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大概在很久之前就一直关注的ipc问题因为一直没有怎么使用也不是很明了,实在是为了自己的懒惰而汗颜了。经典的ipc里面除了自己曾经用到过的pthread_mutex之外,对其他的几种都不了解。自己学习的话也说了不少,可是都没有什么效果,看书似乎都看不动。
最近整理了一下几种ipc方式的使用,一些小问题,在此存档:
一.posix的msgqueue的支持问题。
要说明的是从一开始就觉得所谓的posix的兼容是很好的一个东西,而linux对posix的兼容性很好也是一直以来发展linuxer的一个重要的游说砝码。但是在开始测试posix message queue的时候遭到了当头一棒。程序编译通过,连接出错!然后google到nptl的知识,声称posix msgqueue的支持在mm分支中发展。晕先。不甘心的同时在新下载的2.6.18里面发现了如下说明:
2.6.18的内核里面关于posix message-queue的选项说明:
CONFIG_POSIX_MQUEUE:
POSIX variant of message queues is a part of IPC. In POSIX message
queues every message has a priority which decides about succession
of receiving it by a process. If you want to compile and run
programs written e.g. for Solaris with use of its POSIX message
queues (functions mq_*) say Y here. To use this feature you will
also need mqueue library, available from
POSIX message queues are visible as a filesystem called 'mqueue'
and can be mounted somewhere if you want to do filesystem
operations on message queues.
If unsure, say Y.
Symbol: POSIX_MQUEUE [=y]
Prompt: POSIX Message Queues
Defined at init/Kconfig:118
Depends on: NET && EXPERIMENTAL
同时在2.6.16里面这个还是没有的,真是庆幸啊,要是早点开始关注这个岂不是要郁闷很久或者麻烦很久。遵照上面内核编译系统给出的信息,上网站一看原来已经转到了:http://www.geocities.com/wronski12/posix_ipc/index.html.下载了:libmqueue-4.41.tar.gz。经典的三步之后再编译。bingle!
程序清单:posixqueue.c
#include
#include
#include
#include
#include
#include
#include
#include
#define MSGQUEUE_NAME "/tllmsgqueue"
#define MAXMSGNAMELENGTH 32
#define MSGQUEUE_LENGTH 128
#define MSG_LENGTH 64
struct parameters
{
char msgQueueName[MAXMSGNAMELENGTH];
struct mq_attr msgattr;
unsigned int timeInterval;
};
void msgSendThread(void * data)
{
//pthread_detach(pthread_self());
struct parameters * para=(struct parameters *)data;
mq_unlink(para->msgQueueName);
mqd_t mqid;
char buffer[MSG_LENGTH]={0};
unsigned int counter=0;
mode_t mode;
mode=S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH;
mqid=mq_open(para->msgQueueName,para->msgattr.mq_flags,mode,&(para->msgattr));
if(mqid == -1)
{
switch(errno)
{
case EACCES:
printf("EACCES------------\n");
break;
case EEXIST:
printf("EEXIST------------\n");
break;
case EINTR:
printf("EINTR------------\n");
break;
case EINVAL:
printf("EINVAL------------\n");
break;
case ENAMETOOLONG:
printf("ENAMETOOLONG------------\n");
case ENOENT:
printf("ENOENT------------\n");
break;
case ENOMEM:
printf("ENOMEM------------\n");
break;
case ENOSPC:
printf("ENOSPC------------\n");
break;
case EFAULT:
printf("EFAULT------------\n");
break;
case EMFILE:
printf("EMFILE------------\n");
break;
case ENFILE:
printf("ENFILE------------\n");
break;
default:
break;
}
printf("SendThread:open msqueue failed!\n");
return;
}
for(;countermsgQueueName,para->msgattr.mq_flags,mode,&(para->msgattr));
if(mqid == -1)
{
switch(errno)
{
case EACCES:
printf("EACCES------------\n");
break;
case EEXIST:
printf("EEXIST------------\n");
break;
case EINTR:
printf("EINTR------------\n");
break;
case EINVAL:
printf("EINVAL------------\n");
break;
case ENAMETOOLONG:
printf("ENAMETOOLONG------------\n");
case ENOENT:
printf("ENOENT------------\n");
break;
case ENOMEM:
printf("ENOMEM------------\n");
break;
case ENOSPC:
printf("ENOSPC------------\n");
break;
case EFAULT:
printf("EFAULT------------\n");
break;
case EMFILE:
printf("EMFILE------------\n");
break;
case ENFILE:
printf("ENFILE------------\n");
break;
default:
break;
}
printf("ReceiveThread:open msqueue failed!\n");
return;
}
unsigned int nreads=0;
for(;;)
{
mq_getattr(mqid,&privateAttr);
while(privateAttr.mq_curmsgs>0)
{
cread:
nreads=mq_receive(mqid,buffer,MSG_LENGTH,NULL);
if(strncmp(buffer,"quit",4) ==0 )
{
goto rend;
}
printf("\t\tread %d bytes,message is:%s.\n",nreads,buffer);
mq_getattr(mqid,&privateAttr);
}
goto cread;
}
rend:
mq_unlink(para->msgQueueName);
mq_close(mqid);
printf("now receive thread quit.\n");
return;
}
int main(void)
{
struct parameters myPara;
memset((void *)&myPara,0,sizeof(struct parameters));
strncat(myPara.msgQueueName,MSGQUEUE_NAME,MAXMSGNAMELENGTH);
//myPara.msgattr.mq_flags=O_RDWR|O_CREAT|O_NONBLOCK;
myPara.msgattr.mq_flags=O_RDWR|O_CREAT;
myPara.msgattr.mq_maxmsg=MSGQUEUE_LENGTH;
myPara.msgattr.mq_msgsize=MSG_LENGTH;
myPara.msgattr.mq_curmsgs=0;
myPara.timeInterval=1;
pthread_t pids;
pthread_t pidr;
pthread_create(&pids,NULL,(void *)msgSendThread,&myPara);
pthread_create(&pidr,NULL,(void *)msgReceiveThread,&myPara);
pthread_join(pids,NULL);
pthread_join(pidr,NULL);
printf("now main thread quit.\n");
return 0;
}
二.mmap的问题:
因为前面的posix的消息队列的问题慢慢就觉得posix毕竟还是不如sysV在unix系列的操作系统上来得通用,然后先把sysV的ipc方式都试用了一遍再试用posix方式的时候,犯了思维惯性的错误。因为sysV的share memory方式是“自动扩展”的(或者是达到一种“自动扩展”的效果),所以在试用posix方式shm的时候没有注意mmap是不具备“自动扩展”功能的,所以就一直卡在“总线错误”这个运行错误上。其实说起来这个错误提示也是有点怪,google了很久也没有明确的说明。好在最后还是搞定了。
程序清单:posixshm.c
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include "myerr.h"
#define SEM_WRITER "/tmptestllsemw"
#define SEM_READER "/tmptestllsemr"
#define SHM_NAME "/tmptestllshm"
#define SHMSIZE 64
struct ThreadPara
{
sem_t * reader;
sem_t * writer;
int shmid;
int shmsize;
};
void writerThread(void * data)
{
unsigned int counter=0;
struct ThreadPara * myPa=(struct ThreadPara *)data;
char * buffer;
buffer=mmap(NULL,myPa->shmsize,PROT_READ|PROT_WRITE,MAP_SHARED,myPa->shmid,0);
printf("writer:get buffer address is:%x.\n",(unsigned int)buffer);
for(counter=0;counterwriter);
sprintf((char *)buffer,"this is the posix shm #%d message",counter);
sem_post(myPa->reader);
sleep(1);
}
sem_wait(myPa->writer);
memset(buffer,0,myPa->shmsize);
sprintf(buffer,"quitnow");
sem_post(myPa->reader);
munmap(buffer,myPa->shmsize);
printf("now send thread quit.\n");
return;
}
void readerThread(void * data)
{
struct ThreadPara * myPa=(struct ThreadPara *)data;
void * buffer;
buffer=mmap(NULL,myPa->shmsize,PROT_READ|PROT_READ,MAP_SHARED,myPa->shmid,0);
printf("reader:get buffer address is:%x.\n",(unsigned int )buffer);
for(;;)
{
sem_wait(myPa->reader);
if(strncmp((char *)buffer,"quitnow",7) == 0)
{
break;
}
printf("\tYes,i got buffer:%s.\tthis is shm realization.\n",(char *)buffer);
sem_post(myPa->writer);
}
munmap(buffer,myPa->shmsize);
printf("now receive thread quit.\n");
return;
}
int main(void)
{
struct ThreadPara myPara;
int oFlag;
mode_t oMode;
memset(&myPara,0,sizeof(struct ThreadPara));
oFlag=O_CREAT;
oMode=S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH;
sem_unlink(SEM_READER);
sem_unlink(SEM_WRITER);
myPara.reader=sem_open(SEM_READER,oFlag,oMode,0);
if(myPara.reader
三.如果是简单的信号量的使用的话还是posix的信号量用起来简单一些,和mutex有点象吧。
最后:其他没什么问题。一些说明就是虽然这里说的ipc的问题,但是到底是将多个工作流程实现为多进程,还是将多个工作流程实现为多线程。还是具体问题具体分析吧,比如考虑到实时性,考虑的进程轮换的开销等等,不过大致的想来似乎是一样,按照“内核线程”的模型,多线程似乎还节省了进程切换的开销呢。呵呵。先这么臆断吧,也不知道是不是正确的,有机会测试一下。
而这里图个方便,就全部都是采用开线程测试的。也是做个备忘的意思,几个程序的清单如下:
sysvqueue.c
#include
#include
#include
#include
#include
#include
#include
#include
#define MSGQUEUE_NAME "/tmp/tllmsgqueue"
#define MSGQUEUE_ID 0
#define MAXMSGNAMELENGTH 32
#define MSGQUEUE_LENGTH 128
#define MSG_LENGTH 64
struct parameters
{
key_t mqid;
struct msqid_ds qds;
int oflag;
};
void msgSendThread(void * data)
{
//pthread_detach(pthread_self());
struct parameters * para=(struct parameters *)data;
int mqid;
char buffer[MSG_LENGTH]={0};
unsigned int counter=0;
mqid=msgget(para->mqid,para->oflag);
if(mqid == -1)
{
return;
}
for(;countermqid,para->oflag);
if(mqid == -1)
{
return;
}
unsigned int nreads=0;
for(;;)
{
msgctl(mqid,IPC_STAT,&(para->qds));
while(para->qds.msg_qnum>0)
{
doread:
nreads=msgrcv(mqid,buffer,MSG_LENGTH,0,0);
if(errno == EIDRM)
{
goto abquit;
}
if(strncmp(buffer,"quit",4)==0)
{
goto endreceive;
}
printf("read %hd bytes,message is:%s.\n",nreads,buffer);
msgctl(mqid,IPC_STAT,&(para->qds));
}
goto doread;
}
endreceive:
msgctl(mqid,IPC_RMID,NULL);
abquit:
printf("receive thread quit now .\n");
return;
}
int main(void)
{
struct parameters myPara;
memset((void *)&myPara,0,sizeof(struct parameters));
#ifdef PRIVATEIPC
myPara.mqid=IPC_PRIVATE;
#else
myPara.mqid=ftok(MSGQUEUE_NAME,MSGQUEUE_ID);
#endif
myPara.oflag=IPC_CREAT;
pthread_t pids;
pthread_t pidr;
pthread_create(&pids,NULL,(void *)msgSendThread,&myPara);
pthread_create(&pidr,NULL,(void *)msgReceiveThread,&myPara);
pthread_join(pidr,NULL);
//printf("\tnow is here!\n");
pthread_join(pids,NULL);
printf("main thread quit now.\n");
return 0;
}
sysvsem.c
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define SEM_NAME "/tmp/testllsem"
#define SEM_ID 0
#define BUFFERSIZE 64
#if defined(__GNU_LIBRARY__) && !defined(_SEM_SEMUN_UNDEFINED)
/* union semun is defined by including */
#else
/* according to X/OPEN we have to define it ourselves */
union semun {
int val; /* value for SETVAL */
struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
unsigned short *array; /* array for GETALL, SETALL */
/* Linux specific part: */
struct seminfo *__buf; /* buffer for IPC_INFO */
};
#endif
struct ThreadPara
{
key_t kid;
int semid;
unsigned int readerIndex;
unsigned int writerIndex;
char buffer[BUFFERSIZE];
};
void writerThread(void * data)
{
unsigned int counter=0;
struct ThreadPara * myPa=(struct ThreadPara *)data;
struct sembuf semops;
semops.sem_flg=SEM_UNDO;
for(;counterwriterIndex;
semops.sem_op=-1;
//semops.sem_flg=SEM_UNDO;
semop(myPa->semid,&semops,1);
sprintf(myPa->buffer,"this is the #%d message",counter);
semops.sem_num=myPa->readerIndex;
semops.sem_op=1;
//semops.sem_flg=0;
semop(myPa->semid,&semops,1);
//sleep(1);
}
semops.sem_num=myPa->writerIndex;
semops.sem_op=-1;
//semops.sem_flg=0;
semop(myPa->semid,&semops,1);
memset(myPa->buffer,0,BUFFERSIZE);
sprintf(myPa->buffer,"quitnow");
semops.sem_num=myPa->readerIndex;
semops.sem_op=1;
//semops.sem_flg=0;
semop(myPa->semid,&semops,1);
printf("now send thread quit.\n");
return;
}
void readerThread(void * data)
{
struct ThreadPara * myPa=(struct ThreadPara *)data;
struct sembuf semops;
semops.sem_flg=SEM_UNDO;
for(;;)
{
semops.sem_num=myPa->readerIndex;
semops.sem_op=-1;
//semops.sem_flg=0;
semop(myPa->semid,&semops,1);
if(strncmp(myPa->buffer,"quitnow",7) == 0)
{
break;
}
printf("\tYes,i got buffer:%s.\n",myPa->buffer);
semops.sem_num=myPa->writerIndex;
semops.sem_op=1;
//semops.sem_flg=0;
semop(myPa->semid,&semops,1);
}
printf("now receive thread quit.\n");
return;
}
int main(void)
{
struct ThreadPara myPara;
int oFlag;
//mode_t oMode;
union semun arg;
memset(&myPara,0,sizeof(struct ThreadPara));
oFlag=IPC_CREAT|IPC_EXCL;
//oMode=S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH;
#ifdef PRIVATEIPC
myPara.kid=IPC_PRIVATE;
#else
myPara.kid=ftok(SEM_NAME,SEM_ID);
#endif
myPara.semid=semget(myPara.kid,2,oFlag);
myPara.readerIndex=0;
myPara.writerIndex=1;
arg.val=0;
semctl(myPara.semid,myPara.readerIndex,SETVAL,arg);
arg.val=1;
semctl(myPara.semid,myPara.writerIndex,SETVAL,arg);
if(myPara.semid
sysvshm.c
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define SEM_NAME "/tmp/testllsem"
#define SEM_ID 0
#define SHM_NAME "/tmp/testllshm"
#define SHM_ID 0
#define SHMSIZE 64
#if defined(__GNU_LIBRARY__) && !defined(_SEM_SEMUN_UNDEFINED)
/* union semun is defined by including */
#else
/* according to X/OPEN we have to define it ourselves */
union semun {
int val; /* value for SETVAL */
struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
unsigned short *array; /* array for GETALL, SETALL */
/* Linux specific part: */
struct seminfo *__buf; /* buffer for IPC_INFO */
};
#endif
struct ThreadPara
{
key_t ksemid;
key_t kshmid;
int semid;
int shmid;
unsigned int readerIndex;
unsigned int writerIndex;
int shmsize;
};
void writerThread(void * data)
{
unsigned int counter=0;
struct ThreadPara * myPa=(struct ThreadPara *)data;
void * buffer;
struct sembuf semops;
semops.sem_flg=SEM_UNDO;
buffer=shmat(myPa->shmid,NULL,0);
for(;counterwriterIndex;
semops.sem_op=-1;
//semops.sem_flg=SEM_UNDO;
semop(myPa->semid,&semops,1);
sprintf(buffer,"this is the #%d message",counter);
semops.sem_num=myPa->readerIndex;
semops.sem_op=1;
//semops.sem_flg=0;
semop(myPa->semid,&semops,1);
//sleep(1);
}
semops.sem_num=myPa->writerIndex;
semops.sem_op=-1;
//semops.sem_flg=0;
semop(myPa->semid,&semops,1);
memset(buffer,0,myPa->shmsize);
sprintf(buffer,"quitnow");
semops.sem_num=myPa->readerIndex;
semops.sem_op=1;
//semops.sem_flg=0;
semop(myPa->semid,&semops,1);
shmdt(buffer);
printf("now send thread quit.\n");
return;
}
void readerThread(void * data)
{
struct ThreadPara * myPa=(struct ThreadPara *)data;
void * buffer;
struct sembuf semops;
semops.sem_flg=SEM_UNDO;
buffer=shmat(myPa->shmid,NULL,SHM_RDONLY);
for(;;)
{
semops.sem_num=myPa->readerIndex;
semops.sem_op=-1;
//semops.sem_flg=0;
semop(myPa->semid,&semops,1);
if(strncmp(buffer,"quitnow",7) == 0)
{
break;
}
printf("\tYes,i got buffer:%s.\tthis is shm realization.\n",(char *)buffer);
semops.sem_num=myPa->writerIndex;
semops.sem_op=1;
//semops.sem_flg=0;
semop(myPa->semid,&semops,1);
}
shmdt(buffer);
printf("now receive thread quit.\n");
return;
}
int main(void)
{
struct ThreadPara myPara;
int oFlag;
//mode_t oMode;
union semun arg;
memset(&myPara,0,sizeof(struct ThreadPara));
oFlag=IPC_CREAT|IPC_EXCL;
//oMode=S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH;
#ifdef PRIVATEIPC
myPara.ksemid=IPC_PRIVATE;
myPara.kshmid=IPC_PRIVATE;
#else
myPara.ksemid=ftok(SEM_NAME,SEM_ID);
myPara.kshmid=ftok(SHM_NAME,SHM_ID);
#endif
myPara.shmsize=SHMSIZE;
myPara.semid=semget(myPara.ksemid,2,oFlag);
if(myPara.semid
posixsem.c
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define SEM_WRITER "/testllposixsemw"
#define SEM_READER "/testllposixsemr"
#define BUFFERSIZE 64
struct ThreadPara
{
sem_t * reader;
sem_t * writer;
char buffer[BUFFERSIZE];
};
void writerThread(void * data)
{
unsigned int counter=0;
struct ThreadPara * myPa=(struct ThreadPara *)data;
for(;counterwriter);
sprintf(myPa->buffer,"writer:this is the POSIX_SEM #%d message",counter);
sem_post(myPa->reader);
//sleep(1);
}
sem_wait(myPa->writer);
memset(myPa->buffer,0,BUFFERSIZE);
sprintf(myPa->buffer,"quitnow");
sem_post(myPa->reader);
printf("now send thread quit.\n");
return;
}
void readerThread(void * data)
{
struct ThreadPara * myPa=(struct ThreadPara *)data;
for(;;)
{
sem_wait(myPa->reader);
if(strncmp(myPa->buffer,"quitnow",7) == 0)
{
break;
}
printf("\treader:Yes,i got buffer:%s.\n",myPa->buffer);
sem_post(myPa->writer);
//sleep(3);
}
printf("now receive thread quit.\n");
return;
}
int main(void)
{
struct ThreadPara myPara;
int oFlag;
mode_t oMode;
memset(&myPara,0,sizeof(struct ThreadPara));
//oFlag=O_CREAT|O_EXCL;
oFlag=O_CREAT;
oMode=S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH;
myPara.reader=sem_open(SEM_READER,oFlag,oMode,0);
if(myPara.reader
外加一个简陋的Makefile。
CFLAGS=-O9 -Wall -g -D__POSIX_SOURCE
CINCLUDES=
CLIBS=-lpthread -lrt
POSIXQUEUELIB=-lmqueue
CC=gcc
all:tm one two tcrc pq vq psem vsem vshm pshm
pshm:posixshm.c
$(CC) $(CFLAGS) $(CINCLUDES) $(CLIBS) -o pshm posixshm.c
vshm:sysvshm.c
$(CC) $(CFLAGS) $(CINCLUDES) $(CLIBS) -o vshm sysvshm.c
psem:posixsem.c
$(CC) $(CFLAGS) $(CINCLUDES) $(CLIBS) -o psem posixsem.c
vsem:sysvsem.c
$(CC) $(CFLAGS) $(CINCLUDES) $(CLIBS) -o vsem sysvsem.c
vq:sysvqueue.c
$(CC) $(CFLAGS) $(CINCLUDES) $(CLIBS) -o vq sysvqueue.c
pq:posixqueue.c
$(CC) $(CFLAGS) $(CINCLUDES) $(CLIBS) $(POSIXQUEUELIB) -o pq posixqueue.c
tcrc:testcrc.c
$(CC) $(CFLAGS) $(CINCLUDES) $(CLIBS) -o tcrc testcrc.c
tm:testmain.c
$(CC) $(CFLAGS) $(CINCLUDES) $(CLIBS) -o tm testmain.c
one:one.c
$(CC) $(CFLAGS) $(CINCLUDES) $(CLIBS) -o one one.c
two:two.c
$(CC) $(CFLAGS) $(CINCLUDES) $(CLIBS) -o two two.c
clean:
rm -f vshm
rm -f pshm
rm -f vsem
rm -f psem
rm -f pq
rm -f vq
rm -f tcrc
rm -f one
rm -f two
rm -f tm
rm -f a.out
留此备忘。
本文来自ChinaUnix博客,如果查看原文请点:http://blog.chinaunix.net/u/17564/showart_194971.html |
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