com.google.mr4c.content.S3ContentFactory.java Source code

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Here is the source code for com.google.mr4c.content.S3ContentFactory.java

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/**
  * Copyright 2014 Google Inc. All rights reserved.
  * 
  * 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 com.google.mr4c.content;

import com.google.mr4c.config.category.MR4CConfig;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URI;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class S3ContentFactory extends AbstractContentFactory implements ContentFactory {

    private static Configuration s_config = new Configuration();
    private static S3Credentials s_cred;
    private String m_scheme;

    public S3ContentFactory(String scheme) {
        m_scheme = scheme;
    }

    public Path toPath(URI uri) {
        if (!uri.getScheme().equals(m_scheme)) {
            throw new IllegalArgumentException(String.format("Expecting %s URI [%s]", m_scheme, uri));
        }
        return new Path(uri);
    }

    public InputStream readContentAsStream(URI uri) throws IOException {
        Path path = toPath(uri);
        return getFileSystem(uri).open(path);
    }

    public long getContentLength(URI uri) throws IOException {
        Path path = toPath(uri);
        FileSystem fs = getFileSystem(uri);
        FileStatus file = fs.getFileStatus(path);
        return file.getLen();
    }

    public OutputStream getOutputStreamForContent(URI uri) throws IOException {
        Path path = toPath(uri);
        return getFileSystem(uri).create(path);
    }

    public void ensureParentExists(URI uri) throws IOException {
        // S3 creates directories as needed
    }

    public boolean exists(URI uri) throws IOException {
        Path path = toPath(uri);
        return getFileSystem(uri).exists(path);
    }

    public boolean deleteContent(URI uri) throws IOException {
        Path path = toPath(uri);
        return getFileSystem(uri).delete(path, false);
    }

    public static FileSystem getFileSystem(URI uri) throws IOException {
        ensureCredentials();
        return FileSystem.get(uri, s_config);
    }

    public static S3Credentials getCredentials() {
        return s_cred;
    }

    public synchronized static void setCredentials(S3Credentials cred) {
        s_cred = cred;
        cred.applyTo(s_config);
    }

    private synchronized static void ensureCredentials() {
        if (s_cred != null && s_cred.isValid()) {
            return;
        }

        S3Credentials cred = S3Credentials.extractFrom(MR4CConfig.getDefaultInstance());
        if (cred != null && cred.isValid()) {
            setCredentials(cred);
            return;
        }

        cred = S3Credentials.extractFrom(s_config);
        if (cred != null && cred.isValid()) {
            setCredentials(cred);
            return;
        }

        throw new IllegalStateException("No S3 credentials found in MR4C configuration or Hadoop configuration");

    }

}