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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 org.apache.logging.log4j.message.ParameterizedMessage;
import org.apache.logging.log4j.util.Supplier;
import org.apache.lucene.util.CollectionUtil;
import org.elasticsearch.Version;
import org.elasticsearch.cluster.metadata.IndexMetaData;
import org.elasticsearch.cluster.metadata.MetaData;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.routing.RecoverySource;
import org.elasticsearch.cluster.routing.RoutingNode;
import org.elasticsearch.cluster.routing.RoutingNodes;
import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.cluster.routing.UnassignedInfo.AllocationStatus;
import org.elasticsearch.cluster.routing.allocation.RoutingAllocation;
import org.elasticsearch.cluster.routing.allocation.decider.Decision;
import org.elasticsearch.common.component.AbstractComponent;
import org.elasticsearch.common.settings.Setting;
import org.elasticsearch.common.settings.Setting.Property;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.env.ShardLockObtainFailedException;
import org.elasticsearch.gateway.AsyncShardFetch.FetchResult;
import org.elasticsearch.gateway.TransportNodesListGatewayStartedShards.NodeGatewayStartedShards;
import org.elasticsearch.index.shard.ShardStateMetaData;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Set;
import java.util.function.Function;
import java.util.stream.Collectors;
/**
* The primary shard allocator allocates unassigned primary shards to nodes that hold
* valid copies of the unassigned primaries. It does this by iterating over all unassigned
* primary shards in the routing table and fetching shard metadata from each node in the cluster
* that holds a copy of the shard. The shard metadata from each node is compared against the
* set of valid allocation IDs and for all valid shard copies (if any), the primary shard allocator
* executes the allocation deciders to chose a copy to assign the primary shard to.
*
* Note that the PrimaryShardAllocator does *not* allocate primaries on index creation
* (see {@link org.elasticsearch.cluster.routing.allocation.allocator.BalancedShardsAllocator}),
* nor does it allocate primaries when a primary shard failed and there is a valid replica
* copy that can immediately be promoted to primary, as this takes place in {@link RoutingNodes#failShard}.
*/
public abstract class PrimaryShardAllocator extends AbstractComponent {
private static final Function INITIAL_SHARDS_PARSER = (value) -> {
switch (value) {
case "quorum":
case "quorum-1":
case "half":
case "one":
case "full":
case "full-1":
case "all-1":
case "all":
return value;
default:
Integer.parseInt(value); // it can be parsed that's all we care here?
return value;
}
};
public static final Setting NODE_INITIAL_SHARDS_SETTING =
new Setting<>("gateway.initial_shards", (settings) -> settings.get("gateway.local.initial_shards", "quorum"), INITIAL_SHARDS_PARSER,
Property.Dynamic, Property.NodeScope);
@Deprecated
public static final Setting INDEX_RECOVERY_INITIAL_SHARDS_SETTING =
new Setting<>("index.recovery.initial_shards", (settings) -> NODE_INITIAL_SHARDS_SETTING.get(settings) , INITIAL_SHARDS_PARSER,
Property.Dynamic, Property.IndexScope);
public PrimaryShardAllocator(Settings settings) {
super(settings);
logger.debug("using initial_shards [{}]", NODE_INITIAL_SHARDS_SETTING.get(settings));
}
public void allocateUnassigned(RoutingAllocation allocation) {
final RoutingNodes routingNodes = allocation.routingNodes();
final MetaData metaData = allocation.metaData();
final RoutingNodes.UnassignedShards.UnassignedIterator unassignedIterator = routingNodes.unassigned().iterator();
while (unassignedIterator.hasNext()) {
final ShardRouting shard = unassignedIterator.next();
if (shard.primary() == false) {
continue;
}
if (shard.recoverySource().getType() != RecoverySource.Type.EXISTING_STORE &&
shard.recoverySource().getType() != RecoverySource.Type.SNAPSHOT) {
continue;
}
final AsyncShardFetch.FetchResult shardState = fetchData(shard, allocation);
if (shardState.hasData() == false) {
logger.trace("{}: ignoring allocation, still fetching shard started state", shard);
allocation.setHasPendingAsyncFetch();
unassignedIterator.removeAndIgnore(AllocationStatus.FETCHING_SHARD_DATA, allocation.changes());
continue;
}
// don't create a new IndexSetting object for every shard as this could cause a lot of garbage
// on cluster restart if we allocate a boat load of shards
final IndexMetaData indexMetaData = metaData.getIndexSafe(shard.index());
final Set inSyncAllocationIds = indexMetaData.inSyncAllocationIds(shard.id());
final boolean snapshotRestore = shard.recoverySource().getType() == RecoverySource.Type.SNAPSHOT;
final boolean recoverOnAnyNode = recoverOnAnyNode(indexMetaData);
final NodeShardsResult nodeShardsResult;
final boolean enoughAllocationsFound;
if (inSyncAllocationIds.isEmpty()) {
assert Version.indexCreated(indexMetaData.getSettings()).before(Version.V_5_0_0_alpha1) :
"trying to allocate a primary with an empty in sync allocation id set, but index is new";
// when we load an old index (after upgrading cluster) or restore a snapshot of an old index
// fall back to old version-based allocation mode
// Note that once the shard has been active, lastActiveAllocationIds will be non-empty
nodeShardsResult = buildVersionBasedNodeShardsResult(shard, snapshotRestore || recoverOnAnyNode, allocation.getIgnoreNodes(shard.shardId()), shardState);
if (snapshotRestore || recoverOnAnyNode) {
enoughAllocationsFound = nodeShardsResult.allocationsFound > 0;
} else {
enoughAllocationsFound = isEnoughVersionBasedAllocationsFound(indexMetaData, nodeShardsResult);
}
logger.debug("[{}][{}]: version-based allocation for pre-{} index found {} allocations of {}", shard.index(), shard.id(), Version.V_5_0_0_alpha1, nodeShardsResult.allocationsFound, shard);
} else {
assert inSyncAllocationIds.isEmpty() == false;
// use allocation ids to select nodes
nodeShardsResult = buildAllocationIdBasedNodeShardsResult(shard, snapshotRestore || recoverOnAnyNode,
allocation.getIgnoreNodes(shard.shardId()), inSyncAllocationIds, shardState);
enoughAllocationsFound = nodeShardsResult.orderedAllocationCandidates.size() > 0;
logger.debug("[{}][{}]: found {} allocation candidates of {} based on allocation ids: [{}]", shard.index(), shard.id(), nodeShardsResult.orderedAllocationCandidates.size(), shard, inSyncAllocationIds);
}
if (enoughAllocationsFound == false){
if (snapshotRestore) {
// let BalancedShardsAllocator take care of allocating this shard
logger.debug("[{}][{}]: missing local data, will restore from [{}]", shard.index(), shard.id(), shard.recoverySource());
} else if (recoverOnAnyNode) {
// let BalancedShardsAllocator take care of allocating this shard
logger.debug("[{}][{}]: missing local data, recover from any node", shard.index(), shard.id());
} else {
// we can't really allocate, so ignore it and continue
unassignedIterator.removeAndIgnore(AllocationStatus.NO_VALID_SHARD_COPY, allocation.changes());
logger.debug("[{}][{}]: not allocating, number_of_allocated_shards_found [{}]", shard.index(), shard.id(), nodeShardsResult.allocationsFound);
}
continue;
}
final NodesToAllocate nodesToAllocate = buildNodesToAllocate(
allocation, nodeShardsResult.orderedAllocationCandidates, shard, false
);
if (nodesToAllocate.yesNodeShards.isEmpty() == false) {
NodeGatewayStartedShards nodeShardState = nodesToAllocate.yesNodeShards.get(0);
logger.debug("[{}][{}]: allocating [{}] to [{}] on primary allocation", shard.index(), shard.id(), shard, nodeShardState.getNode());
unassignedIterator.initialize(nodeShardState.getNode().getId(), nodeShardState.allocationId(), ShardRouting.UNAVAILABLE_EXPECTED_SHARD_SIZE, allocation.changes());
} else if (nodesToAllocate.throttleNodeShards.isEmpty() == true && nodesToAllocate.noNodeShards.isEmpty() == false) {
// The deciders returned a NO decision for all nodes with shard copies, so we check if primary shard
// can be force-allocated to one of the nodes.
final NodesToAllocate nodesToForceAllocate = buildNodesToAllocate(
allocation, nodeShardsResult.orderedAllocationCandidates, shard, true
);
if (nodesToForceAllocate.yesNodeShards.isEmpty() == false) {
NodeGatewayStartedShards nodeShardState = nodesToForceAllocate.yesNodeShards.get(0);
logger.debug("[{}][{}]: allocating [{}] to [{}] on forced primary allocation",
shard.index(), shard.id(), shard, nodeShardState.getNode());
unassignedIterator.initialize(nodeShardState.getNode().getId(), nodeShardState.allocationId(),
ShardRouting.UNAVAILABLE_EXPECTED_SHARD_SIZE, allocation.changes());
} else if (nodesToForceAllocate.throttleNodeShards.isEmpty() == false) {
logger.debug("[{}][{}]: throttling allocation [{}] to [{}] on forced primary allocation",
shard.index(), shard.id(), shard, nodesToForceAllocate.throttleNodeShards);
unassignedIterator.removeAndIgnore(AllocationStatus.DECIDERS_THROTTLED, allocation.changes());
} else {
logger.debug("[{}][{}]: forced primary allocation denied [{}]", shard.index(), shard.id(), shard);
unassignedIterator.removeAndIgnore(AllocationStatus.DECIDERS_NO, allocation.changes());
}
} else {
// we are throttling this, but we have enough to allocate to this node, ignore it for now
logger.debug("[{}][{}]: throttling allocation [{}] to [{}] on primary allocation", shard.index(), shard.id(), shard, nodesToAllocate.throttleNodeShards);
unassignedIterator.removeAndIgnore(AllocationStatus.DECIDERS_THROTTLED, allocation.changes());
}
}
}
private static final Comparator NO_STORE_EXCEPTION_FIRST_COMPARATOR =
Comparator.comparing((NodeGatewayStartedShards state) -> state.storeException() == null).reversed();
private static final Comparator PRIMARY_FIRST_COMPARATOR =
Comparator.comparing(NodeGatewayStartedShards::primary).reversed();
/**
* Builds a list of nodes. If matchAnyShard is set to false, only nodes that have an allocation id matching
* inSyncAllocationIds are added to the list. Otherwise, any node that has a shard is added to the list, but
* entries with matching allocation id are always at the front of the list.
*/
protected NodeShardsResult buildAllocationIdBasedNodeShardsResult(ShardRouting shard, boolean matchAnyShard,
Set ignoreNodes, Set inSyncAllocationIds,
FetchResult shardState) {
List nodeShardStates = new ArrayList<>();
int numberOfAllocationsFound = 0;
for (NodeGatewayStartedShards nodeShardState : shardState.getData().values()) {
DiscoveryNode node = nodeShardState.getNode();
String allocationId = nodeShardState.allocationId();
if (ignoreNodes.contains(node.getId())) {
continue;
}
if (nodeShardState.storeException() == null) {
if (allocationId == null && nodeShardState.legacyVersion() == ShardStateMetaData.NO_VERSION) {
logger.trace("[{}] on node [{}] has no shard state information", shard, nodeShardState.getNode());
} else if (allocationId != null) {
assert nodeShardState.legacyVersion() == ShardStateMetaData.NO_VERSION : "Allocation id and legacy version cannot be both present";
logger.trace("[{}] on node [{}] has allocation id [{}]", shard, nodeShardState.getNode(), allocationId);
} else {
logger.trace("[{}] on node [{}] has no allocation id, out-dated shard (shard state version: [{}])", shard, nodeShardState.getNode(), nodeShardState.legacyVersion());
}
} else {
final String finalAllocationId = allocationId;
if (nodeShardState.storeException() instanceof ShardLockObtainFailedException) {
logger.trace((Supplier) () -> new ParameterizedMessage("[{}] on node [{}] has allocation id [{}] but the store can not be opened as it's locked, treating as valid shard", shard, nodeShardState.getNode(), finalAllocationId), nodeShardState.storeException());
} else {
logger.trace((Supplier) () -> new ParameterizedMessage("[{}] on node [{}] has allocation id [{}] but the store can not be opened, treating as no allocation id", shard, nodeShardState.getNode(), finalAllocationId), nodeShardState.storeException());
allocationId = null;
}
}
if (allocationId != null) {
assert nodeShardState.storeException() == null ||
nodeShardState.storeException() instanceof ShardLockObtainFailedException :
"only allow store that can be opened or that throws a ShardLockObtainFailedException while being opened but got a store throwing " + nodeShardState.storeException();
numberOfAllocationsFound++;
if (matchAnyShard || inSyncAllocationIds.contains(nodeShardState.allocationId())) {
nodeShardStates.add(nodeShardState);
}
}
}
final Comparator comparator; // allocation preference
if (matchAnyShard) {
// prefer shards with matching allocation ids
Comparator matchingAllocationsFirst = Comparator.comparing(
(NodeGatewayStartedShards state) -> inSyncAllocationIds.contains(state.allocationId())).reversed();
comparator = matchingAllocationsFirst.thenComparing(NO_STORE_EXCEPTION_FIRST_COMPARATOR).thenComparing(PRIMARY_FIRST_COMPARATOR);
} else {
comparator = NO_STORE_EXCEPTION_FIRST_COMPARATOR.thenComparing(PRIMARY_FIRST_COMPARATOR);
}
nodeShardStates.sort(comparator);
if (logger.isTraceEnabled()) {
logger.trace("{} candidates for allocation: {}", shard, nodeShardStates.stream().map(s -> s.getNode().getName()).collect(Collectors.joining(", ")));
}
return new NodeShardsResult(nodeShardStates, numberOfAllocationsFound);
}
/**
* used by old version-based allocation
*/
private boolean isEnoughVersionBasedAllocationsFound(IndexMetaData indexMetaData, NodeShardsResult nodeShardsResult) {
// check if the counts meets the minimum set
int requiredAllocation = 1;
// if we restore from a repository one copy is more then enough
String initialShards = INDEX_RECOVERY_INITIAL_SHARDS_SETTING.get(indexMetaData.getSettings(), settings);
if ("quorum".equals(initialShards)) {
if (indexMetaData.getNumberOfReplicas() > 1) {
requiredAllocation = ((1 + indexMetaData.getNumberOfReplicas()) / 2) + 1;
}
} else if ("quorum-1".equals(initialShards) || "half".equals(initialShards)) {
if (indexMetaData.getNumberOfReplicas() > 2) {
requiredAllocation = ((1 + indexMetaData.getNumberOfReplicas()) / 2);
}
} else if ("one".equals(initialShards)) {
requiredAllocation = 1;
} else if ("full".equals(initialShards) || "all".equals(initialShards)) {
requiredAllocation = indexMetaData.getNumberOfReplicas() + 1;
} else if ("full-1".equals(initialShards) || "all-1".equals(initialShards)) {
if (indexMetaData.getNumberOfReplicas() > 1) {
requiredAllocation = indexMetaData.getNumberOfReplicas();
}
} else {
requiredAllocation = Integer.parseInt(initialShards);
}
return nodeShardsResult.allocationsFound >= requiredAllocation;
}
/**
* Split the list of node shard states into groups yes/no/throttle based on allocation deciders
*/
private NodesToAllocate buildNodesToAllocate(RoutingAllocation allocation,
List nodeShardStates,
ShardRouting shardRouting,
boolean forceAllocate) {
List yesNodeShards = new ArrayList<>();
List throttledNodeShards = new ArrayList<>();
List noNodeShards = new ArrayList<>();
for (NodeGatewayStartedShards nodeShardState : nodeShardStates) {
RoutingNode node = allocation.routingNodes().node(nodeShardState.getNode().getId());
if (node == null) {
continue;
}
Decision decision = forceAllocate ? allocation.deciders().canForceAllocatePrimary(shardRouting, node, allocation) :
allocation.deciders().canAllocate(shardRouting, node, allocation);
if (decision.type() == Decision.Type.THROTTLE) {
throttledNodeShards.add(nodeShardState);
} else if (decision.type() == Decision.Type.NO) {
noNodeShards.add(nodeShardState);
} else {
yesNodeShards.add(nodeShardState);
}
}
return new NodesToAllocate(Collections.unmodifiableList(yesNodeShards), Collections.unmodifiableList(throttledNodeShards), Collections.unmodifiableList(noNodeShards));
}
/**
* Builds a list of previously started shards. If matchAnyShard is set to false, only shards with the highest shard version are added to
* the list. Otherwise, any existing shard is added to the list, but entries with highest version are always at the front of the list.
*/
NodeShardsResult buildVersionBasedNodeShardsResult(ShardRouting shard, boolean matchAnyShard, Set ignoreNodes,
AsyncShardFetch.FetchResult shardState) {
final List allocationCandidates = new ArrayList<>();
int numberOfAllocationsFound = 0;
long highestVersion = ShardStateMetaData.NO_VERSION;
for (NodeGatewayStartedShards nodeShardState : shardState.getData().values()) {
long version = nodeShardState.legacyVersion();
DiscoveryNode node = nodeShardState.getNode();
if (ignoreNodes.contains(node.getId())) {
continue;
}
if (nodeShardState.storeException() == null) {
if (version == ShardStateMetaData.NO_VERSION && nodeShardState.allocationId() == null) {
logger.trace("[{}] on node [{}] has no shard state information", shard, nodeShardState.getNode());
} else if (version != ShardStateMetaData.NO_VERSION) {
assert nodeShardState.allocationId() == null : "Allocation id and legacy version cannot be both present";
logger.trace("[{}] on node [{}] has version [{}] of shard", shard, nodeShardState.getNode(), version);
} else {
// shard was already selected in a 5.x cluster as primary for recovery, was initialized (and wrote a new state file) but
// did not make it to STARTED state before the cluster crashed (otherwise list of active allocation ids would be
// non-empty and allocation id - based allocation mode would be chosen).
// Prefer this shard copy again.
version = Long.MAX_VALUE;
logger.trace("[{}] on node [{}] has allocation id [{}]", shard, nodeShardState.getNode(), nodeShardState.allocationId());
}
} else {
final long finalVersion = version;
if (nodeShardState.storeException() instanceof ShardLockObtainFailedException) {
logger.trace((Supplier) () -> new ParameterizedMessage("[{}] on node [{}] has version [{}] but the store can not be opened as it's locked, treating as valid shard", shard, nodeShardState.getNode(), finalVersion), nodeShardState.storeException());
if (nodeShardState.allocationId() != null) {
version = Long.MAX_VALUE; // shard was already selected in a 5.x cluster as primary, prefer this shard copy again.
} else {
version = 0L; // treat as lowest version so that this shard is the least likely to be selected as primary
}
} else {
// disregard the reported version and assign it as no version (same as shard does not exist)
logger.trace((Supplier) () -> new ParameterizedMessage("[{}] on node [{}] has version [{}] but the store can not be opened, treating no version", shard, nodeShardState.getNode(), finalVersion), nodeShardState.storeException());
version = ShardStateMetaData.NO_VERSION;
}
}
if (version != ShardStateMetaData.NO_VERSION) {
numberOfAllocationsFound++;
// If we've found a new "best" candidate, clear the
// current candidates and add it
if (version > highestVersion) {
highestVersion = version;
if (matchAnyShard == false) {
allocationCandidates.clear();
}
allocationCandidates.add(nodeShardState);
} else if (version == highestVersion) {
// If the candidate is the same, add it to the
// list, but keep the current candidate
allocationCandidates.add(nodeShardState);
}
}
}
// sort array so the node with the highest version is at the beginning
CollectionUtil.timSort(allocationCandidates, Comparator.comparing(NodeGatewayStartedShards::legacyVersion).reversed());
if (logger.isTraceEnabled()) {
StringBuilder sb = new StringBuilder("[");
for (NodeGatewayStartedShards n : allocationCandidates) {
sb.append("[").append(n.getNode().getName()).append("]").append(" -> ").append(n.legacyVersion()).append(", ");
}
sb.append("]");
logger.trace("{} candidates for allocation: {}", shard, sb.toString());
}
return new NodeShardsResult(Collections.unmodifiableList(allocationCandidates), numberOfAllocationsFound);
}
/**
* Return {@code true} if the index is configured to allow shards to be
* recovered on any node
*/
private boolean recoverOnAnyNode(IndexMetaData metaData) {
return (IndexMetaData.isOnSharedFilesystem(metaData.getSettings()) || IndexMetaData.isOnSharedFilesystem(this.settings))
&& IndexMetaData.INDEX_SHARED_FS_ALLOW_RECOVERY_ON_ANY_NODE_SETTING.get(metaData.getSettings(), this.settings);
}
protected abstract AsyncShardFetch.FetchResult fetchData(ShardRouting shard, RoutingAllocation allocation);
static class NodeShardsResult {
public final List orderedAllocationCandidates;
public final int allocationsFound;
public NodeShardsResult(List orderedAllocationCandidates, int allocationsFound) {
this.orderedAllocationCandidates = orderedAllocationCandidates;
this.allocationsFound = allocationsFound;
}
}
static class NodesToAllocate {
final List yesNodeShards;
final List throttleNodeShards;
final List noNodeShards;
public NodesToAllocate(List yesNodeShards,
List throttleNodeShards,
List noNodeShards) {
this.yesNodeShards = yesNodeShards;
this.throttleNodeShards = throttleNodeShards;
this.noNodeShards = noNodeShards;
}
}
}
