frankgh commented on code in PR #357: URL: https://github.com/apache/cassandra-sidecar/pull/357#discussion_r3307382125
########## server/src/main/java/org/apache/cassandra/sidecar/configmanagement/FileBasedConfigurationProvider.java: ########## @@ -0,0 +1,139 @@ +/* + * 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.cassandra.sidecar.configmanagement; + +import java.io.IOException; +import java.io.UncheckedIOException; +import java.nio.charset.StandardCharsets; +import java.nio.file.Files; +import java.nio.file.Path; +import java.nio.file.StandardCopyOption; +import java.util.Objects; +import java.util.concurrent.ConcurrentHashMap; + +import io.vertx.core.json.JsonObject; +import org.apache.cassandra.sidecar.cluster.instance.InstanceMetadata; +import org.jetbrains.annotations.NotNull; +import org.jetbrains.annotations.Nullable; + +/** + * File-based implementation of {@link ConfigurationProvider} that persists configuration + * overlays as JSON files within a configuration store directory. + * + * <p>Each instance's overlay is stored at {@code {configDir}/{instanceId}/overlay.json}. + * Writes are atomic (write to temp file, then rename) to prevent corruption from crashes. + * + * <p>Concurrency is handled via {@link ConcurrentHashMap#compute}, which provides per-key + * mutual exclusion. + */ +public class FileBasedConfigurationProvider implements ConfigurationProvider +{ + private static final String CONFIG_FILE_NAME = "overlay.json"; + + private final Path configDir; + private final ConcurrentHashMap<Integer, ConfigurationOverlaySnapshot> overlays = new ConcurrentHashMap<>(); + + public FileBasedConfigurationProvider(Path configDir) + { + this.configDir = Objects.requireNonNull(configDir, "configDir must not be null"); + } + + @Override + @Nullable + public ConfigurationOverlaySnapshot getOverlay(InstanceMetadata instance) + { + return readFromDisk(instance); + } + + @Override + public boolean storeOverlay(InstanceMetadata instance, + @Nullable String originalHash, + @NotNull ConfigurationOverlaySnapshot newSnapshot) + { + Objects.requireNonNull(newSnapshot, "newSnapshot must not be null"); + return overlays.compute(instance.id(), (k, cached) -> { + ConfigurationOverlaySnapshot current = cached != null ? cached : readFromDisk(instance); + + if (current == null && originalHash != null) + { + return null; + } + + if (current != null && (originalHash == null || !current.hash().equals(originalHash))) + { + return current; + } + + writeToDisk(instance, newSnapshot); + return newSnapshot; + }) == newSnapshot; Review Comment: Can we avoid as much as possible perform IO here? ```suggestion boolean storeOverlay = overlays.compute(instance.id(), (k, cached) -> { ConfigurationOverlaySnapshot current = cached != null ? cached : readFromDisk(instance); if (current == null && originalHash != null) { return null; } if (current != null && (originalHash == null || !current.hash().equals(originalHash))) { return current; } return newSnapshot; }) == newSnapshot; if (storeOverlay) { writeToDisk(instance, newSnapshot); } return storeOverlay; ``` -- 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] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
