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ACE_linux：读写锁

2024-11-05 02:13:01   209人阅读

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

技术分享
 1 #include <iostream> 2 #include "ace/Thread_Manager.h" 3 #include "ace/Guard_T.h" 4 #include "ace/OS_NS_time.h" 5  6 using namespace std; 7 ACE_RW_Thread_Mutex  mutex; 8  9 ACE_THR_FUNC_RETURN ThreadFunRead(void *arg) 10 {11     ACE_thread_t threadId=ACE_Thread_Manager::instance()->thr_self();12 13     ACE_Read_Guard<ACE_RW_Thread_Mutex> guard(mutex);14     cout<<"Thread ReadLock  begin  NO:"<<threadId<<endl;15 16 17     //ACE_OS::sleep(4);18     cout<<"Thread ReadLock  end    NO:"<<threadId<<endl;19     return NULL; 20 } 21 ACE_THR_FUNC_RETURN ThreadFunWrite(void *arg) 22 {23     ACE_thread_t threadId=ACE_Thread_Manager::instance()->thr_self();24 25     ACE_Write_Guard<ACE_RW_Thread_Mutex> guard(mutex);26     cout<<"Thread WriteLock begin  NO:"<<threadId<<endl;27 28     ACE_OS::sleep(1);//休眠1s29     cout<<"Thread WriteLock end    NO:"<<threadId<<endl;30     return NULL; 31 }32 33 int main(int argc, char *argv[]) 34 { 35     //1000纳秒=1ms36     timespec_t t;37     t.tv_sec=0;t.tv_nsec=1000;38 39     ACE_Thread_Manager* pThrMgr = ACE_Thread_Manager::instance();40     //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！41     for(int i=0;i<4;i++)42     {43         pThrMgr->spawn((ACE_THR_FUNC)ThreadFunRead); 44         ACE_OS::nanosleep (&t);45         pThrMgr->spawn((ACE_THR_FUNC)ThreadFunWrite); 46         ACE_OS::nanosleep (&t);47     }48     pThrMgr->wait();49 50     return 0; 51 }
RW_lock.cpp

4.示例运行结果

技术分享
$ ./ttThread ReadLock  begin  NO:140015069234944Thread ReadLock  end    NO:140015069234944Thread WriteLock begin  NO:140015058745088Thread WriteLock end    NO:140015058745088Thread WriteLock begin  NO:140015037765376Thread WriteLock end    NO:140015037765376Thread WriteLock begin  NO:140015016785664Thread WriteLock end    NO:140015016785664Thread WriteLock begin  NO:140014658778880Thread WriteLock end    NO:140014658778880Thread ReadLock  begin  NO:140015048255232Thread ReadLock  end    NO:140015048255232Thread ReadLock  begin  NO:140015027275520Thread ReadLock  end    NO:140015027275520Thread ReadLock  begin  NO:140015006295808Thread ReadLock  end    NO:140015006295808
执行结果

5.Makefile

技术分享
#binTHE_INCLUDE      = -I./                     -I${ACE_ROOT}/THE_LIBPATH      = -L./                     -L${ACE_ROOT}/lib/THE_LIB = -g -D_DEBUG_ -lACE# -lxtiCFLAGS = ${THE_LIB} ${THE_INCLUDE} ${THE_LIBPATH}CC=g++SRC=$(wildcard *.cpp)OBJ=$(addprefix ./, $(addsuffix .o, $(basename $(SRC))))TARGET=ttall: $(TARGET)$(TARGET): $(SRC)    $(CC) -o $@ $^ $(CFLAGS)    @echo make all done%.o: %.cpp    $(CC) $(CFLAGS) -o $@ -c $<clean:    rm -f $(TARGET) $(OBJ)
Makefile

 

ACE_linux：读写锁


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