Fix: sessiond: size-based notification occasionally not triggered

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

diff --git a/src/bin/lttng-sessiond/rotate.c b/src/bin/lttng-sessiond/rotate.c
index 813a1a0dc0847d699da2cf72251e8af0d4c88e45..1cbff999a283b14ea1b8dd06c1448a3ad58c47c2 100644 (file)
--- a/src/bin/lttng-sessiond/rotate.c
+++ b/src/bin/lttng-sessiond/rotate.c
@@ -25,6 +25,8 @@
 
 #include <lttng/notification/channel-internal.h>
 #include <lttng/rotate-internal.h>
+#include <lttng/condition/condition-internal.h>
+#include <lttng/action/action-internal.h>
 
 #include "session.h"
 #include "rotate.h"
@@ -45,21 +47,23 @@ int subscribe_session_consumed_size_rotation(struct ltt_session *session, uint64
        int ret;
        enum lttng_condition_status condition_status;
        enum lttng_notification_channel_status nc_status;
-       struct lttng_action *action;
+       const uint64_t eventfd_increment_value = 1;
        const struct lttng_credentials session_creds = {
-               .uid = session->uid,
-               .gid = session->gid,
+               .uid = LTTNG_OPTIONAL_INIT_VALUE(session->uid),
+               .gid = LTTNG_OPTIONAL_INIT_VALUE(session->gid),
        };
+       struct lttng_condition *rotate_condition;
+       struct lttng_action *notify_action = NULL;
 
-       session->rotate_condition = lttng_condition_session_consumed_size_create();
-       if (!session->rotate_condition) {
+       rotate_condition = lttng_condition_session_consumed_size_create();
+       if (!rotate_condition) {
                ERR("Failed to create session consumed size condition object");
                ret = -1;
                goto end;
        }
 
        condition_status = lttng_condition_session_consumed_size_set_threshold(
-                       session->rotate_condition, size);
+                       rotate_condition, size);
        if (condition_status != LTTNG_CONDITION_STATUS_OK) {
                ERR("Could not set session consumed size condition threshold (size = %" PRIu64 ")",
                                size);
@@ -69,7 +73,7 @@ int subscribe_session_consumed_size_rotation(struct ltt_session *session, uint64
 
        condition_status =
                        lttng_condition_session_consumed_size_set_session_name(
-                               session->rotate_condition, session->name);
+                               rotate_condition, session->name);
        if (condition_status != LTTNG_CONDITION_STATUS_OK) {
                ERR("Could not set session consumed size condition session name (name = %s)",
                                session->name);
@@ -77,34 +81,47 @@ int subscribe_session_consumed_size_rotation(struct ltt_session *session, uint64
                goto end;
        }
 
-       action = lttng_action_notify_create();
-       if (!action) {
+       notify_action = lttng_action_notify_create();
+       if (!notify_action) {
                ERR("Could not create notify action");
                ret = -1;
                goto end;
        }
 
-       session->rotate_trigger = lttng_trigger_create(session->rotate_condition,
-                       action);
+       assert(!session->rotate_trigger);
+       session->rotate_trigger = lttng_trigger_create(rotate_condition,
+                       notify_action);
        if (!session->rotate_trigger) {
                ERR("Could not create size-based rotation trigger");
                ret = -1;
                goto end;
        }
 
+       /* Ensure this trigger is not visible to external users. */
+       lttng_trigger_set_hidden(session->rotate_trigger);
        lttng_trigger_set_credentials(
                        session->rotate_trigger, &session_creds);
 
        nc_status = lttng_notification_channel_subscribe(
-                       rotate_notification_channel, session->rotate_condition);
+                       rotate_notification_channel, rotate_condition);
        if (nc_status != LTTNG_NOTIFICATION_CHANNEL_STATUS_OK) {
                ERR("Could not subscribe to session consumed size notification");
                ret = -1;
                goto end;
        }
 
+       ret = lttng_write(rotate_notification_channel_subscription_change_eventfd,
+                         &eventfd_increment_value,
+                         sizeof(eventfd_increment_value));
+       if (ret != sizeof(eventfd_increment_value)) {
+               PERROR("Failed to wake up rotation thread as writing to the rotation thread notification channel subscription change eventfd failed");
+               ret = -1;
+               goto end;
+       }
+
        ret = notification_thread_command_register_trigger(
-                       notification_thread_handle, session->rotate_trigger);
+                       notification_thread_handle, session->rotate_trigger,
+                       true);
        if (ret < 0 && ret != -LTTNG_ERR_TRIGGER_EXISTS) {
                ERR("Register trigger, %s", lttng_strerror(ret));
                ret = -1;
@@ -114,6 +131,11 @@ int subscribe_session_consumed_size_rotation(struct ltt_session *session, uint64
        ret = 0;
 
 end:
+       lttng_condition_put(rotate_condition);
+       lttng_action_put(notify_action);
+       if (ret) {
+               lttng_trigger_put(session->rotate_trigger);
+       }
        return ret;
 }
 
@@ -122,23 +144,37 @@ int unsubscribe_session_consumed_size_rotation(struct ltt_session *session,
 {
        int ret = 0;
        enum lttng_notification_channel_status status;
+       const uint64_t eventfd_increment_value = 1;
 
+       assert(session->rotate_trigger);
        status = lttng_notification_channel_unsubscribe(
                        rotate_notification_channel,
-                       session->rotate_condition);
+                       lttng_trigger_get_const_condition(session->rotate_trigger));
        if (status != LTTNG_NOTIFICATION_CHANNEL_STATUS_OK) {
                ERR("Session unsubscribe error: %d", (int) status);
                ret = -1;
                goto end;
        }
 
-       ret = notification_thread_command_unregister_trigger(
-                       notification_thread_handle, session->rotate_trigger);
+       ret = lttng_write(rotate_notification_channel_subscription_change_eventfd,
+                         &eventfd_increment_value,
+                         sizeof(eventfd_increment_value));
+       if (ret != sizeof(eventfd_increment_value)) {
+               PERROR("Failed to wake up rotation thread as writing to the rotation thread notification channel subscription change eventfd failed");
+               ret = -1;
+               goto end;
+       }
+
+       ret = notification_thread_command_unregister_trigger(notification_thread_handle,
+                                                            session->rotate_trigger);
        if (ret != LTTNG_OK) {
                ERR("Session unregister trigger error: %d", ret);
                goto end;
        }
 
+       lttng_trigger_put(session->rotate_trigger);
+       session->rotate_trigger = NULL;
+
        ret = 0;
 end:
        return ret;