[Tarantool-patches] [PATCH v4] qsync: provide box.info.synchro interface for monitoring

[Kirill Yukhin]

Hello,

On 08 апр 15:18, Cyrill Gorcunov wrote:
> In commit 14fa5fd82 (cfg: support symbolic evaluation of
> replication_synchro_quorum) we implemented support of
> symbolic evaluation of `replication_synchro_quorum` parameter
> and there is no easy way to obtain it current run-time value,
> ie evaluated number value.
> 
> Moreover we would like to fetch queue length on transaction
> limbo for tests and extend this statistics in future. Thus
> lets add them.
> 
> Closes #5191
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov at gmail.com>
> 
> @TarantoolBot document
> Title: Provide `box.info.synchro` interface
> 
> The `box.info.synchro` leaf provides information about details of
> synchronous replication.
> 
> In particular `quorum` represent the current value of synchronous
> replication quorum defined by `replication_synchro_quorum`
> configuration parameter because it can be set as dynamic formula
> such as `N/2+1` and the value depends on current number of replicas.
> 
> Since synchronous replication does not commit data immediately
> but waits for its propagation to replicas the data sits in a queue
> gathering `commit` responses from remote nodes. Current number of
> entries waiting in the queue is shown via `queue.len` member.
> 
> A typical output is the following
> 
> ``` Lua
> tarantool> box.info.synchro
> ---
> - queue:
>     len: 0
>   quorum: 1
> ...
> ```
> 
> The `len` member shows current number of entries in the queue.
> And the `quorum` member shows an evaluated value of
> `replication_synchro_quorum` parameter.
> ---
> issue https://github.com/tarantool/tarantool/issues/5191
> branch gorcunov/gh-5191-qsync-stat-4

I've checked your patch into master.

--
Regards, Kirill Yukhin