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Use apidoc directive in distributed-data.md (#22904) (#31017)

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Andrei Arlou 2022-01-13 17:22:29 +02:00 • committed by GitHub
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akka-docs/src/main/paradox/distributed-data.md
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@ -22,12 +22,12 @@ For the full documentation of this feature and for new projects see @ref:[Distri
## Using the Replicator ## Using the Replicator
The `akka.cluster.ddata.Replicator` actor provides the API for interacting with the data. The @apidoc[akka.cluster.ddata.Replicator] actor provides the API for interacting with the data.
The `Replicator` actor must be started on each node in the cluster, or group of nodes tagged The `Replicator` actor must be started on each node in the cluster, or group of nodes tagged
with a specific role. It communicates with other `Replicator` instances with the same path with a specific role. It communicates with other `Replicator` instances with the same path
(without address) that are running on other nodes . For convenience it can be used with the (without address) that are running on other nodes . For convenience it can be used with the
`akka.cluster.ddata.DistributedData` extension but it can also be started as an ordinary @apidoc[akka.cluster.ddata.DistributedData] extension but it can also be started as an ordinary
actor using the `Replicator.props`. If it is started as an ordinary actor it is important actor using the @apidoc[Replicator.props](akka.cluster.ddata.Replicator$) {scala="#props(settings:akka.cluster.ddata.ReplicatorSettings):akka.actor.Props" java="#props(akka.cluster.ddata.ReplicatorSettings)"}. If it is started as an ordinary actor it is important
that it is given the same name, started on same path, on all nodes. that it is given the same name, started on same path, on all nodes.
Cluster members with status @ref:[WeaklyUp](typed/cluster-membership.md#weakly-up), Cluster members with status @ref:[WeaklyUp](typed/cluster-membership.md#weakly-up),
@ -39,7 +39,7 @@ as part of the cluster. So 3 nodes + 5 `WeaklyUp` is essentially a
3 node cluster as far as consistent actions are concerned. 3 node cluster as far as consistent actions are concerned.
Below is an example of an actor that schedules tick messages to itself and for each tick Below is an example of an actor that schedules tick messages to itself and for each tick
adds or removes elements from a `ORSet` (observed-remove set). It also subscribes to adds or removes elements from a @apidoc[ORSet](akka.cluster.ddata.ORSet) (observed-remove set). It also subscribes to
changes of this. changes of this.
Scala Scala
@ -53,18 +53,18 @@ Java
For the full documentation of this feature and for new projects see @ref:[Distributed Data - Update](typed/distributed-data.md#update). For the full documentation of this feature and for new projects see @ref:[Distributed Data - Update](typed/distributed-data.md#update).
To modify and replicate a data value you send a `Replicator.Update` message to the local To modify and replicate a data value you send a @apidoc[Replicator.Update](akka.cluster.ddata.Replicator.Update) message to the local
`Replicator`. @apidoc[akka.cluster.ddata.Replicator].
The current data value for the `key` of the `Update` is passed as parameter to the `modify` The current data value for the `key` of the `Update` is passed as parameter to the @scala[@scaladoc[modify](akka.cluster.ddata.Replicator.Update#modify:Option[A]=%3EA)]@java[@javadoc[modify()](akka.cluster.ddata.Replicator.Update#modify())]
function of the `Update`. The function is supposed to return the new value of the data, which function of the `Update`. The function is supposed to return the new value of the data, which
will then be replicated according to the given consistency level. will then be replicated according to the given consistency level.
The `modify` function is called by the `Replicator` actor and must therefore be a pure The `modify` function is called by the `Replicator` actor and must therefore be a pure
function that only uses the data parameter and stable fields from enclosing scope. It must function that only uses the data parameter and stable fields from enclosing scope. It must
for example not access the sender (@scala[`sender()`]@java[`getSender()`]) reference of an enclosing actor. for example not access the sender (@scala[@scaladoc[sender()](akka.actor.Actor#sender():akka.actor.ActorRef)]@java[@javadoc[getSender()](akka.actor.AbstractActor#getSender())]) reference of an enclosing actor.
`Update` is intended to only be sent from an actor running in same local `ActorSystem` `Update` is intended to only be sent from an actor running in same local @apidoc[akka.actor.ActorSystem]
as the `Replicator`, because the `modify` function is typically not serializable. as the `Replicator`, because the `modify` function is typically not serializable.
Scala Scala
@ -73,10 +73,10 @@ Scala
Java Java
: @@snip [DistributedDataDocTest.java](/akka-docs/src/test/java/jdocs/ddata/DistributedDataDocTest.java) { #update } : @@snip [DistributedDataDocTest.java](/akka-docs/src/test/java/jdocs/ddata/DistributedDataDocTest.java) { #update }
As reply of the `Update` a `Replicator.UpdateSuccess` is sent to the sender of the As reply of the `Update` a @apidoc[Replicator.UpdateSuccess](akka.cluster.ddata.Replicator.UpdateSuccess) is sent to the sender of the
`Update` if the value was successfully replicated according to the supplied `Update` if the value was successfully replicated according to the supplied
@ref:[write consistency level](typed/distributed-data.md#write-consistency) within the supplied timeout. Otherwise a `Replicator.UpdateFailure` subclass is @ref:[write consistency level](typed/distributed-data.md#write-consistency) within the supplied timeout. Otherwise a @apidoc[Replicator.UpdateFailure](akka.cluster.ddata.Replicator.UpdateFailure) subclass is
sent back. Note that a `Replicator.UpdateTimeout` reply does not mean that the update completely failed sent back. Note that a @apidoc[Replicator.UpdateTimeout](akka.cluster.ddata.Replicator.UpdateTimeout) reply does not mean that the update completely failed
or was rolled back. It may still have been replicated to some nodes, and will eventually or was rolled back. It may still have been replicated to some nodes, and will eventually
be replicated to all nodes with the gossip protocol. be replicated to all nodes with the gossip protocol.
@ -93,15 +93,15 @@ Scala
Java Java
: @@snip [DistributedDataDocTest.java](/akka-docs/src/test/java/jdocs/ddata/DistributedDataDocTest.java) { #update-response2 } : @@snip [DistributedDataDocTest.java](/akka-docs/src/test/java/jdocs/ddata/DistributedDataDocTest.java) { #update-response2 }
You will always see your own writes. For example if you send two `Update` messages You will always see your own writes. For example if you send two @apidoc[akka.cluster.ddata.Replicator.Update] messages
changing the value of the same `key`, the `modify` function of the second message will changing the value of the same `key`, the `modify` function of the second message will
see the change that was performed by the first `Update` message. see the change that was performed by the first `Update` message.
It is possible to abort the `Update` when inspecting the state parameter that is passed in to It is possible to abort the `Update` when inspecting the state parameter that is passed in to
the `modify` function by throwing an exception. That happens before the update is performed and the `modify` function by throwing an exception. That happens before the update is performed and
a `Replicator.ModifyFailure` is sent back as reply. a @apidoc[Replicator.ModifyFailure](akka.cluster.ddata.Replicator.ModifyFailure) is sent back as reply.
In the `Update` message you can pass an optional request context, which the `Replicator` In the `Update` message you can pass an optional request context, which the @apidoc[akka.cluster.ddata.Replicator]
does not care about, but is included in the reply messages. This is a convenient does not care about, but is included in the reply messages. This is a convenient
way to pass contextual information (e.g. original sender) without having to use `ask` way to pass contextual information (e.g. original sender) without having to use `ask`
or maintain local correlation data structures. or maintain local correlation data structures.
@ -117,7 +117,7 @@ Java
For the full documentation of this feature and for new projects see @ref:[Distributed Data - Get](typed/distributed-data.md#get). For the full documentation of this feature and for new projects see @ref:[Distributed Data - Get](typed/distributed-data.md#get).
To retrieve the current value of a data you send `Replicator.Get` message to the To retrieve the current value of a data you send @apidoc[Replicator.Get](akka.cluster.ddata.Replicator.Get) message to the
`Replicator`. You supply a consistency level which has the following meaning: `Replicator`. You supply a consistency level which has the following meaning:
Scala Scala
@ -126,9 +126,9 @@ Scala
Java Java
: @@snip [DistributedDataDocTest.java](/akka-docs/src/test/java/jdocs/ddata/DistributedDataDocTest.java) { #get } : @@snip [DistributedDataDocTest.java](/akka-docs/src/test/java/jdocs/ddata/DistributedDataDocTest.java) { #get }
As reply of the `Get` a `Replicator.GetSuccess` is sent to the sender of the As reply of the `Get` a @apidoc[Replicator.GetSuccess](akka.cluster.ddata.Replicator.GetSuccess) is sent to the sender of the
`Get` if the value was successfully retrieved according to the supplied @ref:[read consistency level](typed/distributed-data.md#read-consistency) within the supplied timeout. Otherwise a `Replicator.GetFailure` is sent. `Get` if the value was successfully retrieved according to the supplied @ref:[read consistency level](typed/distributed-data.md#read-consistency) within the supplied timeout. Otherwise a @apidoc[Replicator.GetFailure](akka.cluster.ddata.Replicator.GetFailure) is sent.
If the key does not exist the reply will be `Replicator.NotFound`. If the key does not exist the reply will be @apidoc[Replicator.NotFound](akka.cluster.ddata.Replicator.NotFound).
Scala Scala
: @@snip [DistributedDataDocSpec.scala](/akka-docs/src/test/scala/docs/ddata/DistributedDataDocSpec.scala) { #get-response1 } : @@snip [DistributedDataDocSpec.scala](/akka-docs/src/test/scala/docs/ddata/DistributedDataDocSpec.scala) { #get-response1 }
@ -143,9 +143,9 @@ Scala
Java Java
: @@snip [DistributedDataDocTest.java](/akka-docs/src/test/java/jdocs/ddata/DistributedDataDocTest.java) { #get-response2 } : @@snip [DistributedDataDocTest.java](/akka-docs/src/test/java/jdocs/ddata/DistributedDataDocTest.java) { #get-response2 }
In the `Get` message you can pass an optional request context in the same way as for the In the @apidoc[akka.cluster.ddata.Replicator.Get] message you can pass an optional request context in the same way as for the
`Update` message, described above. For example the original sender can be passed and replied @apidoc[akka.cluster.ddata.Replicator.Update] message, described above. For example the original sender can be passed and replied
to after receiving and transforming `GetSuccess`. to after receiving and transforming @apidoc[akka.cluster.ddata.Replicator.GetSuccess].
Scala Scala
: @@snip [DistributedDataDocSpec.scala](/akka-docs/src/test/scala/docs/ddata/DistributedDataDocSpec.scala) { #get-request-context } : @@snip [DistributedDataDocSpec.scala](/akka-docs/src/test/scala/docs/ddata/DistributedDataDocSpec.scala) { #get-request-context }
@ -157,15 +157,15 @@ Java
For the full documentation of this feature and for new projects see @ref:[Distributed Data - Subscribe](typed/distributed-data.md#subscribe). For the full documentation of this feature and for new projects see @ref:[Distributed Data - Subscribe](typed/distributed-data.md#subscribe).
You may also register interest in change notifications by sending `Replicator.Subscribe` You may also register interest in change notifications by sending @apidoc[Replicator.Subscribe](akka.cluster.ddata.Replicator.Subscribe)
message to the `Replicator`. It will send `Replicator.Changed` messages to the registered message to the `Replicator`. It will send @apidoc[Replicator.Changed](akka.cluster.ddata.Replicator.Changed) messages to the registered
subscriber when the data for the subscribed key is updated. Subscribers will be notified subscriber when the data for the subscribed key is updated. Subscribers will be notified
periodically with the configured `notify-subscribers-interval`, and it is also possible to periodically with the configured `notify-subscribers-interval`, and it is also possible to
send an explicit `Replicator.FlushChanges` message to the `Replicator` to notify the subscribers send an explicit `Replicator.FlushChanges` message to the `Replicator` to notify the subscribers
immediately. immediately.
The subscriber is automatically removed if the subscriber is terminated. A subscriber can The subscriber is automatically removed if the subscriber is terminated. A subscriber can
also be deregistered with the `Replicator.Unsubscribe` message. also be deregistered with the @apidoc[Replicator.Unsubscribe](akka.cluster.ddata.Replicator.Unsubscribe) message.
Scala Scala
: @@snip [DistributedDataDocSpec.scala](/akka-docs/src/test/scala/docs/ddata/DistributedDataDocSpec.scala) { #subscribe } : @@snip [DistributedDataDocSpec.scala](/akka-docs/src/test/scala/docs/ddata/DistributedDataDocSpec.scala) { #subscribe }
@ -177,7 +177,7 @@ Java
For the full documentation of this feature and for new projects see @ref:[Distributed Data Consistency](typed/distributed-data.md#consistency). For the full documentation of this feature and for new projects see @ref:[Distributed Data Consistency](typed/distributed-data.md#consistency).
Here is an example of using `WriteMajority` and `ReadMajority`: Here is an example of using @apidoc[akka.cluster.ddata.Replicator.WriteMajority] and @apidoc[akka.cluster.ddata.Replicator.ReadMajority]:
Scala Scala
: @@snip [ShoppingCart.scala](/akka-docs/src/test/scala/docs/ddata/ShoppingCart.scala) { #read-write-majority } : @@snip [ShoppingCart.scala](/akka-docs/src/test/scala/docs/ddata/ShoppingCart.scala) { #read-write-majority }
@ -199,11 +199,11 @@ Scala
Java Java
: @@snip [ShoppingCart.java](/akka-docs/src/test/java/jdocs/ddata/ShoppingCart.java) { #add-item } : @@snip [ShoppingCart.java](/akka-docs/src/test/java/jdocs/ddata/ShoppingCart.java) { #add-item }
In some rare cases, when performing an `Update` it is needed to first try to fetch latest data from In some rare cases, when performing an @apidoc[akka.cluster.ddata.Replicator.Update] it is needed to first try to fetch latest data from
other nodes. That can be done by first sending a `Get` with `ReadMajority` and then continue with other nodes. That can be done by first sending a @apidoc[akka.cluster.ddata.Replicator.Get] with @apidoc[akka.cluster.ddata.Replicator.ReadMajority] and then continue with
the `Update` when the `GetSuccess`, `GetFailure` or `NotFound` reply is received. This might be the @apidoc[akka.cluster.ddata.Replicator.Update] when the @apidoc[akka.cluster.ddata.Replicator.GetSuccess], @apidoc[akka.cluster.ddata.Replicator.GetFailure] or @apidoc[akka.cluster.ddata.Replicator.NotFound] reply is received. This might be
needed when you need to base a decision on latest information or when removing entries from an `ORSet` needed when you need to base a decision on latest information or when removing entries from an @apidoc[akka.cluster.ddata.ORSet]
or `ORMap`. If an entry is added to an `ORSet` or `ORMap` from one node and removed from another or @apidoc[akka.cluster.ddata.ORMap]. If an entry is added to an `ORSet` or `ORMap` from one node and removed from another
node the entry will only be removed if the added entry is visible on the node where the removal is node the entry will only be removed if the added entry is visible on the node where the removal is
performed (hence the name observed-removed set). performed (hence the name observed-removed set).
@ -242,7 +242,7 @@ As deleted keys continue to be included in the stored data on each node as well
messages, a continuous series of updates and deletes of top-level entities will result in messages, a continuous series of updates and deletes of top-level entities will result in
growing memory usage until an ActorSystem runs out of memory. To use Akka Distributed Data growing memory usage until an ActorSystem runs out of memory. To use Akka Distributed Data
where frequent adds and removes are required, you should use a fixed number of top-level data where frequent adds and removes are required, you should use a fixed number of top-level data
types that support both updates and removals, for example `ORMap` or `ORSet`. types that support both updates and removals, for example @apidoc[akka.cluster.ddata.ORMap] or @apidoc[akka.cluster.ddata.ORSet].
@@@ @@@
@ -278,6 +278,6 @@ paper by Mark Shapiro et. al.
## Configuration ## Configuration
The `DistributedData` extension can be configured with the following properties: The @apidoc[akka.cluster.ddata.DistributedData] extension can be configured with the following properties:
@@snip [reference.conf](/akka-distributed-data/src/main/resources/reference.conf) { #distributed-data } @@snip [reference.conf](/akka-distributed-data/src/main/resources/reference.conf) { #distributed-data }