blob: 19da912e660efdfab178f4b90d3ce0215384cbbe [file] [log] [blame]
/*
* 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"
#if !defined(WEBRTC_WIN)
#include <sched.h>
#endif
#include <stdint.h>
#include <time.h>
#include <algorithm>
#include "rtc_base/atomic_ops.h"
#include "rtc_base/checks.h"
#include "rtc_base/time_utils.h"
namespace rtc {
namespace {
#if defined(WEBRTC_WIN)
void CALLBACK RaiseFlag(ULONG_PTR param) {
*reinterpret_cast<bool*>(param) = true;
}
#else
struct ThreadAttributes {
ThreadAttributes() { pthread_attr_init(&attr); }
~ThreadAttributes() { pthread_attr_destroy(&attr); }
pthread_attr_t* operator&() { return &attr; }
pthread_attr_t attr;
};
#endif // defined(WEBRTC_WIN)
}
PlatformThread::PlatformThread(ThreadRunFunctionDeprecated func,
void* obj,
absl::string_view thread_name)
: run_function_deprecated_(func), obj_(obj), name_(thread_name) {
RTC_DCHECK(func);
RTC_DCHECK(name_.length() < 64);
spawned_thread_checker_.DetachFromThread();
}
PlatformThread::PlatformThread(ThreadRunFunction func,
void* obj,
absl::string_view thread_name,
ThreadPriority priority /*= kNormalPriority*/)
: run_function_(func), priority_(priority), obj_(obj), name_(thread_name) {
RTC_DCHECK(func);
RTC_DCHECK(!name_.empty());
// TODO(tommi): Consider lowering the limit to 15 (limit on Linux).
RTC_DCHECK(name_.length() < 64);
spawned_thread_checker_.DetachFromThread();
}
PlatformThread::~PlatformThread() {
RTC_DCHECK(thread_checker_.CalledOnValidThread());
#if defined(WEBRTC_WIN)
RTC_DCHECK(!thread_);
RTC_DCHECK(!thread_id_);
#endif // defined(WEBRTC_WIN)
}
#if defined(WEBRTC_WIN)
DWORD WINAPI PlatformThread::StartThread(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);
static_cast<PlatformThread*>(param)->Run();
return 0;
}
#else
void* PlatformThread::StartThread(void* param) {
static_cast<PlatformThread*>(param)->Run();
return 0;
}
#endif // defined(WEBRTC_WIN)
void PlatformThread::Start() {
RTC_DCHECK(thread_checker_.CalledOnValidThread());
RTC_DCHECK(!thread_) << "Thread already started?";
#if defined(WEBRTC_WIN)
stop_ = false;
// 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.
thread_ = ::CreateThread(nullptr, 1024 * 1024, &StartThread, this,
STACK_SIZE_PARAM_IS_A_RESERVATION, &thread_id_);
RTC_CHECK(thread_) << "CreateThread failed";
RTC_DCHECK(thread_id_);
#else
ThreadAttributes attr;
// Set the stack stack size to 1M.
pthread_attr_setstacksize(&attr, 1024 * 1024);
RTC_CHECK_EQ(0, pthread_create(&thread_, &attr, &StartThread, this));
#endif // defined(WEBRTC_WIN)
}
bool PlatformThread::IsRunning() const {
RTC_DCHECK(thread_checker_.CalledOnValidThread());
#if defined(WEBRTC_WIN)
return thread_ != nullptr;
#else
return thread_ != 0;
#endif // defined(WEBRTC_WIN)
}
PlatformThreadRef PlatformThread::GetThreadRef() const {
#if defined(WEBRTC_WIN)
return thread_id_;
#else
return thread_;
#endif // defined(WEBRTC_WIN)
}
void PlatformThread::Stop() {
RTC_DCHECK(thread_checker_.CalledOnValidThread());
if (!IsRunning())
return;
#if defined(WEBRTC_WIN)
// Set stop_ to |true| on the worker thread.
bool queued = QueueAPC(&RaiseFlag, reinterpret_cast<ULONG_PTR>(&stop_));
// Queuing the APC can fail if the thread is being terminated.
RTC_CHECK(queued || GetLastError() == ERROR_GEN_FAILURE);
WaitForSingleObject(thread_, INFINITE);
CloseHandle(thread_);
thread_ = nullptr;
thread_id_ = 0;
#else
if (!run_function_)
RTC_CHECK_EQ(1, AtomicOps::Increment(&stop_flag_));
RTC_CHECK_EQ(0, pthread_join(thread_, nullptr));
if (!run_function_)
AtomicOps::ReleaseStore(&stop_flag_, 0);
thread_ = 0;
#endif // defined(WEBRTC_WIN)
spawned_thread_checker_.DetachFromThread();
}
// TODO(tommi): Deprecate the loop behavior in PlatformThread.
// * Introduce a new callback type that returns void.
// * Remove potential for a busy loop in PlatformThread.
// * Delegate the responsibility for how to stop the thread, to the
// implementation that actually uses the thread.
// All implementations will need to be aware of how the thread should be stopped
// and encouraging a busy polling loop, can be costly in terms of power and cpu.
void PlatformThread::Run() {
// Attach the worker thread checker to this thread.
RTC_DCHECK(spawned_thread_checker_.CalledOnValidThread());
rtc::SetCurrentThreadName(name_.c_str());
if (run_function_) {
SetPriority(priority_);
run_function_(obj_);
return;
}
// TODO(tommi): Delete the rest of this function when looping isn't supported.
#if RTC_DCHECK_IS_ON
// These constants control the busy loop detection algorithm below.
// |kMaxLoopCount| controls the limit for how many times we allow the loop
// to run within a period, before DCHECKing.
// |kPeriodToMeasureMs| controls how long that period is.
static const int kMaxLoopCount = 1000;
static const int kPeriodToMeasureMs = 100;
int64_t loop_stamps[kMaxLoopCount] = {};
int64_t sequence_nr = 0;
#endif
do {
// The interface contract of Start/Stop is that for a successful call to
// Start, there should be at least one call to the run function. So we
// call the function before checking |stop_|.
if (!run_function_deprecated_(obj_))
break;
#if RTC_DCHECK_IS_ON
auto id = sequence_nr % kMaxLoopCount;
loop_stamps[id] = rtc::TimeMillis();
if (sequence_nr > kMaxLoopCount) {
auto compare_id = (id + 1) % kMaxLoopCount;
auto diff = loop_stamps[id] - loop_stamps[compare_id];
RTC_DCHECK_GE(diff, 0);
if (diff < kPeriodToMeasureMs) {
RTC_NOTREACHED() << "This thread is too busy: " << name_ << " " << diff
<< "ms sequence=" << sequence_nr << " "
<< loop_stamps[id] << " vs " << loop_stamps[compare_id]
<< ", " << id << " vs " << compare_id;
}
}
++sequence_nr;
#endif
#if defined(WEBRTC_WIN)
// Alertable sleep to permit RaiseFlag to run and update |stop_|.
SleepEx(0, true);
} while (!stop_);
#else
#if defined(WEBRTC_MAC) || defined(WEBRTC_ANDROID)
sched_yield();
#else
static const struct timespec ts_null = {0};
nanosleep(&ts_null, nullptr);
#endif
} while (!AtomicOps::AcquireLoad(&stop_flag_));
#endif // defined(WEBRTC_WIN)
}
bool PlatformThread::SetPriority(ThreadPriority priority) {
#if RTC_DCHECK_IS_ON
if (run_function_) {
// The non-deprecated way of how this function gets called, is that it must
// be called on the worker thread itself.
RTC_DCHECK(!thread_checker_.CalledOnValidThread());
RTC_DCHECK(spawned_thread_checker_.CalledOnValidThread());
} else {
// In the case of deprecated use of this method, it must be called on the
// same thread as the PlatformThread object is constructed on.
RTC_DCHECK(thread_checker_.CalledOnValidThread());
RTC_DCHECK(IsRunning());
}
#endif
#if defined(WEBRTC_WIN)
return SetThreadPriority(thread_, priority) != FALSE;
#elif defined(__native_client__) || defined(WEBRTC_FUCHSIA)
// Setting thread priorities is not supported in NaCl or Fuchsia.
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 kLowPriority:
param.sched_priority = low_prio;
break;
case kNormalPriority:
// The -1 ensures that the kHighPriority is always greater or equal to
// kNormalPriority.
param.sched_priority = (low_prio + top_prio - 1) / 2;
break;
case kHighPriority:
param.sched_priority = std::max(top_prio - 2, low_prio);
break;
case kHighestPriority:
param.sched_priority = std::max(top_prio - 1, low_prio);
break;
case kRealtimePriority:
param.sched_priority = top_prio;
break;
}
return pthread_setschedparam(thread_, policy, &param) == 0;
#endif // defined(WEBRTC_WIN)
}
#if defined(WEBRTC_WIN)
bool PlatformThread::QueueAPC(PAPCFUNC function, ULONG_PTR data) {
RTC_DCHECK(thread_checker_.CalledOnValidThread());
RTC_DCHECK(IsRunning());
return QueueUserAPC(function, thread_, data) != FALSE;
}
#endif
} // namespace rtc