tkalkirill commented on code in PR #3358: URL: https://github.com/apache/ignite-3/pull/3358#discussion_r1522637888
########## modules/table/src/main/java/org/apache/ignite/internal/table/distributed/LowWatermarkImpl.java: ########## @@ -0,0 +1,280 @@ +/* + * 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.ignite.internal.table.distributed; + +import static org.apache.ignite.internal.failure.FailureType.CRITICAL_ERROR; +import static org.apache.ignite.internal.util.CompletableFutures.nullCompletedFuture; +import static org.apache.ignite.internal.util.IgniteUtils.inBusyLock; + +import java.util.ArrayList; +import java.util.List; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.CopyOnWriteArrayList; +import java.util.concurrent.Executors; +import java.util.concurrent.ScheduledExecutorService; +import java.util.concurrent.ScheduledFuture; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.atomic.AtomicReference; +import org.apache.ignite.internal.failure.FailureContext; +import org.apache.ignite.internal.failure.FailureProcessor; +import org.apache.ignite.internal.hlc.HybridClock; +import org.apache.ignite.internal.hlc.HybridTimestamp; +import org.apache.ignite.internal.lang.ByteArray; +import org.apache.ignite.internal.lang.NodeStoppingException; +import org.apache.ignite.internal.logger.IgniteLogger; +import org.apache.ignite.internal.logger.Loggers; +import org.apache.ignite.internal.manager.IgniteComponent; +import org.apache.ignite.internal.schema.configuration.LowWatermarkConfiguration; +import org.apache.ignite.internal.thread.NamedThreadFactory; +import org.apache.ignite.internal.tx.TxManager; +import org.apache.ignite.internal.util.ByteUtils; +import org.apache.ignite.internal.util.IgniteSpinBusyLock; +import org.apache.ignite.internal.util.IgniteUtils; +import org.apache.ignite.internal.vault.VaultEntry; +import org.apache.ignite.internal.vault.VaultManager; +import org.jetbrains.annotations.Nullable; + +/** + * Class to manage the low watermark. + * + * <p>Low watermark is the node's local time, which ensures that read-only transactions have completed by this time, and new read-only + * transactions will only be created after this time, and we can safely delete obsolete/garbage data such as: obsolete versions of table + * rows, remote indexes, remote tables, etc. + * + * @see <a href="https://cwiki.apache.org/confluence/display/IGNITE/IEP-91%3A+Transaction+protocol";>IEP-91</a> + */ +public class LowWatermarkImpl implements IgniteComponent, LowWatermark { + private static final IgniteLogger LOG = Loggers.forClass(LowWatermarkImpl.class); + + static final ByteArray LOW_WATERMARK_VAULT_KEY = new ByteArray("low-watermark"); + + private final LowWatermarkConfiguration lowWatermarkConfig; + + private final HybridClock clock; + + private final TxManager txManager; + + private final VaultManager vaultManager; + + private final List<LowWatermarkChangedListener> updateListeners = new CopyOnWriteArrayList<>(); + + private final ScheduledExecutorService scheduledThreadPool; + + private final IgniteSpinBusyLock busyLock = new IgniteSpinBusyLock(); + + private final AtomicBoolean closeGuard = new AtomicBoolean(); + + private volatile @Nullable HybridTimestamp lowWatermark; + + private final AtomicReference<ScheduledFuture<?>> lastScheduledTaskFuture = new AtomicReference<>(); + + private final FailureProcessor failureProcessor; + + /** + * Constructor. + * + * @param nodeName Node name. + * @param lowWatermarkConfig Low watermark configuration. + * @param clock A hybrid logical clock. + * @param txManager Transaction manager. + * @param vaultManager Vault manager. + * @param failureProcessor Failure processor tha is used to handle critical errors. + */ + public LowWatermarkImpl( + String nodeName, + LowWatermarkConfiguration lowWatermarkConfig, + HybridClock clock, + TxManager txManager, + VaultManager vaultManager, + FailureProcessor failureProcessor + ) { + this.lowWatermarkConfig = lowWatermarkConfig; + this.clock = clock; + this.txManager = txManager; + this.vaultManager = vaultManager; + this.failureProcessor = failureProcessor; + + scheduledThreadPool = Executors.newSingleThreadScheduledExecutor( + NamedThreadFactory.create(nodeName, "low-watermark-updater", LOG) + ); + } + + /** + * Starts the watermark manager. + */ + @Override + public CompletableFuture<Void> start() { + inBusyLock(busyLock, () -> { + lowWatermark = readLowWatermarkFromVault(); + }); + + return nullCompletedFuture(); + } + + /** + * Schedule watermark updates. + */ + public void scheduleUpdates() { + inBusyLock(busyLock, () -> { + HybridTimestamp lowWatermarkCandidate = lowWatermark; + + if (lowWatermarkCandidate == null) { + LOG.info("Previous value of the low watermark was not found, will schedule to update it"); + + scheduleUpdateLowWatermarkBusy(); + + return; + } + + LOG.info("Low watermark has been scheduled to be updated: {}", lowWatermarkCandidate); + + txManager.updateLowWatermark(lowWatermarkCandidate) + .thenComposeAsync(unused -> inBusyLock(busyLock, () -> notifyListeners(lowWatermarkCandidate)), scheduledThreadPool) + .whenComplete((unused, throwable) -> { + if (throwable == null) { + inBusyLock(busyLock, this::scheduleUpdateLowWatermarkBusy); Review Comment: I looked at the code again, maybe this code is not needed, maybe in this method it will be enough to schedule low watermark updates and that’s it? Because each component can get a low watermark at the start and do with it whatever they want and need. What do you think? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
