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The implementation module of Ehcache 3
/*
* Copyright Terracotta, Inc.
*
* Licensed 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.ehcache.impl.internal.loaderwriter.writebehind;
import org.ehcache.impl.internal.concurrent.ConcurrentHashMap;
import org.ehcache.impl.internal.loaderwriter.writebehind.operations.BatchOperation;
import org.ehcache.impl.internal.loaderwriter.writebehind.operations.DeleteOperation;
import org.ehcache.impl.internal.loaderwriter.writebehind.operations.DeleteAllOperation;
import org.ehcache.impl.internal.loaderwriter.writebehind.operations.SingleOperation;
import org.ehcache.impl.internal.loaderwriter.writebehind.operations.WriteOperation;
import org.ehcache.impl.internal.loaderwriter.writebehind.operations.WriteAllOperation;
import org.ehcache.spi.loaderwriter.CacheLoaderWriter;
import org.ehcache.spi.loaderwriter.WriteBehindConfiguration;
import org.ehcache.spi.loaderwriter.WriteBehindConfiguration.BatchingConfiguration;
import org.ehcache.core.spi.service.ExecutionService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.AbstractMap.SimpleEntry;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.LinkedHashMap;
import java.util.Map.Entry;
import java.util.Set;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static org.ehcache.impl.internal.executor.ExecutorUtil.shutdown;
import static org.ehcache.impl.internal.executor.ExecutorUtil.shutdownNow;
import static org.ehcache.impl.internal.executor.ExecutorUtil.waitFor;
/**
*
* @author cdennis
*/
public class BatchingLocalHeapWriteBehindQueue extends AbstractWriteBehind {
private static final Logger LOGGER = LoggerFactory.getLogger(BatchingLocalHeapWriteBehindQueue.class);
private final CacheLoaderWriter cacheLoaderWriter;
private final ConcurrentMap> latest = new ConcurrentHashMap<>();
private final BlockingQueue executorQueue;
private final ExecutorService executor;
private final ScheduledExecutorService scheduledExecutor;
private final long maxWriteDelayMs;
private final int batchSize;
private final boolean coalescing;
private volatile Batch openBatch;
public BatchingLocalHeapWriteBehindQueue(ExecutionService executionService, String defaultThreadPool, WriteBehindConfiguration config, CacheLoaderWriter cacheLoaderWriter) {
super(cacheLoaderWriter);
this.cacheLoaderWriter = cacheLoaderWriter;
BatchingConfiguration batchingConfig = config.getBatchingConfiguration();
this.maxWriteDelayMs = batchingConfig.getMaxDelayUnit().toMillis(batchingConfig.getMaxDelay());
this.batchSize = batchingConfig.getBatchSize();
this.coalescing = batchingConfig.isCoalescing();
this.executorQueue = new LinkedBlockingQueue<>(config.getMaxQueueSize() / batchSize);
if (config.getThreadPoolAlias() == null) {
this.executor = executionService.getOrderedExecutor(defaultThreadPool, executorQueue);
} else {
this.executor = executionService.getOrderedExecutor(config.getThreadPoolAlias(), executorQueue);
}
if (config.getThreadPoolAlias() == null) {
this.scheduledExecutor = executionService.getScheduledExecutor(defaultThreadPool);
} else {
this.scheduledExecutor = executionService.getScheduledExecutor(config.getThreadPoolAlias());
}
}
@Override
protected SingleOperation getOperation(K key) {
return latest.get(key);
}
@Override
protected void addOperation(SingleOperation operation) {
latest.put(operation.getKey(), operation);
synchronized (this) {
if (openBatch == null) {
openBatch = newBatch();
}
if (openBatch.add(operation)) {
submit(openBatch);
openBatch = null;
}
}
}
@Override
public void start() {
//no-op
}
@Override
public void stop() {
try {
synchronized (this) {
if (openBatch != null) {
waitFor(submit(openBatch));
openBatch = null;
}
}
} catch (ExecutionException e) {
LOGGER.error("Exception running batch on shutdown", e);
} finally {
/*
* The scheduled executor should only contain cancelled tasks, but these
* can stall a regular shutdown for up to max-write-delay. So we just
* kill it now.
*/
shutdownNow(scheduledExecutor);
shutdown(executor);
}
}
private Batch newBatch() {
if (coalescing) {
return new CoalescingBatch(batchSize);
} else {
return new SimpleBatch(batchSize);
}
}
private Future submit(Batch batch) {
return executor.submit(batch);
}
/**
* Gets the best estimate for items in the queue still awaiting processing.
* Since the value returned is a rough estimate, it can sometimes be more than
* the number of items actually in the queue but not less.
*
* @return the amount of elements still awaiting processing.
*/
@Override
public long getQueueSize() {
Batch snapshot = openBatch;
return executorQueue.size() * batchSize + (snapshot == null ? 0 : snapshot.size());
}
abstract class Batch implements Runnable {
private final int batchSize;
private final ScheduledFuture expireTask;
Batch(int size) {
this.batchSize = size;
this.expireTask = scheduledExecutor.schedule(() -> {
synchronized (BatchingLocalHeapWriteBehindQueue.this) {
if (openBatch == Batch.this) {
submit(openBatch);
openBatch = null;
}
}
}, maxWriteDelayMs, MILLISECONDS);
}
public boolean add(SingleOperation operation) {
internalAdd(operation);
return size() >= batchSize;
}
@Override
public void run() {
try {
List> batches = createMonomorphicBatches(operations());
// execute the batch operations
for (BatchOperation batch : batches) {
try {
batch.performOperation(cacheLoaderWriter);
} catch (Exception e) {
LOGGER.warn("Exception while bulk processing in write behind queue", e);
}
}
} finally {
try {
for (SingleOperation op : operations()) {
latest.remove(op.getKey(), op);
}
} finally {
LOGGER.debug("Cancelling batch expiry task");
expireTask.cancel(false);
}
}
}
protected abstract void internalAdd(SingleOperation operation);
protected abstract Iterable> operations();
protected abstract int size();
}
private class SimpleBatch extends Batch {
private final List> operations;
SimpleBatch(int size) {
super(size);
this.operations = new ArrayList<>(size);
}
@Override
public void internalAdd(SingleOperation operation) {
operations.add(operation);
}
@Override
protected List> operations() {
return operations;
}
@Override
protected int size() {
return operations.size();
}
}
private class CoalescingBatch extends Batch {
private final LinkedHashMap> operations;
public CoalescingBatch(int size) {
super(size);
this.operations = new LinkedHashMap<>(size);
}
@Override
public void internalAdd(SingleOperation operation) {
operations.put(operation.getKey(), operation);
}
@Override
protected Iterable> operations() {
return operations.values();
}
@Override
protected int size() {
return operations.size();
}
}
private static List> createMonomorphicBatches(Iterable> batch) {
final List> closedBatches = new ArrayList<>();
Set activeDeleteKeys = new HashSet<>();
Set activeWrittenKeys = new HashSet<>();
List activeDeleteBatch = new ArrayList<>();
List> activeWriteBatch = new ArrayList<>();
for (SingleOperation item : batch) {
if (item instanceof WriteOperation) {
if (activeDeleteKeys.contains(item.getKey())) {
//close the current delete batch
closedBatches.add(new DeleteAllOperation<>(activeDeleteBatch));
activeDeleteBatch = new ArrayList<>();
activeDeleteKeys = new HashSet<>();
}
activeWriteBatch.add(new SimpleEntry<>(item.getKey(), ((WriteOperation) item).getValue()));
activeWrittenKeys.add(item.getKey());
} else if (item instanceof DeleteOperation) {
if (activeWrittenKeys.contains(item.getKey())) {
//close the current write batch
closedBatches.add(new WriteAllOperation<>(activeWriteBatch));
activeWriteBatch = new ArrayList<>();
activeWrittenKeys = new HashSet<>();
}
activeDeleteBatch.add(item.getKey());
activeDeleteKeys.add(item.getKey());
} else {
throw new AssertionError();
}
}
if (!activeWriteBatch.isEmpty()) {
closedBatches.add(new WriteAllOperation<>(activeWriteBatch));
}
if (!activeDeleteBatch.isEmpty()) {
closedBatches.add(new DeleteAllOperation<>(activeDeleteBatch));
}
return closedBatches;
}
}