handle empty sessions

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>

diff --git a/include/lttng/rotate.h b/include/lttng/rotate.h
index 65afcaac7db54ec609ccc405ae72ddb4e2933661..c340fb1c7c42d19f0729e32e443582a8cb83a699 100644 (file)
--- a/include/lttng/rotate.h
+++ b/include/lttng/rotate.h
@@ -39,10 +39,15 @@ enum lttng_rotate_status {
         * retrieve the path for the chunk.
         */
        LTTNG_ROTATE_EXPIRED = 2,
+       /*
+        * Nothing to rotate, it happens on the first rotation when tracing
+        * only in user-space and no app was started.
+        */
+       LTTNG_ROTATE_EMPTY = 3,
        /*
         * On error.
         */
-       LTTNG_ROTATE_ERROR = 3,
+       LTTNG_ROTATE_ERROR = 4,
 };
 
 /*

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index ed112489b5e5ee53b71cd196574299461fa57e15..6c815eff15a701e4a563f10e677dfcdb5c60170f 100644 (file)
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -4192,6 +4192,7 @@ int cmd_rotate_session(struct ltt_session *session,
 
        session->rotate_count++;
        session->rotate_pending = 1;
+       session->rotate_status = LTTNG_ROTATE_STARTED;
 
        /*
         * Create the path name for the next chunk.
@@ -4279,7 +4280,13 @@ int cmd_rotate_pending(struct ltt_session *session,
                goto end;
        }
 
-       if (session->rotate_pending) {
+       if (session->rotate_status == LTTNG_ROTATE_ERROR) {
+               DBG("An error occurred during rotation");
+               (*pending_return)->status = LTTNG_ROTATE_ERROR;
+       } else if (session->rotate_status == LTTNG_ROTATE_EMPTY) {
+               DBG("Nothing to rotate");
+               (*pending_return)->status = LTTNG_ROTATE_EMPTY;
+       } else if (session->rotate_pending) {
                DBG("Session %s, rotate_id %" PRIu64 " still pending",
                                session->name, session->rotate_count);
                (*pending_return)->status = LTTNG_ROTATE_STARTED;

diff --git a/src/bin/lttng-sessiond/rotate.c b/src/bin/lttng-sessiond/rotate.c
index bcd0b828dcedc715712dbf06b22767ffef19fc2d..f1085e42e5708114c554fb09cef0306ad670f3c8 100644 (file)
--- a/src/bin/lttng-sessiond/rotate.c
+++ b/src/bin/lttng-sessiond/rotate.c
@@ -169,7 +169,7 @@ int rename_first_chunk(struct ltt_session *session,
         */
        ret = session_rename_chunk(session, tmppath, tmppath2, 1);
        if (ret < 0) {
-               PERROR("Rename first trace directory");
+               ERR("Rename first trace directory");
                ret = -LTTNG_ERR_ROTATE_NO_DATA;
                goto error;
        }
@@ -201,13 +201,12 @@ int rename_complete_chunk(struct ltt_session *session, time_t ts)
 
        new_path = zmalloc(PATH_MAX * sizeof(char));
        if (!new_path) {
+               session->rotate_status = LTTNG_ROTATE_ERROR;
                ERR("Alloc new_path");
                ret = -1;
                goto end;
        }
 
-       fprintf(stderr, "COUNT: %d\n", session->rotate_count);
-
        if (session->rotate_count == 1) {
                char start_time[16];
 
@@ -233,8 +232,15 @@ int rename_complete_chunk(struct ltt_session *session, time_t ts)
                                        new_path);
                        if (ret) {
                                ERR("Rename kernel session");
-                               ret = -1;
-                               goto end;
+                               /*
+                                * This is not a fatal error for the rotation
+                                * thread, we just need to inform the client
+                                * that a problem occurred with the rotation.
+                                * Returning 0, same for the other errors
+                                * below.
+                                */
+                               ret = 0;
+                               goto error;
                        }
                }
                if (session->ust_session) {
@@ -246,8 +252,8 @@ int rename_complete_chunk(struct ltt_session *session, time_t ts)
                                        new_path);
                        if (ret) {
                                ERR("Rename ust session");
-                               ret = -1;
-                               goto end;
+                               ret = 0;
+                               goto error;
                        }
                }
        } else {
@@ -268,8 +274,8 @@ int rename_complete_chunk(struct ltt_session *session, time_t ts)
                                new_path, 0);
                if (ret) {
                        ERR("Session rename");
-                       ret = -1;
-                       goto end;
+                       ret = 0;
+                       goto error;
                }
        }
 
@@ -282,6 +288,10 @@ int rename_complete_chunk(struct ltt_session *session, time_t ts)
                        "%s", new_path);
        session->rotate_pending = 0;
 
+       goto end;
+
+error:
+       session->rotate_status = LTTNG_ROTATE_ERROR;
 end:
        free(new_path);
        return ret;

diff --git a/src/bin/lttng-sessiond/rotation-thread.c b/src/bin/lttng-sessiond/rotation-thread.c
index e50903f691405b213a70bc04993a0521c4c723ea..4f7ac86e5b082eb931ab5fa5493405bc758cc247 100644 (file)
--- a/src/bin/lttng-sessiond/rotation-thread.c
+++ b/src/bin/lttng-sessiond/rotation-thread.c
@@ -313,6 +313,7 @@ int handle_channel_rotation_pipe(int fd, uint32_t revents,
                time_t now = time(NULL);
 
                if (now == (time_t) -1) {
+                       channel_info->session->rotate_status = LTTNG_ROTATE_ERROR;
                        ret = LTTNG_ERR_ROTATE_NOT_AVAILABLE;
                        goto end;
                }

diff --git a/src/bin/lttng-sessiond/session.h b/src/bin/lttng-sessiond/session.h
index 9e5c3151bb1c26a947e970301355effdd23db364..41a894079e5244b131b9c6cc76c1f18c9f8bfd5b 100644 (file)
--- a/src/bin/lttng-sessiond/session.h
+++ b/src/bin/lttng-sessiond/session.h
@@ -136,6 +136,7 @@ struct ltt_session {
         */
        uint64_t rotate_count;
        unsigned int rotate_pending:1;
+       enum lttng_rotate_status rotate_status;
        /*
         * Number of channels waiting for a rotate.
         * When this number reaches 0, we can handle the rename of the chunk

diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index 85e2f1a7d34af70608f9f9f50734356a8c9cfeed..368e5866713a9418eab4dcd4e11be9ae60f71b32 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -6286,7 +6286,7 @@ int ust_app_regenerate_statedump_all(struct ltt_ust_session *usess)
  */
 int ust_app_rotate_session(struct ltt_session *session)
 {
-       int ret = 0;
+       int ret = 0, nr_channels = 0, nr_app = 0;
        struct lttng_ht_iter iter;
        struct ust_app *app;
        struct ltt_ust_session *usess = session->ust_session;
@@ -6312,6 +6312,7 @@ int ust_app_rotate_session(struct ltt_session *session)
                        struct buffer_reg_channel *reg_chan;
                        struct consumer_socket *socket;
 
+                       nr_channels++;
                        /* Get consumer socket to use to push the metadata.*/
                        socket = consumer_find_socket_by_bitness(reg->bits_per_long,
                                        usess->consumer);
@@ -6390,6 +6391,7 @@ int ust_app_rotate_session(struct ltt_session *session)
                                /* Session not associated with this app. */
                                continue;
                        }
+                       nr_app++;
                        ret = snprintf(pathname, PATH_MAX, DEFAULT_UST_TRACE_DIR "/%s",
                                        ua_sess->path);
                        if (ret < 0) {
@@ -6461,6 +6463,11 @@ int ust_app_rotate_session(struct ltt_session *session)
                break;
        }
 
+       if (nr_app == 0 && nr_channels == 0) {
+               session->rotate_pending = 0;
+               session->rotate_status = LTTNG_ROTATE_EMPTY;
+       }
+
        ret = LTTNG_OK;
 
 error:

diff --git a/src/bin/lttng/commands/rotate.c b/src/bin/lttng/commands/rotate.c
index 246f398007f7bca581dd9cc72a3bf28a0ef8534c..c2e5580fc56dc68cbbe6a9d4e592aee6e0b38f5b 100644 (file)
--- a/src/bin/lttng/commands/rotate.c
+++ b/src/bin/lttng/commands/rotate.c
@@ -183,6 +183,10 @@ static int rotate_tracing(void)
                        }
                }
 
+               ret = CMD_SUCCESS;
+               goto end;
+       case LTTNG_ROTATE_EMPTY:
+               MSG("Empty session, nothing to rotate.");
                ret = CMD_SUCCESS;
                goto end;
        }

diff --git a/src/common/consumer/consumer.c b/src/common/consumer/consumer.c
index ef69d65a4892a29b40b82954b46d55935c06020c..240cb3e83bf4f41045b55543bab9eb77a6c654e0 100644 (file)
--- a/src/common/consumer/consumer.c
+++ b/src/common/consumer/consumer.c
@@ -3956,6 +3956,13 @@ int lttng_consumer_rotate_channel(uint64_t key, char *path,
        }
        pthread_mutex_lock(&channel->lock);
        snprintf(channel->pathname, PATH_MAX, "%s", path);
+       ret = utils_mkdir_recursive(channel->pathname, S_IRWXU | S_IRWXG,
+                       channel->uid, channel->gid);
+       if (ret < 0) {
+               ERR("Trace directory creation error");
+               ret = -1;
+               goto end_unlock_channel;
+       }
 
        cds_lfht_for_each_entry_duplicate(ht->ht,
                        ht->hash_fct(&channel->key, lttng_ht_seed),
@@ -3969,14 +3976,6 @@ int lttng_consumer_rotate_channel(uint64_t key, char *path,
                 * Lock stream because we are about to change its state.
                 */
                pthread_mutex_lock(&stream->lock);
-               ret = utils_mkdir_recursive(channel->pathname, S_IRWXU | S_IRWXG,
-                               stream->uid, stream->gid);
-               if (ret < 0) {
-                       if (errno != EEXIST) {
-                               ERR("Trace directory creation error");
-                               goto end_unlock;
-                       }
-               }
 
                memcpy(stream->channel_ro_pathname, channel->pathname, PATH_MAX);
                ret = lttng_consumer_sample_snapshot_positions(stream);
@@ -4221,10 +4220,17 @@ int lttng_consumer_rotate_rename(char *current_path, char *new_path,
 
        }
        ret = rename(current_path, new_path);
-       if (ret < 0) {
+       /*
+        * If a domain has not yet created its channel, the domain-specific
+        * folder might not exist, but this is not an error.
+        */
+       if (ret < 0 && errno != ENOENT) {
                PERROR("Rename completed rotation chunk");
+               goto end;
        }
 
+       ret = 0;
+
 end:
        return ret;
 }

diff --git a/src/lib/lttng-ctl/rotate.c b/src/lib/lttng-ctl/rotate.c
index 7a6dcbd690b32bef4a708cb4b662a8ae80f9e86b..49d3a26b6d7571310237c5eadc5cf32ccf9283fa 100644 (file)
--- a/src/lib/lttng-ctl/rotate.c
+++ b/src/lib/lttng-ctl/rotate.c
@@ -188,14 +188,23 @@ int lttng_rotate_session_pending(
        }
 
        rotate_handle->status = pending_return->status;
-       if (pending_return->status == LTTNG_ROTATE_COMPLETED) {
+       switch(pending_return->status) {
+       /* Not pending anymore */
+       case LTTNG_ROTATE_COMPLETED:
                snprintf(rotate_handle->output_path, PATH_MAX, "%s",
                                pending_return->output_path);
+       case LTTNG_ROTATE_EXPIRED:
+       case LTTNG_ROTATE_EMPTY:
                ret = 0;
-       } else if (pending_return->status == LTTNG_ROTATE_STARTED) {
+               break;
+       /* Still pending */
+       case LTTNG_ROTATE_STARTED:
                ret = 1;
-       } else {
+               break;
+       /* Error */
+       default:
                ret = -1;
+               break;
        }
 
 end: