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/*
* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "rtc_base/platform_thread.h"
#include <algorithm>
#include <functional>
#include <optional>
#include <string>
#include <utility>
#include "absl/strings/string_view.h"
#include "rtc_base/platform_thread_types.h"
#if !defined(WEBRTC_WIN)
#include <sched.h>
#endif
#include "rtc_base/checks.h"
namespace webrtc {
namespace {
#if defined(WEBRTC_WIN)
int Win32PriorityFromThreadPriority(ThreadPriority priority) {
switch (priority) {
case ThreadPriority::kLow:
return THREAD_PRIORITY_BELOW_NORMAL;
case ThreadPriority::kNormal:
return THREAD_PRIORITY_NORMAL;
case ThreadPriority::kHigh:
return THREAD_PRIORITY_ABOVE_NORMAL;
case ThreadPriority::kRealtime:
return THREAD_PRIORITY_TIME_CRITICAL;
}
}
#endif
bool SetPriority(ThreadPriority priority) {
#if defined(WEBRTC_WIN)
return SetThreadPriority(GetCurrentThread(),
Win32PriorityFromThreadPriority(priority)) != FALSE;
#elif defined(__native_client__) || defined(WEBRTC_FUCHSIA) || \
(defined(__EMSCRIPTEN__) && !defined(__EMSCRIPTEN_PTHREADS__))
// Setting thread priorities is not supported in NaCl, Fuchsia or Emscripten
// without pthreads.
return true;
#elif defined(WEBRTC_CHROMIUM_BUILD) && defined(WEBRTC_LINUX)
// TODO(tommi): Switch to the same mechanism as Chromium uses for changing
// thread priorities.
return true;
#else
const int policy = SCHED_FIFO;
const int min_prio = sched_get_priority_min(policy);
const int max_prio = sched_get_priority_max(policy);
if (min_prio == -1 || max_prio == -1) {
return false;
}
if (max_prio - min_prio <= 2)
return false;
// Convert webrtc priority to system priorities:
sched_param param;
const int top_prio = max_prio - 1;
const int low_prio = min_prio + 1;
switch (priority) {
case ThreadPriority::kLow:
param.sched_priority = low_prio;
break;
case ThreadPriority::kNormal:
// The -1 ensures that the kHighPriority is always greater or equal to
// kNormalPriority.
param.sched_priority = (low_prio + top_prio - 1) / 2;
break;
case ThreadPriority::kHigh:
param.sched_priority = std::max(top_prio - 2, low_prio);
break;
case ThreadPriority::kRealtime:
param.sched_priority = top_prio;
break;
}
return pthread_setschedparam(pthread_self(), policy, ¶m) == 0;
#endif // defined(WEBRTC_WIN)
}
#if defined(WEBRTC_WIN)
DWORD WINAPI RunPlatformThread(void* param) {
// The GetLastError() function only returns valid results when it is called
// after a Win32 API function that returns a "failed" result. A crash dump
// contains the result from GetLastError() and to make sure it does not
// falsely report a Windows error we call SetLastError here.
::SetLastError(ERROR_SUCCESS);
auto function = static_cast<std::function<void()>*>(param);
(*function)();
delete function;
return 0;
}
#else
void* RunPlatformThread(void* param) {
auto function = static_cast<std::function<void()>*>(param);
(*function)();
delete function;
return nullptr;
}
#endif // defined(WEBRTC_WIN)
} // namespace
PlatformThread::PlatformThread(Handle handle, bool joinable)
: handle_(handle), joinable_(joinable) {}
PlatformThread::PlatformThread(PlatformThread&& rhs)
: handle_(rhs.handle_), joinable_(rhs.joinable_) {
rhs.handle_ = std::nullopt;
}
PlatformThread& PlatformThread::operator=(PlatformThread&& rhs) {
Finalize();
handle_ = rhs.handle_;
joinable_ = rhs.joinable_;
rhs.handle_ = std::nullopt;
return *this;
}
PlatformThread::~PlatformThread() {
Finalize();
}
PlatformThread PlatformThread::SpawnJoinable(
std::function<void()> thread_function,
absl::string_view name,
ThreadAttributes attributes) {
return SpawnThread(std::move(thread_function), name, attributes,
/*joinable=*/true);
}
PlatformThread PlatformThread::SpawnDetached(
std::function<void()> thread_function,
absl::string_view name,
ThreadAttributes attributes) {
return SpawnThread(std::move(thread_function), name, attributes,
/*joinable=*/false);
}
std::optional<PlatformThread::Handle> PlatformThread::GetHandle() const {
return handle_;
}
#if defined(WEBRTC_WIN)
bool PlatformThread::QueueAPC(PAPCFUNC function, ULONG_PTR data) {
RTC_DCHECK(handle_.has_value());
return handle_.has_value() ? QueueUserAPC(function, *handle_, data) != FALSE
: false;
}
#endif
void PlatformThread::Finalize() {
if (!handle_.has_value())
return;
#if defined(WEBRTC_WIN)
if (joinable_)
WaitForSingleObject(*handle_, INFINITE);
CloseHandle(*handle_);
#else
if (joinable_)
RTC_CHECK_EQ(0, pthread_join(*handle_, nullptr));
#endif
handle_ = std::nullopt;
}
PlatformThread PlatformThread::SpawnThread(
std::function<void()> thread_function,
absl::string_view name,
ThreadAttributes attributes,
bool joinable) {
RTC_DCHECK(thread_function);
RTC_DCHECK(!name.empty());
// TODO(tommi): Consider lowering the limit to 15 (limit on Linux).
RTC_DCHECK(name.length() < 64);
auto start_thread_function_ptr =
new std::function<void()>([thread_function = std::move(thread_function),
name = std::string(name), attributes] {
SetCurrentThreadName(name.c_str());
SetPriority(attributes.priority);
thread_function();
});
#if defined(WEBRTC_WIN)
// See bug 2902 for background on STACK_SIZE_PARAM_IS_A_RESERVATION.
// Set the reserved stack stack size to 1M, which is the default on Windows
// and Linux.
DWORD thread_id = 0;
PlatformThread::Handle handle = ::CreateThread(
nullptr, 1024 * 1024, &RunPlatformThread, start_thread_function_ptr,
STACK_SIZE_PARAM_IS_A_RESERVATION, &thread_id);
RTC_CHECK(handle) << "CreateThread failed";
#else
pthread_attr_t attr;
pthread_attr_init(&attr);
// Set the stack stack size to 1M.
pthread_attr_setstacksize(&attr, 1024 * 1024);
pthread_attr_setdetachstate(
&attr, joinable ? PTHREAD_CREATE_JOINABLE : PTHREAD_CREATE_DETACHED);
PlatformThread::Handle handle;
RTC_CHECK_EQ(0, pthread_create(&handle, &attr, &RunPlatformThread,
start_thread_function_ptr));
pthread_attr_destroy(&attr);
#endif // defined(WEBRTC_WIN)
return PlatformThread(handle, joinable);
}
} // namespace webrtc
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