Clean-up: remove dead assignment from ht cleanup thread launcher

[lttng-tools.git] / src / bin / lttng-sessiond / ht-cleanup.c

diff --git a/src/bin/lttng-sessiond/ht-cleanup.c b/src/bin/lttng-sessiond/ht-cleanup.c
index b5f58d06722e14c0659138904429dc6014b295d4..f5aab3309280daa9c4550b967334ebe8f6449278 100644 (file)
--- a/src/bin/lttng-sessiond/ht-cleanup.c
+++ b/src/bin/lttng-sessiond/ht-cleanup.c
@@ -15,19 +15,90 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#define _GNU_SOURCE
 #define _LGPL_SOURCE
 #include <assert.h>
 
 #include <common/hashtable/hashtable.h>
 #include <common/common.h>
 #include <common/utils.h>
+#include <pthread.h>
 
 #include "lttng-sessiond.h"
 #include "health-sessiond.h"
 #include "testpoint.h"
+#include "utils.h"
+#include "ht-cleanup.h"
 
-void *thread_ht_cleanup(void *data)
+static int ht_cleanup_quit_pipe[2] = { -1, -1 };
+
+/*
+ * Check if the ht_cleanup thread quit pipe was triggered.
+ *
+ * Return true if it was triggered else false;
+ */
+static bool check_quit_pipe(int fd, uint32_t events)
+{
+       return (fd == ht_cleanup_quit_pipe[0] && (events & LPOLLIN));
+}
+
+static int init_pipe(int *pipe_fds)
+{
+       int ret, i;
+
+       ret = pipe(pipe_fds);
+       if (ret < 0) {
+               PERROR("ht_cleanup thread quit pipe");
+               goto error;
+       }
+
+       for (i = 0; i < 2; i++) {
+               ret = fcntl(pipe_fds[i], F_SETFD, FD_CLOEXEC);
+               if (ret < 0) {
+                       PERROR("fcntl ht_cleanup_quit_pipe");
+                       goto error;
+               }
+       }
+error:
+       return ret;
+}
+
+/*
+ * Create a poll set with O_CLOEXEC and add the thread quit pipe to the set.
+ */
+static int set_pollset(struct lttng_poll_event *events, size_t size)
+{
+       int ret;
+
+       ret = lttng_poll_create(events, size, LTTNG_CLOEXEC);
+       if (ret < 0) {
+               goto error;
+       }
+
+       ret = lttng_poll_add(events, ht_cleanup_quit_pipe[0],
+                       LPOLLIN | LPOLLERR);
+       if (ret < 0) {
+               goto error;
+       }
+
+       ret = lttng_poll_add(events, ht_cleanup_pipe[0], LPOLLIN | LPOLLERR);
+       if (ret < 0) {
+               DBG("[ht-thread] lttng_poll_add error %d.", ret);
+               goto error;
+       }
+
+       return 0;
+
+error:
+       return ret;
+}
+
+static void cleanup_ht_cleanup_thread(void *data)
+{
+       utils_close_pipe(ht_cleanup_quit_pipe);
+       utils_close_pipe(ht_cleanup_pipe);
+}
+
+static void *thread_ht_cleanup(void *data)
 {
        int ret, i, pollfd, err = -1;
        ssize_t size_ret;
@@ -48,26 +119,17 @@ void *thread_ht_cleanup(void *data)
 
        health_code_update();
 
-       ret = sessiond_set_ht_cleanup_thread_pollset(&events, 2);
+       ret = set_pollset(&events, 2);
        if (ret < 0) {
                DBG("[ht-thread] sessiond_set_ht_cleanup_thread_pollset error %d.", ret);
                goto error_poll_create;
        }
 
-       /* Add pipe to the pollset. */
-       ret = lttng_poll_add(&events, ht_cleanup_pipe[0], LPOLLIN | LPOLLERR);
-       if (ret < 0) {
-               DBG("[ht-thread] lttng_poll_add error %d.", ret);
-               goto error;
-       }
-
        health_code_update();
 
        while (1) {
+       restart:
                DBG3("[ht-thread] Polling.");
-
-               /* Inifinite blocking call, waiting for transmission */
-restart:
                health_poll_entry();
                ret = lttng_poll_wait(&events, -1);
                DBG3("[ht-thread] Returning from poll on %d fds.",
@@ -78,13 +140,12 @@ restart:
                         * Restart interrupted system call.
                         */
                        if (errno == EINTR) {
-                               goto restart;
+                               continue;
                        }
                        goto error;
                }
 
                nb_fd = ret;
-
                for (i = 0; i < nb_fd; i++) {
                        struct lttng_ht *ht;
 
@@ -94,11 +155,6 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
-                       if (!revents) {
-                               /* No activity for this FD (poll implementation). */
-                               continue;
-                       }
-
                        if (pollfd != ht_cleanup_pipe[0]) {
                                continue;
                        }
@@ -121,6 +177,13 @@ restart:
                                lttng_ht_destroy(ht);
 
                                health_code_update();
+
+                               /*
+                                * Ensure that we never process the quit pipe
+                                * event while there is still data available
+                                * on the ht clean pipe.
+                                */
+                               goto restart;
                        } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
                                ERR("ht cleanup pipe error");
                                goto error;
@@ -147,7 +210,7 @@ restart:
                        }
 
                        /* Thread quit pipe has been closed. Killing thread. */
-                       ret = sessiond_check_ht_cleanup_quit(pollfd, revents);
+                       ret = check_quit_pipe(pollfd, revents);
                        if (ret) {
                                err = 0;
                                DBG("[ht-cleanup] quit.");
@@ -171,3 +234,45 @@ error_testpoint:
        rcu_unregister_thread();
        return NULL;
 }
+
+static bool shutdown_ht_cleanup_thread(void *data)
+{
+       int ret;
+
+       ret = notify_thread_pipe(ht_cleanup_quit_pipe[1]);
+       if (ret < 0) {
+               ERR("write error on ht_cleanup quit pipe");
+               goto end;
+       }
+end:
+       return ret;
+}
+
+struct lttng_thread *launch_ht_cleanup_thread(void)
+{
+       int ret;
+       struct lttng_thread *thread;
+
+       ret = init_pipe(ht_cleanup_pipe);
+       if (ret) {
+               goto error;
+       }
+
+       ret = init_pipe(ht_cleanup_quit_pipe);
+       if (ret) {
+               goto error;
+       }
+
+       thread = lttng_thread_create("HT cleanup",
+                       thread_ht_cleanup,
+                       shutdown_ht_cleanup_thread,
+                       cleanup_ht_cleanup_thread,
+                       NULL);
+       if (!thread) {
+               goto error;
+       }
+       return thread;
+error:
+       cleanup_ht_cleanup_thread(NULL);
+       return NULL;
+}