Merge pull request #18290 from akka/wip-18288-leveldb-query-doc-patriknw

=per #18288 Add docs of leveldb queries

akka-docs/rst/scala/code/docs/persistence/query/LeveldbPersistenceQueryDocSpec.scala

@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2015 Typesafe Inc. <http://www.typesafe.com>
+ */
+package docs.persistence.query
+
+import akka.persistence.journal.{ EventAdapter, EventSeq }
+import akka.testkit.AkkaSpec
+import akka.persistence.query.PersistenceQuery
+import akka.persistence.query.journal.leveldb.LeveldbReadJournal
+import akka.persistence.journal.leveldb.Tagged
+import akka.persistence.query.EventsByPersistenceId
+import akka.stream.scaladsl.Source
+import akka.persistence.query.EventEnvelope
+import akka.stream.ActorMaterializer
+import akka.persistence.query.AllPersistenceIds
+import akka.persistence.query.EventsByTag
+import scala.annotation.tailrec
+
+object LeveldbPersistenceQueryDocSpec {
+  //#tagger
+  import akka.persistence.journal.WriteEventAdapter
+  import akka.persistence.journal.leveldb.Tagged
+
+  class ColorTagger extends WriteEventAdapter {
+    val colors = Set("green", "black", "blue")
+    override def toJournal(event: Any): Any = event match {
+      case s: String ⇒
+        var tags = colors.foldLeft(Set.empty[String]) { (acc, c) ⇒
+          if (s.contains(c)) acc + c else acc
+        }
+        if (tags.isEmpty) event
+        else Tagged(event, tags)
+      case _ ⇒ event
+    }
+
+    override def manifest(event: Any): String = ""
+  }
+  //#tagger
+}
+
+class LeveldbPersistenceQueryDocSpec(config: String) extends AkkaSpec(config) {
+
+  def this() = this("")
+
+  "LeveldbPersistentQuery" must {
+    "demonstrate how get ReadJournal" in {
+      //#get-read-journal
+      import akka.persistence.query.PersistenceQuery
+      import akka.persistence.query.journal.leveldb.LeveldbReadJournal
+
+      val queries = PersistenceQuery(system).readJournalFor(LeveldbReadJournal.Identifier)
+      //#get-read-journal
+    }
+
+    "demonstrate EventsByPersistenceId" in {
+      //#EventsByPersistenceId
+      import akka.persistence.query.EventsByPersistenceId
+      implicit val mat = ActorMaterializer()(system)
+      val queries = PersistenceQuery(system).readJournalFor(LeveldbReadJournal.Identifier)
+
+      val src: Source[EventEnvelope, Unit] =
+        queries.query(EventsByPersistenceId("some-persistence-id", 0L, Long.MaxValue))
+
+      val events: Source[Any, Unit] = src.map(_.event)
+      //#EventsByPersistenceId
+    }
+
+    "demonstrate AllPersistenceIds" in {
+      //#AllPersistenceIds
+      import akka.persistence.query.AllPersistenceIds
+      implicit val mat = ActorMaterializer()(system)
+      val queries = PersistenceQuery(system).readJournalFor(LeveldbReadJournal.Identifier)
+
+      val src: Source[String, Unit] = queries.query(AllPersistenceIds)
+      //#AllPersistenceIds
+    }
+
+    "demonstrate EventsByTag" in {
+      //#EventsByTag
+      import akka.persistence.query.EventsByTag
+      implicit val mat = ActorMaterializer()(system)
+      val queries = PersistenceQuery(system).readJournalFor(LeveldbReadJournal.Identifier)
+
+      val src: Source[EventEnvelope, Unit] =
+        queries.query(EventsByTag(tag = "green", offset = 0L))
+      //#EventsByTag
+    }
+
+  }
+
+}