org.apache.flink.runtime.checkpoint.hooks.MasterHooks Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.runtime.checkpoint.hooks;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.core.io.SimpleVersionedSerializer;
import org.apache.flink.runtime.checkpoint.MasterState;
import org.apache.flink.runtime.checkpoint.MasterTriggerRestoreHook;
import org.apache.flink.runtime.concurrent.FutureUtils;
import org.apache.flink.util.ExceptionUtils;
import org.apache.flink.util.FlinkException;
import org.apache.flink.util.LambdaUtil;
import org.apache.flink.util.Preconditions;
import org.slf4j.Logger;
import javax.annotation.Nullable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionException;
import java.util.concurrent.Executor;
/**
* Collection of methods to deal with checkpoint master hooks.
*/
public class MasterHooks {
// ------------------------------------------------------------------------
// lifecycle
// ------------------------------------------------------------------------
/**
* Resets the master hooks.
*
* @param hooks The hooks to reset
*
* @throws FlinkException Thrown, if the hooks throw an exception.
*/
public static void reset(
final Collection> hooks,
final Logger log) throws FlinkException {
for (MasterTriggerRestoreHook hook : hooks) {
final String id = hook.getIdentifier();
try {
hook.reset();
}
catch (Throwable t) {
ExceptionUtils.rethrowIfFatalErrorOrOOM(t);
throw new FlinkException("Error while resetting checkpoint master hook '" + id + '\'', t);
}
}
}
/**
* Closes the master hooks.
*
* @param hooks The hooks to close
*
* @throws FlinkException Thrown, if the hooks throw an exception.
*/
public static void close(
final Collection> hooks,
final Logger log) throws FlinkException {
for (MasterTriggerRestoreHook hook : hooks) {
try {
hook.close();
}
catch (Throwable t) {
log.warn("Failed to cleanly close a checkpoint master hook (" + hook.getIdentifier() + ")", t);
}
}
}
// ------------------------------------------------------------------------
// checkpoint triggering
// ------------------------------------------------------------------------
/**
* Trigger master hook and return a completable future with state.
* @param hook The master hook given
* @param checkpointId The checkpoint ID of the triggering checkpoint
* @param timestamp The (informational) timestamp for the triggering checkpoint
* @param executor An executor that can be used for asynchronous I/O calls
* @param The type of data produced by the hook
* @return the completable future with state
*/
public static CompletableFuture triggerHook(
MasterTriggerRestoreHook hook,
long checkpointId,
long timestamp,
Executor executor) {
final String id = hook.getIdentifier();
final SimpleVersionedSerializer serializer = hook.createCheckpointDataSerializer();
try {
// call the hook!
final CompletableFuture resultFuture =
hook.triggerCheckpoint(checkpointId, timestamp, executor);
if (resultFuture == null) {
return CompletableFuture.completedFuture(null);
}
return resultFuture
.thenApply(result -> {
// if the result of the future is not null, return it as state
if (result == null) {
return null;
}
else if (serializer != null) {
try {
final int version = serializer.getVersion();
final byte[] bytes = serializer.serialize(result);
return new MasterState(id, bytes, version);
}
catch (Throwable t) {
ExceptionUtils.rethrowIfFatalErrorOrOOM(t);
throw new CompletionException(new FlinkException(
"Failed to serialize state of master hook '" + id + '\'', t));
}
}
else {
throw new CompletionException(new FlinkException(
"Checkpoint hook '" + id + " is stateful but creates no serializer"));
}
})
.exceptionally((throwable) -> {
throw new CompletionException(new FlinkException(
"Checkpoint master hook '" + id + "' produced an exception",
throwable.getCause()));
});
}
catch (Throwable t) {
return FutureUtils.completedExceptionally(new FlinkException(
"Error while triggering checkpoint master hook '" + id + '\'', t));
}
}
// ------------------------------------------------------------------------
// checkpoint restoring
// ------------------------------------------------------------------------
/**
* Calls the restore method given checkpoint master hooks and passes the given master
* state to them where state with a matching name is found.
*
* If state is found and no hook with the same name is found, the method throws an
* exception, unless the {@code allowUnmatchedState} flag is set.
*
* @param masterHooks The hooks to call restore on
* @param states The state to pass to the hooks
* @param checkpointId The checkpoint ID of the restored checkpoint
* @param allowUnmatchedState If true, the method fails if not all states are picked up by a hook.
* @param log The logger for log messages
*
* @throws FlinkException Thrown, if the hooks throw an exception, or the state+
* deserialization fails.
*/
public static void restoreMasterHooks(
final Map> masterHooks,
final Collection states,
final long checkpointId,
final boolean allowUnmatchedState,
final Logger log) throws FlinkException {
// early out
if (states == null || states.isEmpty() || masterHooks == null || masterHooks.isEmpty()) {
log.info("No master state to restore");
return;
}
log.info("Calling master restore hooks");
// collect the hooks
final LinkedHashMap> allHooks = new LinkedHashMap<>(masterHooks);
// first, deserialize all hook state
final ArrayList, Object>> hooksAndStates = new ArrayList<>();
for (MasterState state : states) {
if (state != null) {
final String name = state.name();
final MasterTriggerRestoreHook hook = allHooks.remove(name);
if (hook != null) {
log.debug("Found state to restore for hook '{}'", name);
Object deserializedState = deserializeState(state, hook);
hooksAndStates.add(new Tuple2<>(hook, deserializedState));
}
else if (!allowUnmatchedState) {
throw new IllegalStateException("Found state '" + state.name() +
"' which is not resumed by any hook.");
}
else {
log.info("Dropping unmatched state from '{}'", name);
}
}
}
// now that all is deserialized, call the hooks
for (Tuple2, Object> hookAndState : hooksAndStates) {
restoreHook(hookAndState.f1, hookAndState.f0, checkpointId);
}
// trigger the remaining hooks without checkpointed state
for (MasterTriggerRestoreHook hook : allHooks.values()) {
restoreHook(null, hook, checkpointId);
}
}
private static T deserializeState(MasterState state, MasterTriggerRestoreHook hook) throws FlinkException {
@SuppressWarnings("unchecked")
final MasterTriggerRestoreHook typedHook = (MasterTriggerRestoreHook) hook;
final String id = hook.getIdentifier();
try {
final SimpleVersionedSerializer deserializer = typedHook.createCheckpointDataSerializer();
if (deserializer == null) {
throw new FlinkException("null serializer for state of hook " + hook.getIdentifier());
}
return deserializer.deserialize(state.version(), state.bytes());
}
catch (Throwable t) {
throw new FlinkException("Cannot deserialize state for master hook '" + id + '\'', t);
}
}
private static void restoreHook(
final Object state,
final MasterTriggerRestoreHook hook,
final long checkpointId) throws FlinkException {
@SuppressWarnings("unchecked")
final T typedState = (T) state;
@SuppressWarnings("unchecked")
final MasterTriggerRestoreHook typedHook = (MasterTriggerRestoreHook) hook;
try {
typedHook.restoreCheckpoint(checkpointId, typedState);
}
catch (FlinkException e) {
throw e;
}
catch (Throwable t) {
// catch all here, including Errors that may come from dependency and classpath issues
ExceptionUtils.rethrowIfFatalError(t);
throw new FlinkException("Error while calling restoreCheckpoint on checkpoint hook '"
+ hook.getIdentifier() + '\'', t);
}
}
// ------------------------------------------------------------------------
// hook management
// ------------------------------------------------------------------------
/**
* Wraps a hook such that the user-code classloader is applied when the hook is invoked.
* @param hook the hook to wrap
* @param userClassLoader the classloader to use
*/
public static MasterTriggerRestoreHook wrapHook(
MasterTriggerRestoreHook hook,
ClassLoader userClassLoader) {
return new WrappedMasterHook<>(hook, userClassLoader);
}
private static class WrappedMasterHook implements MasterTriggerRestoreHook {
private final MasterTriggerRestoreHook hook;
private final ClassLoader userClassLoader;
WrappedMasterHook(MasterTriggerRestoreHook hook, ClassLoader userClassLoader) {
this.hook = Preconditions.checkNotNull(hook);
this.userClassLoader = Preconditions.checkNotNull(userClassLoader);
}
@Override
public void reset() throws Exception {
LambdaUtil.withContextClassLoader(userClassLoader, hook::reset);
}
@Override
public void close() throws Exception {
LambdaUtil.withContextClassLoader(userClassLoader, hook::close);
}
@Override
public String getIdentifier() {
return LambdaUtil.withContextClassLoader(userClassLoader, hook::getIdentifier);
}
@Nullable
@Override
public CompletableFuture triggerCheckpoint(long checkpointId, long timestamp, final Executor executor) throws Exception {
final Executor wrappedExecutor = new Executor() {
@Override
public void execute(Runnable command) {
executor.execute(new WrappedCommand(userClassLoader, command));
}
};
return LambdaUtil.withContextClassLoader(
userClassLoader,
() -> hook.triggerCheckpoint(checkpointId, timestamp, wrappedExecutor));
}
@Override
public void restoreCheckpoint(long checkpointId, @Nullable T checkpointData) throws Exception {
LambdaUtil.withContextClassLoader(
userClassLoader,
() -> hook.restoreCheckpoint(checkpointId, checkpointData));
}
@Nullable
@Override
public SimpleVersionedSerializer createCheckpointDataSerializer() {
return LambdaUtil.withContextClassLoader(userClassLoader, hook::createCheckpointDataSerializer);
}
private static class WrappedCommand implements Runnable {
private final ClassLoader userClassLoader;
private final Runnable command;
WrappedCommand(ClassLoader userClassLoader, Runnable command) {
this.userClassLoader = Preconditions.checkNotNull(userClassLoader);
this.command = Preconditions.checkNotNull(command);
}
@Override
public void run() {
LambdaUtil.withContextClassLoader(userClassLoader, command::run);
}
}
}
// ------------------------------------------------------------------------
/** This class is not meant to be instantiated. */
private MasterHooks() {}
}