Have separate routine and http endpoint to create timeline on safekeepers. It is
not used yet, i.e. timeline is still created implicitly, but we'll change that
once infrastructure for learning which tlis are assigned to which safekeepers
will be ready, preventing accidental creation by compute.
Changes format of safekeeper control file, allowing to store set of
peers. Knowing peers provides a part of foundation for peer
recovery (calculating min horizons like truncate_lsn for WAL truncation and
commit_lsn for sync-safekeepers replacement) and proper membership change;
similarly, we don't yet use it for now.
Employing cf file version bump, extracts tenant_id and timeline_id to top level
where it is more suitable. Also adds a bunch of LSNs there and rename
truncate_lsn to more specific peer_horizon_lsn.
When several AppendRequest's can be read from socket without blocking,
they are processed together and fsync() to segment file is only called
once. Segment file is no longer opened for every write request, now
last opened file is cached inside PhysicalStorage. New metric for WAL
flushes was added to the storage, FLUSH_WAL_SECONDS. More errors were
added to storage for non-sequential WAL writes, now write_lsn can be
moved only with calls to truncate_lsn(new_lsn).
New messages have been added to ProposerAcceptorMessage enum. They
can't be deserialized directly and now are used only for optimizing
flushes. Existing protocol wasn't changed and flush will be called for
every AppendRequest, as it was before.
wal_storage.rs was split up from timeline.rs, safekeeper.rs and send_wal.rs,
and now contains all WAL related code from the safekeeper. Now there are
PhysicalStorage for persisting WAL to disk and WalReader for reading it.
This allows optimizing PhysicalStorage without affecting too much of other
code.
Also there is a separate structure for persisting control file now in
control_file.rs.
Currently ztimelineids are unique, but all APIs accept the pair, so let's keep
it everywhere for uniformity.
Carry around ZTTId containing both ZTenantId and ZTimelineId for simplicity.
(existing clusters on staging ought to be preprocessed for that)
This patch includes attach/detach http endpoints in pageservers. Some
changes in callmemaybe handling inside safekeeper and an integrational
test to check migration with and without load. There are still some
rough edges that will be addressed in follow up patches
Do it separately with SafekeeperPostgresCommand enum as a result. Since query is
always C string, switch postgres_backend process_query argument from Bytes to
&str.
Make passing ztli/ztenant id in safekeeper connection string optional; this is
needed for upcoming intra-safekeeper heartbeat cmd which is not bound to any
timeline.
