From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 27 Jan 2014 04:23:36 +0000 (-0500)
Subject: Fix: relayd: notify parent of readiness when all threads ready
X-Git-Tag: v2.5.0-rc1~237
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=3fd2739803ea7273c6483060ac042942af06b1d4;p=lttng-tools.git

Fix: relayd: notify parent of readiness when all threads ready

- relayd start using daemonize common lib,
- wait for health check thread, listener and live listener threads to be
  ready before letting the parent know it is ready (in daemon and
  background modes).

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

diff --git a/src/bin/lttng-relayd/health-relayd.c b/src/bin/lttng-relayd/health-relayd.c
index 01e54d2ea..89b6402fa 100644
--- a/src/bin/lttng-relayd/health-relayd.c
+++ b/src/bin/lttng-relayd/health-relayd.c
@@ -300,6 +300,8 @@ void *thread_manage_health(void *data)
 		goto error;
 	}
 
+	lttng_relay_notify_ready();
+
 	while (1) {
 		DBG("Health check ready");
 
diff --git a/src/bin/lttng-relayd/live.c b/src/bin/lttng-relayd/live.c
index e6f381df7..19322f4a0 100644
--- a/src/bin/lttng-relayd/live.c
+++ b/src/bin/lttng-relayd/live.c
@@ -259,6 +259,8 @@ void *thread_listener(void *data)
 		goto error_poll_add;
 	}
 
+	lttng_relay_notify_ready();
+
 	while (1) {
 		health_code_update();
 
diff --git a/src/bin/lttng-relayd/lttng-relayd.h b/src/bin/lttng-relayd/lttng-relayd.h
index d0e0473b2..4d2361567 100644
--- a/src/bin/lttng-relayd/lttng-relayd.h
+++ b/src/bin/lttng-relayd/lttng-relayd.h
@@ -240,5 +240,6 @@ extern const char *tracing_group_name;
 extern const char * const config_section_name;
 
 struct relay_stream *relay_stream_find_by_id(uint64_t stream_id);
+void lttng_relay_notify_ready(void);
 
 #endif /* LTTNG_RELAYD_H */
diff --git a/src/bin/lttng-relayd/main.c b/src/bin/lttng-relayd/main.c
index 7ac5630fb..86bad26b3 100644
--- a/src/bin/lttng-relayd/main.c
+++ b/src/bin/lttng-relayd/main.c
@@ -45,6 +45,7 @@
 #include <common/compat/poll.h>
 #include <common/compat/socket.h>
 #include <common/defaults.h>
+#include <common/daemonize.h>
 #include <common/futex.h>
 #include <common/sessiond-comm/sessiond-comm.h>
 #include <common/sessiond-comm/inet.h>
@@ -64,6 +65,16 @@
 /* command line options */
 char *opt_output_path;
 static int opt_daemon, opt_background;
+
+/*
+ * We need to wait for listener and live listener threads, as well as
+ * health check thread, before being ready to signal readiness.
+ */
+#define NR_LTTNG_RELAY_READY	3
+static int lttng_relay_ready = NR_LTTNG_RELAY_READY;
+static int recv_child_signal;	/* Set to 1 when a SIGUSR1 signal is received. */
+static pid_t child_ppid;	/* Internal parent PID use with daemonize. */
+
 static struct lttng_uri *control_uri;
 static struct lttng_uri *data_uri;
 static struct lttng_uri *live_uri;
@@ -509,6 +520,9 @@ void sighandler(int sig)
 		DBG("SIGTERM caught");
 		stop_threads();
 		break;
+	case SIGUSR1:
+		CMM_STORE_SHARED(recv_child_signal, 1);
+		break;
 	default:
 		break;
 	}
@@ -548,11 +562,26 @@ int set_signal_handler(void)
 		return ret;
 	}
 
-	DBG("Signal handler set for SIGTERM, SIGPIPE and SIGINT");
+	if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
+		PERROR("sigaction");
+		return ret;
+	}
+
+	DBG("Signal handler set for SIGTERM, SIGUSR1, SIGPIPE and SIGINT");
 
 	return ret;
 }
 
+void lttng_relay_notify_ready(void)
+{
+	/* Notify the parent of the fork() process that we are ready. */
+	if (opt_daemon || opt_background) {
+		if (uatomic_sub_return(&lttng_relay_ready, 1) == 0) {
+			kill(child_ppid, SIGUSR1);
+		}
+	}
+}
+
 /*
  * Init thread quit pipe.
  *
@@ -722,6 +751,8 @@ void *relay_thread_listener(void *data)
 		goto error_poll_add;
 	}
 
+	lttng_relay_notify_ready();
+
 	while (1) {
 		health_code_update();
 
@@ -2822,11 +2853,6 @@ int main(int argc, char **argv)
 	void *status;
 	struct relay_local_data *relay_ctx;
 
-	/* Create thread quit pipe */
-	if ((ret = init_thread_quit_pipe()) < 0) {
-		goto error;
-	}
-
 	/* Parse arguments */
 	progname = argv[0];
 	if ((ret = set_options(argc, argv)) < 0) {
@@ -2853,11 +2879,27 @@ int main(int argc, char **argv)
 
 	/* Daemonize */
 	if (opt_daemon || opt_background) {
-		ret = daemon(0, opt_background);
+		int i;
+
+		ret = lttng_daemonize(&child_ppid, &recv_child_signal,
+			!opt_background);
 		if (ret < 0) {
-			PERROR("daemon");
 			goto exit;
 		}
+
+		/*
+		 * We are in the child. Make sure all other file
+		 * descriptors are closed, in case we are called with
+		 * more opened file descriptors than the standard ones.
+		 */
+		for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) {
+			(void) close(i);
+		}
+	}
+
+	/* Create thread quit pipe */
+	if ((ret = init_thread_quit_pipe()) < 0) {
+		goto error;
 	}
 
 	/* We need those values for the file/dir creation. */