+per #16541 initial version of the Persistence Query module

2015-06-08 12:26:19 +02:00 · 2015-06-08 12:26:19 +02:00 · f849793f36
commit f849793f36
parent 09aff42d40
23 changed files with 1051 additions and 14 deletions
--- a/akka-persistence-query/src/main/scala/akka/persistence/query/PersistenceQuery.scala
+++ b/akka-persistence-query/src/main/scala/akka/persistence/query/PersistenceQuery.scala
@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2009-2015 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.persistence.query
+
+import java.util.concurrent.atomic.AtomicReference
+
+import akka.actor._
+import akka.event.Logging
+
+import scala.annotation.tailrec
+import scala.util.Failure
+
+/**
+ * Persistence extension for queries.
+ */
+object PersistenceQuery extends ExtensionId[PersistenceQuery] with ExtensionIdProvider {
+  /**
+   * Java API.
+   */
+  override def get(system: ActorSystem): PersistenceQuery = super.get(system)
+
+  def createExtension(system: ExtendedActorSystem): PersistenceQuery = new PersistenceQuery(system)
+
+  def lookup() = PersistenceQuery
+
+  /** INTERNAL API. */
+  private[persistence] case class PluginHolder(plugin: scaladsl.ReadJournal) extends Extension
+
+}
+
+class PersistenceQuery(system: ExtendedActorSystem) extends Extension {
+  import PersistenceQuery._
+
+  private val log = Logging(system, getClass)
+
+  /** Discovered query plugins. */
+  private val readJournalPluginExtensionIds = new AtomicReference[Map[String, ExtensionId[PluginHolder]]](Map.empty)
+
+  /**
+   * Returns the [[akka.persistence.query.scaladsl.ReadJournal]] specified by the given read journal configuration entry.
+   */
+  @tailrec final def readJournalFor(readJournalPluginId: String): scaladsl.ReadJournal = {
+    val configPath = readJournalPluginId
+    val extensionIdMap = readJournalPluginExtensionIds.get
+    extensionIdMap.get(configPath) match {
+      case Some(extensionId) ⇒
+        extensionId(system).plugin
+      case None ⇒
+        val extensionId = new ExtensionId[PluginHolder] {
+          override def createExtension(system: ExtendedActorSystem): PluginHolder =
+            PluginHolder(createPlugin(configPath))
+        }
+        readJournalPluginExtensionIds.compareAndSet(extensionIdMap, extensionIdMap.updated(configPath, extensionId))
+        readJournalFor(readJournalPluginId) // Recursive invocation.
+    }
+  }
+
+  /**
+   * Java API
+   *
+   * Returns the [[akka.persistence.query.javadsl.ReadJournal]] specified by the given read journal configuration entry.
+   */
+  final def getReadJournalFor(readJournalPluginId: String): javadsl.ReadJournal =
+    new javadsl.ReadJournal(readJournalFor(readJournalPluginId))
+
+  private def createPlugin(configPath: String): scaladsl.ReadJournal = {
+    require(!isEmpty(configPath) && system.settings.config.hasPath(configPath),
+      s"'reference.conf' is missing persistence read journal plugin config path: '${configPath}'")
+    val pluginActorName = configPath
+    val pluginConfig = system.settings.config.getConfig(configPath)
+    val pluginClassName = pluginConfig.getString("class")
+    log.debug(s"Create plugin: ${pluginActorName} ${pluginClassName}")
+    val pluginClass = system.dynamicAccess.getClassFor[AnyRef](pluginClassName).get
+
+    val plugin = system.dynamicAccess.createInstanceFor[scaladsl.ReadJournal](pluginClass, (classOf[ExtendedActorSystem], system) :: Nil)
+      .orElse(system.dynamicAccess.createInstanceFor[scaladsl.ReadJournal](pluginClass, Nil))
+      .recoverWith {
+        case ex: Exception ⇒ Failure.apply(new IllegalArgumentException(s"Unable to create read journal plugin instance for path [$configPath], class [$pluginClassName]!", ex))
+      }
+
+    // TODO possibly apply event adapters here
+    plugin.get
+  }
+
+  /** Check for default or missing identity. */
+  private def isEmpty(text: String) = text == null || text.length == 0
+}
+