RATIS-2045. SnapshotInstallationHandler doesn't notify follower when snapshotIndex is -1 and firstAvailableLogIndex is 0 (#1053)
diff --git a/ratis-server/src/main/java/org/apache/ratis/server/impl/SnapshotInstallationHandler.java b/ratis-server/src/main/java/org/apache/ratis/server/impl/SnapshotInstallationHandler.java
index 3e5ac2b..f03e2d8 100644
--- a/ratis-server/src/main/java/org/apache/ratis/server/impl/SnapshotInstallationHandler.java
+++ b/ratis-server/src/main/java/org/apache/ratis/server/impl/SnapshotInstallationHandler.java
@@ -221,7 +221,8 @@
// Check if snapshot index is already at par or ahead of the first
// available log index of the Leader.
final long snapshotIndex = state.getLog().getSnapshotIndex();
- if (snapshotIndex + 1 >= firstAvailableLogIndex && firstAvailableLogIndex > INVALID_LOG_INDEX) {
+ if (snapshotIndex != INVALID_LOG_INDEX && snapshotIndex + 1 >= firstAvailableLogIndex &&
+ firstAvailableLogIndex > INVALID_LOG_INDEX) {
// State Machine has already installed the snapshot. Return the
// latest snapshot index to the Leader.
