frontend: Use channel shutdown to synchronize handler thread shutdown.

This allows the handler to fully control the shutdown procedure.
pthread_cancel did not play well with pthread_cond_*wait in multiple threads
and the respective locked mutex.

diff --git a/src/frontend/sock.c b/src/frontend/sock.c
index 8e2bc59dbf53d771d3eb6da298e97b8d5a46ab2f..063b2ca3d1d6528d0a22c7304faab65408e398c2 100644 (file)
--- a/src/frontend/sock.c
+++ b/src/frontend/sock.c
@@ -211,14 +211,30 @@ connection_handler(void *data)
        assert(chan);
 
        while (42) {
+               struct timespec timeout = { 0, 500000000 }; /* .5 seconds */
                connection_t conn;
+               int status;
+
+               errno = 0;
+               status = sdb_channel_select(chan, NULL, &conn, NULL, NULL, &timeout);
+               if (status) {
+                       char buf[1024];
+
+                       if (errno == ETIMEDOUT)
+                               continue;
+                       if (errno == EBADF) /* channel shut down */
+                               break;
+
+                       sdb_log(SDB_LOG_ERR, "sock: Failed to read from channel: %s",
+                                       sdb_strerror(errno, buf, sizeof(buf)));
+                       continue;
+               }
 
-               sdb_channel_select(chan, NULL, &conn, NULL, NULL, NULL);
                if (conn.fd < 0)
                        continue;
 
                if (conn.client_addr.ss_family != AF_UNIX) {
-                       sdb_log(SDB_LOG_ERR, "Accepted connection using unexpected "
+                       sdb_log(SDB_LOG_ERR, "sock: Accepted connection using unexpected "
                                        "family type %d", conn.client_addr.ss_family);
                        continue;
                }
@@ -364,10 +380,12 @@ sdb_fe_sock_listen_and_serve(sdb_fe_socket_t *sock, sdb_fe_loop_t *loop)
                }
        }
 
-       for (i = 0; i < SDB_STATIC_ARRAY_LEN(handler_threads); ++i)
-               pthread_cancel(handler_threads[i]);
-       for (i = 0; i < SDB_STATIC_ARRAY_LEN(handler_threads); ++i)
-               pthread_join(handler_threads[i], NULL);
+       sdb_log(SDB_LOG_INFO, "sock: Waiting for connection handler threads "
+                       "to terminate");
+       if (! sdb_channel_shutdown(chan))
+               for (i = 0; i < SDB_STATIC_ARRAY_LEN(handler_threads); ++i)
+                       pthread_join(handler_threads[i], NULL);
+       /* else: we tried our best; let the operating system clean up */
        return 0;
 } /* sdb_fe_sock_listen_and_server */