jojochuang commented on code in PR #9406: URL: https://github.com/apache/ozone/pull/9406#discussion_r2600495538
########## hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/snapshot/OMSnapshotDirectoryMetrics.java: ########## @@ -0,0 +1,360 @@ +/* + * 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.hadoop.ozone.om.snapshot; + +import static org.apache.hadoop.ozone.OzoneConsts.ROCKSDB_SST_SUFFIX; +import static org.apache.hadoop.ozone.om.OMConfigKeys.OZONE_OM_SNAPSHOT_DIRECTORY_METRICS_UPDATE_INTERVAL; +import static org.apache.hadoop.ozone.om.OMConfigKeys.OZONE_OM_SNAPSHOT_DIRECTORY_METRICS_UPDATE_INTERVAL_DEFAULT; + +import com.google.common.annotations.VisibleForTesting; +import java.io.File; +import java.io.IOException; +import java.util.Collections; +import java.util.HashMap; +import java.util.Map; +import java.util.Timer; +import java.util.TimerTask; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicLong; +import java.util.concurrent.atomic.AtomicReference; +import org.apache.commons.io.FileUtils; +import org.apache.hadoop.hdds.annotation.InterfaceAudience; +import org.apache.hadoop.hdds.conf.OzoneConfiguration; +import org.apache.hadoop.hdds.utils.db.DBStore; +import org.apache.hadoop.hdds.utils.db.RDBStore; +import org.apache.hadoop.metrics2.MetricsCollector; +import org.apache.hadoop.metrics2.MetricsInfo; +import org.apache.hadoop.metrics2.MetricsSource; +import org.apache.hadoop.metrics2.MetricsSystem; +import org.apache.hadoop.metrics2.annotation.Metric; +import org.apache.hadoop.metrics2.annotation.Metrics; +import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem; +import org.apache.hadoop.metrics2.lib.MetricsRegistry; +import org.apache.hadoop.metrics2.lib.MutableGaugeLong; +import org.apache.hadoop.ozone.OzoneConsts; +import org.apache.hadoop.ozone.om.OMMetadataManager; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Metrics for tracking db.snapshots directory space usage and SST file counts. + * Provides both aggregate metrics and per-checkpoint-directory metrics. + * Metrics are updated asynchronously to avoid blocking operations. + */ [email protected] +@Metrics(about = "OM Snapshot Directory Metrics", context = OzoneConsts.OZONE) +public final class OMSnapshotDirectoryMetrics implements MetricsSource { + private static final Logger LOG = + LoggerFactory.getLogger(OMSnapshotDirectoryMetrics.class); + private static final String SOURCE_NAME = + OMSnapshotDirectoryMetrics.class.getSimpleName(); + + // Aggregate metrics + private @Metric MutableGaugeLong dbSnapshotsDirSize; + private @Metric MutableGaugeLong totalSstFilesCount; + private @Metric MutableGaugeLong numSnapshots; + + private final AtomicLong lastUpdateTime = new AtomicLong(0); + private final AtomicReference<CompletableFuture<Void>> currentUpdateFutureRef = + new AtomicReference<>(); + private final OMMetadataManager metadataManager; + private final MetricsRegistry registry = new MetricsRegistry(SOURCE_NAME); + + // Per-checkpoint-directory metrics storage + private volatile Map<String, CheckpointMetrics> checkpointMetricsMap = new HashMap<>(); + + private Timer updateTimer; + + /** + * Starts the periodic metrics update task. + * + * @param conf OzoneConfiguration for reading update interval + */ + public void start(OzoneConfiguration conf) { + long updateInterval = conf.getTimeDuration(OZONE_OM_SNAPSHOT_DIRECTORY_METRICS_UPDATE_INTERVAL, + OZONE_OM_SNAPSHOT_DIRECTORY_METRICS_UPDATE_INTERVAL_DEFAULT, + TimeUnit.MILLISECONDS); + + updateTimer = new Timer("OMSnapshotDirectoryMetricsUpdate", true); + updateTimer.schedule(new TimerTask() { + @Override + public void run() { + updateMetricsAsync(); + } + }, 0, updateInterval); + } + + /** + * Stops the periodic metrics update task. + */ + public void stop() { + if (updateTimer != null) { + updateTimer.cancel(); + updateTimer = null; + } + } + + public void unRegister() { + stop(); + MetricsSystem ms = DefaultMetricsSystem.instance(); + ms.unregisterSource(SOURCE_NAME); + } + + /** + * Internal class to store per-checkpoint metrics. + */ + private static class CheckpointMetrics { + private final long size; + private final int sstFileCount; + + CheckpointMetrics(long size, int sstFileCount) { + this.size = size; + this.sstFileCount = sstFileCount; + } + + public long getSize() { + return size; + } + + public int getSstFileCount() { + return sstFileCount; + } + } + + private OMSnapshotDirectoryMetrics(OMMetadataManager metadataManager) { + this.metadataManager = metadataManager; + } + + public static OMSnapshotDirectoryMetrics create(String parent, + OMMetadataManager metadataManager) { + MetricsSystem ms = DefaultMetricsSystem.instance(); + return ms.register(SOURCE_NAME, + parent, + new OMSnapshotDirectoryMetrics(metadataManager)); + } + + /** + * Updates all metrics (aggregate and per-checkpoint) asynchronously + * in a background thread. + */ + public void updateMetricsAsync() { + CompletableFuture<Void> currentUpdateFuture = currentUpdateFutureRef.get(); + if (currentUpdateFuture != null && !currentUpdateFuture.isDone()) { + return; + } + + CompletableFuture<Void> newFuture = CompletableFuture.runAsync(() -> { + try { + updateMetrics(); + lastUpdateTime.set(System.currentTimeMillis()); + } catch (Exception e) { + LOG.warn("Failed to update snapshot directory metrics", e); + } finally { + currentUpdateFutureRef.set(null); + } + }); + + // Atomically set the future only if the current value matches what we checked + // This prevents race conditions where multiple threads try to set a new future + CompletableFuture<Void> expected = currentUpdateFutureRef.get(); + if (expected == null || expected.isDone()) { + // Only set if still null or done (double-check after creating future) + if (!currentUpdateFutureRef.compareAndSet(expected, newFuture)) { + // Another thread set a future, cancel this one + newFuture.cancel(false); + } + } else { + // Another thread started an update, cancel this one + newFuture.cancel(false); + } + } + + /** + * Updates all metrics synchronously - both aggregate and per-checkpoint-directory. + */ + @VisibleForTesting + void updateMetrics() throws IOException { + DBStore store = metadataManager.getStore(); + if (!(store instanceof RDBStore)) { + LOG.debug("Store is not RDBStore, skipping snapshot directory metrics update"); + resetMetrics(); + return; + } + + RDBStore rdbStore = (RDBStore) store; + String snapshotsParentDir = rdbStore.getSnapshotsParentDir(); + + if (snapshotsParentDir == null) { + resetMetrics(); + return; + } + + File snapshotsDir = new File(snapshotsParentDir); + if (!snapshotsDir.exists() || !snapshotsDir.isDirectory()) { + resetMetrics(); + return; + } + + try { + // Calculate aggregate metrics + long totalSize = FileUtils.sizeOfDirectory(snapshotsDir); Review Comment: does it take into account of hard links by any chance? -- This is an automated message from the Apache Git Service. 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