Package org.apache.hadoop.fs.cosn

Class BufferPool

java.lang.Object

org.apache.hadoop.fs.cosn.BufferPool

public final class BufferPool
extends java.lang.Object

BufferPool class is used to manage the buffers during program execution. It is provided in a thread-safe singleton mode,and keeps the program's memory and disk consumption at a stable value.

Method Summary

Modifier and Type	Method	Description
ByteBufferWrapper	getBuffer(int bufferSize)	Obtain a buffer from this buffer pool through the method.
static BufferPool	getInstance()	Use this method to get the instance of BufferPool.
void	initialize(org.apache.hadoop.conf.Configuration conf)	Create buffers correctly by reading the buffer file directory, buffer pool size,and file block size in the configuration.
void	returnBuffer(ByteBufferWrapper byteBufferWrapper)	return the byte buffer wrapper to the buffer pool.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getInstance

public static BufferPool getInstance()

Use this method to get the instance of BufferPool.

Returns:

the instance of BufferPool

initialize

public void initialize(org.apache.hadoop.conf.Configuration conf)
                throws java.io.IOException

Create buffers correctly by reading the buffer file directory, buffer pool size,and file block size in the configuration.

Parameters:

conf - Provides configurations for the Hadoop runtime

Throws:

java.io.IOException - Configuration errors, insufficient or no access for memory or disk space may cause this exception

getBuffer

public ByteBufferWrapper getBuffer(int bufferSize)
                            throws java.io.IOException

Obtain a buffer from this buffer pool through the method.

Parameters:

bufferSize - expected buffer size to get

Returns:

a buffer wrapper that satisfies the bufferSize.

Throws:

java.io.IOException - if the buffer pool not initialized, or the bufferSize parameter is not within the range[1MB to the single buffer size]

returnBuffer

public void returnBuffer(ByteBufferWrapper byteBufferWrapper)
                  throws java.lang.InterruptedException,
                         java.io.IOException

return the byte buffer wrapper to the buffer pool.

Parameters:

byteBufferWrapper - the byte buffer wrapper getting from the pool

Throws:

java.lang.InterruptedException - if interrupted while waiting

java.io.IOException - some io error occurs