C++ sem_v函数代码示例

static int
doTerminateInstance(	struct nc_state_t *nc,
			ncMetadata *meta,
			char *instanceId,
			int *shutdownState,
			int *previousState)
{
	ncInstance *instance, *vninstance;
	virConnectPtr *conn;
	int err;

	sem_p (inst_sem); 
	instance = find_instance(&global_instances, instanceId);
	sem_v (inst_sem);
	if (instance == NULL) 
		return NOT_FOUND;

	/* try stopping the KVM domain */
	conn = check_hypervisor_conn();
	if (conn) {
	        sem_p(hyp_sem);
	        virDomainPtr dom = virDomainLookupByName(*conn, instanceId);
		sem_v(hyp_sem);
		if (dom) {
			/* also protect 'destroy' commands, just in case */
			sem_p (hyp_sem);
			err = virDomainDestroy (dom);
			sem_v (hyp_sem);
			if (err==0) {
				logprintfl (EUCAINFO, "destroyed domain for instance %s\n", instanceId);
			}
			sem_p(hyp_sem);
			virDomainFree(dom); /* necessary? */
			sem_v(hyp_sem);
		} else {
			if (instance->state != BOOTING)
				logprintfl (EUCAWARN, "warning: domain %s to be terminated not running on hypervisor\n", instanceId);
		}
	} 

	/* change the state and let the monitoring_thread clean up state */
    sem_p (inst_sem);
    if (instance->state==BOOTING) {
        change_state (instance, CANCELED);
    } else {
        change_state (instance, SHUTOFF);
    }
    sem_v (inst_sem);
	*previousState = instance->stateCode;
	*shutdownState = instance->stateCode;

	return OK;
}

int main(int argc, char *argv[])
{
	//前面一大块4个人物其实都是一样的，就是看看semget是不是分配成功，共享区是不是分享成功
    	int i,item,shmid;
	semaphore mutex,pan,orange;
    	union semun sem_union;
	void *shared_memory = (void *)0;
	struct shared_use_st *shared_stuff;

	if ( (mutex=semget((key_t)KEY_MUTEX,1,0666|IPC_CREAT)) == -1 ) {
		fprintf(stderr,"Failed to create semaphore!"); 
		exit(EXIT_FAILURE);
	}
	if ( (pan = semget((key_t)KEY_PAN,1,0666|IPC_CREAT)) == -1 ) {
		fprintf(stderr,"Failed to create semaphore!"); 
		exit(EXIT_FAILURE);
	}
	if ( (orange = semget((key_t)KEY_ORANGE,1,0666|IPC_CREAT)) == -1 ) {
		fprintf(stderr,"Failed to create semaphore!"); 
		exit(EXIT_FAILURE);
	}
	if ( (shmid = shmget((key_t)KEY_SHM,sizeof(struct shared_use_st),0666|IPC_CREAT)) == -1 ) {
		fprintf(stderr,"Failed to create shared memory!"); 
		exit(EXIT_FAILURE);
	}

	if ( (shared_memory = shmat(shmid,(void *)0,0) ) == (void *)-1) {
		fprintf(stderr,"shmat failed\n");
		exit(EXIT_FAILURE);
	}
	shared_stuff = (struct shared_use_st *)shared_memory;
	//这个是模仿老师的30个，其实通过sleep的时间调整，能让dad和mother经常拿到不同盘子，比较接近的话，会一直拿到一样的盘子的
	for(i=0;i<30;i++)
	{
		sleep(0.9);
		sem_p(pan);
		sem_p(mutex);
		(shared_stuff->hi) = ((shared_stuff->hi)+1) % BUFFER_SIZE;
		item  = ((int)shared_stuff->hi)+1;
		printf("Mother use pan %d put the orange\n",item);
		sem_v(mutex);
		sem_v(orange);
	}

    	if (shmdt(shared_memory) == -1) {
       		fprintf(stderr, "shmdt failed\n"); 
		exit(EXIT_FAILURE);
	}
	printf("Finish!\n");
	getchar();
  	exit(EXIT_SUCCESS);
}

int diskutil_loop (const char * path, const long long offset, char * lodev, int lodev_size)
{
    int found = 0;
    int done = 0;
    int ret = OK;
    char * output;

    // we retry because we cannot atomically obtain a free loopback
    // device on all distros (some versions of 'losetup' allow a file
    // argument with '-f' options, but some do not)
    for (int i=0; i<LOOP_RETRIES; i++) {
        sem_p (loop_sem);
        output = pruntf (TRUE, "%s %s -f", helpers_path[ROOTWRAP], helpers_path[LOSETUP]);
        sem_v (loop_sem);
        if (output==NULL) // there was a problem
            break;
        if (strstr (output, "/dev/loop")) {
            strncpy (lodev, output, lodev_size);
            char * ptr = strrchr (lodev, '\n');
            if (ptr) {
                *ptr = '\0';
                found = 1;
            }
        }
        free (output);

        if (found) {
            boolean do_log = ((i+1)==LOOP_RETRIES); // log error on last try only
            logprintfl (EUCADEBUG, "{%u} attaching file %s\n", (unsigned int)pthread_self(), path);
            logprintfl (EUCADEBUG, "{%u}             to %s at offset %lld\n", (unsigned int)pthread_self(), lodev, offset);
            sem_p (loop_sem);
            output = pruntf (do_log, "%s %s -o %lld %s %s", helpers_path[ROOTWRAP], helpers_path[LOSETUP], offset, lodev, path);
            sem_v (loop_sem);
            if (output==NULL) {
                logprintfl (EUCADEBUG, "{%u} cannot attach to loop device %s (will retry)\n", (unsigned int)pthread_self(), lodev);
            } else {
                free (output);
                done = 1;
                break;
            }
        }
        
        sleep (1);
        found = 0;
    }
    if (!done) {
        logprintfl (EUCAINFO, "{%u} error: cannot find free loop device or attach to one\n", (unsigned int)pthread_self());
        ret = ERROR;
    }
    
    return ret;
}

static int
doDescribeInstances(	struct nc_state_t *nc,
			ncMetadata *meta,
			char **instIds,
			int instIdsLen,
			ncInstance ***outInsts,
			int *outInstsLen)
{
	ncInstance *instance;
	int total, i, j, k;

	*outInstsLen = 0;
	*outInsts = NULL;

	sem_p (inst_sem);
	if (instIdsLen == 0) /* describe all instances */
		total = total_instances (&global_instances);
	else 
		total = instIdsLen;

	*outInsts = malloc(sizeof(ncInstance *)*total);
	if ((*outInsts) == NULL) {
		sem_v (inst_sem);
		return OUT_OF_MEMORY;
	}

	k = 0;
	for (i=0; (instance = get_instance(&global_instances)) != NULL; i++) {
		/* only pick ones the user (or admin)  is allowed to see */
		if (strcmp(meta->userId, nc->admin_user_id) 
				&& strcmp(meta->userId, instance->userId))
			continue;

		if (instIdsLen > 0) {
			for (j=0; j < instIdsLen; j++)
				if (!strcmp(instance->instanceId, instIds[j]))
					break;

			if (j >= instIdsLen)
				/* instance of not relavance right now */
				continue;
		}

		(* outInsts)[k++] = instance;
	}
	*outInstsLen = k;
	sem_v (inst_sem);

	return OK;
}

static int 
doAttachSystemDisk (    struct nc_state_t *nc,
                           ncMetadata *meta,
                           char *instanceId,
                           char *isoPath)
{
    ncInstance *instance;
    virConnectPtr *conn;
    virDomainPtr dom = NULL;
    char xml[MAX_PATH]={'\0'};
    int err;
    snprintf (xml, sizeof(xml), "<disk type='block' device='cdrom'><source dev='%s'/><target dev='hdc' bus='ide'/><readonly/></disk>", isoPath);  
    //logprintfl(EUCAINFO, "doAttachSystemDisk(): founded %s [%s---%s---%d]\n", instanceId,__FILE__, __FUNCTION__, __LINE__);
    sem_p(inst_sem);
    instance = find_instance(&global_instances, instanceId);
    sem_v(inst_sem);
    if (instance == NULL || (instance->state != RUNNING&& instance->state !=  BLOCKED&& instance->state !=PAUSED)) {
        logprintfl(EUCAINFO, "doAttachSystemDisk(): found %s failed or instance->state!=RUNNING||BLOCKED||PAUSED [file:%s---line:%d]\n", instanceId, __FILE__, __LINE__);
        return NOT_FOUND;
    }
    conn = check_hypervisor_conn();
    if (conn) {
/*
        snprintf(cmd, sizeof(cmd), "virsh attach-disk %s %s hdc --type cdrom --mode readonly",instanceId, isoPath);
        logprintfl(EUCAINFO, "xiongm: cmd=%s [%s---%s---%d]\n",cmd, __FILE__, __FUNCTION__, __LINE__);
        system(cmd);
*/
        dom = NULL;
        sem_p(hyp_sem);
        dom = virDomainLookupByName(*conn, instanceId);
        sem_v(hyp_sem);
        if (dom) {
            sem_p (hyp_sem);
            err = virDomainAttachDevice (dom, xml);
            sem_v (hyp_sem);
            if(err != 0) {
                logprintfl(EUCAINFO,"virDomainAttachDevice failed. err=%d\n",err);
                return 1;
            }
        }
        logprintfl(EUCAINFO,"doAttachSystemDisk success.\n");
        return 0;  
    }
    else {
        logprintfl(EUCAINFO, "doAttachSystemDisk(): no connect hypervisior [file:%s---line:%d]\n",__FILE__, __LINE__);
        return 1;
    }       
}

int disconnect_iscsi_target (const char *dev_string) 
{
    int pid, retval, status;
    assert (strlen (home));

    logprintfl (EUCAINFO, "disconnect_iscsi_target invoked (dev_string=%s)\n", dev_string);

    sem_p (iscsi_sem);
    pid = fork();
    if (!pid) {
        if ( dev_string && strlen(dev_string) ) logprintfl(EUCADEBUG, "disconnect_iscsi_target(): running command: %s %s,%s\n", disconnect_storage_cmd_path, home, dev_string);
        if (vrun("%s %s,%s", disconnect_storage_cmd_path, home, dev_string) != 0) {
            logprintfl (EUCAERROR, "ERROR: disconnect_iscsi_target failed\n");
            exit(1);
        }
        exit(0);
    } else {
        retval = timewait(pid, &status, 90);
        if (retval) {
            retval = WEXITSTATUS(status);
        } else {
            kill(pid, SIGKILL);
            retval = -1;
        }
    }
    sem_v (iscsi_sem);

    return retval;
}

//!
//! Detach a local device that is iSCSI and disconnect the session.
//!
//! @param[in] sc_url - The URL to reach the cluster's SC at.
//! @param[in] use_ws_sec - boolean to determine use of WS-SEC.
//! @param[in] ws_sec_policy_file - Policy file path for WS-SEC
//! @param[in] attachment_token - The volume/token string received in the request that will be used
//! @param[in] connect_string - The connect string used for attachment, to be re-used on disconnect
//! @param[in] local_ip - The local host's external IP
//! @param[in] local_iqn - The local host's IQN
//!
//! @return
//!
//! @pre
//!
//! @post
//!
//! @note should only be invoked after detachment from the guest
//!
int disconnect_ebs_volume(char *sc_url, int use_ws_sec, char *ws_sec_policy_file, char *attachment_token, char *connect_string, char *local_ip, char *local_iqn)
{
    int ret = EUCA_ERROR;
    int norescan = 0;                  //send a 0 to indicate no rescan requested
    ebs_volume_data *vol_data = NULL;

    if (attachment_token == NULL || connect_string == NULL || local_ip == NULL || local_iqn == NULL) {
        LOGERROR("Cannont disconnect ebs volume. Got NULL input parameters.\n");
        return EUCA_ERROR;
    }

    LOGTRACE("Disconnecting an EBS volume\n");

    if (deserialize_volume(attachment_token, &vol_data) != EUCA_OK) {
        LOGERROR("Could not deserialize attachment token string %s\n", attachment_token);
        return EUCA_ERROR;
    }

    LOGTRACE("Requesting volume lock\n");
    sem_p(vol_sem);
    {
        LOGTRACE("Got volume lock\n");
        ret = cleanup_volume_attachment(sc_url, use_ws_sec, ws_sec_policy_file, vol_data, connect_string, local_ip, local_iqn, norescan);
        LOGTRACE("cleanup_volume_attachment returned: %d\n", ret);
        LOGTRACE("Releasing volume lock\n");
    }
    sem_v(vol_sem);
    LOGTRACE("Released volume lock\n");

    EUCA_FREE(vol_data);
    return ret;
}

int diskutil_unloop (const char * lodev)
{
    int ret = OK;
    char * output;
    int retried = 0;

    logprintfl (EUCADEBUG, "{%u} detaching from loop device %s\n", (unsigned int)pthread_self(), lodev);

    // we retry because we have seen spurious errors from 'losetup -d' on Xen:
    //     ioctl: LOOP_CLR_FD: Device or resource bus
    for (int i=0; i<LOOP_RETRIES; i++) {
        boolean do_log = ((i+1)==LOOP_RETRIES); // log error on last try only
        sem_p (loop_sem);
        output = pruntf (do_log, "%s %s -d %s", helpers_path[ROOTWRAP], helpers_path[LOSETUP], lodev);
        sem_v (loop_sem);
        if (!output) {           
            ret = ERROR;
        } else {
            ret = OK;
            free (output);
            break;
        }
        logprintfl (EUCADEBUG, "{%u} cannot detach loop device %s (will retry)\n", (unsigned int)pthread_self(), lodev);
        retried++;
        sleep (1);
    }
    if (ret == ERROR) {
        logprintfl (EUCAWARN, "{%u} error: cannot detach loop device\n", (unsigned int)pthread_self());
    } else if (retried) {
        logprintfl (EUCAINFO, "{%u} succeeded to detach %s after %d retries\n", (unsigned int)pthread_self(), lodev, retried);
    }

    return ret;
}

static int
doRebootInstance(	struct nc_state_t *nc,
			ncMetadata *meta,
			char *instanceId) 
{
    sem_p (inst_sem); 
    ncInstance *instance = find_instance (&global_instances, instanceId);
    sem_v (inst_sem);
    if ( instance == NULL ) {
        logprintfl (EUCAERROR, "cannot find instance %s\n", instanceId);
        return ERROR;
    }
    
    pthread_t tcb;
    // since shutdown/restart may take a while, we do them in a thread
    if ( pthread_create (&tcb, NULL, rebooting_thread, (void *)instance) ) {
        logprintfl (EUCAERROR, "failed to spawn a reboot thread\n");
        return ERROR_FATAL;
    }
    if (pthread_detach(tcb)) {
      logprintfl (EUCAERROR, "failed to detach the rebooting thread\n");
      return ERROR_FATAL;
    }
    
    return OK;
}

int main()
{
	int	semid, shmid;
	char	*shmaddr;
	
	if ((shmid = createshm(".", 'm', SHM_SIZE)) == -1){
		exit (1);
	}
	
	if((shmaddr = shmat (shmid, (char *)0, 0)) == (char *)-1){
		perror ("attach shared memory error!\n");
		exit (1);
	}
	
	if((semid = opensem("." ,'s')) == -1){
		exit (1);
	}
	
	while(1){
		printf("reader: ");
		sem_p(semid,0);			/* P操作 */
		
		printf("%s", shmaddr);
		
		sem_v(semid,0);			/* V操作 */
	}
}

/* wait for file 'appear' to appear or for file 'disappear' to disappear */
static int wait_for_file (const char * appear, const char * disappear, const int iterations, const char * name)
{
    int done, i;
    if (!appear && !disappear) return 1;

    for ( i=0, done=0; i<iterations && !done; i++ ) {
		struct stat mystat;
        sem_p (sc_sem);
        int check = ( (appear    && (stat (appear,    &mystat)==0)) ||
                      (disappear && (stat (disappear, &mystat)!=0)) );
        sem_v (sc_sem);
        if (check) {
            done++;
        } else {
	  		if (i==0) {
	    		logprintfl (EUCAINFO, "waiting for %s to become ready...\n", name);
	  		}
            sleep (10);
        }
    }

    if (!done) {
        logprintfl (EUCAERROR, "ERROR: timed out waiting for %s to become ready\n", name);
        return 1;
    }
    return 0;
}

//!
//! Handles the reboot request of an instance.
//!
//! @param[in] nc a pointer to the NC state structure to initialize
//! @param[in] pMeta a pointer to the node controller (NC) metadata structure
//! @param[in] instanceId the instance identifier string (i-XXXXXXXX)
//!
//! @return EUCA_OK on success or proper error code. Known error code returned include:
//!         EUCA_ERROR, EUCA_NOT_FOUND_ERROR, and EUCA_FATAL_ERROR.
//!
static int doRebootInstance(struct nc_state_t *nc, ncMetadata * pMeta, char *instanceId)
{
    pthread_t tcb = { 0 };
    ncInstance *instance = NULL;
    rebooting_thread_params *params = NULL;

    sem_p(inst_sem);
    {
        instance = find_instance(&global_instances, instanceId);
    }
    sem_v(inst_sem);

    if (instance == NULL) {
        LOGERROR("[%s] cannot find instance\n", instanceId);
        return (EUCA_NOT_FOUND_ERROR);
    }

    params = EUCA_ZALLOC(1, sizeof(rebooting_thread_params));
    memcpy(&(params->instance), instance, sizeof(ncInstance));
    memcpy(&(params->nc), nc, sizeof(struct nc_state_t));
    // since shutdown/restart may take a while, we do them in a thread
    if (pthread_create(&tcb, NULL, rebooting_thread, params)) {
        LOGERROR("[%s] failed to spawn a reboot thread\n", instanceId);
        return (EUCA_FATAL_ERROR);
    }
    set_corrid_pthread(get_corrid() != NULL ? get_corrid()->correlation_id : NULL, tcb);
    if (pthread_detach(tcb)) {
        LOGERROR("[%s] failed to detach the rebooting thread\n", instanceId);
        return (EUCA_FATAL_ERROR);
    }

    return (EUCA_OK);
}

int main()
{
  void *shared_memory = NULL;
  struct shm_buff *shm_buff_inst;
  char buffer[BUFSIZ];
  int shmid,semid;
  ignore_signal();
  semid = semget(ftok(".",'a'),1,0666|IPC_CREAT);
  init_sem(semid,1);
  shmid = shmget(ftok(".",'b'),sizeof(struct shm_buff),0666|IPC_CREAT);
  if(shmid == -1)
   {
    perror("shmget failed");
    del_sem(semid);
    exit(1);
   }
   shared_memory=shmat(shmid,(void*)0,0);
   if(shared_memory==(void*)-1)
   {
    perror("shmat");
    del_sem(semid);
    exit(1);
   }
   printf("memory attached at %X\n",(int)shared_memory);
   shm_buff_inst = (struct shm_buff*)shared_memory;
   do
   {
     sem_p(semid);
     printf("enter some text to the shared memory(enter'quit'to exit):");
     if(fgets(shm_buff_inst->buffer,SHM_BUFF_SZ,stdin)==NULL)
     {
      perror("fgets");
      sem_v(semid);
      break;
     }
     shm_buff_inst->pid=getpid();
     sem_v(semid);
   } while(strncmp(shm_buff_inst->buffer,"quit",4)!=0);
   del_sem(semid);
   if(shmdt(shared_memory)==1)
   {
    perror("shmdt");
    exit(1);
   }
  exit(0); 
}

int staebchen_nehmen(int my_id, int pos) {
  sem_p(sem[pos]);
  int n=staebchen[pos];
  if (n==1) {
    printf("%i nimmt %i\n", my_id, pos);
    staebchen[pos]--; // ergibt 0, gibt aber chance zur fehlererkennung
    sem_v(sem[pos]);
    return 1;
  } else if (n==0) {
    sem_v(sem[pos]);
    return 0;
  } else {
    printf("Fehler: staebchen[%i]=%i\n", pos, n);
    sem_v(sem[pos]);
    exit(1);
  }
}

int create_instance_backing (ncInstance * instance)
{
    int ret = ERROR;
    virtualMachine * vm = &(instance->params);
    artifact * sentinel = NULL;

    // ensure instance directory exists
    set_path (instance->instancePath,    sizeof (instance->instancePath),    instance, NULL);
    if (ensure_directories_exist (instance->instancePath, 0, NULL, "root", BACKING_DIRECTORY_PERM) == -1)
        goto out;

    // set various instance-directory-relative paths in the instance struct
    set_path (instance->xmlFilePath,     sizeof (instance->xmlFilePath),     instance, "instance.xml");
    set_path (instance->libvirtFilePath, sizeof (instance->libvirtFilePath), instance, "libvirt.xml");
    set_path (instance->consoleFilePath, sizeof (instance->consoleFilePath), instance, "console.log");
    if (strstr (instance->platform, "windows")) {
        // generate the floppy file for windows instances
        if (makeWindowsFloppy (nc_state.home, instance->instancePath, instance->keyName, instance->instanceId)) {
            logprintfl (EUCAERROR, "[%s] error: could not create windows bootup script floppy\n", instance->instanceId);
            goto out;
        } else {
            set_path (instance->floppyFilePath, sizeof (instance->floppyFilePath), instance, "floppy");
        }
    }
    
    char work_prefix [1024]; // {userId}/{instanceId}
    set_id (instance, NULL, work_prefix, sizeof (work_prefix));
    
    // compute tree of dependencies
    sentinel = vbr_alloc_tree (vm, // the struct containing the VBR
                               FALSE, // for Xen and KVM we do not need to make disk bootable
                               TRUE, // make working copy of runtime-modifiable files
                               (instance->do_inject_key)?(instance->keyName):(NULL), // the SSH key
                               instance->instanceId); // ID is for logging
    if (sentinel == NULL) {
        logprintfl (EUCAERROR, "[%s] error: failed to prepare backing for instance\n", instance->instanceId);
        goto out;
    }

    sem_p (disk_sem);
    // download/create/combine the dependencies
    int rc = art_implement_tree (sentinel, work_bs, cache_bs, work_prefix, INSTANCE_PREP_TIMEOUT_USEC);
    sem_v (disk_sem);

    if (rc != OK) {
        logprintfl (EUCAERROR, "[%s] error: failed to implement backing for instance\n", instance->instanceId);
        goto out;
    }

    if (save_instance_struct (instance)) // update instance checkpoint now that the struct got updated
        goto out;

    ret = OK;
 out:
    if (sentinel)
        art_free (sentinel);
    return ret;
}