Package org.springframework.batch.support.transaction

Class TransactionAwareBufferedWriter

java.lang.Object

java.io.Writer

org.springframework.batch.support.transaction.TransactionAwareBufferedWriter

All Implemented Interfaces:

Closeable, Flushable, Appendable, AutoCloseable

public class TransactionAwareBufferedWriter
extends Writer

Wrapper for a FileChannel that delays actually writing to or closing the buffer if a transaction is active. If a transaction is detected on the call to Writer.write(String) the parameter is buffered and passed on to the underlying writer only when the transaction is committed.

Author:

Dave Syer, Michael Minella, Niels Ferguson

Field Summary

Fields inherited from class java.io.Writer

lock

Constructor Summary

Constructors

Constructor	Description
TransactionAwareBufferedWriter(FileChannel channel, Runnable closeCallback)	Create a new instance with the underlying file channel provided, and a callback to execute on close.

Method Summary

Modifier and Type	Method	Description
void	close()
void	flush()
long	getBufferSize()	Convenience method for clients to determine if there is any unflushed data.
void	setEncoding(String encoding)
void	setForceSync(boolean forceSync)	Flag to indicate that changes should be force-synced to disk on flush.
void	write(char[] cbuf, int off, int len)
void	write(String str, int off, int len)

Methods inherited from class java.io.Writer

append, append, append, nullWriter, write, write, write

Methods inherited from class java.lang.Object

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

Constructor Details

TransactionAwareBufferedWriter

public TransactionAwareBufferedWriter(FileChannel channel,
 Runnable closeCallback)

Create a new instance with the underlying file channel provided, and a callback to execute on close. The callback should clean up related resources like output streams or channels.

Parameters:

channel - channel used to do the actual file IO

closeCallback - callback to execute on close

Method Details

setEncoding

public void setEncoding(String encoding)

setForceSync

public void setForceSync(boolean forceSync)

Flag to indicate that changes should be force-synced to disk on flush. Defaults to false, which means that even with a local disk changes could be lost if the OS crashes in between a write and a cache flush. Setting to true may result in slower performance for usage patterns involving many frequent writes.

Parameters:

forceSync - the flag value to set

getBufferSize

public long getBufferSize()

Convenience method for clients to determine if there is any unflushed data.

Returns:

the current size (in bytes) of unflushed buffered data

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in class Writer

Throws:

IOException

flush

public void flush()
           throws IOException

Specified by:

flush in interface Flushable

Specified by:

flush in class Writer

Throws:

IOException

write

public void write(char[] cbuf,
 int off,
 int len)
           throws IOException

Specified by:

write in class Writer

Throws:

IOException

write

public void write(String str,
 int off,
 int len)
           throws IOException

Overrides:

write in class Writer

Throws:

IOException