Example usage for org.apache.hadoop.io SecureIOUtils createForWrite

Introduction

In this page you can find the example usage for org.apache.hadoop.io SecureIOUtils createForWrite.

Prototype

public static FileOutputStream createForWrite(File f, int permissions) throws IOException 

Source Link

Document

Open the specified File for write access, ensuring that it does not exist.

Usage

From source file:it.crs4.pydoop.mapreduce.pipes.TaskLog.java

License:Apache License

private static synchronized void writeToIndexFile(String logLocation, boolean isCleanup) throws IOException {
    // To ensure atomicity of updates to index file, write to temporary index
    // file first and then rename.
    File tmpIndexFile = getTmpIndexFile(currentTaskid, isCleanup);

    BufferedOutputStream bos = new BufferedOutputStream(SecureIOUtils.createForWrite(tmpIndexFile, 0644));
    DataOutputStream dos = new DataOutputStream(bos);
    //the format of the index file is
    //LOG_DIR: <the dir where the task logs are really stored>
    //STDOUT: <start-offset in the stdout file> <length>
    //STDERR: <start-offset in the stderr file> <length>
    //SYSLOG: <start-offset in the syslog file> <length>
    try {// w ww. j  a va  2 s  .c  o  m
        dos.writeBytes(LogFileDetail.LOCATION + logLocation + "\n" + LogName.STDOUT.toString() + ":");
        dos.writeBytes(Long.toString(prevOutLength) + " ");
        dos.writeBytes(Long.toString(new File(logLocation, LogName.STDOUT.toString()).length() - prevOutLength)
                + "\n" + LogName.STDERR + ":");
        dos.writeBytes(Long.toString(prevErrLength) + " ");
        dos.writeBytes(Long.toString(new File(logLocation, LogName.STDERR.toString()).length() - prevErrLength)
                + "\n" + LogName.SYSLOG.toString() + ":");
        dos.writeBytes(Long.toString(prevLogLength) + " ");
        dos.writeBytes(Long.toString(new File(logLocation, LogName.SYSLOG.toString()).length() - prevLogLength)
                + "\n");
        dos.close();
        dos = null;
    } finally {
        IOUtils.cleanup(LOG, dos);
    }

    File indexFile = getIndexFile(currentTaskid, isCleanup);
    Path indexFilePath = new Path(indexFile.getAbsolutePath());
    Path tmpIndexFilePath = new Path(tmpIndexFile.getAbsolutePath());

    if (localFS == null) {// set localFS once
        localFS = FileSystem.getLocal(new Configuration());
    }
    localFS.rename(tmpIndexFilePath, indexFilePath);
}

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