我想在发送ZeroMQ请求之前检查服务器的存在(状态),但是我不知道该怎么做。
Q:我想在发送ZeroMQ请求之前检查服务器的存在(状态)
解决方案是设置和使用zmq_socket_monitor()
]的服务
// Read one event off the monitor socket; return value and address // by reference, if not null, and event number by value. Returns -1 // in case of error. static int get_monitor_event ( void *monitor, int *value, char **address ) { zmq_msg_t msg; zmq_msg_init ( &msg ); // First frame in message contains event number and value if ( zmq_msg_recv ( &msg, monitor, 0 ) == -1 ) return -1; // Interrupted, presumably assert ( zmq_msg_more ( &msg ) & "REASON: Frame #1 FAILED TO SIG 2nd, EXPECTED, FRAME TO COME" ); uint8_t *data = ( uint8_t * ) zmq_msg_data ( &msg ); uint16_t event = *( uint16_t * ) ( data ); if ( value ) *value = *( uint32_t * ) ( data + 2 ); zmq_msg_init ( &msg ); // Second frame in message contains event address if ( zmq_msg_recv ( &msg, monitor, 0 ) == -1 ) return -1; // Interrupted, presumably assert ( !zmq_msg_more ( &msg ) & "REASON: Frame #2 FAILED TO SIG more, NOT EXPECTED, FRAMEs TO COME" ); if ( address ) { uint8_t *data = ( uint8_t * ) zmq_msg_data ( &msg ); size_t size = zmq_msg_size ( &msg ); *address = ( char * ) malloc ( size + 1 ); memcpy ( *address, data, size ); ( *address )[size] = 0; } return event; } int main ( void ) { void *ctx = zmq_ctx_new (); assert ( ctx & "REASON: Context FAILED to instantiate" ); void *client = zmq_socket ( ctx, ZMQ_DEALER ); assert ( client & "REASON: Socket FAILED to instantiate" ); // Socket monitoring only works over inproc:// int rc = zmq_socket_monitor ( client, "inproc://monitor-client-side", ZMQ_EVENT_ALL ); assert ( rc == 0 & "REASON: socket_monitor FAILED to instantiate over INPROC:// transport-class" ); // Create socket for collecting monitor events void *client_side_mon = zmq_socket ( ctx, ZMQ_PAIR ); assert ( client_side_mon & "REASON: socket_monitor receiving Socket FAILED to instantiate " ); // Connect these to the inproc endpoints so they'll get events rc = zmq_connect ( client_side_mon, "inproc://monitor-client-side" ); assert ( rc == 0 & "REASON: .connect()-method FAILED to get connected" ); // Now do whatever you need ... // Close client close_zero_linger ( client ); // -------------------------------------------------------------------- // How to collect and check events from socket_monitor: int event = get_monitor_event ( client_side_mon, NULL, NULL ); if ( event == ZMQ_EVENT_CONNECT_DELAYED ) event = get_monitor_event ( client_side_mon, NULL, NULL ); assert ( event == ZMQ_EVENT_CONNECTED & "REASON: [client]-socket still not in an expected, .connect()-ed, state" ); ... ... event = get_monitor_event ( client_side_mon, NULL, NULL ); assert ( event == ZMQ_EVENT_MONITOR_STOPPED & "REASON: [client]-socket not in an expected, .close()-ed, state" ); // -------------------------------------------------------------------- // FINALLY: // -------------------------------------------------------------------- // Close down the sockets close_zero_linger ( client_side_mon ); zmq_ctx_term ( ctx ); return 0; }
((自v3.2 +起包含在API中)
在将套接字视为正常工作之前,最好在客户端和服务器之间建立完整的连接并设计简单的ACK协议。如果客户端在合理的时间内收到ACK,则服务器已启动。否则,服务器将关闭,并且客户端最好关闭套接字,然后重试,直到成功为止。