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Swirlds is a software platform designed to build fully-distributed applications that harness the power of the cloud without servers. Now you can develop applications with fairness in decision making, speed, trust and reliability, at a fraction of the cost of traditional server-based platforms.
/*
* Copyright (C) 2023-2024 Hedera Hashgraph, LLC
*
* 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 com.swirlds.merkledb;
import static com.swirlds.common.threading.manager.AdHocThreadManager.getStaticThreadManager;
import static com.swirlds.logging.legacy.LogMarker.EXCEPTION;
import static com.swirlds.logging.legacy.LogMarker.MERKLE_DB;
import static com.swirlds.merkledb.MerkleDb.MERKLEDB_COMPONENT;
import com.swirlds.common.config.singleton.ConfigurationHolder;
import com.swirlds.common.threading.framework.config.ThreadConfiguration;
import com.swirlds.merkledb.config.MerkleDbConfig;
import com.swirlds.merkledb.files.DataFileCompactor;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
import java.io.IOException;
import java.nio.channels.ClosedByInterruptException;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
/**
* This class is responsible for coordinating compaction tasks for a {@link MerkleDbDataSource}.
* It provides convenient API for starting compactions for each of the three storage types. Also, this class makes sure
* that there are no concurrent compactions for the same storage type. And finally it provides a way to stop all compactions
* and keep them disabled until they are explicitly enabled again.
* The compaction tasks are executed in a background thread pool.
* The number of threads in the pool is defined by {@link MerkleDbConfig#compactionThreads()} property.
*
*/
@SuppressWarnings("rawtypes")
class MerkleDbCompactionCoordinator {
private static final Logger logger = LogManager.getLogger(MerkleDbCompactionCoordinator.class);
// Timeout to wait for all currently running compaction tasks to stop during compactor shutdown
private static final long SHUTDOWN_TIMEOUT_MILLIS = 60_000;
/**
* An executor service to run compaction tasks. Accessed using {@link #getCompactionExecutor()}.
*/
private static ExecutorService compactionExecutor = null;
static synchronized ExecutorService getCompactionExecutor() {
if (compactionExecutor == null) {
final MerkleDbConfig config = ConfigurationHolder.getConfigData(MerkleDbConfig.class);
compactionExecutor = new ThreadPoolExecutor(
config.compactionThreads(),
config.compactionThreads(),
50L,
TimeUnit.MILLISECONDS,
new LinkedBlockingQueue<>(),
new ThreadConfiguration(getStaticThreadManager())
.setThreadGroup(new ThreadGroup("Compaction"))
.setComponent(MERKLEDB_COMPONENT)
.setThreadName("Compacting")
.setExceptionHandler((t, ex) ->
logger.error(EXCEPTION.getMarker(), "Uncaught exception during merging", ex))
.buildFactory());
}
return compactionExecutor;
}
public static final String HASH_STORE_DISK_SUFFIX = "HashStoreDisk";
public static final String OBJECT_KEY_TO_PATH_SUFFIX = "ObjectKeyToPath";
public static final String PATH_TO_KEY_VALUE_SUFFIX = "PathToKeyValue";
private final AtomicBoolean compactionEnabled = new AtomicBoolean();
// we need a map of exactly three elements, one per storage
final ConcurrentMap> compactionFuturesByName = new ConcurrentHashMap<>(3);
private final CompactionTask objectKeyToPathTask;
private final CompactionTask hashesStoreDiskTask;
private final CompactionTask pathToKeyValueTask;
@Nullable
private final DataFileCompactor objectKeyToPath;
@Nullable
private final DataFileCompactor hashesStoreDisk;
@NonNull
private final DataFileCompactor pathToKeyValue;
// Number of compaction tasks currently running. Checked during shutdown to make sure all
// tasks are stopped
private final AtomicInteger tasksRunning = new AtomicInteger(0);
/**
* Creates a new instance of {@link MerkleDbCompactionCoordinator}.
* @param tableName the name of the table
* @param objectKeyToPath an object key to path store
* @param hashesStoreDisk a hash store
* @param pathToKeyValue a path to key-value store
*/
public MerkleDbCompactionCoordinator(
@NonNull String tableName,
@Nullable DataFileCompactor objectKeyToPath,
@Nullable DataFileCompactor hashesStoreDisk,
@NonNull DataFileCompactor pathToKeyValue) {
this.objectKeyToPath = objectKeyToPath;
this.hashesStoreDisk = hashesStoreDisk;
this.pathToKeyValue = pathToKeyValue;
if (objectKeyToPath != null) {
objectKeyToPathTask = new CompactionTask(tableName + OBJECT_KEY_TO_PATH_SUFFIX, objectKeyToPath);
} else {
objectKeyToPathTask = null;
}
if (hashesStoreDisk != null) {
hashesStoreDiskTask = new CompactionTask(tableName + HASH_STORE_DISK_SUFFIX, hashesStoreDisk);
} else {
hashesStoreDiskTask = null;
}
this.pathToKeyValueTask = new CompactionTask(tableName + PATH_TO_KEY_VALUE_SUFFIX, pathToKeyValue);
}
/**
* Compacts the object key to path store asynchronously if it's present.
*/
void compactDiskStoreForKeyToPathAsync() {
if (objectKeyToPathTask == null) {
return;
}
submitCompactionTaskForExecution(objectKeyToPathTask);
}
/**
* Compacts the hash store asynchronously if it's present.
*/
void compactDiskStoreForHashesAsync() {
if (hashesStoreDiskTask == null) {
return;
}
submitCompactionTaskForExecution(hashesStoreDiskTask);
}
/**
* Compacts the path to key-value store asynchronously.
*/
void compactPathToKeyValueAsync() {
submitCompactionTaskForExecution(pathToKeyValueTask);
}
/**
* Enables background compaction.
*/
void enableBackgroundCompaction() {
compactionEnabled.set(true);
}
/**
* Pauses compaction of all data file compactors. It may not stop compaction
* immediately, but as soon as compaction process needs to update data source state, which is
* critical for snapshots (e.g. update an index), it will be stopped until {@link
* #resumeCompaction()}} is called.
*/
public void pauseCompaction() throws IOException {
if (hashesStoreDisk != null) {
hashesStoreDisk.pauseCompaction();
}
pathToKeyValue.pauseCompaction();
if (objectKeyToPath != null) {
objectKeyToPath.pauseCompaction();
}
}
/** Resumes previously stopped data file collection compaction. */
public void resumeCompaction() throws IOException {
if (hashesStoreDisk != null) {
hashesStoreDisk.resumeCompaction();
}
pathToKeyValue.resumeCompaction();
if (objectKeyToPath != null) {
objectKeyToPath.resumeCompaction();
}
}
/**
* Stops all compactions in progress and disables background compaction.
* All subsequent calls to compacting methods will be ignored until {@link #enableBackgroundCompaction()} is called.
*/
void stopAndDisableBackgroundCompaction() {
compactionEnabled.set(false);
// Interrupt all running compaction tasks, if any
synchronized (compactionFuturesByName) {
for (var futureEntry : compactionFuturesByName.values()) {
futureEntry.cancel(true);
}
compactionFuturesByName.clear();
}
// Wait till all the tasks are stopped
final long now = System.currentTimeMillis();
try {
while ((tasksRunning.get() != 0) && (System.currentTimeMillis() - now < SHUTDOWN_TIMEOUT_MILLIS)) {
Thread.sleep(1);
}
} catch (final InterruptedException e) {
logger.warn(MERKLE_DB.getMarker(), "Interrupted while waiting for compaction tasks to complete", e);
}
// If some tasks are still running, there is nothing else to than to log it
if (tasksRunning.get() != 0) {
logger.error(MERKLE_DB.getMarker(), "Failed to stop all compactions tasks");
}
}
/**
* Submits a compaction task for execution. If a compaction task for the same storage type is already in progress,
* the call is effectively no op.
* @param task a compaction task to execute
*/
private void submitCompactionTaskForExecution(CompactionTask task) {
synchronized (compactionFuturesByName) {
if (!compactionEnabled.get()) {
return;
}
if (compactionFuturesByName.containsKey(task.id)) {
Future future = compactionFuturesByName.get(task.id);
if (future.isDone()) {
compactionFuturesByName.remove(task.id);
} else {
logger.debug(MERKLE_DB.getMarker(), "Compaction for {} is already in progress", task.id);
return;
}
}
final ExecutorService executor = getCompactionExecutor();
compactionFuturesByName.put(task.id, executor.submit(task));
}
}
boolean isCompactionEnabled() {
return compactionEnabled.get();
}
/**
* A helper class representing a task to run compaction for a specific storage type.
*/
private class CompactionTask implements Callable {
// Task ID
private final String id;
// Compactor to run
private final DataFileCompactor compactor;
public CompactionTask(@NonNull String id, @NonNull DataFileCompactor compactor) {
this.id = id;
this.compactor = compactor;
}
@Override
public Boolean call() {
tasksRunning.incrementAndGet();
try {
return compactor.compact();
} catch (final InterruptedException | ClosedByInterruptException e) {
logger.info(MERKLE_DB.getMarker(), "Interrupted while compacting, this is allowed.", e);
} catch (Exception e) {
// It is important that we capture all exceptions here, otherwise a single exception
// will stop all future merges from happening.
logger.error(EXCEPTION.getMarker(), "[{}] Compaction failed", id, e);
} finally {
tasksRunning.decrementAndGet();
}
return false;
}
}
}