[Weighted Shard Routing] Fail open requests on search shard failures #5072
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,156 @@ | ||
| /* | ||
| * SPDX-License-Identifier: Apache-2.0 | ||
| * | ||
| * The OpenSearch Contributors require contributions made to | ||
| * this file be licensed under the Apache-2.0 license or a | ||
| * compatible open source license. | ||
| */ | ||
|
|
||
| package org.opensearch.cluster.routing; | ||
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||
| import org.apache.logging.log4j.LogManager; | ||
| import org.apache.logging.log4j.Logger; | ||
| import org.apache.logging.log4j.message.ParameterizedMessage; | ||
| import org.opensearch.OpenSearchException; | ||
| import org.opensearch.action.search.SearchShardIterator; | ||
| import org.opensearch.cluster.ClusterState; | ||
| import org.opensearch.cluster.metadata.WeightedRoutingMetadata; | ||
| import org.opensearch.cluster.node.DiscoveryNode; | ||
| import org.opensearch.index.shard.ShardId; | ||
| import org.opensearch.rest.RestStatus; | ||
| import org.opensearch.search.SearchShardTarget; | ||
|
|
||
| import java.util.List; | ||
| import java.util.Map; | ||
| import java.util.stream.Stream; | ||
|
|
||
| /** | ||
| * This class contains logic to find next shard to retry search request in case of failure from other shard copy. | ||
| * This decides if retryable shard search requests can be tried on shard copies present in data | ||
| * nodes whose attribute value weight for weighted shard routing is set to zero. | ||
| */ | ||
|
|
||
| public enum FailAwareWeightedRouting { | ||
| INSTANCE; | ||
|
|
||
| private static final Logger logger = LogManager.getLogger(FailAwareWeightedRouting.class); | ||
|
|
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| private final static List<RestStatus> internalErrorRestStatusList = List.of( | ||
| RestStatus.INTERNAL_SERVER_ERROR, | ||
| RestStatus.BAD_GATEWAY, | ||
| RestStatus.SERVICE_UNAVAILABLE, | ||
| RestStatus.GATEWAY_TIMEOUT | ||
| ); | ||
|
|
||
| public static FailAwareWeightedRouting getInstance() { | ||
| return INSTANCE; | ||
|
|
||
| } | ||
|
|
||
| /** | ||
| * * | ||
| * @return true if exception is due to cluster availability issues | ||
| */ | ||
| private boolean isInternalFailure(Exception exception) { | ||
| if (exception instanceof OpenSearchException) { | ||
| // checking for 5xx failures | ||
| return internalErrorRestStatusList.contains(((OpenSearchException) exception).status()); | ||
| } | ||
| return false; | ||
| } | ||
|
|
||
| /** | ||
| * This function checks if the shard is present in data node with weighted routing weight set to 0, | ||
| * In such cases we fail open, if shard search request for the shard from other shard copies fail with non | ||
| * retryable exception. | ||
| * | ||
| * @param nodeId the node with the shard copy | ||
| * @return true if the node has attribute value with shard routing weight set to zero, else false | ||
| */ | ||
| private boolean isWeighedAway(String nodeId, ClusterState clusterState) { | ||
| DiscoveryNode node = clusterState.nodes().get(nodeId); | ||
| WeightedRoutingMetadata weightedRoutingMetadata = clusterState.metadata().weightedRoutingMetadata(); | ||
| if (weightedRoutingMetadata != null) { | ||
| WeightedRouting weightedRouting = weightedRoutingMetadata.getWeightedRouting(); | ||
| if (weightedRouting != null && weightedRouting.isSet()) { | ||
| // Fetch weighted routing attributes with weight set as zero | ||
| Stream<String> keys = weightedRouting.weights() | ||
| .entrySet() | ||
| .stream() | ||
| .filter(entry -> entry.getValue().intValue() == WeightedRoutingMetadata.WEIGHED_AWAY_WEIGHT) | ||
| .map(Map.Entry::getKey); | ||
|
|
||
| for (Object key : keys.toArray()) { | ||
| if (node.getAttributes().get(weightedRouting.attributeName()).equals(key.toString())) { | ||
| return true; | ||
| } | ||
| } | ||
| } | ||
| } | ||
| return false; | ||
| } | ||
|
|
||
| /** | ||
| * This function returns next shard copy to retry search request in case of failure from previous copy returned | ||
| * by the iterator. It has the logic to fail open ie request shard copies present in nodes with weighted shard | ||
| * routing weight set to zero | ||
| * | ||
| * @param shardIt Shard Iterator containing order in which shard copies for a shard need to be requested | ||
| * @return the next shard copy | ||
| */ | ||
| public SearchShardTarget findNext(final SearchShardIterator shardIt, ClusterState clusterState, Exception exception) { | ||
| SearchShardTarget next = shardIt.nextOrNull(); | ||
| while (next != null && isWeighedAway(next.getNodeId(), clusterState)) { | ||
| SearchShardTarget nextShard = next; | ||
| if (canFailOpen(nextShard.getShardId(), exception, clusterState)) { | ||
| logger.info( | ||
| () -> new ParameterizedMessage("{}: Fail open executed due to exception {}", nextShard.getShardId(), exception) | ||
| ); | ||
| break; | ||
| } | ||
| next = shardIt.nextOrNull(); | ||
| } | ||
| return next; | ||
| } | ||
|
|
||
| /** | ||
| * This function returns next shard copy to retry search request in case of failure from previous copy returned | ||
| * by the iterator. It has the logic to fail open ie request shard copies present in nodes with weighted shard | ||
| * routing weight set to zero | ||
| * | ||
| * @param shardsIt Shard Iterator containing order in which shard copies for a shard need to be requested | ||
| * @return the next shard copy | ||
| */ | ||
| public ShardRouting findNext(final ShardsIterator shardsIt, ClusterState clusterState, Exception exception) { | ||
| ShardRouting next = shardsIt.nextOrNull(); | ||
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| while (next != null && isWeighedAway(next.currentNodeId(), clusterState)) { | ||
| ShardRouting nextShard = next; | ||
| if (canFailOpen(nextShard.shardId(), exception, clusterState)) { | ||
| logger.info(() -> new ParameterizedMessage("{}: Fail open executed due to exception {}", nextShard.shardId(), exception)); | ||
|
There was a problem hiding this comment. nitL incorrect usage of logger with exception |
||
| break; | ||
| } | ||
| next = shardsIt.nextOrNull(); | ||
| } | ||
| return next; | ||
| } | ||
|
|
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| /** | ||
| * * | ||
| * @return true if can fail open ie request shard copies present in nodes with weighted shard | ||
| * routing weight set to zero | ||
| */ | ||
| private boolean canFailOpen(ShardId shardId, Exception exception, ClusterState clusterState) { | ||
| return isInternalFailure(exception) || hasInActiveShardCopies(clusterState, shardId); | ||
| } | ||
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| private boolean hasInActiveShardCopies(ClusterState clusterState, ShardId shardId) { | ||
| List<ShardRouting> shards = clusterState.routingTable().shardRoutingTable(shardId).shards(); | ||
| for (ShardRouting shardRouting : shards) { | ||
| if (!shardRouting.active()) { | ||
| return true; | ||
| } | ||
| } | ||
| return false; | ||
| } | ||
| } | ||
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I don't think this is the most apt way to create singletons, you could achieve it by a static property