Added reporting of snapshot status PARTIAL on _status endpoint (elastic#28692)

Author: redbearsam

server/src/main/java/org/elasticsearch/action/admin/cluster/snapshots/status/TransportSnapshotsStatusAction.java

@@ -242,11 +242,11 @@ private SnapshotsStatusResponse buildResponse(SnapshotsStatusRequest request, Li
                             state = SnapshotsInProgress.State.FAILED;
                             break;
                         case SUCCESS:
-                        case PARTIAL:
-                            // Translating both PARTIAL and SUCCESS to SUCCESS for now
-                            // TODO: add the differentiation on the metadata level in the next major release
                             state = SnapshotsInProgress.State.SUCCESS;
                             break;
+                        case PARTIAL:
+                            state = SnapshotsInProgress.State.PARTIAL;
+                            break;
                         default:
                             throw new IllegalArgumentException("Unknown snapshot state " + snapshotInfo.state());
                     }

server/src/main/java/org/elasticsearch/cluster/SnapshotsInProgress.java

@@ -235,6 +235,21 @@ public static boolean completed(ObjectContainer<ShardSnapshotStatus> shards) {
         return true;
     }
 
+    /**
+     * Checks if all shards in the list have completed successfully
+     *
+     * @param shards list of shard statuses
+     * @return true if any shard has failed, false otherwise
+     */
+    public static boolean partiallyCompleted(ObjectContainer<ShardSnapshotStatus> shards) {
+        for (ObjectCursor<ShardSnapshotStatus> status : shards) {
+            if (status.value.state().failed() == true) {
+                return true;
+            }
+        }
+        return false;
+    }
+
 
     public static class ShardSnapshotStatus {
         private final State state;
@@ -316,7 +331,8 @@ public enum State {
         FAILED((byte) 3, true, true),
         ABORTED((byte) 4, false, true),
         MISSING((byte) 5, true, true),
-        WAITING((byte) 6, false, false);
+        WAITING((byte) 6, false, false),
+        PARTIAL((byte) 7, false, false);
 
         private byte value;
 
@@ -358,6 +374,8 @@ public static State fromValue(byte value) {
                     return MISSING;
                 case 6:
                     return WAITING;
+                case 7:
+                    return PARTIAL;
                 default:
                     throw new IllegalArgumentException("No snapshot state for value [" + value + "]");
             }

server/src/main/java/org/elasticsearch/snapshots/SnapshotShardsService.java

@@ -84,6 +84,7 @@
 import static java.util.Collections.emptyMap;
 import static java.util.Collections.unmodifiableMap;
 import static org.elasticsearch.cluster.SnapshotsInProgress.completed;
+import static org.elasticsearch.cluster.SnapshotsInProgress.partiallyCompleted;
 import static org.elasticsearch.transport.EmptyTransportResponseHandler.INSTANCE_SAME;
 
 /**
@@ -588,9 +589,14 @@ public ClusterTasksResult<UpdateIndexShardSnapshotStatusRequest> execute(Cluster
                         if (completed(shards.values()) == false) {
                             entries.add(new SnapshotsInProgress.Entry(entry, shards.build()));
                         } else {
-                            // Snapshot is finished - mark it as done
-                            // TODO: Add PARTIAL_SUCCESS status?
-                            SnapshotsInProgress.Entry updatedEntry = new SnapshotsInProgress.Entry(entry, State.SUCCESS, shards.build());
+                            SnapshotsInProgress.Entry updatedEntry;
+                            if (partiallyCompleted(shards.values()) == true) {
+                                // Snapshot partially completed
+                                updatedEntry = new SnapshotsInProgress.Entry(entry, State.PARTIAL, shards.build());
+                            } else {
+                                // Snapshot is finished - mark it as done
+                                updatedEntry = new SnapshotsInProgress.Entry(entry, State.SUCCESS, shards.build());
+                            }
                             entries.add(updatedEntry);
                             // Finalize snapshot in the repository
                             snapshotsService.endSnapshot(updatedEntry);