From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 14 Jul 2011 22:02:13 +0000 (-0400)
Subject: kconsumerd: signals should only set flag and write into pipe (part 1)
X-Git-Tag: v2.0-pre1~40
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=3dcd27214e19ba1175a7ac4057d3ce2c7b99c599

kconsumerd: signals should only set flag and write into pipe (part 1)

Simplify signal reception. Left todo.

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

diff --git a/liblttkconsumerd/liblttkconsumerd.c b/liblttkconsumerd/liblttkconsumerd.c
index c1bad734d..de942a198 100644
--- a/liblttkconsumerd/liblttkconsumerd.c
+++ b/liblttkconsumerd/liblttkconsumerd.c
@@ -69,6 +69,12 @@ static int kconsumerd_thread_pipe[2];
 /* pipe to wake the poll thread when necessary */
 static int kconsumerd_poll_pipe[2];
 
+/*
+ * TODO: create a should_quit pipe to let the signal handler wake up the
+ * fd receiver thread. It should be initialized before any signal can be
+ * received by the library.
+ */
+
 /* timeout parameter, to control the polling thread grace period */
 static int kconsumerd_poll_timeout = -1;
 
@@ -78,8 +84,13 @@ static int kconsumerd_error_socket;
 /* socket to exchange commands with sessiond */
 static char *kconsumerd_command_sock_path;
 
-/* flag to inform the polling thread to kconsumerd_quit when all fd hung up */
-static int kconsumerd_quit = 0;
+/*
+ * flag to inform the polling thread to quit when all fd hung up.
+ * Updated by the kconsumerd_thread_receive_fds when it notices that all
+ * fds has hung up. Also updated by the signal handler
+ * (kconsumerd_should_exit()). Read by the polling threads.
+ */
+static volatile int kconsumerd_quit = 0;
 
 /*
  * kconsumerd_set_error_socket
@@ -790,7 +801,6 @@ end:
 		free(local_kconsumerd_fd);
 		local_kconsumerd_fd = NULL;
 	}
-	kconsumerd_cleanup();
 	return NULL;
 }
 
@@ -835,6 +845,8 @@ void *kconsumerd_thread_receive_fds(void *data)
 		goto end;
 	}
 
+	/* TODO: poll on socket and "should_quit" fd pipe */
+	/* TODO: change blocking call into non-blocking call */
 	/* Blocking call, waiting for transmission */
 	sock = lttcomm_accept_unix_sock(client_socket);
 	if (sock <= 0) {
@@ -843,6 +855,8 @@ void *kconsumerd_thread_receive_fds(void *data)
 	}
 	while (1) {
 		/* We first get the number of fd we are about to receive */
+		/* TODO: poll on sock and "should_quit" fd pipe */
+		/* TODO: change recv into a non-blocking call */
 		ret = lttcomm_recv_unix_sock(sock, &tmp,
 				sizeof(struct lttcomm_kconsumerd_header));
 		if (ret <= 0) {
@@ -853,6 +867,10 @@ void *kconsumerd_thread_receive_fds(void *data)
 			DBG("Received STOP command");
 			goto end;
 		}
+		if (kconsumerd_quit) {
+			DBG("kconsumerd_thread_receive_fds received quit from signal");
+			goto end;
+		}
 		/* we received a command to add or update fds */
 		ret = kconsumerd_consumerd_recv_fd(sock, tmp.payload_size, tmp.cmd_type);
 		if (ret <= 0) {
@@ -890,19 +908,35 @@ end:
  *
  *  Cleanup the daemon's socket on exit
  */
-void kconsumerd_cleanup()
+void kconsumerd_cleanup(void)
 {
 	struct kconsumerd_fd *iter;
 
 	/* remove the socket file */
 	unlink(kconsumerd_command_sock_path);
 
-	/* close all outfd */
+	/*
+	 * close all outfd. Called when there are no more threads
+	 * running (after joining on the threads), no need to protect
+	 * list iteration with mutex.
+	 */
 	cds_list_for_each_entry(iter, &kconsumerd_data.fd_list.head, list) {
 		kconsumerd_del_fd(iter);
 	}
 }
 
+/*
+ * Called from signal handler.
+ */
+void kconsumerd_should_exit(void)
+{
+	kconsumerd_quit = 1;
+	/*
+	 * TODO: write into a should_quit pipe to wake up the fd
+	 * receiver thread.
+	 */
+}
+
 /*
  * kconsumerd_send_error
  *
diff --git a/liblttkconsumerd/liblttkconsumerd.h b/liblttkconsumerd/liblttkconsumerd.h
index 8dc6b6270..83c769acf 100644
--- a/liblttkconsumerd/liblttkconsumerd.h
+++ b/liblttkconsumerd/liblttkconsumerd.h
@@ -61,7 +61,8 @@ int kconsumerd_create_poll_pipe();
 int kconsumerd_send_error(enum lttcomm_return_code cmd);
 void *kconsumerd_thread_poll_fds(void *data);
 void *kconsumerd_thread_receive_fds(void *data);
-void kconsumerd_cleanup();
+void kconsumerd_should_exit(void);
+void kconsumerd_cleanup(void);
 void kconsumerd_set_error_socket(int sock);
 void kconsumerd_set_command_socket_path(char *sock);
 
diff --git a/ltt-kconsumerd/ltt-kconsumerd.c b/ltt-kconsumerd/ltt-kconsumerd.c
index 60134e831..b5e854179 100644
--- a/ltt-kconsumerd/ltt-kconsumerd.c
+++ b/ltt-kconsumerd/ltt-kconsumerd.c
@@ -67,7 +67,7 @@ static void sighandler(int sig)
 		return;
 	}
 
-	kconsumerd_cleanup();
+	kconsumerd_should_exit();
 }
 
 /*