com.squareup.tape2

Class ObjectQueue<T>

java.lang.Object

com.squareup.tape2.ObjectQueue<T>

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, java.lang.Iterable<T>

public abstract class ObjectQueue<T>
extends java.lang.Object
implements java.lang.Iterable<T>, java.io.Closeable

A queue of objects.

Nested Class Summary

Nested Classes

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

Constructor Summary

Constructors

Constructor and Description
ObjectQueue()

Method Summary

Modifier and Type	Method and Description
abstract void	add(T entry) Enqueues an entry that can be processed at any time.
java.util.List<T>	asList() Returns the entries in the queue as an unmodifiable List.
void	clear() Clears this queue.
static <T> ObjectQueue<T>	create(QueueFile qf, ObjectQueue.Converter<T> converter) A queue for objects that are atomically and durably serialized to file.
static <T> ObjectQueue<T>	createInMemory() A queue for objects that are not serious enough to be written to disk.
abstract QueueFile	file() The underlying QueueFile backing this queue, or null if it's only in memory.
boolean	isEmpty() Returns true if this queue contains no entries.
abstract T	peek() Returns the head of the queue, or null if the queue is empty.
java.util.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.
abstract void	remove(int n) Removes n entries from the head of the queue.
abstract 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

Methods inherited from interface java.lang.Iterable

forEach, iterator, spliterator

Methods inherited from interface java.io.Closeable

close

Constructor Detail

ObjectQueue

public ObjectQueue()

Method Detail

create

public static <T> ObjectQueue<T> create(QueueFile qf,
                                        ObjectQueue.Converter<T> converter)

A queue for objects that are atomically and durably serialized to file.

createInMemory

public static <T> ObjectQueue<T> createInMemory()

A queue for objects that are not serious enough to be written to disk. Objects in this queue are kept in memory and will not be serialized.

file

@Nullable
public abstract QueueFile file()

The underlying QueueFile backing this queue, or null if it's only in memory.

size

public abstract int size()

Returns the number of entries in the queue.

isEmpty

public boolean isEmpty()

Returns true if this queue contains no entries.

add

public abstract void add(T entry)
                  throws java.io.IOException

Enqueues an entry that can be processed at any time.

Throws:

java.io.IOException

peek

@Nullable
public abstract T peek()
                          throws java.io.IOException

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

Throws:

java.io.IOException

peek

public java.util.List<T> peek(int max)
                       throws java.io.IOException

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.

Throws:

java.io.IOException

asList

public java.util.List<T> asList()
                         throws java.io.IOException

Returns the entries in the queue as an unmodifiable List.

Throws:

java.io.IOException

remove

public void remove()
            throws java.io.IOException

Removes the head of the queue.

Throws:

java.io.IOException

remove

public abstract void remove(int n)
                     throws java.io.IOException

Removes n entries from the head of the queue.

Throws:

java.io.IOException

clear

public void clear()
           throws java.io.IOException

Clears this queue. Also truncates the file to the initial size.

Throws:

java.io.IOException