MutexHandle &mutex) {
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int err = ::mtx_trylock(&mutex);
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switch (err) {
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case thrd_success:
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return true;
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case thrd_busy:
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return false;
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default:
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c11threads::handleError(err);
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}
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}
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// Skip error checking for the unsafe versions.
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static void unsafeLock(MutexHandle &mutex) {
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(void)::mtx_lock(&mutex);
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}
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static void unsafeUnlock(MutexHandle &mutex) {
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(void)::mtx_unlock(&mutex);
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}
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};
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}
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#endif
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