使用 Unix 域套接字的 IPC

Question

我有两个不同的应用程序，其中一个必须将数据输入另一个。我正在使用 Unix 域套接字在它们之间进行通信。客户端挂钩到套接字，检查服务器连接，如果可用，则发送数据。服务器等待客户端连接，只要有一些数据可用，它就会读取数据并将其写入文件。客户端的主要功能是：

CLIENT:
int main(int argc, char* argv[]) {

if (argc < 2) {
    printf("Usage: Operating_Mode Path_to_DAQ_dataset output_file cudaBF\n");
    printf("Operating_Mode = 0 : Real Time BF processing\nUsage: Operating_Mode output_file cudaBF\n");
    printf("Operating_Mode = 1 : Pre-recorded data BF processing\nUsage: Operating_Mode Path_to_DAQ_dataset output_file cudaBF\n");
    return 1;
}

/*******************************************/
int s, len , packetTransferCount;
struct sockaddr_un remote;

if ((s = socket(AF_UNIX,SOCK_STREAM, 0)) == -1) {
    perror("socket");
}

remote.sun_family = AF_UNIX;
strcpy(remote.sun_path, SOCKET_DISPLAY_PATH);
len = strlen(remote.sun_path) + sizeof(remote.sun_family);    
/*******************************************/

pthread_t threadBF;

struct beamRecordedArgs processParams;
processParams.dataPath = argv[2];
processParams.bfOutputFile = argv[3];

pthread_create(&threadBF,NULL,beamProcessRecorded,(void *)&processParams);

packetTransferCount = 0;
while(processStatus != COMPLETE){
if(processStatus == TRANSFER){
    printf("Checking for display...\n");
    if (connect(s, (struct sockaddr *)&remote, len) == -1) {
        printf("No display process found\n");
        processStatus = PROCESS;
}
    else{
        printf("Display process found.. Transferring packet\n");
        send(s, txPackDisp, sizeof(txPackDisp), 0);
        close(s);
        processStatus = PROCESS;
        printf("PACKETS TRANSFERRED : %d\n",++packetTransferCount);
    }
}
else{
    while(processStatus == PROCESS){
        //sleep(1);
    }
}
}

pthread_join(threadBF,NULL);

return 0;
}

对于服务器：

SERVER:
int main(void)
{

int dispSock, lenSock, packetTransferCount;
struct sockaddr_un localDisp;

if ((dispSock = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
    perror("socket");
    exit(-1);
}
localDisp.sun_family = AF_UNIX;
strcpy(localDisp.sun_path, SOCKET_DISPLAY_PATH);
unlink(localDisp.sun_path);
lenSock = strlen(localDisp.sun_path) + sizeof(localDisp.sun_family);
if (bind(dispSock, (struct sockaddr *)&localDisp, lenSock) == -1) {
    perror("bind");
    exit(-1);
}
if (listen(dispSock, 5) == -1) {
    perror("listen");
    exit(-1);
}

packetTransferCount = 0;

do{
    struct sockaddr_un remoteDisp;
    int dispSockCon,dispConn;
    dispConn = sizeof(remoteDisp);

    if ((dispSockCon = accept(dispSock, (struct sockaddr *)&remoteDisp, &dispConn)) == -1) {
        perror("accept");
        exit(-1);
    }
    printf("Connected.\n");

    int status = recv(dispSockCon, &rxPack, PACKET_SIZE*sizeof(float),0);

    if (status != -1){
        FILE *fp;
        fp = fopen("bfo_sock","w");
        fwrite(rxPack, PACKET_LENGTH, sizeof(float), fp);
        fclose(fp);
    }
    else{
        printf("Error in receiving packets\n");
    }
    close(dispSockCon);
}while(1);

close(dispSock);
unlink(SOCKET_DISPLAY_PATH);
return 0;
}

我面临的问题是，客户端在连接到服务器后只能发送一个数据包（不管是先启动还是已经运行），之后它根本没有检测到服务器进程，即使它的运行和其他进程可以检测到它。通常一次传输的数据大小约为 13.3 KB。我在终端上看到的打印输出是：

Number of packets to be processed in BF : 60
PACKETS PROCESSED : 1
Checking for display...
Display process found.. Transferring packet
PACKETS TRANSFERRED : 1
PACKETS PROCESSED : 2
Checking for display...
No display process found
PACKETS PROCESSED : 3
Checking for display...
No display process found

如果有人能指出我在这里出错的方向，这对我真的很有帮助，因为我对使用套接字的 IPC 还很陌生。

Answer 1

嗯，我发现了这里的问题。问题是每次我想传输一个数据包并在此之后关闭它时，我都需要重新创建套接字连接。所以，服务器的 main 保持不变，但客户端现在变成了：

int main(int argc, char* argv[]) {

if (argc < 2) {
    printf("Usage: Operating_Mode Path_to_DAQ_dataset output_file cudaBF\n");
    printf("Operating_Mode = 0 : Real Time BF processing\nUsage: Operating_Mode output_file cudaBF\n");
    printf("Operating_Mode = 1 : Pre-recorded data BF processing\nUsage: Operating_Mode Path_to_DAQ_dataset output_file cudaBF\n");
    return 1;
}

int packetTransferCount;
pthread_t threadBF;

struct beamRecordedArgs processParams;
processParams.dataPath = argv[2];
processParams.bfOutputFile = argv[3];

pthread_create(&threadBF,NULL,beamProcessRecorded,(void *)&processParams);

packetTransferCount = 0;
while(processStatus != COMPLETE){
if(processStatus == TRANSFER){
/****************************************************************/ 
/*This part was outside the loop, moving it inside creates a new 
socket connector everytime I was to transfera packet and I close it before 
the loops ends */       
    int s, len;
struct sockaddr_un remote;

    if ((s = socket(AF_UNIX,SOCK_STREAM, 0)) == -1) {
    perror("socket");
}

remote.sun_family = AF_UNIX;
strcpy(remote.sun_path, SOCKET_DISPLAY_PATH);
len = strlen(remote.sun_path) + sizeof(remote.sun_family);    
/****************************************************************/  
    printf("Checking for display...\n");
    int dispConStatus = connect(s, (struct sockaddr *)&remote, len);
    if ( dispConStatus == -1) {
        printf("No display process found\n");
        processStatus = PROCESS;
    }
    else{
        printf("Display process found.. Transferring packet\n");
        send(s, txPackDisp, sizeof(txPackDisp), 0);
        processStatus = PROCESS;
        printf("PACKETS TRANSFERRED : %d\n",++packetTransferCount);
    }
    close(s);
}
else{
    while(processStatus == PROCESS){
        //sleep(1);
    }
}
}

pthread_join(threadBF,NULL);

return 0;
}