org.vishia.util

Class PipeRingBuffer

java.lang.Object

org.vishia.util.PipeRingBuffer

All Implemented Interfaces:

java.lang.Appendable

public class PipeRingBuffer
extends java.lang.Object
implements java.lang.Appendable

This class is a RingBuffer which can use as pipe. Typical applications are thread-intercommunication. Therefore the routines of this class are thread-safe.

In opposite to PipedReader and PipedWriter this class contains a method to read a line: getLine(char[]). It is similar BufferedReader. In opposite to Pipe this class deals with simple Appendable, not with that channels. It may be more simple for application.

The pipe holds characters in a buffer. The buffer will be filled with the append(CharSequence, int, int) or offer(CharSequence, int, int) and read out with getLine(char[]). The buffer may have a larger size, for example more as 1 MByte to hold larger data. The storing of characters is organized in a ring strucuture.

• The offer(CharSequence, int, int) routine does never block, it returns false if there is no space in the buffer. But on writing its data it synchronizes with this class to prevent inconsistent data.
• The append methods blocks if there is no space until any other thread has read out enough data.
• The getLine(char[]) method checks whether at least on char is in the Buffer. If the buffer is emtpy, it returns -1. If the buffer is not empty, it expects that a line may be found, because it may be presumed that other threads writes whole lines. But it is possible that another thread has written only a part of a line with append(CharSequence). In this case the other thread should work to complete. Therefore this thread waits 20 milliseconds, enough time for thread switch, and tries to complete the line. If this thread has a higher priority and the writing thread is very low, all other threads should work too. Only in that case the reading thread finishes its wait, try again, wait again etc.
• The get(Appendable, String) does never wait. But it synchronized to prevent inconsistent data.

Field Summary

Fields

Modifier and Type	Field and Description
private char[]	buffer
private int	posr
private int	posw
static java.lang.String	sVersion Version, history and license.
private int	zchars

Constructor Summary

Constructors

Constructor and Description
PipeRingBuffer(int buffersize)

Method Summary

Modifier and Type	Method and Description
java.lang.Appendable	append(char c)
java.lang.Appendable	append(java.lang.CharSequence csq)
java.lang.Appendable	append(java.lang.CharSequence csq, int start, int end)
int	get(java.lang.Appendable dst, java.lang.String charsBreak) Gets the available number of characters from Buffer till any of the charsBreak are found.
(package private) int	getLine(char[] dst)
boolean	offer(java.lang.CharSequence csq, int from, int to)
int	skip(java.lang.String charsBreak) Skips over all characters which are member of charsBreak

Methods inherited from class java.lang.Object

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

Field Detail

sVersion

public static final java.lang.String sVersion

Version, history and license.

• not ready yet!
• 2013-12-31 Hartmut new

Copyright/Copyleft: For this source the LGPL Lesser General Public License, published by the Free Software Foundation is valid. It means:

1. You can use this source without any restriction for any desired purpose.
2. You can redistribute copies of this source to everybody.
3. Every user of this source, also the user of redistribute copies with or without payment, must accept this license for further using.
4. But the LPGL is not appropriate for a whole software product, if this source is only a part of them. It means, the user must publish this part of source, but don't need to publish the whole source of the own product.
5. You can study and modify (improve) this source for own using or for redistribution, but you have to license the modified sources likewise under this LGPL Lesser General Public License. You mustn't delete this Copyright/Copyleft inscription in this source file.

If you are intent to use this sources without publishing its usage, you can get a second license subscribing a special contract with the author.

See Also:

Constant Field Values

buffer

private final char[] buffer

posw

private int posw

posr

private int posr

zchars

private int zchars

Constructor Detail

PipeRingBuffer

public PipeRingBuffer(int buffersize)

Method Detail

append

public java.lang.Appendable append(java.lang.CharSequence csq)
                            throws java.io.IOException

Specified by:

append in interface java.lang.Appendable

Throws:

java.io.IOException

offer

public boolean offer(java.lang.CharSequence csq,
                     int from,
                     int to)

append

public java.lang.Appendable append(char c)
                            throws java.io.IOException

Specified by:

append in interface java.lang.Appendable

Throws:

java.io.IOException

append

public java.lang.Appendable append(java.lang.CharSequence csq,
                                   int start,
                                   int end)
                            throws java.io.IOException

Specified by:

append in interface java.lang.Appendable

Throws:

java.io.IOException

getLine

int getLine(char[] dst)

get

public int get(java.lang.Appendable dst,
               java.lang.String charsBreak)

Gets the available number of characters from Buffer till any of the charsBreak are found.

Parameters:

dst -

charsBreak -

Returns:

0 if the buffer has not characters to read. It is empty.
>0 if a charsBreak is reached,
<0 if some chars are read, but a charsBreak is not found till end of buffer.

skip

public int skip(java.lang.String charsBreak)

Skips over all characters which are member of charsBreak

Parameters:

charsBreak - Characters to skip, for example "\r\n" to skip over both newline or return.

Returns:

the number of skipped characters.