net.sf.lucis.core.impl.FSStore.java Source code

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Here is the source code for net.sf.lucis.core.impl.FSStore.java

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/*
 * Copyright (C) the original author or authors.
 *
 * Licensed 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 net.sf.lucis.core.impl;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

import net.derquinse.common.io.DurableFiles;
import net.sf.lucis.core.Checkpoint;
import net.sf.lucis.core.Store;
import net.sf.lucis.core.StoreException;

import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;

import com.google.common.io.ByteSource;

/**
 * File system-based store.
 * @author Andres Rodriguez
 * @param <T> Checkpoint type.
 */
public class FSStore<T> extends AbstractStore implements Store<T> {
    /** Name of the control file. */
    private static final String CONTROL_FILE = "checkpoint.ctl";
    /** Directory that contains de index. */
    private final File file;
    /** Control file. */
    private final File control;
    /** Index store. */
    private final FSDirectory directory;
    /** Checkpoint serializer. */
    private final Checkpoint<T> serializer;

    public FSStore(final Checkpoint<T> serializer, final String indexDir) {
        checkNotNull(serializer, "A checkpoint serializer must be provided.");
        this.serializer = serializer;
        try {
            this.file = new File(indexDir);
            checkArgument(file.exists() && file.isDirectory(), "Invalid index directory");
            this.control = new File(file, CONTROL_FILE);
            checkArgument(!control.isDirectory(), "Control file cannot be a directory");
            this.directory = FSDirectory.open(file);
        } catch (IOException e) {
            throw new StoreException(e);
        }
    }

    public Directory getDirectory() {
        return directory;
    }

    private void close(Closeable closeable) {
        if (closeable == null) {
            return;
        }
        try {
            closeable.close();
        } catch (IOException ioe) {
        }
    }

    public T getCheckpoint() {
        if (!control.exists()) {
            return null;
        }
        try {
            final FileInputStream stream = new FileInputStream(control);
            try {
                return serializer.read(stream);
            } finally {
                close(stream);
            }
        } catch (FileNotFoundException fnfe) {
            // Nothing.
        } catch (IOException e) {
            throw new StoreException(e);
        }
        return null;
    }

    public void setCheckpoint(T checkpoint) {
        byte[] data;
        try {
            final ByteArrayOutputStream bos = new ByteArrayOutputStream(256);
            serializer.write(checkpoint, bos);
            data = bos.toByteArray();
            DurableFiles.copy(ByteSource.wrap(data), control);
        } catch (IOException e) {
            throw new StoreException(e);
        } finally {
            changed();
        }
    }

    public Object getVersion() {
        try {
            return getCheckpoint();
        } catch (StoreException e) {
            return null;
        }
    }

    @Override
    public String toString() {
        return "FSStore[" + file.getAbsolutePath() + "]";
    }

}