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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/threading/platform_thread.h"
#include <errno.h>
#include <pthread.h>
#include <sched.h>
#include <stddef.h>
#include <stdint.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <memory>
#include "base/debug/activity_tracker.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/no_destructor.h"
#include "base/threading/platform_thread_internal_posix.h"
#include "base/threading/scoped_blocking_call.h"
#include "base/threading/thread_id_name_manager.h"
#include "build/build_config.h"
#if !defined(OS_MACOSX) && !defined(OS_FUCHSIA) && !defined(OS_NACL)
#include "base/posix/can_lower_nice_to.h"
#endif
#if defined(OS_LINUX)
#include <sys/syscall.h>
#endif
#if defined(OS_FUCHSIA)
#include <zircon/process.h>
#else
#include <sys/resource.h>
#endif
namespace base {
void InitThreading();
void TerminateOnThread();
size_t GetDefaultThreadStackSize(const pthread_attr_t& attributes);
namespace {
struct ThreadParams {
ThreadParams()
: delegate(nullptr), joinable(false), priority(ThreadPriority::NORMAL) {}
PlatformThread::Delegate* delegate;
bool joinable;
ThreadPriority priority;
};
void* ThreadFunc(void* params) {
PlatformThread::Delegate* delegate = nullptr;
{
std::unique_ptr<ThreadParams> thread_params(
static_cast<ThreadParams*>(params));
delegate = thread_params->delegate;
if (!thread_params->joinable)
base::ThreadRestrictions::SetSingletonAllowed(false);
#if !defined(OS_NACL)
// Threads on linux/android may inherit their priority from the thread
// where they were created. This explicitly sets the priority of all new
// threads.
PlatformThread::SetCurrentThreadPriority(thread_params->priority);
#endif
}
ThreadIdNameManager::GetInstance()->RegisterThread(
PlatformThread::CurrentHandle().platform_handle(),
PlatformThread::CurrentId());
delegate->ThreadMain();
ThreadIdNameManager::GetInstance()->RemoveName(
PlatformThread::CurrentHandle().platform_handle(),
PlatformThread::CurrentId());
base::TerminateOnThread();
return nullptr;
}
bool CreateThread(size_t stack_size,
bool joinable,
PlatformThread::Delegate* delegate,
PlatformThreadHandle* thread_handle,
ThreadPriority priority) {
DCHECK(thread_handle);
base::InitThreading();
pthread_attr_t attributes;
pthread_attr_init(&attributes);
// Pthreads are joinable by default, so only specify the detached
// attribute if the thread should be non-joinable.
if (!joinable)
pthread_attr_setdetachstate(&attributes, PTHREAD_CREATE_DETACHED);
// Get a better default if available.
if (stack_size == 0)
stack_size = base::GetDefaultThreadStackSize(attributes);
if (stack_size > 0)
pthread_attr_setstacksize(&attributes, stack_size);
std::unique_ptr<ThreadParams> params(new ThreadParams);
params->delegate = delegate;
params->joinable = joinable;
params->priority = priority;
pthread_t handle;
int err = pthread_create(&handle, &attributes, ThreadFunc, params.get());
bool success = !err;
if (success) {
// ThreadParams should be deleted on the created thread after used.
ignore_result(params.release());
} else {
// Value of |handle| is undefined if pthread_create fails.
handle = 0;
errno = err;
PLOG(ERROR) << "pthread_create";
}
*thread_handle = PlatformThreadHandle(handle);
pthread_attr_destroy(&attributes);
return success;
}
#if defined(OS_LINUX)
// Store the thread ids in local storage since calling the SWI can
// expensive and PlatformThread::CurrentId is used liberally. Clear
// the stored value after a fork() because forking changes the thread
// id. Forking without going through fork() (e.g. clone()) is not
// supported, but there is no known usage. Using thread_local is
// fine here (despite being banned) since it is going to be allowed
// and we can't use ThreadLocalStorage because of re-entrancy due to
// CHECK/DCHECKs.
thread_local pid_t g_thread_id = -1;
class InitAtFork {
public:
InitAtFork() { pthread_atfork(nullptr, nullptr, internal::ClearTidCache); }
};
#endif // defined(OS_LINUX)
} // namespace
#if defined(OS_LINUX)
namespace internal {
void ClearTidCache() {
g_thread_id = -1;
}
} // namespace internal
#endif // defined(OS_LINUX)
// static
PlatformThreadId PlatformThread::CurrentId() {
// Pthreads doesn't have the concept of a thread ID, so we have to reach down
// into the kernel.
#if defined(OS_MACOSX)
return pthread_mach_thread_np(pthread_self());
#elif defined(OS_LINUX)
static NoDestructor<InitAtFork> init_at_fork;
if (g_thread_id == -1) {
g_thread_id = syscall(__NR_gettid);
} else {
DCHECK_EQ(g_thread_id, syscall(__NR_gettid))
<< "Thread id stored in TLS is different from thread id returned by "
"the system. It is likely that the process was forked without going "
"through fork().";
}
return g_thread_id;
#elif defined(OS_ANDROID)
return gettid();
#elif defined(OS_FUCHSIA)
return zx_thread_self();
#elif defined(OS_SOLARIS) || defined(OS_QNX)
return pthread_self();
#elif defined(OS_NACL) && defined(__GLIBC__)
return pthread_self();
#elif defined(OS_NACL) && !defined(__GLIBC__)
// Pointers are 32-bits in NaCl.
return reinterpret_cast<int32_t>(pthread_self());
#elif defined(OS_POSIX) && defined(OS_AIX)
return pthread_self();
#elif defined(OS_POSIX) && !defined(OS_AIX)
return reinterpret_cast<int64_t>(pthread_self());
#endif
}
// static
PlatformThreadRef PlatformThread::CurrentRef() {
return PlatformThreadRef(pthread_self());
}
// static
PlatformThreadHandle PlatformThread::CurrentHandle() {
return PlatformThreadHandle(pthread_self());
}
// static
void PlatformThread::YieldCurrentThread() {
sched_yield();
}
// static
void PlatformThread::Sleep(TimeDelta duration) {
struct timespec sleep_time, remaining;
// Break the duration into seconds and nanoseconds.
// NOTE: TimeDelta's microseconds are int64s while timespec's
// nanoseconds are longs, so this unpacking must prevent overflow.
sleep_time.tv_sec = duration.InSeconds();
duration -= TimeDelta::FromSeconds(sleep_time.tv_sec);
sleep_time.tv_nsec = duration.InMicroseconds() * 1000; // nanoseconds
while (nanosleep(&sleep_time, &remaining) == -1 && errno == EINTR)
sleep_time = remaining;
}
// static
const char* PlatformThread::GetName() {
return ThreadIdNameManager::GetInstance()->GetName(CurrentId());
}
// static
bool PlatformThread::CreateWithPriority(size_t stack_size, Delegate* delegate,
PlatformThreadHandle* thread_handle,
ThreadPriority priority) {
return CreateThread(stack_size, true /* joinable thread */, delegate,
thread_handle, priority);
}
// static
bool PlatformThread::CreateNonJoinable(size_t stack_size, Delegate* delegate) {
return CreateNonJoinableWithPriority(stack_size, delegate,
ThreadPriority::NORMAL);
}
// static
bool PlatformThread::CreateNonJoinableWithPriority(size_t stack_size,
Delegate* delegate,
ThreadPriority priority) {
PlatformThreadHandle unused;
bool result = CreateThread(stack_size, false /* non-joinable thread */,
delegate, &unused, priority);
return result;
}
// static
void PlatformThread::Join(PlatformThreadHandle thread_handle) {
// Record the event that this thread is blocking upon (for hang diagnosis).
base::debug::ScopedThreadJoinActivity thread_activity(&thread_handle);
// Joining another thread may block the current thread for a long time, since
// the thread referred to by |thread_handle| may still be running long-lived /
// blocking tasks.
base::internal::ScopedBlockingCallWithBaseSyncPrimitives scoped_blocking_call(
FROM_HERE, base::BlockingType::MAY_BLOCK);
CHECK_EQ(0, pthread_join(thread_handle.platform_handle(), nullptr));
}
// static
void PlatformThread::Detach(PlatformThreadHandle thread_handle) {
CHECK_EQ(0, pthread_detach(thread_handle.platform_handle()));
}
// Mac and Fuchsia have their own Set/GetCurrentThreadPriority()
// implementations.
#if !defined(OS_MACOSX) && !defined(OS_FUCHSIA)
// static
bool PlatformThread::CanIncreaseThreadPriority(ThreadPriority priority) {
#if defined(OS_NACL)
return false;
#else
auto platform_specific_ability =
internal::CanIncreaseCurrentThreadPriorityForPlatform(priority);
if (platform_specific_ability)
return platform_specific_ability.value();
return internal::CanLowerNiceTo(
internal::ThreadPriorityToNiceValue(priority));
#endif // defined(OS_NACL)
}
// static
void PlatformThread::SetCurrentThreadPriorityImpl(ThreadPriority priority) {
#if defined(OS_NACL)
NOTIMPLEMENTED();
#else
if (internal::SetCurrentThreadPriorityForPlatform(priority))
return;
// setpriority(2) should change the whole thread group's (i.e. process)
// priority. However, as stated in the bugs section of
// Linux/NPTL implementation of POSIX threads, the nice value is a per-thread
// attribute". Also, 0 is prefered to the current thread id since it is
const int nice_setting = internal::ThreadPriorityToNiceValue(priority);
if (setpriority(PRIO_PROCESS, 0, nice_setting)) {
DVPLOG(1) << "Failed to set nice value of thread ("
<< PlatformThread::CurrentId() << ") to " << nice_setting;
}
#endif // defined(OS_NACL)
}
// static
ThreadPriority PlatformThread::GetCurrentThreadPriority() {
#if defined(OS_NACL)
NOTIMPLEMENTED();
return ThreadPriority::NORMAL;
#else
// Mirrors SetCurrentThreadPriority()'s implementation.
auto platform_specific_priority =
internal::GetCurrentThreadPriorityForPlatform();
if (platform_specific_priority)
return platform_specific_priority.value();
// Need to clear errno before calling getpriority():
errno = 0;
int nice_value = getpriority(PRIO_PROCESS, 0);
if (errno != 0) {
DVPLOG(1) << "Failed to get nice value of thread ("
<< PlatformThread::CurrentId() << ")";
return ThreadPriority::NORMAL;
}
return internal::NiceValueToThreadPriority(nice_value);
#endif // !defined(OS_NACL)
}
#endif // !defined(OS_MACOSX) && !defined(OS_FUCHSIA)
// static
size_t PlatformThread::GetDefaultThreadStackSize() {
pthread_attr_t attributes;
pthread_attr_init(&attributes);
return base::GetDefaultThreadStackSize(attributes);
}
} // namespace base