操作系统中关于信号量操作的代码示例(Linux + windows)

有一个生产者进程，有两个消费者进程。生产者产生1-100的100个数。两个消费者从共享内存中取数。

/*windows 部分*/

// Thread.cpp : 定义控制台应用程序的入口点。
//-----------Windows下生产者、消费者实例程序---------------------
//--------------author:zhangwei----------------------------------
//--------------Date  12/10/2004---------------------------------
#include "stdafx.h"

//作为仓库存放数据，最多可以放五个数据
int array[5];

//记录生成数据的个数
int pointer;

//记录取得的数据的位置
int pointerget;

//用来保存数据和
int sum;

//临界区对象
CRITICAL_SECTION csArray;

//句柄，保存Full信号量
HANDLE hFull;

//句柄，保存Empty信号量
HANDLE hEmpty;

//生产者函数
DWORD WINAPI Producer(LPVOID lpParam)
{
 int i = 0;
 pointer = 0;
 while( i < 100 )
 {
  
  WaitForSingleObject(hEmpty,INFINITE);
  EnterCriticalSection( &csArray);
  array[(pointer++)%5] = i + 1;
  LeaveCriticalSection( &csArray);
  ReleaseSemaphore(hFull,1,NULL);
  i++;
 }
 
 return 0;
}

//消费者函数A
DWORD WINAPI ConsumerA(LPVOID lpParam)
{
 while(1)
 {
  WaitForSingleObject(hFull,INFINITE);
  EnterCriticalSection( &csArray);
  sum += array[(pointerget ++ )%5];
  printf("ConsumerA get %d /n",array[(pointerget -1)%5]);
  if(pointerget == 100)
   printf("The sum is %d",sum);
  LeaveCriticalSection( &csArray);
  ReleaseSemaphore(hEmpty,1,NULL);
 }
 return 0;
}

//消费者函数B
DWORD WINAPI ConsumerB(LPVOID lpParam)
{
 while(1)
 {
  WaitForSingleObject(hFull,INFINITE);
  EnterCriticalSection( &csArray);
  sum += array[(pointerget ++ )%5];
  printf("ConsumerB get %d /n",array[(pointerget -1 )%5]);
  if(pointerget == 100)
   printf("The sum is %d",sum);
  LeaveCriticalSection( &csArray);
  ReleaseSemaphore(hEmpty,1,NULL);
 }
 return 0;
}

//主函数
void main()
{
 HANDLE hThreadProducer,hThreadConsumerA,hThreadComsumerB;
 sum = 0;
 pointerget = 0;

 InitializeCriticalSection( &csArray);
 hFull = CreateSemaphore(NULL,0,5,NULL);
 hEmpty = CreateSemaphore(NULL,5,5,NULL);

 hThreadProducer = CreateThread(NULL,0,
  Producer,NULL,0,NULL);
 hThreadConsumerA = CreateThread(NULL,0,
  ConsumerA,NULL,0,NULL);
 hThreadComsumerB = CreateThread(NULL,0,
  ConsumerB,NULL,0,NULL);
 
 _getch();
}

/*Linux 部分*/

#include <sys/mman.h>
#include <sys/types.h>
#include <linux/sem.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <time.h>

#define MAXSEM 5

//声明三个信号灯ID
int fullid;
int emptyid;
int mutxid;
int main()
{
  struct sembuf P,V;;
  union semun arg;

  //声明共享内存
  int *array;
  int *sum;
  int *set;
  int *get;

  //映射共享内存
  array = (int *)mmap(NULL , sizeof( int )*5,PROT_READ|PROT_WRITE,MAP_SHARED|MAP_ANONYMOUS,-1,0);
  sum = (int *)mmap(NULL , sizeof( int ),PROT_READ|PROT_WRITE,MAP_SHARED|MAP_ANONYMOUS,-1,0);
  get = (int *)mmap(NULL , sizeof( int ),PROT_READ|PROT_WRITE,MAP_SHARED|MAP_ANONYMOUS,-1,0);
  set = (int *)mmap(NULL , sizeof( int ),PROT_READ|PROT_WRITE,MAP_SHARED|MAP_ANONYMOUS,-1,0);
  *sum = 0;
  *get = 0;
  *set = 0;
 
  //生成信号灯
  fullid= semget(IPC_PRIVATE,1,IPC_CREAT|00666); 
  emptyid=semget(IPC_PRIVATE,1,IPC_CREAT|00666);
  mutxid=semget(IPC_PRIVATE,1,IPC_CREAT|00666);
 
  //为信号灯赋值
  arg.val = 0;
  if(semctl(fullid , 0 , SETVAL , arg) == -1) perror("semctl setval error");

  arg.val = MAXSEM;
  if(semctl(emptyid , 0 ,SETVAL , arg) == -1) perror("semctl setval error");

  arg.val = 1;
  if(semctl(mutxid , 0 ,SETVAL , arg) == -1) perror("setctl setval error");
 

  //初始化P,V操作
  V.sem_num=0;
  V.sem_op =1;
  V.sem_flg=SEM_UNDO;
  P.sem_num=0;
  P.sem_op =-1;
  P.sem_flg=SEM_UNDO;

  //生产者进程
  if(fork() == 0 )  {

      int i = 0;
      while( i < 100)
 {

   semop(emptyid , &P ,1 );
   semop(mutxid , &P , 1);
  
   array[*(set)%MAXSEM] = i + 1;
   printf("Producer %d/n", array[(*set)%MAXSEM]);
   (*set)++;

   semop(mutxid , &V , 1);
   semop(fullid , &V , 1);
   i++; 
       }
      sleep(10);
      printf("Producer is over");
       exit(0);
    }else {
      //ConsumerA  进程
      if(fork()==0) {
    
        while(1){

   semop(fullid , &P , 1);
   semop(mutxid , &P , 1);

   if(*get == 100)
     break;
   *sum += array[(*get)%MAXSEM];
 

   printf("The ComsumerA Get Number %d/n", array[(*get)%MAXSEM] );

         (*get)++;
   if( *get ==100)
     printf("The sum is %d /n ", *sum);
   semop(mutxid , &V , 1);
   semop(emptyid , &V ,1 );
   sleep(1);

 }
 printf("ConsumerA is over");
  exit(0);

    }else {
      //Consumer B进程
       if(fork()==0) {
         while(1){

   semop(fullid , &P , 1);
   semop(mutxid , &P , 1);

   if(*get == 100)
     break;

   *sum += array[(*get)%MAXSEM];

   printf("The ComsumerB Get Number %d/n", array[(*get)%MAXSEM] );  
          (*get)++;
   if( *get ==100)
     printf("The sum is %d /n ", *sum);
   semop(mutxid , &V , 1);
   semop(emptyid , &V ,1 );
   sleep(1);

 }
  printf("ConsumerB is over");
   exit(0);
       }
     }
    }
  // sleep(20);
  return 0;
}

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