vdb_reader.h File Reference

SQLite-backed playback for VLink .vdb / .vdbx bag files. More...

#include <future>
#include <memory>
#include <string>
#include <vector>
#include "./bag_reader.h"

Include dependency graph for vdb_reader.h:

Go to the source code of this file.

Classes
class	vlink::VDBReader
	Concrete SQLite-backed BagReader implementation with full random-access support. More...

Namespaces
	vlink

Detailed Description

SQLite-backed playback for VLink .vdb / .vdbx bag files.

VDBReader is the concrete BagReader implementation for the SQLite container that VLink uses for recordings that require true random-access indexing, in-place repair, and tag-based navigation. Splits are described by a .vdbx JSON manifest pointing at one or more sibling .vdb files; this reader follows the manifest transparently.

VDB schema

Table	Key columns	Purpose
messages	id, url_id, ts_us, action, data	recorded payloads ordered by timestamp
urls	id, url, ser_type, schema_type	per-topic identity dictionary
schemas	id, ser_type, schema_type, blob	embedded schema descriptors
metadata	key, value	tag name, version, capture machine, etc.
stats	url_id, count, bytes, loss	per-URL aggregate counters
index	ts_us, message_id	timestamp -> message random-access index

Reader states

+---------+   play()         +---------+   pause()        +---------+
| stopped | ---------------> | playing | ---------------> | paused  |
+---------+                  +---------+                  +---------+
     ^                            |  ^                          |
     |                            |  | resume() / pause_to_next()|
     +--- stop() / EOF -----------+  +--------------------------+
                                  |
                                  |  jump(time, rate, times)
                                  v
                              +---------+
                              | seeking |  SQL index lookup
                              +---------+

Example

auto reader = vlink::BagReader::create("/data/recording.vdb");
 
reader->register_output_callback([](const vlink::Frame& frame) {
  dispatch(frame.url, frame.data);
});
 
reader->async_run();
reader->play({});

See also

BagReader, VCAPReader