Client Side Timeline/Backup LSN Support

[Jubilee101]

Currently pgmoneta has little support for fetching/extracting LSN info related to timeline and backup. We would like the following feature:

• [x] .history file streaming
• [x] .history file parsing
• [x] Corresponding prometheus support
• [x] Make sure pgmoneta starts fetching WAL segments of the next timeline when the current one ends
• [x] Extracting starting/ending LSN from backup_label into backup.info

Some references: https://www.highgo.ca/2021/11/01/the-postgresql-timeline-concept/ https://developer.aliyun.com/article/234 https://www.postgresql.org/docs/current/protocol-replication.html

[Jubilee101]

Close this as most tasks have been done. I'll later submit a separate issue for server side LSN. That'll tie into the extension project, and require looking into postgres internals - base backup command as well as mvcc stuff.