294 lines
9.4 KiB
C++
294 lines
9.4 KiB
C++
/*
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* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "rtc_base/platform_thread.h"
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#if !defined(WEBRTC_WIN)
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#include <sched.h>
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#endif
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#include <stdint.h>
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#include <time.h>
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#include <algorithm>
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#include "rtc_base/atomicops.h"
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#include "rtc_base/checks.h"
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#include "rtc_base/timeutils.h"
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namespace rtc {
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namespace {
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#if defined(WEBRTC_WIN)
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void CALLBACK RaiseFlag(ULONG_PTR param) {
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*reinterpret_cast<bool*>(param) = true;
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}
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#else
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struct ThreadAttributes {
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ThreadAttributes() { pthread_attr_init(&attr); }
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~ThreadAttributes() { pthread_attr_destroy(&attr); }
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pthread_attr_t* operator&() { return &attr; }
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pthread_attr_t attr;
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};
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#endif // defined(WEBRTC_WIN)
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}
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PlatformThread::PlatformThread(ThreadRunFunctionDeprecated func,
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void* obj,
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const char* thread_name)
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: run_function_deprecated_(func),
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obj_(obj),
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name_(thread_name ? thread_name : "webrtc") {
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RTC_DCHECK(func);
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RTC_DCHECK(name_.length() < 64);
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spawned_thread_checker_.DetachFromThread();
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}
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PlatformThread::PlatformThread(ThreadRunFunction func,
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void* obj,
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const char* thread_name,
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ThreadPriority priority /*= kNormalPriority*/)
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: run_function_(func), priority_(priority), obj_(obj), name_(thread_name) {
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RTC_DCHECK(func);
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RTC_DCHECK(!name_.empty());
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// TODO(tommi): Consider lowering the limit to 15 (limit on Linux).
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RTC_DCHECK(name_.length() < 64);
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spawned_thread_checker_.DetachFromThread();
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}
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PlatformThread::~PlatformThread() {
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RTC_DCHECK(thread_checker_.CalledOnValidThread());
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#if defined(WEBRTC_WIN)
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RTC_DCHECK(!thread_);
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RTC_DCHECK(!thread_id_);
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#endif // defined(WEBRTC_WIN)
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}
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#if defined(WEBRTC_WIN)
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DWORD WINAPI PlatformThread::StartThread(void* param) {
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// The GetLastError() function only returns valid results when it is called
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// after a Win32 API function that returns a "failed" result. A crash dump
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// contains the result from GetLastError() and to make sure it does not
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// falsely report a Windows error we call SetLastError here.
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::SetLastError(ERROR_SUCCESS);
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static_cast<PlatformThread*>(param)->Run();
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return 0;
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}
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#else
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void* PlatformThread::StartThread(void* param) {
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static_cast<PlatformThread*>(param)->Run();
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return 0;
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}
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#endif // defined(WEBRTC_WIN)
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void PlatformThread::Start() {
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RTC_DCHECK(thread_checker_.CalledOnValidThread());
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RTC_DCHECK(!thread_) << "Thread already started?";
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#if defined(WEBRTC_WIN)
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stop_ = false;
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// See bug 2902 for background on STACK_SIZE_PARAM_IS_A_RESERVATION.
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// Set the reserved stack stack size to 1M, which is the default on Windows
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// and Linux.
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thread_ = ::CreateThread(nullptr, 1024 * 1024, &StartThread, this,
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STACK_SIZE_PARAM_IS_A_RESERVATION, &thread_id_);
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RTC_CHECK(thread_) << "CreateThread failed";
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RTC_DCHECK(thread_id_);
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#else
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ThreadAttributes attr;
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// Set the stack stack size to 1M.
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pthread_attr_setstacksize(&attr, 1024 * 1024);
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RTC_CHECK_EQ(0, pthread_create(&thread_, &attr, &StartThread, this));
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#endif // defined(WEBRTC_WIN)
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}
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bool PlatformThread::IsRunning() const {
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RTC_DCHECK(thread_checker_.CalledOnValidThread());
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#if defined(WEBRTC_WIN)
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return thread_ != nullptr;
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#else
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return thread_ != 0;
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#endif // defined(WEBRTC_WIN)
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}
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PlatformThreadRef PlatformThread::GetThreadRef() const {
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#if defined(WEBRTC_WIN)
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return thread_id_;
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#else
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return thread_;
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#endif // defined(WEBRTC_WIN)
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}
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void PlatformThread::Stop() {
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RTC_DCHECK(thread_checker_.CalledOnValidThread());
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if (!IsRunning())
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return;
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#if defined(WEBRTC_WIN)
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// Set stop_ to |true| on the worker thread.
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bool queued = QueueAPC(&RaiseFlag, reinterpret_cast<ULONG_PTR>(&stop_));
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// Queuing the APC can fail if the thread is being terminated.
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RTC_CHECK(queued || GetLastError() == ERROR_GEN_FAILURE);
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WaitForSingleObject(thread_, INFINITE);
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CloseHandle(thread_);
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thread_ = nullptr;
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thread_id_ = 0;
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#else
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if (!run_function_)
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RTC_CHECK_EQ(1, AtomicOps::Increment(&stop_flag_));
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RTC_CHECK_EQ(0, pthread_join(thread_, nullptr));
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if (!run_function_)
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AtomicOps::ReleaseStore(&stop_flag_, 0);
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thread_ = 0;
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#endif // defined(WEBRTC_WIN)
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spawned_thread_checker_.DetachFromThread();
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}
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// TODO(tommi): Deprecate the loop behavior in PlatformThread.
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// * Introduce a new callback type that returns void.
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// * Remove potential for a busy loop in PlatformThread.
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// * Delegate the responsibility for how to stop the thread, to the
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// implementation that actually uses the thread.
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// All implementations will need to be aware of how the thread should be stopped
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// and encouraging a busy polling loop, can be costly in terms of power and cpu.
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void PlatformThread::Run() {
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// Attach the worker thread checker to this thread.
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RTC_DCHECK(spawned_thread_checker_.CalledOnValidThread());
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rtc::SetCurrentThreadName(name_.c_str());
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if (run_function_) {
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SetPriority(priority_);
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run_function_(obj_);
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return;
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}
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// TODO(tommi): Delete the rest of this function when looping isn't supported.
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#if RTC_DCHECK_IS_ON
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// These constants control the busy loop detection algorithm below.
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// |kMaxLoopCount| controls the limit for how many times we allow the loop
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// to run within a period, before DCHECKing.
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// |kPeriodToMeasureMs| controls how long that period is.
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static const int kMaxLoopCount = 1000;
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static const int kPeriodToMeasureMs = 100;
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int64_t loop_stamps[kMaxLoopCount] = {};
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int64_t sequence_nr = 0;
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#endif
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do {
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// The interface contract of Start/Stop is that for a successful call to
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// Start, there should be at least one call to the run function. So we
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// call the function before checking |stop_|.
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if (!run_function_deprecated_(obj_))
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break;
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#if RTC_DCHECK_IS_ON
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auto id = sequence_nr % kMaxLoopCount;
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loop_stamps[id] = rtc::TimeMillis();
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if (sequence_nr > kMaxLoopCount) {
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auto compare_id = (id + 1) % kMaxLoopCount;
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auto diff = loop_stamps[id] - loop_stamps[compare_id];
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RTC_DCHECK_GE(diff, 0);
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if (diff < kPeriodToMeasureMs) {
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RTC_NOTREACHED() << "This thread is too busy: " << name_ << " " << diff
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<< "ms sequence=" << sequence_nr << " "
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<< loop_stamps[id] << " vs " << loop_stamps[compare_id]
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<< ", " << id << " vs " << compare_id;
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}
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}
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++sequence_nr;
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#endif
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#if defined(WEBRTC_WIN)
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// Alertable sleep to permit RaiseFlag to run and update |stop_|.
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SleepEx(0, true);
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} while (!stop_);
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#else
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#if defined(WEBRTC_MAC) || defined(WEBRTC_ANDROID)
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sched_yield();
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#else
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static const struct timespec ts_null = {0};
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nanosleep(&ts_null, nullptr);
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#endif
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} while (!AtomicOps::AcquireLoad(&stop_flag_));
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#endif // defined(WEBRTC_WIN)
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}
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bool PlatformThread::SetPriority(ThreadPriority priority) {
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#if RTC_DCHECK_IS_ON
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if (run_function_) {
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// The non-deprecated way of how this function gets called, is that it must
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// be called on the worker thread itself.
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RTC_DCHECK(!thread_checker_.CalledOnValidThread());
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RTC_DCHECK(spawned_thread_checker_.CalledOnValidThread());
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} else {
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// In the case of deprecated use of this method, it must be called on the
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// same thread as the PlatformThread object is constructed on.
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RTC_DCHECK(thread_checker_.CalledOnValidThread());
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RTC_DCHECK(IsRunning());
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}
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#endif
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#if defined(WEBRTC_WIN)
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return SetThreadPriority(thread_, priority) != FALSE;
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#elif defined(__native_client__) || defined(WEBRTC_FUCHSIA)
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// Setting thread priorities is not supported in NaCl or Fuchsia.
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return true;
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#elif defined(WEBRTC_CHROMIUM_BUILD) && defined(WEBRTC_LINUX)
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// TODO(tommi): Switch to the same mechanism as Chromium uses for changing
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// thread priorities.
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return true;
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#else
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#ifdef WEBRTC_THREAD_RR
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const int policy = SCHED_RR;
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#else
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const int policy = SCHED_FIFO;
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#endif
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const int min_prio = sched_get_priority_min(policy);
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const int max_prio = sched_get_priority_max(policy);
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if (min_prio == -1 || max_prio == -1) {
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return false;
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}
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if (max_prio - min_prio <= 2)
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return false;
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// Convert webrtc priority to system priorities:
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sched_param param;
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const int top_prio = max_prio - 1;
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const int low_prio = min_prio + 1;
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switch (priority) {
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case kLowPriority:
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param.sched_priority = low_prio;
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break;
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case kNormalPriority:
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// The -1 ensures that the kHighPriority is always greater or equal to
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// kNormalPriority.
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param.sched_priority = (low_prio + top_prio - 1) / 2;
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break;
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case kHighPriority:
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param.sched_priority = std::max(top_prio - 2, low_prio);
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break;
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case kHighestPriority:
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param.sched_priority = std::max(top_prio - 1, low_prio);
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break;
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case kRealtimePriority:
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param.sched_priority = top_prio;
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break;
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}
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return pthread_setschedparam(thread_, policy, ¶m) == 0;
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#endif // defined(WEBRTC_WIN)
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}
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#if defined(WEBRTC_WIN)
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bool PlatformThread::QueueAPC(PAPCFUNC function, ULONG_PTR data) {
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RTC_DCHECK(thread_checker_.CalledOnValidThread());
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RTC_DCHECK(IsRunning());
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return QueueUserAPC(function, thread_, data) != FALSE;
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}
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#endif
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} // namespace rtc
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