vdb_writer.h 文件参考

SQLite-backed recorder that produces .vdb / .vdbx bag files with batched WAL commits. 更多...

#include <memory>
#include <string>
#include "./bag_writer.h"

vdb_writer.h 的引用(Include)关系图:

浏览源代码.

类
class	vlink::VDBWriter
	Concrete SQLite-backed BagWriter implementation with WAL caching and batch commits. 更多...

命名空间
	vlink

详细描述

SQLite-backed recorder that produces .vdb / .vdbx bag files with batched WAL commits.

VDBWriter materialises BagWriter on top of SQLite. Messages are accumulated in an in-memory cache and flushed to disk in WAL-mode transactions so that the write amplification remains bounded even at high publish rates; outstanding writes are committed during close() and an optional VACUUM step compacts the file on exit.

VDB schema

Table	Purpose
messages	(id, url_id, ts_us, action, data) – one row per recorded message
urls	(id, url, ser_type, schema_type) – topic dictionary
schemas	(id, ser_type, schema_type, blob) – embedded schema descriptors
metadata	(key, value) – tag, machine name, vlink version, capture time
stats	(url_id, count, bytes, loss) – per-URL aggregates updated on flush

Writer states

+----------+   on_begin()       +---------+   push()/push_schema()   +-----------+
|  closed  | -----------------> | opening | -----------------------> | recording |
+----------+                    +---------+                          +-----------+
     ^                                                                     |
     |                                                                     v cache full / split
     |                                                              +------------+
     |                                                              | committing |
     |                                                              | WAL flush  |
     |                                                              +------------+
     |                                                                     |
     +-------------------- on_end() / dtor ----------------------- finalising
                                                                           |
                                                                           v
                                                                       (optional)
                                                                       vacuum

Example

vlink::BagWriter::Config cfg;
cfg.compress = vlink::BagWriter::kCompressLzav;
cfg.wal_mode = true;
 
auto writer = vlink::BagWriter::create("/data/recording.vdb", cfg);
 
writer->async_run();
 
vlink::Frame frame;
frame.timestamp   = -1;  // < 0 => writer auto-assigns from its clock (0 is recorded verbatim)
frame.url         = "dds://lidar/front";
frame.ser_type    = "demo.proto.PointCloud";
frame.schema_type = vlink::SchemaType::kProtobuf;
frame.action_type = vlink::ActionType::kPublish;
frame.data        = serialized_bytes;
writer->push(frame);

参见

BagWriter, VCAPWriter