Enhance babeltrace API with position save/restore

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/converter/babeltrace-lib.c b/converter/babeltrace-lib.c
index e08c0ada0c0a87c4ac9dd40916f088cd1785b30d..3797508155831cf84847cd4ec2d346c94ce70f88 100644 (file)
--- a/converter/babeltrace-lib.c
+++ b/converter/babeltrace-lib.c
@@ -33,6 +33,21 @@
 #include <babeltrace/ctf/types.h>
 #include <babeltrace/ctf-ir/metadata.h>
 
+struct stream_saved_pos {
+       /*
+        * Use file_stream pointer to check if the trace collection we
+        * restore to match the one we saved from, for each stream.
+        */
+       struct ctf_file_stream *file_stream;
+       size_t cur_index;       /* current index in packet index */
+       ssize_t offset;         /* offset from base, in bits. EOF for end of file. */
+};
+
+struct babeltrace_saved_pos {
+       struct trace_collection *tc;
+       GArray *stream_saved_pos;       /* Contains struct stream_saved_pos */
+};
+
 /*
  * struct babeltrace_iter: data structure representing an iterator on a trace
  * collection.
@@ -40,6 +55,7 @@
 struct babeltrace_iter {
        struct ptr_heap *stream_heap;
        struct trace_collection *tc;
+       struct trace_collection_pos *end_pos;
 };
 
 static int stream_read_event(struct ctf_file_stream *sin)
@@ -69,7 +85,10 @@ int stream_compare(void *a, void *b)
                return 0;
 }
 
-struct babeltrace_iter *babeltrace_iter_create(struct trace_collection *tc)
+/* TODO: use begin_pos/end_pos */
+struct babeltrace_iter *babeltrace_iter_create(struct trace_collection *tc,
+               struct trace_collection_pos *begin_pos,
+               struct trace_collection_pos *end_pos)
 {
        int i, stream_id;
        int ret = 0;
@@ -201,7 +220,7 @@ int convert_trace(struct trace_descriptor *td_write,
        sout = container_of(td_write, struct ctf_text_stream_pos,
                        trace_descriptor);
 
-       iter = babeltrace_iter_create(trace_collection_read);
+       iter = babeltrace_iter_create(trace_collection_read, NULL, NULL);
        while (babeltrace_iter_read_event(iter, &stream, &event) == 0) {
                ret = sout->parent.event_cb(&sout->parent, stream);
                if (ret) {

diff --git a/include/babeltrace/babeltrace.h b/include/babeltrace/babeltrace.h
index dfe6112d0b9747e5c021fd9ceb1dd3231dcabbec..6c3fe967e635ee05973a08c3d35dcdc027e9b64f 100644 (file)
--- a/include/babeltrace/babeltrace.h
+++ b/include/babeltrace/babeltrace.h
@@ -22,11 +22,37 @@ struct babeltrace_iter;
 struct trace_collection;
 struct ctf_stream_event;
 struct ctf_stream;
+struct babeltrace_saved_pos;
+
+struct trace_collection_pos {
+       enum {
+               BT_SEEK_TIME,           /* uses u.seek_time */
+               BT_SEEK_RESTORE,        /* uses u.restore */
+               BT_SEEK_CUR,
+               BT_SEEK_BEGIN,
+               BT_SEEK_END,
+       } type;
+       union {
+               uint64_t seek_time;
+               struct babeltrace_saved_pos *restore;
+       } u;
+};
 
 /*
  * babeltrace_iter_create - Allocate a trace collection iterator.
+ *
+ * begin_pos and end_pos are optional parameters to specify the position
+ * at which the trace collection should be seeked upon iterator
+ * creation, and the position at which iteration will start returning
+ * "EOF".
+ *
+ * By default, if begin_pos is NULL, a BT_SEEK_CUR is performed at
+ * creation. By default, if end_pos is NULL, a BT_SEEK_END (end of
+ * trace) is the EOF criterion.
  */
-struct babeltrace_iter *babeltrace_iter_create(struct trace_collection *tc);
+struct babeltrace_iter *babeltrace_iter_create(struct trace_collection *tc,
+               struct trace_collection_pos *begin_pos,
+               struct trace_collection_pos *end_pos);
 
 /*
  * babeltrace_iter_destroy - Free a trace collection iterator.
@@ -41,34 +67,28 @@ void babeltrace_iter_destroy(struct babeltrace_iter *iter);
 int babeltrace_iter_next(struct babeltrace_iter *iter);
 
 /*
- * babeltrace_iter_get_pos - Get the current trace collection position.
+ * babeltrace_iter_save_pos - Save the current trace collection position.
  *
  * The position returned by this function needs to be freed by
  * babeltrace_iter_free_pos after use.
  */
-struct babeltrace_iter_pos *
-       babeltrace_iter_get_pos(struct babeltrace_iter *iter);
+struct trace_collection_pos *
+       babeltrace_iter_save_pos(struct babeltrace_iter *iter);
 
 /*
  * babeltrace_iter_free_pos - Free the position.
  */
-void babeltrace_iter_free_pos(struct babeltrace_iter_pos *pos);
-
-/*
- * babeltrace_iter_seek_pos - Seek the trace collection to the position.
- */
-int babeltrace_iter_seek_pos(struct babeltrace_iter *iter,
-               struct babeltrace_iter_pos *pos);
+void babeltrace_iter_free_pos(struct trace_collection_pos *pos);
 
 /*
- * babeltrace_iter_seek_time: Seek the trace collection to the given timestamp.
+ * babeltrace_iter_seek: seek iterator to given position.
  *
- * Return EOF if timestamp is after the last event of the trace collection.
+ * Return EOF if position is after the last event of the trace collection.
  * Return other negative value for other errors.
  * Return 0 for success.
  */
-int babeltrace_iter_seek_time(struct babeltrace_iter *iter,
-               uint64_t timestamp);
+int babeltrace_iter_seek(struct babeltrace_iter *iter,
+               const struct trace_collection_pos *pos);
 
 /*
  * babeltrace_iter_read_event: Read the iterator's current event data.