Lost commit index when a snapshot is captured

When we have no journals and a snapshot is recovered and
immediately captured again, if there was no movement in the
datastore we loose the lastIndex and term from the previous snapshot.
We can safely reuse these from the previous snapshot when no
entry is present in the ReplicatedLog.

Change-Id: Iaeb71edc7ec865bec18dbcb436af76e592eea69d
Signed-off-by: Tomas Cere <tomas.cere@pantheon.tech>
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
(cherry picked from commit aad11d48fcace37e3365388f387e16fa67257a25)

diff --git a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/SnapshotManager.java b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/SnapshotManager.java
index 02269a289bcbef6723d3fb78e34591a1e34328f5..6411d858b99c3a6a4bb489c5c3190878f730f29d 100644 (file)
--- a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/SnapshotManager.java
+++ b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/SnapshotManager.java
@@ -170,14 +170,19 @@ public class SnapshotManager implements SnapshotState {
 
         List<ReplicatedLogEntry> unAppliedEntries = context.getReplicatedLog().getFrom(lastAppliedIndex + 1);
 
-        long lastLogEntryIndex = lastAppliedIndex;
-        long lastLogEntryTerm = lastAppliedTerm;
-        if (lastLogEntry != null) {
+        final long lastLogEntryIndex;
+        final long lastLogEntryTerm;
+        if (lastLogEntry == null) {
+            // When we don't have journal present, for example two captureSnapshots executed right after another with no
+            // new journal we still want to preserve the index and term in the snapshot.
+            lastAppliedIndex = lastLogEntryIndex = context.getReplicatedLog().getSnapshotIndex();
+            lastAppliedTerm = lastLogEntryTerm = context.getReplicatedLog().getSnapshotTerm();
+
+            log.debug("{}: Capturing Snapshot : lastLogEntry is null. Using snapshot values lastAppliedIndex {} and "
+                    + "lastAppliedTerm {} instead.", persistenceId(), lastAppliedIndex, lastAppliedTerm);
+        } else {
             lastLogEntryIndex = lastLogEntry.getIndex();
             lastLogEntryTerm = lastLogEntry.getTerm();
-        } else {
-            log.debug("{}: Capturing Snapshot : lastLogEntry is null. Using lastAppliedIndex {} and "
-                    + "lastAppliedTerm {} instead.", persistenceId(), lastAppliedIndex, lastAppliedTerm);
         }
 
         return new CaptureSnapshot(lastLogEntryIndex, lastLogEntryTerm, lastAppliedIndex, lastAppliedTerm,

diff --git a/opendaylight/md-sal/sal-akka-raft/src/test/java/org/opendaylight/controller/cluster/raft/SnapshotManagerTest.java b/opendaylight/md-sal/sal-akka-raft/src/test/java/org/opendaylight/controller/cluster/raft/SnapshotManagerTest.java
index 14b94d9fb752285b47e156976ec83a860466ea31..88e9a613caa576ce1a803f7b2141c7f2041c0c9f 100644 (file)
--- a/opendaylight/md-sal/sal-akka-raft/src/test/java/org/opendaylight/controller/cluster/raft/SnapshotManagerTest.java
+++ b/opendaylight/md-sal/sal-akka-raft/src/test/java/org/opendaylight/controller/cluster/raft/SnapshotManagerTest.java
@@ -194,12 +194,12 @@ public class SnapshotManagerTest extends AbstractActorTest {
         CaptureSnapshot captureSnapshot = snapshotManager.getCaptureSnapshot();
 
         // LastIndex and LastTerm are picked up from the lastLogEntry
-        assertEquals(-1L, captureSnapshot.getLastIndex());
-        assertEquals(-1L, captureSnapshot.getLastTerm());
+        assertEquals(0, captureSnapshot.getLastIndex());
+        assertEquals(0, captureSnapshot.getLastTerm());
 
         // Since the actor does not have any followers (no peer addresses) lastApplied will be from lastLogEntry
-        assertEquals(-1L, captureSnapshot.getLastAppliedIndex());
-        assertEquals(-1L, captureSnapshot.getLastAppliedTerm());
+        assertEquals(0, captureSnapshot.getLastAppliedIndex());
+        assertEquals(0, captureSnapshot.getLastAppliedTerm());
 
         //
         assertEquals(-1L, captureSnapshot.getReplicatedToAllIndex());