com.squareup.tape

Class FileObjectQueue<T>

java.lang.Object

com.squareup.tape.FileObjectQueue<T>

Type Parameters:

T - The type of elements in the queue.

All Implemented Interfaces:

ObjectQueue<T>

public class FileObjectQueue<T>
extends Object
implements ObjectQueue<T>

Base queue class, implements common functionality for a QueueFile-backed queue manager. This class is not thread safe; instances should be kept thread-confined.

The add( Object ), peek(), remove(), and setListener(ObjectQueue.Listener) methods may throw a FileException if the underlying QueueFile experiences an IOException.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	FileObjectQueue.Converter<T> Convert a byte stream to and from a concrete type.

Nested classes/interfaces inherited from interface com.squareup.tape.ObjectQueue

ObjectQueue.Listener<T>

Constructor Summary

Constructors

Constructor and Description
FileObjectQueue(File file, FileObjectQueue.Converter<T> converter)

Method Summary

Modifier and Type	Method and Description
void	add(T entry) Enqueues an entry that can be processed at any time.
List<T>	asList()
void	close()
T	peek() Returns the head of the queue, or null if the queue is empty.
List<T>	peek(int max) Reads up to max entries from the head of the queue without removing the entries.
void	remove() Removes the head of the queue.
void	remove(int n)
void	setListener(ObjectQueue.Listener<T> listener) Sets a listener on this queue.
int	size() Returns the number of entries in the queue.

Methods inherited from class java.lang.Object

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

Constructor Detail

FileObjectQueue

public FileObjectQueue(File file,
                       FileObjectQueue.Converter<T> converter)
                throws IOException

Throws:

IOException

Method Detail

size

public int size()

Description copied from interface: ObjectQueue

Returns the number of entries in the queue.

Specified by:

size in interface ObjectQueue<T>

add

public final void add(T entry)

Description copied from interface: ObjectQueue

Enqueues an entry that can be processed at any time.

Specified by:

add in interface ObjectQueue<T>

peek

public T peek()

Description copied from interface: ObjectQueue

Returns the head of the queue, or null if the queue is empty. Does not modify the queue.

Specified by:

peek in interface ObjectQueue<T>

peek

public List<T> peek(int max)

Reads up to max entries from the head of the queue without removing the entries. If the queue's size() is less than max then only size() entries are read.

asList

public List<T> asList()

remove

public final void remove()

Description copied from interface: ObjectQueue

Removes the head of the queue.

Specified by:

remove in interface ObjectQueue<T>

remove

public final void remove(int n)
                  throws IOException

Throws:

IOException

close

public final void close()

setListener

public void setListener(ObjectQueue.Listener<T> listener)

Description copied from interface: ObjectQueue

Sets a listener on this queue. Invokes ObjectQueue.Listener.onAdd(com.squareup.tape.ObjectQueue<T>, T) once for each entry that's already in the queue. If an error occurs while reading the data, the listener will not receive further notifications.

Specified by:

setListener in interface ObjectQueue<T>