Fix: relayd: tracefile rotation: viewer opening missing index file

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

diff --git a/src/bin/lttng-relayd/tracefile-array.h b/src/bin/lttng-relayd/tracefile-array.h
index 9158f4fe40c3c16bd5446ea811cc44cef379b966..04d9123d03fc3caa9a3257dd654a11e45d7a94ba 100644 (file)
--- a/src/bin/lttng-relayd/tracefile-array.h
+++ b/src/bin/lttng-relayd/tracefile-array.h
@@ -29,15 +29,30 @@ struct tracefile {
        uint64_t seq_tail;      /* Oldest seqcount. Inclusive. */
 };
 
+enum tracefile_rotate_type {
+       TRACEFILE_ROTATE_READ,
+       TRACEFILE_ROTATE_WRITE,
+};
+
 /*
  * Represents an array of trace files in a stream.
+ * head is the most recent file/trace packet.
+ * tail is the oldest file/trace packet.
+ *
+ * There are two heads: a "read" head and a "write" head. The "write" head is
+ * the position of the newest data file. The "read" head position is only moved
+ * forward when the index is received.
+ *
+ * The viewer uses the "read" head position as upper bound, which
+ * ensures it never attempts to open a non-existing index file.
  */
 struct tracefile_array {
        struct tracefile *tf;
        size_t count;
 
        /* Current head/tail files. */
-       uint64_t file_head;
+       uint64_t file_head_read;
+       uint64_t file_head_write;
        uint64_t file_tail;
 
        /* Overall head/tail seq for the entire array. Inclusive. */
@@ -48,10 +63,10 @@ struct tracefile_array {
 struct tracefile_array *tracefile_array_create(size_t count);
 void tracefile_array_destroy(struct tracefile_array *tfa);
 
-void tracefile_array_file_rotate(struct tracefile_array *tfa);
+void tracefile_array_file_rotate(struct tracefile_array *tfa, enum tracefile_rotate_type type);
 void tracefile_array_commit_seq(struct tracefile_array *tfa);
 
-uint64_t tracefile_array_get_file_index_head(struct tracefile_array *tfa);
+uint64_t tracefile_array_get_read_file_index_head(struct tracefile_array *tfa);
 /* May return -1ULL in the case where we have not received any indexes yet. */
 uint64_t tracefile_array_get_seq_head(struct tracefile_array *tfa);