Fix concurrency issues while overwriting tracefiles in live

[lttng-tools.git] / src / bin / lttng-relayd / lttng-relayd.h

diff --git a/src/bin/lttng-relayd/lttng-relayd.h b/src/bin/lttng-relayd/lttng-relayd.h
index 6fdcca29189edb7e70583326fcebf43d7f1fa9df..0af8e0f1d963199b5a6bb82c28b244a33daa6b6c 100644 (file)
--- a/src/bin/lttng-relayd/lttng-relayd.h
+++ b/src/bin/lttng-relayd/lttng-relayd.h
@@ -96,6 +96,8 @@ struct relay_stream {
        uint64_t tracefile_size_current;
        uint64_t tracefile_count;
        uint64_t tracefile_count_current;
+       /* To inform the viewer up to where it can go back in time. */
+       uint64_t oldest_tracefile_id;
 
        uint64_t total_index_received;
        struct relay_viewer_stream *viewer_stream;
@@ -124,12 +126,24 @@ struct relay_stream {
         * timestamp end, when it is active, this field == -1ULL.
         */
        uint64_t beacon_ts_end;
+       /*
+        * To protect the update of the close_write_flag and the checks of
+        * the tracefile_count_current.
+        * It is taken before checking whenever we need to know if the
+        * writer and reader are working in the same tracefile.
+        */
+       pthread_mutex_t viewer_stream_rotation_lock;
 
        /* Information telling us when to close the stream  */
        unsigned int close_flag:1;
        /* Indicate if the stream was initialized for a data pending command. */
        unsigned int data_pending_check_done:1;
        unsigned int metadata_flag:1;
+       /*
+        * To detect when we start overwriting old data, it is used to
+        * update the oldest_tracefile_id.
+        */
+       unsigned int tracefile_overwrite:1;
 };
 
 /*
@@ -147,15 +161,28 @@ struct relay_viewer_stream {
        char *channel_name;
        uint64_t last_sent_index;
        uint64_t total_index_received;
-       uint64_t tracefile_size;
-       uint64_t tracefile_size_current;
        uint64_t tracefile_count;
        uint64_t tracefile_count_current;
        struct lttng_ht_node_u64 stream_n;
        struct rcu_head rcu_node;
        struct ctf_trace *ctf_trace;
+       /*
+        * This lock blocks only when the writer is about to start overwriting
+        * a file currently read by the reader.
+        */
+       pthread_mutex_t overwrite_lock;
        /* Information telling us if the stream is a metadata stream. */
        unsigned int metadata_flag:1;
+       /*
+        * Information telling us that the stream is closed in write, so
+        * we don't expect new indexes and we can read up to EOF.
+        */
+       unsigned int close_write_flag:1;
+       /*
+        * If the streaming side closes a FD in use in the viewer side,
+        * it sets this flag to inform that it is a normal error.
+        */
+       unsigned int abort_flag:1;
 };
 
 /*