Misc changes as suggested in the PR review
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Debasish Ghosh
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1c07ac1894
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dbafc24fda
7 changed files with 18 additions and 9 deletions
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@ -35,6 +35,8 @@ durable state is stored in a database and fetched as an asynchronous stream to t
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durable state, provided by the `DurableStateStoreQuery` interface, is used to implement tag based searches in
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Akka Projections.
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At present the query is based on _tags_. So if you have not tagged your objects, this query cannot be used.
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The example below shows how to get the `DurableStateStoreQuery` from the `DurableStateStoreRegistry` extension.
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Scala
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@ -22,6 +22,12 @@ To use Akka Persistence, add the module to your project:
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You also have to select durable state store plugin, see @ref:[Persistence Plugins](../persistence-plugins.md).
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@@@ note
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The APIs in the Durable State module are _experimental_ and subject to change based on feedbacks from the
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users and the community.
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@@@
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@@project-info{ projectId="akka-persistence-typed" }
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@ -38,7 +44,9 @@ The current state is always stored in the database. Since only the latest state
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Akka Persistence also supports @ref:[Event Sourcing](persistence.md) based implementation, where only the _events_ that are persisted by the actor are stored, but not the actual state of the actor. By storing all events, using this model,
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a stateful actor can be recovered by replaying the stored events to the actor, which allows it to rebuild its state.
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The database specific implementations can be added to existing Akka Persistence plugin implementations, starting with the JDBC plugin. The plugin would serialize the state and store as a blob with the persistenceId as the primary key.
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The database specific implementations can be added to existing Akka Persistence plugin implementations, starting with the JDBC plugin. The plugin would serialize the state and store as a blob with the persistenceId as the primary key. Since each entity
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lives on one node, consistency is guaranteed and reads can be served directly from memory. For details on how this guarantee
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is ensured, have a look at the @ref:[Cluster Sharding and DurableStateBehavior](#cluster-sharding-and-durablestatebehavior) section below.
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## Example and core API
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@ -30,7 +30,7 @@ trait DurableStateStoreQuery[A] extends DurableStateStore[A] {
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* This will return changes that occurred up to when the `Source` returned by this call is materialized. Changes to
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* objects made since materialization are not guaranteed to be included in the results.
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*
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* @param tag The type of entity to get changes for.
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* @param tag The tag to get changes for.
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* @param offset The offset to get changes since. Must either be [[akka.persistence.query.NoOffset]] to get
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* changes since the beginning of time, or an offset that has been previously returned by this query.
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* Any other offsets are invalid.
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@ -39,7 +39,7 @@ trait DurableStateStoreQuery[A] extends DurableStateStore[A] {
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def currentChanges(tag: String, offset: Offset): Source[DurableStateChange[A], NotUsed]
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/**
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* Get a source of the most recent changes made to objects of the given entity type since the passed in offset.
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* Get a source of the most recent changes made to objects of the given tag since the passed in offset.
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*
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* The returned source will never terminate, it effectively watches for changes to the objects and emits changes as
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* they happen.
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@ -49,7 +49,7 @@ trait DurableStateStoreQuery[A] extends DurableStateStore[A] {
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* in quick succession are likely to be skipped, with only the last update resulting in a change event from this
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* source.
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*
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* @param tag The type of entity to get changes for.
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* @param tag The tag to get changes for.
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* @param offset The offset to get changes since. Must either be [[akka.persistence.query.NoOffset]] to get
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* changes since the beginning of time, or an offset that has been previously returned by this query.
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* Any other offsets are invalid.
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@ -30,7 +30,7 @@ trait DurableStateStoreQuery[A] extends DurableStateStore[A] {
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* This will return changes that occurred up to when the `Source` returned by this call is materialized. Changes to
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* objects made since materialization are not guaranteed to be included in the results.
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*
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* @param tag The type of entity to get changes for.
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* @param tag The tag to get changes for.
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* @param offset The offset to get changes since. Must either be [[akka.persistence.query.NoOffset]] to get
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* changes since the beginning of time, or an offset that has been previously returned by this query.
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* Any other offsets are invalid.
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@ -49,7 +49,7 @@ trait DurableStateStoreQuery[A] extends DurableStateStore[A] {
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* in quick succession are likely to be skipped, with only the last update resulting in a change event from this
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* source.
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*
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* @param tag The type of entity to get changes for.
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* @param tag The tag to get changes for.
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* @param offset The offset to get changes since. Must either be [[akka.persistence.query.NoOffset]] to get
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* changes since the beginning of time, or an offset that has been previously returned by this query.
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* Any other offsets are invalid.
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@ -127,7 +127,6 @@ object DurableStatePersistentBehaviorCompileOnly {
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emptyState = State(0),
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commandHandler = (state, cmd) => throw new NotImplementedError("TODO: process the command & return an Effect"))
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.withTag("tag1")
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.withTag("tag2")
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//#tagging
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}
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@ -13,7 +13,7 @@ import akka.annotation.ApiMayChange
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import akka.persistence.state.scaladsl.{ GetObjectResult => SGetObjectResult }
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/**
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* API for reading durable state objects.
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* API for reading durable state objects with payload `A`.
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*
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* For Scala API see [[akka.persistence.state.scaladsl.DurableStateStore]].
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*
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@ -11,7 +11,7 @@ import akka.annotation.ApiMayChange
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import akka.persistence.state.javadsl.{ GetObjectResult => JGetObjectResult }
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/**
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* API for reading durable state objects.
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* API for reading durable state objects with payload `A`.
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*
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* For Java API see [[akka.persistence.state.javadsl.DurableStateStore]].
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*
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