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Use snapshot-after in config for periodical snapshots in PersistentFSM (#22605)

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* Use snapshot-after in config to periodical snapshot in PersistentFSM (#21563)

* akka.persistence.fsm.snapshot-after is either off or a numerical value

* Use Akka Extension for snapshot-after in PersistentFSM
This commit is contained in:
Richard Imaoka 2017-06-16 21:47:00 +09:00 • committed by Patrik Nordwall
parent 3c8f6dacd8
commit 2ec2d98888
5 changed files with 173 additions and 2 deletions
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20
akka-docs/src/main/paradox/java/persistence.md
View file

@ -790,6 +790,26 @@ A snapshot of state data can be persisted by calling the `saveStateSnapshot()` m
On recovery state data is initialized according to the latest available snapshot, then the remaining domain events are replayed, triggering the
`applyEvent` method.
<a id="periodical-snapshot"></a>
## Periodical snapshot by snapshot-after
You can enable periodical `saveStateSnapshot()` calls in `PersistentFSM` if you turn the following flag on in `reference.conf`
`akka.persistence.fsm.snapshot-after = 1000`
this means `saveStateSnapshot()` is called after the sequence number reaches multiple of 1000.
@@@ note
`saveStateSnapshot()` might not be called exactly at sequence numbers being multiple of the `snapshot-after` configuration value.
This is because `PersistentFSM` works in a sort of "batch" mode when processing and persisting events, and `saveStateSnapshot()`
is called only at the end of the "batch". For example, if you set `akka.persistence.fsm.snapshot-after = 1000`,
it is possible that `saveStateSnapshot()` is called at `lastSequenceNr = 1005, 2003, ... `
A single batch might persist state transition, also there could be multiple domain events to be persisted
if you pass them to `applying` method in the `PersistFSM` DSL.
@@@
## Storage plugins
Storage backends for journals and snapshot stores are pluggable in the Akka persistence extension.

20
akka-docs/src/main/paradox/scala/persistence.md
View file

@ -798,6 +798,26 @@ A snapshot of state data can be persisted by calling the `saveStateSnapshot()` m
On recovery state data is initialized according to the latest available snapshot, then the remaining domain events are replayed, triggering the
`applyEvent` method.
<a id="periodical-snapshot"></a>
## Periodical snapshot by snapshot-after
You can enable periodical `saveStateSnapshot()` calls in `PersistentFSM` if you turn the following flag on in `reference.conf`
`akka.persistence.fsm.snapshot-after = 1000`
this means `saveStateSnapshot()` is called after the sequence number reaches multiple of 1000.
@@@ note
`saveStateSnapshot()` might not be called exactly at sequence numbers being multiple of the `snapshot-after` configuration value.
This is because `PersistentFSM` works in a sort of "batch" mode when processing and persisting events, and `saveStateSnapshot()`
is called only at the end of the "batch". For example, if you set `akka.persistence.fsm.snapshot-after = 1000`,
it is possible that `saveStateSnapshot()` is called at `lastSequenceNr = 1005, 2003, ... `
A single batch might persist state transition, also there could be multiple domain events to be persisted
if you pass them to `applying` method in the `PersistFSM` DSL.
@@@
<a id="storage-plugins"></a>
## Storage plugins