如何解决断开 ZeroMQ 套接字和 ZMQ_EVENT_DISCONNECTED
ZeroMQ API documentation 声明事件(来源 here):
ZMQ_EVENT_disCONNECTED
插座意外断开。事件值是底层网络套接字的 FD。警告:此套接字将被关闭。
此处如何定义“意外”,以及如何在 REQ
-REP
对上触发“干净”断开连接?
我试过了:
-
zmq_close(client)
表示ZMQ_EVENT_disCONNECTED
,虽然我原以为这是干净的 -
zmq_disconnect(client,addr)
在上述不会改变被监控事件之前(即,当显式断开连接成功时,我仍然收到“意外断开连接”的信号)
有没有办法区分干净的套接字关闭和客户端上的 kill -9
? (后者仍然表示FIN
,所以理论上应该可以检测和区分)
下图的代码(从 here 修改;使用 gcc -lzmq zmq_test.c && ./a.out
编译和运行)
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>
#include <zmq.h>
// 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)
{
// First frame in message contains event number and value
zmq_msg_t msg;
zmq_msg_init (&msg);
if (zmq_msg_recv (&msg,monitor,0) == -1)
return -1; // Interruped,presumably
assert (zmq_msg_more (&msg));
uint8_t *data = (uint8_t *) zmq_msg_data (&msg);
uint16_t event = *(uint16_t *) (data);
if (value)
*value = *(uint32_t *) (data + 2);
// Second frame in message contains event address
zmq_msg_init (&msg);
if (zmq_msg_recv (&msg,presumably
assert (!zmq_msg_more (&msg));
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;
}
printf("event: %d\n",event);
return event;
}
static void close_zero_linger(void *socket)
{
int linger = 0;
zmq_setsockopt(socket,ZMQ_LINGER,&linger,sizeof(linger));
zmq_close(socket);
}
static void bounce(void *client,void *server)
{
char send_buf[] = "Hello";
char recv_buf[sizeof(send_buf) / sizeof(send_buf[0])];
zmq_send(client,send_buf,sizeof(send_buf),0);
zmq_recv(server,recv_buf,sizeof(recv_buf),0);
zmq_send(server,0);
zmq_recv(client,0);
}
int main (void)
{
void *ctx = zmq_ctx_new ();
void *client = zmq_socket (ctx,ZMQ_REQ);
void *server = zmq_socket (ctx,ZMQ_REP);
int rc = zmq_socket_monitor (client,"tcp://127.0.0.1:9999",0);
// Monitor all events on client and server sockets
rc = zmq_socket_monitor (server,"inproc://monitor-server",ZMQ_EVENT_ALL)
void *server_mon = zmq_socket (ctx,ZMQ_PAIR);
rc = zmq_connect (server_mon,"inproc://monitor-server");
// Now do a basic ping test
rc = zmq_bind (server,"tcp://127.0.0.1:9998");
rc = zmq_connect (client,"tcp://127.0.0.1:9998");
bounce (client,server);
// Close client
rc = zmq_disconnect(client,"tcp://127.0.0.1:9998");
printf("disconnect: %d\n",rc);
// close_zero_linger (client);
rc = zmq_close(client);
printf("close: %d\n",rc);
// sleep(1); // no difference
// This is the flow of server events
event = get_monitor_event (server_mon,NULL,NULL);
assert (event == ZMQ_EVENT_LISTENING);
event = get_monitor_event (server_mon,NULL);
assert (event == ZMQ_EVENT_ACCEPTED);
event = get_monitor_event (server_mon,NULL);
assert (event == ZMQ_EVENT_HANDSHAKE_SUCCEEDED);
// sleep(1); // no difference
event = get_monitor_event (server_mon,NULL);
// assert (event == ZMQ_EVENT_CLOSED);
// event = get_monitor_event (server_mon,NULL);
// assert (event == ZMQ_EVENT_MONITOR_STOPPED);
assert (event == ZMQ_EVENT_disCONNECTED); // why??
// Close down the sockets
close_zero_linger (server);
close_zero_linger (server_mon);
zmq_ctx_term (ctx);
return 0;
}
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