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// Copyright (C) 2014 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "base/Thread.h"
#include <cerrno>
#include <assert.h>
#include <signal.h>
#include <stdio.h>
#ifndef _MSC_VER
#include <unistd.h>
#endif
namespace android {
namespace base {
Thread::Thread(ThreadFlags flags, int stackSize)
: mThread((pthread_t)NULL), mStackSize(stackSize), mFlags(flags) {}
Thread::~Thread() {
assert(!mStarted || mFinished);
if ((mFlags & ThreadFlags::Detach) == ThreadFlags::NoFlags && mStarted &&
!mJoined) {
// Make sure we reclaim the OS resources.
pthread_join(mThread, nullptr);
}
}
bool Thread::start() {
if (mStarted) {
return false;
}
bool ret = true;
mStarted = true;
const auto useAttributes = mStackSize != 0;
pthread_attr_t attr;
if (useAttributes) {
pthread_attr_init(&attr);
pthread_attr_setstacksize(&attr, mStackSize);
}
if (pthread_create(&mThread, mStackSize ? &attr : nullptr, thread_main,
this)) {
fprintf(stderr, "Thread: failed to create a thread, errno %d\n", errno);
ret = false;
// We _do not_ need to guard this access to |mFinished| because we're
// sure that the launched thread failed, so there can't be parallel
// access.
mFinished = true;
mExitStatus = -errno;
// Nothing to join, so technically it's joined.
mJoined = true;
}
if (useAttributes) {
pthread_attr_destroy(&attr);
}
return ret;
}
bool Thread::wait(intptr_t* exitStatus) {
if (!mStarted || (mFlags & ThreadFlags::Detach) != ThreadFlags::NoFlags) {
return false;
}
// NOTE: Do not hold the lock when waiting for the thread to ensure
// it can update mFinished and mExitStatus properly in thread_main
// without blocking.
if (!mJoined && pthread_join(mThread, NULL)) {
return false;
}
mJoined = true;
if (exitStatus) {
*exitStatus = mExitStatus;
}
return true;
}
bool Thread::tryWait(intptr_t* exitStatus) {
if (!mStarted || (mFlags & ThreadFlags::Detach) != ThreadFlags::NoFlags) {
return false;
}
{
AutoLock locker(mLock);
if (!mFinished) {
return false;
}
}
if (!mJoined) {
if (pthread_join(mThread, NULL)) {
fprintf(stderr, "Thread: failed to join a finished thread, errno %d\n", errno);
}
mJoined = true;
}
if (exitStatus) {
*exitStatus = mExitStatus;
}
return true;
}
// static
void* Thread::thread_main(void* arg) {
intptr_t ret;
{
Thread* self = reinterpret_cast<Thread*>(arg);
if ((self->mFlags & ThreadFlags::MaskSignals) != ThreadFlags::NoFlags) {
Thread::maskAllSignals();
}
if ((self->mFlags & ThreadFlags::Detach) != ThreadFlags::NoFlags) {
if (pthread_detach(pthread_self())) {
// Failed to detach thread
}
}
ret = self->main();
{
AutoLock lock(self->mLock);
self->mFinished = true;
self->mExitStatus = ret;
}
self->onExit();
// |self| is not valid beyond this point
}
// This return value is ignored.
return NULL;
}
// static
void Thread::maskAllSignals() {
sigset_t set;
sigfillset(&set);
pthread_sigmask(SIG_SETMASK, &set, nullptr);
}
// static
void Thread::sleepMs(unsigned n) {
usleep(n * 1000);
}
// static
void Thread::sleepUs(unsigned n) {
usleep(n);
}
// static
void Thread::yield() {
sched_yield();
}
unsigned long getCurrentThreadId() {
pthread_t tid = pthread_self();
// POSIX doesn't require pthread_t to be a numeric type.
// Instead, just pick up the first sizeof(long) bytes as the "id".
static_assert(sizeof(tid) >= sizeof(long),
"Expected pthread_t to be at least sizeof(long) wide");
return *reinterpret_cast<unsigned long*>(&tid);
}
} // namespace base
} // namespace android
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