From ae9e45b342636e7b42eafc15cd105bccfbbbe373 Mon Sep 17 00:00:00 2001
From: David Goulet <dgoulet@efficios.com>
Date: Thu, 1 Nov 2012 11:24:22 -0400
Subject: [PATCH] Add a timeout to UST application socket

By default, a 5 seconds timeout is set on every UST application socket
just after the accept() for both recv and send operation.

This value can be changed through a new environment variable (seconds)
of the session daemon.

This is the first step to fix bug386 where a stopped application can
stalls indefinitely the session daemon when a new command is sent.

The bug 386 is also fixed with the lttng-ust commit:
7bc53e94a229963972aa78880b361b1510fdd268

Fixes #386

Signed-off-by: David Goulet <dgoulet@efficios.com>
---
 src/bin/lttng-sessiond/main.c   | 21 ++++++++++++++++-
 src/common/defaults.h           |  6 +++++
 src/common/sessiond-comm/unix.c | 42 +++++++++++++++++++++++++++++++++
 src/common/sessiond-comm/unix.h |  2 ++
 4 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index 022bbc6d1..90f11d648 100644
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -228,6 +228,11 @@ struct health_state health_thread_app_manage;
 struct health_state health_thread_app_reg;
 struct health_state health_thread_kernel;
 
+/*
+ * Socket timeout for receiving and sending in seconds.
+ */
+static int app_socket_timeout;
+
 static
 void setup_consumerd_path(void)
 {
@@ -1205,6 +1210,12 @@ static void *thread_manage_apps(void *data)
 							goto error;
 						}
 
+						/* Set socket timeout for both receiving and ending */
+						(void) lttcomm_setsockopt_rcv_timeout(ust_cmd.sock,
+								app_socket_timeout);
+						(void) lttcomm_setsockopt_snd_timeout(ust_cmd.sock,
+								app_socket_timeout);
+
 						DBG("Apps with sock %d added to poll set",
 								ust_cmd.sock);
 					}
@@ -3790,7 +3801,7 @@ int main(int argc, char **argv)
 {
 	int ret = 0;
 	void *status;
-	const char *home_path;
+	const char *home_path, *env_app_timeout;
 
 	init_kernel_workarounds();
 
@@ -4070,6 +4081,14 @@ int main(int argc, char **argv)
 	health_init(&ustconsumer64_data.health);
 	health_poll_update(&ustconsumer64_data.health);
 
+	/* Check for the application socket timeout env variable. */
+	env_app_timeout = getenv(DEFAULT_APP_SOCKET_TIMEOUT_ENV);
+	if (env_app_timeout) {
+		app_socket_timeout = atoi(env_app_timeout);
+	} else {
+		app_socket_timeout = DEFAULT_APP_SOCKET_RW_TIMEOUT;
+	}
+
 	/* Create thread to manage the client socket */
 	ret = pthread_create(&health_thread, NULL,
 			thread_manage_health, (void *) NULL);
diff --git a/src/common/defaults.h b/src/common/defaults.h
index 5495531f6..0c0b6ac9c 100644
--- a/src/common/defaults.h
+++ b/src/common/defaults.h
@@ -154,4 +154,10 @@
  */
 #define DEFAULT_DATA_AVAILABILITY_WAIT_TIME 200000  /* usec */
 
+/*
+ * Default receiving and sending timeout for an application socket.
+ */
+#define DEFAULT_APP_SOCKET_RW_TIMEOUT       5  /* sec */
+#define DEFAULT_APP_SOCKET_TIMEOUT_ENV      "LTTNG_APP_SOCKET_TIMEOUT"
+
 #endif /* _DEFAULTS_H */
diff --git a/src/common/sessiond-comm/unix.c b/src/common/sessiond-comm/unix.c
index 9ef04ee0d..2f79f3a28 100644
--- a/src/common/sessiond-comm/unix.c
+++ b/src/common/sessiond-comm/unix.c
@@ -523,3 +523,45 @@ int lttcomm_setsockopt_creds_unix_sock(int sock)
 #else
 #error "Please implement credential support for your OS."
 #endif /* __linux__ */
+
+/*
+ * Set socket reciving timeout.
+ */
+__attribute__((visibility("hidden")))
+int lttcomm_setsockopt_rcv_timeout(int sock, unsigned int sec)
+{
+	int ret;
+	struct timeval tv;
+
+	tv.tv_sec = sec;
+	tv.tv_usec = 0;
+
+	ret = setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
+	if (ret < 0) {
+		PERROR("setsockopt SO_RCVTIMEO");
+		ret = -errno;
+	}
+
+	return ret;
+}
+
+/*
+ * Set socket sending timeout.
+ */
+__attribute__((visibility("hidden")))
+int lttcomm_setsockopt_snd_timeout(int sock, unsigned int sec)
+{
+	int ret;
+	struct timeval tv;
+
+	tv.tv_sec = sec;
+	tv.tv_usec = 0;
+
+	ret = setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
+	if (ret < 0) {
+		PERROR("setsockopt SO_SNDTIMEO");
+		ret = -errno;
+	}
+
+	return ret;
+}
diff --git a/src/common/sessiond-comm/unix.h b/src/common/sessiond-comm/unix.h
index 19b91ce40..34f156ffd 100644
--- a/src/common/sessiond-comm/unix.h
+++ b/src/common/sessiond-comm/unix.h
@@ -45,5 +45,7 @@ extern ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
 		lttng_sock_cred *creds);
 
 extern int lttcomm_setsockopt_creds_unix_sock(int sock);
+extern int lttcomm_setsockopt_rcv_timeout(int sock, unsigned int sec);
+extern int lttcomm_setsockopt_snd_timeout(int sock, unsigned int sec);
 
 #endif	/* _LTTCOMM_UNIX_H */
-- 
2.34.1