update

wangzhengquan

2021-02-08 18705acc13f78ac65458b3dd832545e62fbc9172

 src/pread_write_lock.h

File was renamed from src/read_write_lock.h
@@ -1,9 +1,9 @@
#ifndef _CLOSE_LOCK_H_
#define _CLOSE_LOCK_H_  
#ifndef _PREAD_WRITE_LOCK_H_
#define _PREAD_WRITE_LOCK_H_  

#include "usg_common.h"
#include "psem.h"
class ReadWriteLock {
class PReadWriteLock {
private:
   unsigned int readCount = 0;
  sem_t countMutex;
@@ -11,13 +11,17 @@


public:
   ReadWriteLock() {
   PReadWriteLock() {
      if (sem_init(&countMutex, 1, 1) == -1)
       err_exit(errno, "PReadWriteLock sem_init");

      if (sem_init(&writeMutex, 1, 1) == -1)
       err_exit(errno, "PReadWriteLock sem_init");
   }

   void lockRead() {
      //readCount是共享变量，所以需要实现一个锁来控制读写  
 //synchronized(ReadWriteLock.class){}  
 //synchronized(PReadWriteLock.class){}  
     psem_wait(&countMutex);
    //只有是第一个读者，才将写锁加锁。其他的读者都是进行下一步  
    if(readCount == 0){