FileMessageReader.java

/*
 * Copyright 2015-2016 Providence Authors
 *
 * 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 net.morimekta.providence.logging;

import net.morimekta.providence.PMessage;
import net.morimekta.providence.PServiceCall;
import net.morimekta.providence.descriptor.PMessageDescriptor;
import net.morimekta.providence.descriptor.PService;
import net.morimekta.providence.serializer.Serializer;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

/**
 * A message reader that reads from a single file until the end.
 */
public class FileMessageReader implements MessageReader {
    private final File       file;
    private final Serializer serializer;

    private InputStream in;

    /**
     * Create the file message reader.
     *
     * @param file The file to be read.
     * @param serializer The serializer to use.
     */
    public FileMessageReader(File file, Serializer serializer) {
        this.file = file;
        this.serializer = serializer;
    }

    @Override
    public <Message extends PMessage<Message>>
    Message read(PMessageDescriptor<Message> descriptor)
            throws IOException {
        return serializer.deserialize(getInputStream(), descriptor);
    }

    @Override
    public <Message extends PMessage<Message>>
    PServiceCall<Message> read(PService service) throws IOException {
        return serializer.deserialize(getInputStream(), service);
    }

    @Override
    public void verifyEndOfContent() throws IOException {
        if (in != null) {
            try {
                serializer.verifyEndOfContent(in);
            } finally {
                in = null;
            }
        }
    }

    @Override
    public void close() throws IOException {
        if (in != null) {
            try {
                in.close();
            } finally {
                in = null;
            }
        }
    }

    private InputStream getInputStream() throws FileNotFoundException {
        if (in == null) {
            in = new BufferedInputStream(new FileInputStream(file));
        }
        return in;
    }
}