Handle killed or non-responsive sessiond

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/libust/lttng-ust-comm.c b/libust/lttng-ust-comm.c
index 2fd165730abef212696e2fcc0c1aa3071a25d036..9400b6b8ff9f6fdb74e4461aa6d6e1cf464e0b59 100644 (file)
--- a/libust/lttng-ust-comm.c
+++ b/libust/lttng-ust-comm.c
@@ -513,7 +513,6 @@ void wait_for_sessiond(struct sock_info *sock_info)
 "mainline). LTTng-UST will use polling mode fallback.");
                        }
                        PERROR("futex");
-                       sleep(5);
                }
        }
        return;
@@ -524,8 +523,6 @@ quit:
 
 error:
        ust_unlock();
-       /* Error handling: fallback on a 5 seconds sleep. */
-       sleep(5);
        return;
 }
 
@@ -540,10 +537,25 @@ static
 void *ust_listener_thread(void *arg)
 {
        struct sock_info *sock_info = arg;
-       int sock, ret;
+       int sock, ret, prev_connect_failed = 0, has_waited = 0;
 
        /* Restart trying to connect to the session daemon */
 restart:
+       if (prev_connect_failed) {
+               /* Wait for sessiond availability with pipe */
+               wait_for_sessiond(sock_info);
+               if (has_waited) {
+                       has_waited = 0;
+                       /*
+                        * Sleep for 5 seconds before retrying after a
+                        * sequence of failure / wait / failure. This
+                        * deals with a killed or broken session daemon.
+                        */
+                       sleep(5);
+               }
+               has_waited = 1;
+               prev_connect_failed = 0;
+       }
        ust_lock();
 
        if (lttng_ust_comm_should_quit) {
@@ -563,6 +575,7 @@ restart:
        ret = lttcomm_connect_unix_sock(sock_info->sock_path);
        if (ret < 0) {
                ERR("Error connecting to %s apps socket", sock_info->name);
+               prev_connect_failed = 1;
                /*
                 * If we cannot find the sessiond daemon, don't delay
                 * constructor execution.
@@ -570,9 +583,6 @@ restart:
                ret = handle_register_done(sock_info);
                assert(!ret);
                ust_unlock();
-
-               /* Wait for sessiond availability with pipe */
-               wait_for_sessiond(sock_info);
                goto restart;
        }
 
@@ -595,6 +605,7 @@ restart:
        ret = register_app_to_sessiond(sock);
        if (ret < 0) {
                ERR("Error registering to %s apps socket", sock_info->name);
+               prev_connect_failed = 1;
                /*
                 * If we cannot register to the sessiond daemon, don't
                 * delay constructor execution.
@@ -602,7 +613,6 @@ restart:
                ret = handle_register_done(sock_info);
                assert(!ret);
                ust_unlock();
-               wait_for_sessiond(sock_info);
                goto restart;
        }
        ust_unlock();