Merge pull request #16530 from ywelsch/fix/reuse-alloc-id

Reuse existing allocation id for primary shard allocation

Author: Yannick Welsch

core/src/main/java/org/elasticsearch/cluster/routing/AllocationId.java

@@ -96,6 +96,13 @@ public static AllocationId newInitializing() {
         return new AllocationId(Strings.randomBase64UUID(), null);
     }
 
+    /**
+     * Creates a new allocation id for initializing allocation based on an existing id.
+     */
+    public static AllocationId newInitializing(String existingAllocationId) {
+        return new AllocationId(existingAllocationId, null);
+    }
+
     /**
      * Creates a new allocation id for the target initializing shard that is the result
      * of a relocation.

core/src/main/java/org/elasticsearch/cluster/routing/RoutingNodes.java

@@ -26,6 +26,7 @@
 import org.elasticsearch.cluster.block.ClusterBlocks;
 import org.elasticsearch.cluster.metadata.MetaData;
 import org.elasticsearch.cluster.node.DiscoveryNode;
+import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.Randomness;
 import org.elasticsearch.common.collect.ImmutableOpenMap;
 import org.elasticsearch.index.Index;
@@ -420,11 +421,13 @@ public String prettyPrint() {
 
     /**
      * Moves a shard from unassigned to initialize state
+     *
+     * @param existingAllocationId allocation id to use. If null, a fresh allocation id is generated.
      */
-    public void initialize(ShardRouting shard, String nodeId, long expectedSize) {
+    public void initialize(ShardRouting shard, String nodeId, @Nullable String existingAllocationId, long expectedSize) {
         ensureMutable();
         assert shard.unassigned() : shard;
-        shard.initialize(nodeId, expectedSize);
+        shard.initialize(nodeId, existingAllocationId, expectedSize);
         node(nodeId).add(shard);
         inactiveShardCount++;
         if (shard.primary()) {
@@ -692,10 +695,12 @@ public ShardRouting next() {
 
             /**
              * Initializes the current unassigned shard and moves it from the unassigned list.
+             *
+             * @param existingAllocationId allocation id to use. If null, a fresh allocation id is generated.
              */
-            public void initialize(String nodeId, long expectedShardSize) {
+            public void initialize(String nodeId, @Nullable String existingAllocationId, long expectedShardSize) {
                 innerRemove();
-                nodes.initialize(new ShardRouting(current), nodeId, expectedShardSize);
+                nodes.initialize(new ShardRouting(current), nodeId, existingAllocationId, expectedShardSize);
             }
 
             /**
@@ -711,7 +716,7 @@ public void removeAndIgnore() {
 
             /**
              * Unsupported operation, just there for the interface. Use {@link #removeAndIgnore()} or
-             * {@link #initialize(String, long)}.
+             * {@link #initialize(String, String, long)}.
              */
             @Override
             public void remove() {

core/src/main/java/org/elasticsearch/cluster/routing/ShardRouting.java

@@ -410,14 +410,20 @@ void moveToUnassigned(UnassignedInfo unassignedInfo) {
 
     /**
      * Initializes an unassigned shard on a node.
+     *
+     * @param existingAllocationId allocation id to use. If null, a fresh allocation id is generated.
      */
-    void initialize(String nodeId, long expectedShardSize) {
+    void initialize(String nodeId, @Nullable String existingAllocationId, long expectedShardSize) {
         ensureNotFrozen();
         assert state == ShardRoutingState.UNASSIGNED : this;
         assert relocatingNodeId == null : this;
         state = ShardRoutingState.INITIALIZING;
         currentNodeId = nodeId;
-        allocationId = AllocationId.newInitializing();
+        if (existingAllocationId == null) {
+            allocationId = AllocationId.newInitializing();
+        } else {
+            allocationId = AllocationId.newInitializing(existingAllocationId);
+        }
         this.expectedShardSize = expectedShardSize;
     }
 

core/src/main/java/org/elasticsearch/cluster/routing/allocation/allocator/BalancedShardsAllocator.java

@@ -702,7 +702,7 @@ private boolean allocateUnassigned(RoutingNodes.UnassignedShards unassigned) {
                             if (logger.isTraceEnabled()) {
                                 logger.trace("Assigned shard [{}] to [{}]", shard, minNode.getNodeId());
                             }
-                            routingNodes.initialize(shard, minNode.getNodeId(), allocation.clusterInfo().getShardSize(shard, ShardRouting.UNAVAILABLE_EXPECTED_SHARD_SIZE));
+                            routingNodes.initialize(shard, minNode.getNodeId(), null, allocation.clusterInfo().getShardSize(shard, ShardRouting.UNAVAILABLE_EXPECTED_SHARD_SIZE));
                             changed = true;
                             continue; // don't add to ignoreUnassigned
                         } else {
@@ -790,7 +790,7 @@ private boolean tryRelocateShard(ModelNode minNode, ModelNode maxNode, String id
                             routingNodes.relocate(candidate, minNode.getNodeId(), allocation.clusterInfo().getShardSize(candidate, ShardRouting.UNAVAILABLE_EXPECTED_SHARD_SIZE));
 
                         } else {
-                            routingNodes.initialize(candidate, minNode.getNodeId(), allocation.clusterInfo().getShardSize(candidate, ShardRouting.UNAVAILABLE_EXPECTED_SHARD_SIZE));
+                            routingNodes.initialize(candidate, minNode.getNodeId(), null, allocation.clusterInfo().getShardSize(candidate, ShardRouting.UNAVAILABLE_EXPECTED_SHARD_SIZE));
                         }
                         return true;
 

core/src/main/java/org/elasticsearch/cluster/routing/allocation/command/AbstractAllocateAllocationCommand.java

@@ -242,7 +242,7 @@ protected void initializeUnassignedShard(RoutingAllocation allocation, RoutingNo
             if (shardRoutingChanges != null) {
                 shardRoutingChanges.accept(unassigned);
             }
-            it.initialize(routingNode.nodeId(), allocation.clusterInfo().getShardSize(unassigned, ShardRouting.UNAVAILABLE_EXPECTED_SHARD_SIZE));
+            it.initialize(routingNode.nodeId(), null, allocation.clusterInfo().getShardSize(unassigned, ShardRouting.UNAVAILABLE_EXPECTED_SHARD_SIZE));
             return;
         }
         assert false : "shard to initialize not found in list of unassigned shards";