bag_reader.h File Reference

Abstract player for VLink bag recordings with seek, loop and rate control. More...

#include <cstdint>
#include <future>
#include <memory>
#include <string>
#include <string_view>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include "../base/functional.h"
#include "../base/macros.h"
#include "../base/message_loop.h"
#include "../impl/types.h"
#include "./bag_plugin_interface.h"

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Classes
class	vlink::BagReader
	Format-agnostic VLink bag player driven by an internal MessageLoop. More...
struct	vlink::BagReader::Info
	Aggregated metadata extracted from the bag header, summary and URL index. More...
struct	vlink::BagReader::Info::UrlMeta
	Per-URL accounting entry recorded inside Info::url_metas. More...
struct	vlink::BagReader::Config
	Playback parameters consumed by play(). More...

Namespaces
	vlink

Detailed Description

Abstract player for VLink bag recordings with seek, loop and rate control.

BagReader is the polymorphic base for VLink offline log playback. It owns a private MessageLoop thread, opens a bag file produced by BagWriter, and replays the stored messages back to user-supplied callbacks honouring their original timing. Concrete subclasses provide format-specific I/O: VDBReader for the SQLite-backed .vdb container and VCAPReader for the MCAP-based .vcap container. create() chooses the right one from the file suffix.

Supported formats and behaviour summary:

Suffix	Concrete reader	Storage	Index source
.vdb / .vdbx	VDBReader	SQLite	SQLite tables (elapsed/URL)
.vcap / .vcapx	VCAPReader	MCAP	MCAP summary + chunk index

Internal playback state machine:

*                     play(cfg)              pause()
*      +------------+ -------> +-----------+ -------> +----------+
*      |  kStopped  |          |  kPlaying |          |  kPaused |
*      +------------+ <------- +-----------+ <------- +----------+
*                    stop() /         resume() / pause_to_next()
*                  end-of-bag
* 

Playback features:

• Rate multiplier, loop count and time-window filtering through Config.
• jump() seeks to an arbitrary recording timestamp and may force-resume playback.
• URL whitelist via Config::filter_urls applies after plugin URL remapping.
• check() / reindex() / fix() run asynchronously and report their outcome through std::future<bool>.
• A bound BagPluginInterface may rename URLs, override serialisation types and intercept individual replayed messages.

Example

auto reader = vlink::BagReader::create("/data/drive_log.vdb");
reader->register_ready_callback([] { VLOG_I("bag ready"); });
reader->register_output_callback([](const vlink::Frame& frame) {
    // replay each frame in real-time order
    VLOG_I("us=", frame.timestamp, " url=", frame.url, " bytes=", frame.data.size());
});
reader->async_run();
 
vlink::BagReader::Config cfg;
cfg.rate  = 2.0;                              // play at 2x speed
cfg.times = vlink::BagReader::kInfinite;      // loop forever
reader->play(cfg);

Note

Always call async_run() before play(); the loop thread must be alive to dispatch frames. Output callback timestamps are in microseconds, while Config::begin_time and Config::end_time are expressed in milliseconds.