vaijosh commented on code in PR #3081: URL: https://github.com/apache/hugegraph/pull/3081#discussion_r3666446417
########## hugegraph-store/hg-store-common/src/main/java/org/apache/hugegraph/store/cloud/CloudStorageProviderFactory.java: ########## @@ -0,0 +1,212 @@ +/* + * 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.hugegraph.store.cloud; + +import java.io.IOException; +import java.util.Map; +import java.util.ServiceLoader; +import java.util.concurrent.ConcurrentHashMap; + +import lombok.Getter; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Factory for {@link CloudStorageProvider} instances. + * + * <p>Providers are discovered at class-loading time via {@link ServiceLoader}. + * Any JAR that includes + * {@code META-INF/services/org.apache.hugegraph.store.cloud.CloudStorageProvider} + * is automatically picked up when it is present on the classpath. + * + * <p>Usage: + * <pre> + * CloudStorageConfig cfg = ...; // populated from application.yml + * CloudStorageProvider provider = CloudStorageProviderFactory.initialize(cfg); + * // later: + * CloudStorageProvider active = CloudStorageProviderFactory.getActiveProvider(); + * </pre> + */ +public final class CloudStorageProviderFactory { + + private static final Logger log = LoggerFactory.getLogger(CloudStorageProviderFactory.class); + + /** All discovered providers keyed by {@link CloudStorageProvider#providerName()}. */ + private static final Map<String, CloudStorageProvider> REGISTRY = new ConcurrentHashMap<>(); + + /** The currently active (initialized) provider; null when disabled or not yet initialized. + * -- GETTER -- + * Returns the currently active provider, or + * if cloud storage is + * disabled or + * has not yet been called. + */ + @Getter + private static volatile CloudStorageProvider activeProvider; + + static { + loadProviders(); + } + + private CloudStorageProviderFactory() { + } + + // ----------------------------------------------------------------------- + // Public API + // ----------------------------------------------------------------------- + + /** + * Initializes and activates the cloud storage provider described by {@code config}. + * + * <p>The method is idempotent: if called multiple times, the existing active + * provider is closed before a new one is initialized. + * + * @param config cloud storage configuration + * @return the initialized provider, or {@code null} when + * {@link CloudStorageConfig#isEnabled()} is {@code false} + * @throws IllegalArgumentException if no provider matching {@code config.getProvider()} + * was found on the classpath + */ + public static synchronized CloudStorageProvider initialize(CloudStorageConfig config) { + if (!config.isEnabled()) { + // Disabling cloud storage must deactivate any currently active provider: otherwise a Review Comment: Addressed in latest commit ########## hugegraph-store/hg-store-rocksdb/src/main/java/org/apache/hugegraph/rocksdb/access/RocksDBSession.java: ########## @@ -693,6 +764,70 @@ public void saveSnapshot(String snapshotPath) throws DBStoreException { System.currentTimeMillis() - startTime); } + /** + * Captures a consistent copy of this DB's metadata (CURRENT / MANIFEST-* / OPTIONS-* / WAL) plus + * hard-links to the live SST set into a temporary directory, using a RocksDB + * {@link Checkpoint}. See {@link RocksDBFactory#captureMetadataSnapshot(String)} for the metadata + * rationale. + * + * <p>The temporary directory is a sibling of the DB directory (same filesystem), so SST files + * are hard-linked rather than copied. The caller owns cleanup via + * {@link RocksDBFactory.MetadataSnapshot#cleanup()}. + * + * @return the captured snapshot; never {@code null} + * @throws DBStoreException if the checkpoint cannot be created + */ + RocksDBFactory.MetadataSnapshot captureMetadataCheckpoint() throws DBStoreException { + String tempDir = this.dbPath + "_cloudmeta_" + System.nanoTime(); + cfHandleLock.readLock().lock(); + try (final Checkpoint checkpoint = Checkpoint.create(this.rocksDB)) { + final File tempFile = new File(tempDir); + // Clean any stale temp checkpoint dir from a previous failed/interrupted attempt. + // If it exists, RocksDB checkpoint creation can fail on pre-existing files. + FileUtils.deleteDirectory(tempFile); + checkpoint.createCheckpoint(tempDir); + } catch (final Exception e) { + try { + FileUtils.deleteDirectory(new File(tempDir)); + } catch (IOException ignore) { + // best-effort cleanup of a partial checkpoint + } + log.error("Fail to create metadata checkpoint at {}", tempDir, e); + throw new DBStoreException( + String.format("Fail to create metadata checkpoint at %s", tempDir)); Review Comment: Addressed in latest commit -- This is an automated message from the Apache Git Service. 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