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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you under
* the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.elasticsearch.gateway;
import com.carrotsearch.hppc.ObjectLongHashMap;
import com.carrotsearch.hppc.ObjectLongMap;
import com.carrotsearch.hppc.cursors.ObjectCursor;
import com.carrotsearch.hppc.cursors.ObjectLongCursor;
import org.elasticsearch.cluster.ClusterChangedEvent;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.routing.RoutingNode;
import org.elasticsearch.cluster.routing.RoutingNodes;
import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.cluster.routing.UnassignedInfo;
import org.elasticsearch.cluster.routing.allocation.RoutingAllocation;
import org.elasticsearch.cluster.routing.allocation.decider.Decision;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.common.component.AbstractComponent;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.unit.ByteSizeValue;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.index.store.StoreFileMetaData;
import org.elasticsearch.indices.store.TransportNodesListShardStoreMetaData;
import java.util.Map;
/**
*/
public abstract class ReplicaShardAllocator extends AbstractComponent {
public ReplicaShardAllocator(Settings settings) {
super(settings);
}
/**
* Process existing recoveries of replicas and see if we need to cancel them if we find a better
* match. Today, a better match is one that has full sync id match compared to not having one in
* the previous recovery.
*/
public boolean processExistingRecoveries(RoutingAllocation allocation) {
boolean changed = false;
for (RoutingNodes.RoutingNodesIterator nodes = allocation.routingNodes().nodes(); nodes.hasNext(); ) {
nodes.next();
for (RoutingNodes.RoutingNodeIterator it = nodes.nodeShards(); it.hasNext(); ) {
ShardRouting shard = it.next();
if (shard.primary() == true) {
continue;
}
if (shard.initializing() == false) {
continue;
}
if (shard.relocatingNodeId() != null) {
continue;
}
// if we are allocating a replica because of index creation, no need to go and find a copy, there isn't one...
if (shard.allocatedPostIndexCreate() == false) {
continue;
}
AsyncShardFetch.FetchResult shardStores = fetchData(shard, allocation);
if (shardStores.hasData() == false) {
logger.trace("{}: fetching new stores for initializing shard", shard);
continue; // still fetching
}
ShardRouting primaryShard = allocation.routingNodes().activePrimary(shard);
assert primaryShard != null : "the replica shard can be allocated on at least one node, so there must be an active primary";
TransportNodesListShardStoreMetaData.StoreFilesMetaData primaryStore = findStore(primaryShard, allocation, shardStores);
if (primaryStore == null || primaryStore.allocated() == false) {
// if we can't find the primary data, it is probably because the primary shard is corrupted (and listing failed)
// just let the recovery find it out, no need to do anything about it for the initializing shard
logger.trace("{}: no primary shard store found or allocated, letting actual allocation figure it out", shard);
continue;
}
MatchingNodes matchingNodes = findMatchingNodes(shard, allocation, primaryStore, shardStores);
if (matchingNodes.getNodeWithHighestMatch() != null) {
DiscoveryNode currentNode = allocation.nodes().get(shard.currentNodeId());
DiscoveryNode nodeWithHighestMatch = matchingNodes.getNodeWithHighestMatch();
if (currentNode.equals(nodeWithHighestMatch) == false
&& matchingNodes.isNodeMatchBySyncID(currentNode) == false
&& matchingNodes.isNodeMatchBySyncID(nodeWithHighestMatch) == true) {
// we found a better match that has a full sync id match, the existing allocation is not fully synced
// so we found a better one, cancel this one
logger.debug("cancelling allocation of replica on [{}], sync id match found on node [{}]",
currentNode, nodeWithHighestMatch);
it.moveToUnassigned(new UnassignedInfo(UnassignedInfo.Reason.REALLOCATED_REPLICA,
"existing allocation of replica to [" + currentNode + "] cancelled, sync id match found on node [" + nodeWithHighestMatch + "]",
null, allocation.getCurrentNanoTime(), System.currentTimeMillis()));
changed = true;
}
}
}
}
return changed;
}
public boolean allocateUnassigned(RoutingAllocation allocation) {
boolean changed = false;
final RoutingNodes routingNodes = allocation.routingNodes();
final RoutingNodes.UnassignedShards.UnassignedIterator unassignedIterator = routingNodes.unassigned().iterator();
while (unassignedIterator.hasNext()) {
ShardRouting shard = unassignedIterator.next();
if (shard.primary()) {
continue;
}
// if we are allocating a replica because of index creation, no need to go and find a copy, there isn't one...
if (shard.allocatedPostIndexCreate() == false) {
continue;
}
// pre-check if it can be allocated to any node that currently exists, so we won't list the store for it for nothing
if (canBeAllocatedToAtLeastOneNode(shard, allocation) == false) {
logger.trace("{}: ignoring allocation, can't be allocated on any node", shard);
unassignedIterator.removeAndIgnore();
continue;
}
AsyncShardFetch.FetchResult shardStores = fetchData(shard, allocation);
if (shardStores.hasData() == false) {
logger.trace("{}: ignoring allocation, still fetching shard stores", shard);
allocation.setHasPendingAsyncFetch();
unassignedIterator.removeAndIgnore();
continue; // still fetching
}
ShardRouting primaryShard = routingNodes.activePrimary(shard);
assert primaryShard != null : "the replica shard can be allocated on at least one node, so there must be an active primary";
TransportNodesListShardStoreMetaData.StoreFilesMetaData primaryStore = findStore(primaryShard, allocation, shardStores);
if (primaryStore == null || primaryStore.allocated() == false) {
// if we can't find the primary data, it is probably because the primary shard is corrupted (and listing failed)
// we want to let the replica be allocated in order to expose the actual problem with the primary that the replica
// will try and recover from
// Note, this is the existing behavior, as exposed in running CorruptFileTest#testNoPrimaryData
logger.trace("{}: no primary shard store found or allocated, letting actual allocation figure it out", shard);
continue;
}
MatchingNodes matchingNodes = findMatchingNodes(shard, allocation, primaryStore, shardStores);
if (matchingNodes.getNodeWithHighestMatch() != null) {
RoutingNode nodeWithHighestMatch = allocation.routingNodes().node(matchingNodes.getNodeWithHighestMatch().id());
// we only check on THROTTLE since we checked before before on NO
Decision decision = allocation.deciders().canAllocate(shard, nodeWithHighestMatch, allocation);
if (decision.type() == Decision.Type.THROTTLE) {
logger.debug("[{}][{}]: throttling allocation [{}] to [{}] in order to reuse its unallocated persistent store", shard.index(), shard.id(), shard, nodeWithHighestMatch.node());
// we are throttling this, but we have enough to allocate to this node, ignore it for now
unassignedIterator.removeAndIgnore();
} else {
logger.debug("[{}][{}]: allocating [{}] to [{}] in order to reuse its unallocated persistent store", shard.index(), shard.id(), shard, nodeWithHighestMatch.node());
// we found a match
changed = true;
unassignedIterator.initialize(nodeWithHighestMatch.nodeId(), shard.version(), allocation.clusterInfo().getShardSize(shard, ShardRouting.UNAVAILABLE_EXPECTED_SHARD_SIZE));
}
} else if (matchingNodes.hasAnyData() == false) {
// if we didn't manage to find *any* data (regardless of matching sizes), check if the allocation of the replica shard needs to be delayed
changed |= ignoreUnassignedIfDelayed(unassignedIterator, shard);
}
}
return changed;
}
/**
* Check if the allocation of the replica is to be delayed. Compute the delay and if it is delayed, add it to the ignore unassigned list
* Note: we only care about replica in delayed allocation, since if we have an unassigned primary it
* will anyhow wait to find an existing copy of the shard to be allocated
* Note: the other side of the equation is scheduling a reroute in a timely manner, which happens in the RoutingService
*
* PUBLIC FOR TESTS!
*
* @param unassignedIterator iterator over unassigned shards
* @param shard the shard which might be delayed
* @return true iff allocation is delayed for this shard
*/
public boolean ignoreUnassignedIfDelayed(RoutingNodes.UnassignedShards.UnassignedIterator unassignedIterator, ShardRouting shard) {
// calculate delay and store it in UnassignedInfo to be used by RoutingService
long delay = shard.unassignedInfo().getLastComputedLeftDelayNanos();
if (delay > 0) {
logger.debug("[{}][{}]: delaying allocation of [{}] for [{}]", shard.index(), shard.id(), shard, TimeValue.timeValueNanos(delay));
/**
* mark it as changed, since we want to kick a publishing to schedule future allocation,
* see {@link org.elasticsearch.cluster.routing.RoutingService#clusterChanged(ClusterChangedEvent)}).
*/
unassignedIterator.removeAndIgnore();
return true;
}
return false;
}
/**
* Can the shard be allocated on at least one node based on the allocation deciders.
*/
private boolean canBeAllocatedToAtLeastOneNode(ShardRouting shard, RoutingAllocation allocation) {
for (ObjectCursor cursor : allocation.nodes().dataNodes().values()) {
RoutingNode node = allocation.routingNodes().node(cursor.value.id());
if (node == null) {
continue;
}
// if we can't allocate it on a node, ignore it, for example, this handles
// cases for only allocating a replica after a primary
Decision decision = allocation.deciders().canAllocate(shard, node, allocation);
if (decision.type() == Decision.Type.YES) {
return true;
}
}
return false;
}
/**
* Finds the store for the assigned shard in the fetched data, returns null if none is found.
*/
private TransportNodesListShardStoreMetaData.StoreFilesMetaData findStore(ShardRouting shard, RoutingAllocation allocation, AsyncShardFetch.FetchResult data) {
assert shard.currentNodeId() != null;
DiscoveryNode primaryNode = allocation.nodes().get(shard.currentNodeId());
if (primaryNode == null) {
return null;
}
TransportNodesListShardStoreMetaData.NodeStoreFilesMetaData primaryNodeFilesStore = data.getData().get(primaryNode);
if (primaryNodeFilesStore == null) {
return null;
}
return primaryNodeFilesStore.storeFilesMetaData();
}
private MatchingNodes findMatchingNodes(ShardRouting shard, RoutingAllocation allocation,
TransportNodesListShardStoreMetaData.StoreFilesMetaData primaryStore,
AsyncShardFetch.FetchResult data) {
ObjectLongMap nodesToSize = new ObjectLongHashMap<>();
for (Map.Entry nodeStoreEntry : data.getData().entrySet()) {
DiscoveryNode discoNode = nodeStoreEntry.getKey();
TransportNodesListShardStoreMetaData.StoreFilesMetaData storeFilesMetaData = nodeStoreEntry.getValue().storeFilesMetaData();
if (storeFilesMetaData == null) {
// already allocated on that node...
continue;
}
RoutingNode node = allocation.routingNodes().node(discoNode.id());
if (node == null) {
continue;
}
// check if we can allocate on that node...
// we only check for NO, since if this node is THROTTLING and it has enough "same data"
// then we will try and assign it next time
Decision decision = allocation.deciders().canAllocate(shard, node, allocation);
if (decision.type() == Decision.Type.NO) {
continue;
}
// if it is already allocated, we can't assign to it... (and it might be primary as well)
if (storeFilesMetaData.allocated()) {
continue;
}
// we don't have any files at all, it is an empty index
if (storeFilesMetaData.iterator().hasNext() == false) {
continue;
}
String primarySyncId = primaryStore.syncId();
String replicaSyncId = storeFilesMetaData.syncId();
// see if we have a sync id we can make use of
if (replicaSyncId != null && replicaSyncId.equals(primarySyncId)) {
logger.trace("{}: node [{}] has same sync id {} as primary", shard, discoNode.name(), replicaSyncId);
nodesToSize.put(discoNode, Long.MAX_VALUE);
} else {
long sizeMatched = 0;
for (StoreFileMetaData storeFileMetaData : storeFilesMetaData) {
String metaDataFileName = storeFileMetaData.name();
if (primaryStore.fileExists(metaDataFileName) && primaryStore.file(metaDataFileName).isSame(storeFileMetaData)) {
sizeMatched += storeFileMetaData.length();
}
}
logger.trace("{}: node [{}] has [{}/{}] bytes of re-usable data",
shard, discoNode.name(), new ByteSizeValue(sizeMatched), sizeMatched);
nodesToSize.put(discoNode, sizeMatched);
}
}
return new MatchingNodes(nodesToSize);
}
protected abstract AsyncShardFetch.FetchResult fetchData(ShardRouting shard, RoutingAllocation allocation);
static class MatchingNodes {
private final ObjectLongMap nodesToSize;
private final DiscoveryNode nodeWithHighestMatch;
public MatchingNodes(ObjectLongMap nodesToSize) {
this.nodesToSize = nodesToSize;
long highestMatchSize = 0;
DiscoveryNode highestMatchNode = null;
for (ObjectLongCursor cursor : nodesToSize) {
if (cursor.value > highestMatchSize) {
highestMatchSize = cursor.value;
highestMatchNode = cursor.key;
}
}
this.nodeWithHighestMatch = highestMatchNode;
}
/**
* Returns the node with the highest "non zero byte" match compared to
* the primary.
*/
@Nullable
public DiscoveryNode getNodeWithHighestMatch() {
return this.nodeWithHighestMatch;
}
public boolean isNodeMatchBySyncID(DiscoveryNode node) {
return nodesToSize.get(node) == Long.MAX_VALUE;
}
/**
* Did we manage to find any data, regardless how well they matched or not.
*/
public boolean hasAnyData() {
return nodesToSize.isEmpty() == false;
}
}
}