de.spieleck.app.jacson.source
Class TailSource

java.lang.Object
  de.spieleck.app.jacson.PluginBase
      de.spieleck.app.jacson.source.ChunkSourceBase
          de.spieleck.app.jacson.source.TailSource

All Implemented Interfaces:

JacsonChunkSource, JacsonReporting, JacsonStately

public class TailSource

extends ChunkSourceBase

Implement a JacsonChunkSource which is continuously running and monitoring files for changes.
Note1: This works under the char = byte assumption, i.e. does not treat unicode right!
Note2: This is Java and their might be problems which are so plattform dependand, that there is no Java solutions (e.g. I do not expect this to help with lock rollovers and inodes...)

Author:

fsn

Nested Class Summary

class	TailSource.MetaThread The MetaThread enqueues the changing files
protected class	TailSource.WatchedFile Encapsulate a file with the ability to check for new bytes and a Runnable to fetch new bytes.

Field Summary

protected java.util.LinkedList	chunkQueue The queue of Chunks to be returned
protected int	deltaTime Delay between inspections of queue
static java.lang.String	JACSON_STATE_CHUNK_TYPE
protected java.lang.Thread	metaThread The thread watching ALL files for change
protected ThreadPool	threads A ThreadPool of assignments to read files.
protected TaskQueue	tQueue The threads are queued into above pool by the ThreadQueue.
protected java.util.List	watched The watched Resources
protected int	workers The number of worker Threads

Constructor Summary

TailSource()

Method Summary

void	addWatch(java.lang.String label, java.lang.String fName) Add file to be watched.
void	join() Wait for finish.
java.lang.String	message()
java.lang.String	nextChunk() Deliver a sequence of chunks (that is Strings).
void	setDeltaTime(int deltaTime) Set the delay between file checks
void	setWorkers(int workers) Set the number of workers
void	startWatching() Start watching on the files.

Methods inherited from class de.spieleck.app.jacson.PluginBase

getRegReport, getRegState, registerReport, registerState, summary

Methods inherited from class java.lang.Object

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

Methods inherited from interface de.spieleck.app.jacson.JacsonStately

registerState

Methods inherited from interface de.spieleck.app.jacson.JacsonReporting

registerReport, summary

Field Detail

JACSON_STATE_CHUNK_TYPE

public static final java.lang.String JACSON_STATE_CHUNK_TYPE

See Also:

Constant Field Values

metaThread

protected java.lang.Thread metaThread

The thread watching ALL files for change

threads

protected ThreadPool threads

A ThreadPool of assignments to read files.

tQueue

protected TaskQueue tQueue

The threads are queued into above pool by the ThreadQueue.

deltaTime

protected int deltaTime

Delay between inspections of queue

workers

protected int workers

The number of worker Threads

watched

protected java.util.List watched

The watched Resources

chunkQueue

protected java.util.LinkedList chunkQueue

The queue of Chunks to be returned

Constructor Detail

TailSource

public TailSource()

Method Detail

setWorkers

public void setWorkers(int workers)

Set the number of workers

setDeltaTime

public void setDeltaTime(int deltaTime)

Set the delay between file checks

addWatch

public void addWatch(java.lang.String label,
                     java.lang.String fName)
              throws java.io.IOException

Add file to be watched.

Throws:

java.io.IOException

startWatching

public void startWatching()

Start watching on the files. Calling this more than once will create strange results.

nextChunk

public java.lang.String nextChunk()
                           throws JacsonException

Description copied from interface: JacsonChunkSource

Deliver a sequence of chunks (that is Strings).

Returns:

The next String if available, null if sequence is finished.

Throws:

JacsonException

join

public void join()

Wait for finish. Note this is not a well defined notion, since logfiles may every grow. Therefore this method can exhibt both failes: "never return" or "return prematurely" depending on application. It was good though for the JUnit test.

message

public java.lang.String message()