org.jenkinsci.remoting.nio

Class FifoBuffer

java.lang.Object

org.jenkinsci.remoting.nio.FifoBuffer

All Implemented Interfaces:

Closeable, AutoCloseable

public class FifoBuffer
extends Object
implements Closeable

FIFO buffer for a reader thread and a writer thread to collaborate. Unlike a ring buffer, which uses a fixed memory regardless of the number of bytes currently in the buffer, this implementation uses a single linked list to reduce the memory footprint when the reader closely follows the writer, regardless of the capacity limit set in the constructor. In trilead, the writer puts the data we receive from the network, and the user code acts as a reader. A user code normally drains the buffer more quickly than what the network delivers, so this implementation saves memory while simultaneously allowing us to advertise a bigger window size for a large latency network.

Since:

2.38

Author:

Kohsuke Kawaguchi

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FifoBuffer.CloseCause Explains the reason of the buffer close.

Constructor Summary

Constructors

Constructor and Description
FifoBuffer(int limit)
FifoBuffer(int pageSize, int limit)
FifoBuffer(Object lock, int pageSize, int limit)

Method Summary

Modifier and Type	Method and Description
void	close() Indicates that there will be no more write.
FifoBuffer.CloseCause	getCloseCause() Returns Exception with stacktrace of the command, which invoked the buffer close.
InputStream	getInputStream() Wraps the reader end of it to InputStream
OutputStream	getOutputStream() Wraps writer end of it to OutputStream.
boolean	isClosed() Returns true if the write end of the buffer is already closed, and that no more new data will arrive.
int	peek(int offset, byte[] data)
int	peek(int offset, byte[] data, int start, int len) Peek the specified number of bytes (len) at the specified offset in this buffer (offset) and places it into the specified position (start) of the array (data)
int	read(byte[] buf)
int	read(byte[] buf, int start, int len)
int	readable() Number of bytes available in this buffer that are readable.
int	readNonBlocking(byte[] buf)
int	readNonBlocking(byte[] buf, int start, int len)
int	receive(ReadableByteChannel ch) Read bytes from a channel and stores it into this buffer.
int	send(WritableByteChannel ch) Read from this buffer write as much as possible to the channel until the channel gets filled up.
void	setLimit(int newLimit) Set limit to the number of maximum bytes this buffer can hold.
int	writable() Number of bytes writable.
void	write(byte[] buf)
void	write(byte[] buf, int start, int len)
int	writeNonBlock(ByteBuffer buf) Non-blocking write.

Methods inherited from class java.lang.Object

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

Constructor Detail

FifoBuffer

public FifoBuffer(int pageSize,
                  int limit)

FifoBuffer

public FifoBuffer(int limit)

FifoBuffer

public FifoBuffer(Object lock,
                  int pageSize,
                  int limit)

Method Detail

setLimit

public void setLimit(int newLimit)

Set limit to the number of maximum bytes this buffer can hold. Write methods will block if the size reaches the limit.

readable

public int readable()

Number of bytes available in this buffer that are readable.

Returns:

-1 if the buffer is closed and there's no more data to read. May return non-negative value if the buffer close is requested, but not performed

writable

@Nonnegative
public int writable()

Number of bytes writable.

Returns:

Number of bytes we can write to the buffer. If the buffer is closed, may return the value beyond the limit (JENKINS-37514)

isClosed

public boolean isClosed()

Returns true if the write end of the buffer is already closed, and that no more new data will arrive. Note that there still might be a data left in the buffer to be read. The method may also return true when the close operation is actually requested.

getCloseCause

@CheckForNull
public FifoBuffer.CloseCause getCloseCause()

Returns Exception with stacktrace of the command, which invoked the buffer close.

Returns:

Close cause or null

Since:

3.3

send

public int send(WritableByteChannel ch)
         throws IOException

Read from this buffer write as much as possible to the channel until the channel gets filled up.

Returns:

number of bytes that were written. -1 if this buffer is EOF-ed and there will never be any more data to write.

Throws:

IOException

writeNonBlock

public int writeNonBlock(ByteBuffer buf)

Non-blocking write.

Returns:

Number of writes written, possibly 0.

receive

public int receive(ReadableByteChannel ch)
            throws IOException

Read bytes from a channel and stores it into this buffer.

Returns:

number of bytes read, or -1 if the given channel has reached EOF and no further read is possible.

Throws:

IOException - receive error

write

public void write(byte[] buf)
           throws InterruptedException,
                  IOException

Throws:

InterruptedException

IOException

write

public void write(byte[] buf,
                  int start,
                  int len)
           throws InterruptedException,
                  IOException

Throws:

InterruptedException

IOException

close

public void close()

Indicates that there will be no more write. Once the remaining bytes are drained by the reader, the read method will start returning EOF signals.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

peek

public int peek(int offset,
                byte[] data,
                int start,
                int len)

Peek the specified number of bytes (len) at the specified offset in this buffer (offset) and places it into the specified position (start) of the array (data)

Returns:

number of bytes actually peeked. Can be 0 if the offset goes beyond the current readable size in this buffer. Never negative.

peek

public int peek(int offset,
                byte[] data)

read

public int read(byte[] buf)
         throws InterruptedException

Throws:

InterruptedException

read

public int read(byte[] buf,
                int start,
                int len)
         throws InterruptedException

Throws:

InterruptedException

See Also:

InputStream.read(byte[],int,int)

readNonBlocking

public int readNonBlocking(byte[] buf)

readNonBlocking

public int readNonBlocking(byte[] buf,
                           int start,
                           int len)

See Also:

InputStream.read(byte[],int,int)

getOutputStream

public OutputStream getOutputStream()

Wraps writer end of it to OutputStream.

getInputStream

public InputStream getInputStream()

Wraps the reader end of it to InputStream