!per #3717 Deletion API for snapshots and persistent messages

- single and bulk deletion of messages
- single and bulk deletion of snapshots
- run journal and snapshot store as system actors
- rename physical parameter in delete methods to permanent
- StashSupport.prepend docs and implementation enhancements

akka-docs/rst/java/code/docs/persistence/PersistenceDocTest.java

@@ -101,7 +101,7 @@ public class PersistenceDocTest {
             @Override
             public void preRestart(Throwable reason, Option<Object> message) {
                 if (message.isDefined() && message.get() instanceof Persistent) {
-                    deleteMessage((Persistent) message.get());
+                    deleteMessage(((Persistent) message.get()).sequenceNr());
                 }
                 super.preRestart(reason, message);
             }

akka-docs/rst/java/code/docs/persistence/PersistencePluginDocTest.java

@@ -32,6 +32,10 @@ public class PersistencePluginDocTest {
         @Override
         public void doDelete(SnapshotMetadata metadata) throws Exception {
         }
+
+        @Override
+        public void doDelete(String processorId, SnapshotSelectionCriteria criteria) throws Exception {
+        }
     }
 
     class MyAsyncJournal extends AsyncWriteJournal {
@@ -51,7 +55,7 @@ public class PersistencePluginDocTest {
         }
 
         @Override
-        public Future<Void> doDeleteAsync(String processorId, long sequenceNr, boolean physical) {
+        public Future<Void> doDeleteAsync(String processorId, long fromSequenceNr, long toSequenceNr, boolean permanent) {
             return null;
         }
 

akka-docs/rst/java/persistence.rst

@@ -143,11 +143,12 @@ a replay of that message during recovery it can be deleted.
 Message deletion
 ----------------
 
-A processor can delete messages by calling the ``delete`` method with a ``Persistent`` message object or a
-sequence number as argument. An optional ``physical`` parameter specifies whether the message shall be
-physically deleted from the journal or only marked as deleted. In both cases, the message won't be replayed.
-Later extensions to Akka persistence will allow to replay messages that have been marked as deleted which can
-be useful for debugging purposes, for example.
+A processor can delete a single message by calling the ``deleteMessage`` method with the sequence number of
+that message as argument. An optional ``permanent`` parameter specifies whether the message shall be permanently
+deleted from the journal or only marked as deleted. In both cases, the message won't be replayed. Later extensions
+to Akka persistence will allow to replay messages that have been marked as deleted which can be useful for debugging
+purposes, for example. To delete all messages (journaled by a single processor) up to a specified sequence number,
+processors can call the ``deleteMessages`` method.
 
 Identifiers
 -----------
@@ -315,6 +316,13 @@ If not specified, they default to ``SnapshotSelectionCriteria.latest()`` which s
 To disable snapshot-based recovery, applications should use ``SnapshotSelectionCriteria.none()``. A recovery where no
 saved snapshot matches the specified ``SnapshotSelectionCriteria`` will replay all journaled messages.
 
+Snapshot deletion
+-----------------
+
+A processor can delete a single snapshot by calling the ``deleteSnapshot`` method with the sequence number and the
+timestamp of the snapshot as argument. To bulk-delete snapshots that match a specified ``SnapshotSelectionCriteria``
+argument, processors can call the ``deleteSnapshots`` method.
+
 .. _event-sourcing-java:
 
 Event sourcing