java/src/main/com/google/appengine/api/files/RecordWriteChannel.java

   1 // Copyright 2011 Google Inc. All Rights Reserved.
   2
   3 package com.google.appengine.api.files;
   4
   5 import java.io.IOException;
   6 import java.nio.ByteBuffer;
   7 import java.nio.channels.WritableByteChannel;
   8
   9 /**
  10  * A {@link WritableByteChannel} for writing records to a {@link FileWriteChannel}.
  11  * <p>
  12  * The format of these records is defined by the leveldb log format:
  13  * http://leveldb.googlecode.com/svn/trunk/doc/log_format.txt
  14  * </p>
  15  * <p>
  16  * An instance of {@link RecordWriteChannel} may be obtained from the method:
  17  * {@link FileService#openRecordWriteChannel(AppEngineFile, boolean)}.
  18  * </p>
  19  * Just like {@link WritableByteChannel} If one thread initiates a write operation upon a channel
  20  * then any other thread that attempts to initiate another write operation will block until the
  21  * first operation is complete.
  22  *
  23  *
  24  */
  25 public interface RecordWriteChannel extends WritableByteChannel {
  26
  27     /**
  28      * Writes the data out to FileWriteChannel.
  29      * @see com.google.appengine.api.files.FileWriteChannel#write(ByteBuffer, String)
  30      */
  31     public int write(ByteBuffer src, String sequenceKey) throws IOException;
  32
  33     /**
  34      * Closes the file.
  35      * @see com.google.appengine.api.files.FileWriteChannel#closeFinally()
  36      */
  37     public void closeFinally() throws IllegalStateException, IOException;
  38 }