ACE_linux：读写锁

1.涉及类

ACE_RW_Thread_Mutex //ACE读写锁
ACE_Read_Guard //ACE加读锁
ACE_Write_Guard //ACE加写锁
ACE_Thread_Manager //ACE线程管理

2.简介

ACE读/写锁
读/写锁与互斥体相类似。例如，获取读/写锁的线程也必须释放它。多个线程可同时获取一个读/写锁用于读，但只有一个线程可以获取该锁用于写。当互斥体保护的资源用于读远比用于写要频繁时，读/写互斥体有助于改善并发的执行。
ACE线程库提供了一个叫作ACE_RW_Mutex的类，在C++封装类中可移植地实现了读/写锁的语义。读/写锁将优先选择权给写。因而，如果有多个读和一个写在锁上等待，写将会首先获取它。

3.示例代码

 #include <iostream>
 #include "ace/Thread_Manager.h"
 #include "ace/Guard_T.h"
 #include "ace/OS_NS_time.h"

 using namespace std;
 ACE_RW_Thread_Mutex  mutex;

 ACE_THR_FUNC_RETURN ThreadFunRead(void *arg)
 {
     ACE_thread_t threadId=ACE_Thread_Manager::instance()->thr_self();

     ACE_Read_Guard<ACE_RW_Thread_Mutex> guard(mutex);
     cout<<"Thread ReadLock  begin  NO:"<<threadId<<endl;

     //ACE_OS::sleep(4);
     cout<<"Thread ReadLock  end    NO:"<<threadId<<endl;
     return NULL;
 }
 ACE_THR_FUNC_RETURN ThreadFunWrite(void *arg)
 {
     ACE_thread_t threadId=ACE_Thread_Manager::instance()->thr_self();

     ACE_Write_Guard<ACE_RW_Thread_Mutex> guard(mutex);
     cout<<"Thread WriteLock begin  NO:"<<threadId<<endl;

     ACE_OS::sleep();//休眠1s
     cout<<"Thread WriteLock end    NO:"<<threadId<<endl;
     return NULL;
 }

 int main(int argc, char *argv[])
 {
     //1000纳秒=1ms
     timespec_t t;
     t.tv_sec=;t.tv_nsec=;

     ACE_Thread_Manager* pThrMgr = ACE_Thread_Manager::instance();
     //依次一读一写依次3个循环，结果显示是此读写锁写优先。即：加锁等待队列里写操作永远在读前面！
     for(int i=;i<;i++)
     {
         pThrMgr->spawn((ACE_THR_FUNC)ThreadFunRead);
         ACE_OS::nanosleep (&t);
         pThrMgr->spawn((ACE_THR_FUNC)ThreadFunWrite);
         ACE_OS::nanosleep (&t);
     }
     pThrMgr->wait();

     return ;
 }

RW_lock.cpp

4.示例运行结果

$ ./tt
Thread ReadLock  begin  NO:
Thread ReadLock  end    NO:
Thread WriteLock begin  NO:
Thread WriteLock end    NO:
Thread WriteLock begin  NO:
Thread WriteLock end    NO:
Thread WriteLock begin  NO:
Thread WriteLock end    NO:
Thread WriteLock begin  NO:
Thread WriteLock end    NO:
Thread ReadLock  begin  NO:
Thread ReadLock  end    NO:
Thread ReadLock  begin  NO:
Thread ReadLock  end    NO:
Thread ReadLock  begin  NO:
Thread ReadLock  end    NO:

执行结果

5.Makefile

#bin
THE_INCLUDE      = -I./  \
                   -I${ACE_ROOT}/

THE_LIBPATH      = -L./  \
                   -L${ACE_ROOT}/lib/
THE_LIB = -g -D_DEBUG_ -lACE# -lxti

CFLAGS = ${THE_LIB} ${THE_INCLUDE} ${THE_LIBPATH}
CC=g++
SRC=$(wildcard *.cpp)
OBJ=$(addprefix ./, $(addsuffix .o, $(basename $(SRC))))
TARGET=tt
all: $(TARGET)
$(TARGET): $(SRC)
    $(CC) -o $@ $^ $(CFLAGS)
    @echo make all done
%.o: %.cpp
    $(CC) $(CFLAGS) -o $@ -c $<
clean:
    rm -f $(TARGET) $(OBJ)

Makefile

********************************************************************

高级线程(任务)ACE_Task_Base类来创建线程是更方便和优雅

6.示例代码

 #include <iostream>
 #include "ace/Task.h"

 using namespace std;

 //静态锁
 struct Resource
 {
     static ACE_RW_Thread_Mutex  mutex;
 };
 ACE_RW_Thread_Mutex  Resource::mutex;

 class ThreadFunRead : public ACE_Task_Base {
 public:
     virtual int svc()
     {
         ACE_Read_Guard<ACE_RW_Thread_Mutex> guard(Resource::mutex);
         cout<<"Thread ReadLock  begin  NO:"<<ACE_Thread::self()<<endl;

         //ACE_OS::sleep(4);
         cout<<"Thread ReadLock  end    NO:"<<ACE_Thread::self()<<endl;
         return ;
     }
 };

 class ThreadFunWrite : public ACE_Task_Base {
 public:
     virtual int svc()
     {
         ACE_Write_Guard<ACE_RW_Thread_Mutex> guard(Resource::mutex);
         cout<<"Thread WriteLock begin  NO:"<<ACE_Thread::self()<<endl;

         ACE_OS::sleep();//休眠1s
         cout<<"Thread WriteLock end    NO:"<<ACE_Thread::self()<<endl;
         return ;
     }
 };

 int main(int argc, char *argv[])
 {
     //1000纳秒=1ms
     timespec_t t;
     t.tv_sec=;t.tv_nsec=;

     ACE_Thread_Manager* pThrMgr = ACE_Thread_Manager::instance();
     //依次一读一写依次3个循环，结果显示是此读写锁写优先。即：加锁等待队列里写操作永远在读前面！
     for(int i=;i<;i++)
     {
         ThreadFunRead  threadRead;
         ThreadFunWrite threadWrite;
         threadRead.activate();
         ACE_OS::nanosleep (&t);
         threadWrite.activate();
         ACE_OS::nanosleep (&t);
     }

     pThrMgr->wait();

     return ;
 }

RW_lock.cpp