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!cls #16422 Rename shardResolver and idExtractor

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Patrik Nordwall 2015-06-09 16:02:19 +02:00
parent 70024298ac
commit 5fab2b4521
8 changed files with 120 additions and 100 deletions
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15
akka-docs/rst/scala/cluster-sharding.rst
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@ -57,7 +57,7 @@ The message sent to the entity actor is what ``entityMessage`` returns and that
if needed.
A shard is a group of entities that will be managed together. The grouping is defined by the
``shardResolver`` function shown above. For a specific entity identifier the shard identifier must always
``extractShardId`` function shown above. For a specific entity identifier the shard identifier must always
be the same. Otherwise the entity actor might accidentally be started in several places at the same time.
Creating a good sharding algorithm is an interesting challenge in itself. Try to produce a uniform distribution,
@ -68,8 +68,9 @@ overhead, and increased latency because the coordinator is involved in the routi
shard. The sharding algorithm must be the same on all nodes in a running cluster. It can be changed after stopping
all nodes in the cluster.
A simple sharding algorithm that works fine in most cases is to take the ``hashCode`` of the entity identifier modulo
number of shards.
A simple sharding algorithm that works fine in most cases is to take the absolute value of the ``hashCode`` of
the entity identifier modulo number of shards. As a convenience this is provided by the
``ShardRegion.HashCodeMessageExtractor``.
Messages to the entities are always sent via the local ``ShardRegion``. The ``ShardRegion`` actor reference for a
named entity type is returned by ``ClusterSharding.start`` and it can also be retrieved with ``ClusterSharding.shardRegion``.
@ -98,7 +99,7 @@ method. ``ClusterSharding.start`` gives you the reference which you can pass alo
.. includecode:: ../../../akka-cluster-sharding/src/multi-jvm/scala/akka/cluster/sharding/ClusterShardingSpec.scala#counter-start
The ``idExtractor`` and ``shardResolver`` are two application specific functions to extract the entity
The ``extractEntityId`` and ``extractShardId`` are two application specific functions to extract the entity
identifier and the shard identifier from incoming messages.
.. includecode:: ../../../akka-cluster-sharding/src/multi-jvm/scala/akka/cluster/sharding/ClusterShardingSpec.scala#counter-extractor
@ -109,12 +110,12 @@ This example illustrates two different ways to define the entity identifier in t
* The ``EntityEnvelope`` holds the identifier, and the actual message that is
sent to the entity actor is wrapped in the envelope.
Note how these two messages types are handled in the ``idExtractor`` function shown above.
The message sent to the entity actor is the second part of the tuple return by the ``idExtractor`` and that makes it
Note how these two messages types are handled in the ``extractEntityId`` function shown above.
The message sent to the entity actor is the second part of the tuple return by the ``extractEntityId`` and that makes it
possible to unwrap envelopes if needed.
A shard is a group of entities that will be managed together. The grouping is defined by the
``shardResolver`` function shown above. For a specific entity identifier the shard identifier must always
``extractShardId`` function shown above. For a specific entity identifier the shard identifier must always
be the same.
Creating a good sharding algorithm is an interesting challenge in itself. Try to produce a uniform distribution,