org.apache.flink.runtime.state.IncrementalKeyedStateHandle Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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.apache.flink.runtime.state;
import org.apache.flink.annotation.VisibleForTesting;
import org.apache.flink.util.Preconditions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Map;
import java.util.UUID;
/**
* The handle to states of an incremental snapshot.
*
* The states contained in an incremental snapshot include:
*
* - Created shared state which includes shared files produced since the last
* completed checkpoint. These files can be referenced by succeeding checkpoints if the
* checkpoint succeeds to complete.
* - Referenced shared state which includes the shared files materialized in previous
* checkpoints. Until we this is registered to a {@link SharedStateRegistry}, all referenced
* shared state handles are only placeholders, so that we do not send state handles twice
* from which we know that they already exist on the checkpoint coordinator.
* - Private state which includes all other files, typically mutable, that cannot be shared by
* other checkpoints.
* - Backend meta state which includes the information of existing states.
*
*
* When this should become a completed checkpoint on the checkpoint coordinator, it must first be
* registered with a {@link SharedStateRegistry}, so that all placeholder state handles to
* previously existing state are replaced with the originals.
*
* IMPORTANT: This class currently overrides equals and hash code only for testing purposes. They
* should not be called from production code. This means this class is also not suited to serve as
* a key, e.g. in hash maps.
*/
public class IncrementalKeyedStateHandle implements KeyedStateHandle {
private static final Logger LOG = LoggerFactory.getLogger(IncrementalKeyedStateHandle.class);
private static final long serialVersionUID = -8328808513197388231L;
/**
* UUID to identify the backend which created this state handle. This is in creating the key for the
* {@link SharedStateRegistry}.
*/
private final UUID backendIdentifier;
/**
* The key-group range covered by this state handle.
*/
private final KeyGroupRange keyGroupRange;
/**
* The checkpoint Id.
*/
private final long checkpointId;
/**
* Shared state in the incremental checkpoint.
*/
private final Map sharedState;
/**
* Private state in the incremental checkpoint.
*/
private final Map privateState;
/**
* Primary meta data state of the incremental checkpoint.
*/
private final StreamStateHandle metaStateHandle;
/**
* Once the shared states are registered, it is the {@link SharedStateRegistry}'s
* responsibility to cleanup those shared states.
* But in the cases where the state handle is discarded before performing the registration,
* the handle should delete all the shared states created by it.
*
* This variable is not null iff the handles was registered.
*/
private transient SharedStateRegistry sharedStateRegistry;
public IncrementalKeyedStateHandle(
UUID backendIdentifier,
KeyGroupRange keyGroupRange,
long checkpointId,
Map sharedState,
Map privateState,
StreamStateHandle metaStateHandle) {
this.backendIdentifier = Preconditions.checkNotNull(backendIdentifier);
this.keyGroupRange = Preconditions.checkNotNull(keyGroupRange);
this.checkpointId = checkpointId;
this.sharedState = Preconditions.checkNotNull(sharedState);
this.privateState = Preconditions.checkNotNull(privateState);
this.metaStateHandle = Preconditions.checkNotNull(metaStateHandle);
this.sharedStateRegistry = null;
}
@Override
public KeyGroupRange getKeyGroupRange() {
return keyGroupRange;
}
public long getCheckpointId() {
return checkpointId;
}
public Map getSharedState() {
return sharedState;
}
public Map getPrivateState() {
return privateState;
}
public StreamStateHandle getMetaStateHandle() {
return metaStateHandle;
}
public UUID getBackendIdentifier() {
return backendIdentifier;
}
public SharedStateRegistry getSharedStateRegistry() {
return sharedStateRegistry;
}
@Override
public KeyedStateHandle getIntersection(KeyGroupRange keyGroupRange) {
return KeyGroupRange.EMPTY_KEY_GROUP_RANGE.equals(this.keyGroupRange.getIntersection(keyGroupRange)) ?
null : this;
}
@Override
public void discardState() throws Exception {
SharedStateRegistry registry = this.sharedStateRegistry;
final boolean isRegistered = (registry != null);
LOG.trace("Discarding IncrementalKeyedStateHandle (registered = {}) for checkpoint {} from backend with id {}.",
isRegistered,
checkpointId,
backendIdentifier);
try {
metaStateHandle.discardState();
} catch (Exception e) {
LOG.warn("Could not properly discard meta data.", e);
}
try {
StateUtil.bestEffortDiscardAllStateObjects(privateState.values());
} catch (Exception e) {
LOG.warn("Could not properly discard misc file states.", e);
}
// If this was not registered, we can delete the shared state. We can simply apply this
// to all handles, because all handles that have not been created for the first time for this
// are only placeholders at this point (disposing them is a NOP).
if (isRegistered) {
// If this was registered, we only unregister all our referenced shared states
// from the registry.
for (StateHandleID stateHandleID : sharedState.keySet()) {
registry.unregisterReference(
createSharedStateRegistryKeyFromFileName(stateHandleID));
}
} else {
// Otherwise, we assume to own those handles and dispose them directly.
try {
StateUtil.bestEffortDiscardAllStateObjects(sharedState.values());
} catch (Exception e) {
LOG.warn("Could not properly discard new sst file states.", e);
}
}
}
@Override
public long getStateSize() {
long size = StateUtil.getStateSize(metaStateHandle);
for (StreamStateHandle sharedStateHandle : sharedState.values()) {
size += sharedStateHandle.getStateSize();
}
for (StreamStateHandle privateStateHandle : privateState.values()) {
size += privateStateHandle.getStateSize();
}
return size;
}
@Override
public void registerSharedStates(SharedStateRegistry stateRegistry) {
// This is a quick check to avoid that we register twice with the same registry. However, the code allows to
// register again with a different registry. The implication is that ownership is transferred to this new
// registry. This should only happen in case of a restart, when the CheckpointCoordinator creates a new
// SharedStateRegistry for the current attempt and the old registry becomes meaningless. We also assume that
// an old registry object from a previous run is due to be GCed and will never be used for registration again.
Preconditions.checkState(
sharedStateRegistry != stateRegistry,
"The state handle has already registered its shared states to the given registry.");
sharedStateRegistry = Preconditions.checkNotNull(stateRegistry);
LOG.trace("Registering IncrementalKeyedStateHandle for checkpoint {} from backend with id {}.",
checkpointId,
backendIdentifier);
for (Map.Entry sharedStateHandle : sharedState.entrySet()) {
SharedStateRegistryKey registryKey =
createSharedStateRegistryKeyFromFileName(sharedStateHandle.getKey());
SharedStateRegistry.Result result =
stateRegistry.registerReference(registryKey, sharedStateHandle.getValue());
// This step consolidates our shared handles with the registry, which does two things:
//
// 1) Replace placeholder state handle with already registered, actual state handles.
//
// 2) Deduplicate re-uploads of incremental state due to missing confirmations about
// completed checkpoints.
//
// This prevents the following problem:
// A previous checkpoint n has already registered the state. This can happen if a
// following checkpoint (n + x) wants to reference the same state before the backend got
// notified that checkpoint n completed. In this case, the shared registry did
// deduplication and returns the previous reference.
sharedStateHandle.setValue(result.getReference());
}
}
/**
* Create a unique key to register one of our shared state handles.
*/
@VisibleForTesting
public SharedStateRegistryKey createSharedStateRegistryKeyFromFileName(StateHandleID shId) {
return new SharedStateRegistryKey(String.valueOf(backendIdentifier) + '-' + keyGroupRange, shId);
}
/**
* This method is should only be called in tests! This should never serve as key in a hash map.
*/
@VisibleForTesting
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
IncrementalKeyedStateHandle that = (IncrementalKeyedStateHandle) o;
if (getCheckpointId() != that.getCheckpointId()) {
return false;
}
if (!getBackendIdentifier().equals(that.getBackendIdentifier())) {
return false;
}
if (!getKeyGroupRange().equals(that.getKeyGroupRange())) {
return false;
}
if (!getSharedState().equals(that.getSharedState())) {
return false;
}
if (!getPrivateState().equals(that.getPrivateState())) {
return false;
}
return getMetaStateHandle().equals(that.getMetaStateHandle());
}
/**
* This method should only be called in tests! This should never serve as key in a hash map.
*/
@VisibleForTesting
@Override
public int hashCode() {
int result = getBackendIdentifier().hashCode();
result = 31 * result + getKeyGroupRange().hashCode();
result = 31 * result + (int) (getCheckpointId() ^ (getCheckpointId() >>> 32));
result = 31 * result + getSharedState().hashCode();
result = 31 * result + getPrivateState().hashCode();
result = 31 * result + getMetaStateHandle().hashCode();
return result;
}
@Override
public String toString() {
return "IncrementalKeyedStateHandle{" +
"backendIdentifier=" + backendIdentifier +
", keyGroupRange=" + keyGroupRange +
", checkpointId=" + checkpointId +
", sharedState=" + sharedState +
", privateState=" + privateState +
", metaStateHandle=" + metaStateHandle +
", registered=" + (sharedStateRegistry != null) +
'}';
}
}