Fix: race with the viewer and readiness of streams

[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 638ecbbea2b6d0f8863e27a52c4dad45b846d1e6..d0e0473b2bb8ed5e7ec355da6666e808b5e93ff7 100644 (file)
--- a/src/bin/lttng-relayd/lttng-relayd.h
+++ b/src/bin/lttng-relayd/lttng-relayd.h
@@ -23,9 +23,10 @@
 #include <limits.h>
 #include <urcu.h>
 #include <urcu/wfqueue.h>
+#include <urcu/list.h>
 
 #include <common/hashtable/hashtable.h>
-#include <common/index/lttng-index.h>
+#include <common/index/ctf-index.h>
 
 #include "ctf-trace.h"
 
@@ -38,10 +39,20 @@ struct relay_cmd_queue {
 };
 
 enum connection_type {
-       RELAY_DATA,
-       RELAY_CONTROL,
-       RELAY_VIEWER_COMMAND,
-       RELAY_VIEWER_NOTIFICATION,
+       RELAY_DATA                  = 1,
+       RELAY_CONTROL               = 2,
+       RELAY_VIEWER_COMMAND        = 3,
+       RELAY_VIEWER_NOTIFICATION   = 4,
+};
+
+/*
+ * When we receive a stream, it gets stored in a list (on a per connection
+ * basis) until we have all the streams of the same channel and the metadata
+ * associated with it, then it gets flagged with viewer_ready.
+ */
+struct relay_stream_recv_handle {
+       uint64_t id;    /* stream handle */
+       struct cds_list_head node;
 };
 
 /*
@@ -62,6 +73,16 @@ struct relay_session {
        struct rcu_head rcu_node;
        uint32_t viewer_attached;
        uint32_t stream_count;
+       /* Tell if this session is for a snapshot or not. */
+       unsigned int snapshot:1;
+
+       /*
+        * Indicate version protocol for this session. This is especially useful
+        * for the data thread that has no idea which version it operates on since
+        * linking control/data sockets is non trivial.
+        */
+       uint64_t minor;
+       uint64_t major;
 };
 
 /*
@@ -86,11 +107,21 @@ 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;
        uint64_t last_net_seq_num;
+
+       /*
+        * This node is added to the *control* connection hash table and the
+        * pointer is copied in here so we can access it when deleting this object.
+        * When deleting this, the ctf trace ht MUST NOT be destroyed. This happens
+        * at connection deletion.
+        */
        struct lttng_ht_node_str ctf_trace_node;
+       struct lttng_ht *ctf_traces_ht;
 
        /*
         * To protect from concurrent read/update between the
@@ -106,12 +137,29 @@ 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;
+       /*
+        * Can this stream be used by a viewer or are we waiting for additional
+        * information.
+        */
+       unsigned int viewer_ready:1;
 };
 
 /*
@@ -129,15 +177,32 @@ 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;
+       /* Stop after reading this tracefile. */
+       uint64_t tracefile_count_last;
        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.
+        *
+        * This is nested INSIDE the viewer_stream_rotation_lock.
+        */
+       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;
 };
 
 /*
@@ -151,21 +216,28 @@ struct relay_command {
        struct lttng_ht_node_ulong sock_n;
        struct rcu_head rcu_node;
        enum connection_type type;
-       unsigned int version_check_done:1;
        /* protocol version to use for this session */
        uint32_t major;
        uint32_t minor;
        struct lttng_ht *ctf_traces_ht; /* indexed by path name */
+       uint64_t session_id;
+       struct cds_list_head recv_head;
+       unsigned int version_check_done:1;
 };
 
 struct relay_local_data {
        struct lttng_ht *sessions_ht;
-       struct lttng_ht *viewer_streams_ht;
 };
 
 extern char *opt_output_path;
 
 extern struct lttng_ht *relay_streams_ht;
+extern struct lttng_ht *viewer_streams_ht;
+extern struct lttng_ht *indexes_ht;
+
+extern const char *tracing_group_name;
+
+extern const char * const config_section_name;
 
 struct relay_stream *relay_stream_find_by_id(uint64_t stream_id);