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//==--- Pthreads.cpp - Threading abstraction implementation ---- -*-C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2022 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// Implements threading support for plain pthreads
//
//===----------------------------------------------------------------------===//
#if SWIFT_THREADING_PTHREADS
#if defined(__FreeBSD__) || defined(__OpenBSD__)
#include <pthread_np.h>
#endif
#include "swift/Threading/Impl.h"
#include "swift/Threading/Errors.h"
namespace {
#pragma clang diagnostic push
#pragma GCC diagnostic ignored "-Wglobal-constructors"
class MainThreadRememberer {
private:
pthread_t mainThread_;
public:
MainThreadRememberer() { mainThread_ = pthread_self(); }
pthread_t main_thread() const { return mainThread_; }
};
MainThreadRememberer rememberer;
pthread_mutex_t onceMutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t onceCond = PTHREAD_COND_INITIALIZER;
#pragma clang diagnostic pop
} // namespace
using namespace swift;
using namespace threading_impl;
bool swift::threading_impl::thread_is_main() {
return pthread_equal(pthread_self(), rememberer.main_thread());
}
void swift::threading_impl::once_slow(once_t &predicate, void (*fn)(void *),
void *context) {
std::intptr_t zero = 0;
if (predicate.compare_exchange_strong(zero, (std::intptr_t)1,
std::memory_order_relaxed,
std::memory_order_relaxed)) {
fn(context);
predicate.store((std::intptr_t)-1, std::memory_order_release);
pthread_mutex_lock(&onceMutex);
pthread_mutex_unlock(&onceMutex);
pthread_cond_broadcast(&onceCond);
return;
}
pthread_mutex_lock(&onceMutex);
while (predicate.load(std::memory_order_acquire) >= (std::intptr_t)0) {
pthread_cond_wait(&onceCond, &onceMutex);
}
pthread_mutex_unlock(&onceMutex);
}
#if defined(__OpenBSD__)
std::optional<swift::threading_impl::stack_bounds>
swift::threading_impl::thread_get_current_stack_bounds() {
stack_t sinfo;
if (!pthread_stackseg_np(pthread_self(), &sinfo)) {
stack_bounds result = {
(char *)sinfo.ss_sp - sinfo.ss_size,
sinfo.ss_sp
};
return result;
}
return {};
}
#else
std::optional<swift::threading_impl::stack_bounds>
swift::threading_impl::thread_get_current_stack_bounds() {
pthread_attr_t attr;
size_t size = 0;
void *begin = nullptr;
#if defined(__FreeBSD__)
if (pthread_attr_init(&attr))
return {};
if (pthread_attr_get_np(pthread_self(), &attr)) {
pthread_attr_destroy(&attr);
return {};
}
#elif defined(__linux__)
if (pthread_getattr_np(pthread_self(), &attr))
return {};
#else
// We don't know how to get the thread attr for this platform.
return {};
#endif
if (!pthread_attr_getstack(&attr, &begin, &size)) {
stack_bounds result = { begin, (char *)begin + size };
pthread_attr_destroy(&attr);
return result;
}
pthread_attr_destroy(&attr);
return {};
}
#endif
#endif // SWIFT_THREADING_PTHREADS
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