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/*
 * 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.flink.runtime.state;

import org.apache.flink.util.FileUtils;

import javax.annotation.Nonnull;

import java.io.IOException;
import java.nio.file.Path;
import java.nio.file.Paths;

/**
 * This state handle represents a directory. This class is, for example, used to represent the
 * directory of RocksDB's native checkpoint directories for local recovery.
 */
public class DirectoryStateHandle implements StateObject {

    /** Serial version. */
    private static final long serialVersionUID = 1L;

    /** The path that describes the directory, as a string, to be serializable. */
    private final String directoryString;

    /** (Optional) Size of the directory, used for metrics. Can be 0 if unknown or empty. */
    private final long directorySize;

    /** Transient path cache, to avoid re-parsing the string. */
    private transient Path directory;

    public DirectoryStateHandle(@Nonnull Path directory, long directorySize) {
        this.directory = directory;
        this.directoryString = directory.toString();
        this.directorySize = directorySize;
    }

    public static DirectoryStateHandle forPathWithSize(@Nonnull Path directory) {
        long size;
        try {
            size = FileUtils.getDirectoryFilesSize(directory);
        } catch (IOException e) {
            size = 0L;
        }
        return new DirectoryStateHandle(directory, size);
    }

    @Override
    public void discardState() throws IOException {
        ensurePath();
        FileUtils.deleteDirectory(directory.toFile());
    }

    @Override
    public long getStateSize() {
        return directorySize;
    }

    @Override
    public void collectSizeStats(StateObjectSizeStatsCollector collector) {
        collector.add(StateObjectLocation.LOCAL_DISK, directorySize);
    }

    @Nonnull
    public Path getDirectory() {
        ensurePath();
        return directory;
    }

    private void ensurePath() {
        if (directory == null) {
            directory = Paths.get(directoryString);
        }
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        DirectoryStateHandle that = (DirectoryStateHandle) o;

        return directoryString.equals(that.directoryString);
    }

    @Override
    public int hashCode() {
        return directoryString.hashCode();
    }

    @Override
    public String toString() {
        return "DirectoryStateHandle{"
                + "directory='"
                + directoryString
                + '\''
                + ", directorySize="
                + directorySize
                + '}';
    }
}