muduo之mutex和condition

线程同步所需的mutex和condition，记录一下。

Mutex.h

// Use of this source code is governed by a BSD-style license
// that can be found in the License file.
//
// Author: Shuo Chen (chenshuo at chenshuo dot com)#ifndef MUDUO_BASE_MUTEX_H
#define MUDUO_BASE_MUTEX_H#include "muduo/base/CurrentThread.h"
#include "muduo/base/noncopyable.h"
#include <assert.h>
#include <pthread.h>// Thread safety annotations {
// https://clang.llvm.org/docs/ThreadSafetyAnalysis.html// Enable thread safety attributes only with clang.
// The attributes can be safely erased when compiling with other compilers.
#if defined(__clang__) && (!defined(SWIG))
#define THREAD_ANNOTATION_ATTRIBUTE__(x)   __attribute__((x))
#else
#define THREAD_ANNOTATION_ATTRIBUTE__(x)   // no-op
#endif#define CAPABILITY(x) \THREAD_ANNOTATION_ATTRIBUTE__(capability(x))#define SCOPED_CAPABILITY \THREAD_ANNOTATION_ATTRIBUTE__(scoped_lockable)#define GUARDED_BY(x) \THREAD_ANNOTATION_ATTRIBUTE__(guarded_by(x))#define PT_GUARDED_BY(x) \THREAD_ANNOTATION_ATTRIBUTE__(pt_guarded_by(x))#define ACQUIRED_BEFORE(...) \THREAD_ANNOTATION_ATTRIBUTE__(acquired_before(__VA_ARGS__))#define ACQUIRED_AFTER(...) \THREAD_ANNOTATION_ATTRIBUTE__(acquired_after(__VA_ARGS__))#define REQUIRES(...) \THREAD_ANNOTATION_ATTRIBUTE__(requires_capability(__VA_ARGS__))#define REQUIRES_SHARED(...) \THREAD_ANNOTATION_ATTRIBUTE__(requires_shared_capability(__VA_ARGS__))#define ACQUIRE(...) \THREAD_ANNOTATION_ATTRIBUTE__(acquire_capability(__VA_ARGS__))#define ACQUIRE_SHARED(...) \THREAD_ANNOTATION_ATTRIBUTE__(acquire_shared_capability(__VA_ARGS__))#define RELEASE(...) \THREAD_ANNOTATION_ATTRIBUTE__(release_capability(__VA_ARGS__))#define RELEASE_SHARED(...) \THREAD_ANNOTATION_ATTRIBUTE__(release_shared_capability(__VA_ARGS__))#define TRY_ACQUIRE(...) \THREAD_ANNOTATION_ATTRIBUTE__(try_acquire_capability(__VA_ARGS__))#define TRY_ACQUIRE_SHARED(...) \THREAD_ANNOTATION_ATTRIBUTE__(try_acquire_shared_capability(__VA_ARGS__))#define EXCLUDES(...) \THREAD_ANNOTATION_ATTRIBUTE__(locks_excluded(__VA_ARGS__))#define ASSERT_CAPABILITY(x) \THREAD_ANNOTATION_ATTRIBUTE__(assert_capability(x))#define ASSERT_SHARED_CAPABILITY(x) \THREAD_ANNOTATION_ATTRIBUTE__(assert_shared_capability(x))#define RETURN_CAPABILITY(x) \THREAD_ANNOTATION_ATTRIBUTE__(lock_returned(x))#define NO_THREAD_SAFETY_ANALYSIS \THREAD_ANNOTATION_ATTRIBUTE__(no_thread_safety_analysis)// End of thread safety annotations }#ifdef CHECK_PTHREAD_RETURN_VALUE#ifdef NDEBUG
__BEGIN_DECLS
extern void __assert_perror_fail (int errnum,const char *file,unsigned int line,const char *function)noexcept __attribute__ ((__noreturn__));
__END_DECLS
#endif#define MCHECK(ret) ({ __typeof__ (ret) errnum = (ret);         \if (__builtin_expect(errnum != 0, 0))    \__assert_perror_fail (errnum, __FILE__, __LINE__, __func__);})#else  // CHECK_PTHREAD_RETURN_VALUE#define MCHECK(ret) ({ __typeof__ (ret) errnum = (ret);         \assert(errnum == 0); (void) errnum;})#endif // CHECK_PTHREAD_RETURN_VALUEnamespace muduo
{// Use as data member of a class, eg.
//
// class Foo
// {
//  public:
//   int size() const;
//
//  private:
//   mutable MutexLock mutex_;
//   std::vector<int> data_ GUARDED_BY(mutex_);
// };
class CAPABILITY("mutex") MutexLock : noncopyable
{public:MutexLock(): holder_(0){MCHECK(pthread_mutex_init(&mutex_, NULL));}~MutexLock(){assert(holder_ == 0);MCHECK(pthread_mutex_destroy(&mutex_));}// must be called when locked, i.e. for assertionbool isLockedByThisThread() const{return holder_ == CurrentThread::tid();}void assertLocked() const ASSERT_CAPABILITY(this){assert(isLockedByThisThread());}// internal usagevoid lock() ACQUIRE(){MCHECK(pthread_mutex_lock(&mutex_));assignHolder();}void unlock() RELEASE(){unassignHolder();MCHECK(pthread_mutex_unlock(&mutex_));}pthread_mutex_t* getPthreadMutex() /* non-const */{return &mutex_;}private:friend class Condition;class UnassignGuard : noncopyable{public:explicit UnassignGuard(MutexLock& owner): owner_(owner){owner_.unassignHolder();}~UnassignGuard(){owner_.assignHolder();}private:MutexLock& owner_;};void unassignHolder(){holder_ = 0;}void assignHolder(){holder_ = CurrentThread::tid();}pthread_mutex_t mutex_;pid_t holder_;
};// Use as a stack variable, eg.
// int Foo::size() const
// {
//   MutexLockGuard lock(mutex_);
//   return data_.size();
// }
class SCOPED_CAPABILITY MutexLockGuard : noncopyable
{public:explicit MutexLockGuard(MutexLock& mutex) ACQUIRE(mutex): mutex_(mutex){mutex_.lock();}~MutexLockGuard() RELEASE(){mutex_.unlock();}private:MutexLock& mutex_;
};}  // namespace muduo// Prevent misuse like:
// MutexLockGuard(mutex_);
// A tempory object doesn't hold the lock for long!
#define MutexLockGuard(x) error "Missing guard object name"#endif  // MUDUO_BASE_MUTEX_H

Condition.h

// Use of this source code is governed by a BSD-style license
// that can be found in the License file.
//
// Author: Shuo Chen (chenshuo at chenshuo dot com)#ifndef MUDUO_BASE_CONDITION_H
#define MUDUO_BASE_CONDITION_H#include "muduo/base/Mutex.h"#include <pthread.h>namespace muduo
{//封装了条件变量的操作
class Condition : noncopyable
{public:explicit Condition(MutexLock& mutex): mutex_(mutex){MCHECK(pthread_cond_init(&pcond_, NULL));       //初始化}~Condition(){MCHECK(pthread_cond_destroy(&pcond_));           //销毁}void wait(){MutexLock::UnassignGuard ug(mutex_);MCHECK(pthread_cond_wait(&pcond_, mutex_.getPthreadMutex()));}// returns true if time out, false otherwise.bool waitForSeconds(double seconds);void notify(){MCHECK(pthread_cond_signal(&pcond_));     //一对一}void notifyAll(){MCHECK(pthread_cond_broadcast(&pcond_)); //广播}private:MutexLock& mutex_;pthread_cond_t pcond_;
};}  // namespace muduo#endif  // MUDUO_BASE_CONDITION_H

Condition.cc

// Use of this source code is governed by a BSD-style license
// that can be found in the License file.
//
// Author: Shuo Chen (chenshuo at chenshuo dot com)#include "muduo/base/Condition.h"#include <errno.h>// returns true if time out, false otherwise.
bool muduo::Condition::waitForSeconds(double seconds)
{struct timespec abstime;// FIXME: use CLOCK_MONOTONIC or CLOCK_MONOTONIC_RAW to prevent time rewind.clock_gettime(CLOCK_REALTIME, &abstime);const int64_t kNanoSecondsPerSecond = 1000000000;int64_t nanoseconds = static_cast<int64_t>(seconds * kNanoSecondsPerSecond);abstime.tv_sec += static_cast<time_t>((abstime.tv_nsec + nanoseconds) / kNanoSecondsPerSecond);abstime.tv_nsec = static_cast<long>((abstime.tv_nsec + nanoseconds) % kNanoSecondsPerSecond);MutexLock::UnassignGuard ug(mutex_);return ETIMEDOUT == pthread_cond_timedwait(&pcond_, mutex_.getPthreadMutex(), &abstime);
}

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