com.cloudera.flume.handlers.hdfs.SeqfileEventSource.java Source code

Introduction

Here is the source code for com.cloudera.flume.handlers.hdfs.SeqfileEventSource.java

Source

/**
 * Licensed to Cloudera, Inc. under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  Cloudera, Inc. 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 com.cloudera.flume.handlers.hdfs;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.SequenceFile;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.cloudera.flume.conf.Context;
import com.cloudera.flume.conf.FlumeConfiguration;
import com.cloudera.flume.conf.SourceFactory.SourceBuilder;
import com.cloudera.flume.core.Event;
import com.cloudera.flume.core.EventSource;
import com.google.common.base.Preconditions;

/**
 * This is an iterator for a sequence file.
 */
public class SeqfileEventSource extends EventSource.Base {
    static final Logger LOG = LoggerFactory.getLogger(SeqfileEventSource.class);

    private String fname;
    private SequenceFile.Reader reader;

    public SeqfileEventSource(String fname) {
        this.fname = fname;
    }

    /**
     * We assume that the file is local.
     */
    static public SeqfileEventSource openLocal(String fname) throws IOException {
        SeqfileEventSource src = new SeqfileEventSource(fname);
        src.open();
        return src;
    }

    public Event next() throws IOException {
        Preconditions.checkNotNull(reader);
        WriteableEventKey k = new WriteableEventKey();
        WriteableEvent e = new WriteableEvent();

        boolean ok = reader.next(k, e);

        if (!ok)
            return null;

        Event evt = e.getEvent();
        updateEventProcessingStats(evt);
        return evt;
    }

    @Override
    public void close() throws IOException {
        LOG.debug("closing SeqfileEventSource " + fname);
        if (reader == null) {
            return;
        }
        reader.close();
        reader = null;
    }

    @Override
    public void open() throws IOException {
        LOG.debug("opening SeqfileEventSource " + fname);
        Configuration conf = FlumeConfiguration.get();
        FileSystem fs = FileSystem.getLocal(conf);
        reader = new SequenceFile.Reader(fs, new Path(fname), conf);
    }

    @Override
    public String toString() {
        return "SeqfileEventSource name=" + fname;
    }

    public static SourceBuilder builder() {
        return new SourceBuilder() {

            @Override
            public EventSource build(Context ctx, String... argv) {
                if (argv.length != 1) {
                    throw new IllegalArgumentException("usage: seqfile(filename)");
                }

                return new SeqfileEventSource(argv[0]);
            }

        };
    }

}