Package org.pipecraft.pipes.sync.source

Class EmptyPipe<T>

java.lang.Object

org.pipecraft.pipes.sync.source.EmptyPipe<T>

Type Parameters:

T - The pipe's data type

All Implemented Interfaces:

Closeable, AutoCloseable, BasePipe, Pipe<T>

public class EmptyPipe<T>
extends Object
implements Pipe<T>

A source pipe with no data in it.

Author:

Eyal Schneider

Method Summary

Modifier and Type	Method	Description
void	close()
float	getProgress()
static <C extends Pipe<?>> C	instance()
T	next()
T	peek()
void	start()	Performs pre-processing prior to item flow throw the pipe.

Methods inherited from class java.lang.Object

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

Method Detail

instance

public static <C extends Pipe<?>> C instance()

Returns:

The empty pipe instance. Can be safely shared and re-used.

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

next

public T next()
       throws PipeException,
              InterruptedException

Specified by:

next in interface Pipe<T>

Returns:

The next item in this pipe output, or null if the output end has been reached. May be a blocking operation.

Throws:

PipeException - In case of pipe errors in this pipe or somewhere up-stream while trying to prepare next item to return.

InterruptedException - In case that the operation has been interrupted by another thread.

peek

public T peek()

Specified by:

peek in interface Pipe<T>

Returns:

The next item in the pipe's output. Does not remove it, so next call to next() will return it.

start

public void start()
           throws PipeException,
                  InterruptedException

Description copied from interface: BasePipe

Performs pre-processing prior to item flow throw the pipe. Implementations must call the same method for all their input pipes before accessing their items. This is typically done here.

Specified by:

start in interface BasePipe

Throws:

PipeException - In case of pipe errors in this pipe or somewhere up-stream.

InterruptedException - In case that the operation has been interrupted by another thread.

getProgress

public float getProgress()

Specified by:

getProgress in interface BasePipe

Returns:

The pipe flow progress, as a floating number between 0.0 and 1.0. Important implementation rules: 1) Calling this method before start() call is complete isn't allowed and has an undefined behavior. 2) Implementation should do best effort to provide an estimate of the progress this pipe has made (0.0 - 1.0) 3) When the pipe is fully consumed, getProgress() should return 1.0. 4) Results must be monotonous, i.e. results of consecutive calls may never be decreasing. 5) Thread safety: progress may be maintained by some thread/s but monitoring by other threads. Implementations must be thread safe.