tkalkirill commented on code in PR #1938: URL: https://github.com/apache/ignite-3/pull/1938#discussion_r1169589001
########## modules/table/src/main/java/org/apache/ignite/internal/table/distributed/LowWatermarkManager.java: ########## @@ -0,0 +1,234 @@ +/* + * 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.util.IgniteUtils.inBusyLock; + +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.close.ManuallyCloseable; +import org.apache.ignite.internal.hlc.HybridClock; +import org.apache.ignite.internal.hlc.HybridTimestamp; +import org.apache.ignite.internal.logger.IgniteLogger; +import org.apache.ignite.internal.logger.Loggers; +import org.apache.ignite.internal.schema.configuration.LowWatermarkConfiguration; +import org.apache.ignite.internal.table.distributed.gc.MvGc; +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.VaultManager; +import org.apache.ignite.lang.ByteArray; +import org.apache.ignite.lang.NodeStoppingException; +import org.jetbrains.annotations.Nullable; + +/** + * Class to manage the low watermark. + */ +public class LowWatermarkManager implements ManuallyCloseable { + private static final IgniteLogger LOG = Loggers.forClass(LowWatermarkManager.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 MvGc mvGc; + + private final ScheduledExecutorService scheduledThreadPool; + + private final IgniteSpinBusyLock busyLock = new IgniteSpinBusyLock(); + + private final AtomicBoolean closeGuard = new AtomicBoolean(); + + private final AtomicReference<HybridTimestamp> lowWatermark = new AtomicReference<>(); + + private final AtomicReference<ScheduledFuture<?>> lastScheduledTaskFuture = new AtomicReference<>(); + + /** + * Constructor. + * + * @param nodeName Node name. + * @param lowWatermarkConfig Low watermark configuration. + * @param clock A hybrid logical clock. + * @param txManager Transaction manager. + * @param vaultManager Vault manager. + */ + public LowWatermarkManager( + String nodeName, + LowWatermarkConfiguration lowWatermarkConfig, + HybridClock clock, + TxManager txManager, + VaultManager vaultManager, + MvGc mvGc + ) { + this.lowWatermarkConfig = lowWatermarkConfig; + this.clock = clock; + this.txManager = txManager; + this.vaultManager = vaultManager; + this.mvGc = mvGc; + + scheduledThreadPool = Executors.newSingleThreadScheduledExecutor( + NamedThreadFactory.create(nodeName, "low-watermark-updater", LOG) + ); + } + + /** + * Starts the watermark manager. + */ + public void start() { + inBusyLock(busyLock, () -> { + vaultManager.get(LOW_WATERMARK_VAULT_KEY) + .thenApply(vaultEntry -> inBusyLock(busyLock, () -> { + if (vaultEntry == null) { + scheduleUpdateLowWatermarkBusy(); + + return null; + } + + HybridTimestamp lowWatermark = ByteUtils.fromBytes(vaultEntry.value()); + + this.lowWatermark.set(lowWatermark); + + runGcAndScheduleUpdateLowWatermarkBusy(lowWatermark); + + return lowWatermark; + })) + .whenComplete((lowWatermark, throwable) -> { + if (throwable != null) { + if (!(throwable instanceof NodeStoppingException)) { + LOG.error("Error getting low watermark", throwable); + + // TODO: IGNITE-16899 Perhaps we need to fail the node by FailureHandler + } + } else { + LOG.info( + "Low watermark has been successfully got from the vault and is scheduled to be updated: {}", + lowWatermark + ); + } + }); + }); + } + + @Override + public void close() throws Exception { + if (!closeGuard.compareAndSet(false, true)) { + return; + } + + busyLock.block(); + + ScheduledFuture<?> lastScheduledTaskFuture = this.lastScheduledTaskFuture.get(); + + if (lastScheduledTaskFuture != null) { + lastScheduledTaskFuture.cancel(true); + } + + IgniteUtils.shutdownAndAwaitTermination(scheduledThreadPool, 10, TimeUnit.SECONDS); + } + + /** + * Returns the current low watermark, {@code null} means no low watermark has been assigned yet. + */ + public @Nullable HybridTimestamp getLowWatermark() { + return lowWatermark.get(); + } + + void updateLowWatermark() { + inBusyLock(busyLock, () -> { Review Comment: I use 2 implementations with `Runnable` and `Supplier`, I think that it is not so fundamentally important to create internal methods for these purposes. -- This is an automated message from the Apache Git Service. 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