Package com.wavefront.agent.queueing

Interface TaskQueue<T extends DataSubmissionTask<T>>

Type Parameters:

T - type of objects stored.

All Superinterfaces:

Iterable<T>

All Known Implementing Classes:

FileBasedTaskQueue, InMemorySubmissionQueue, InstrumentedTaskQueueDelegate, SQSSubmissionQueue, TaskQueueStub

public interface TaskQueue<T extends DataSubmissionTask<T>>
extends Iterable<T>

Proxy-specific queue interface, which is basically a wrapper for a Tape queue. This allows us to potentially support more than one backing storage in the future.

Author:

[email protected].

Method Summary

Modifier and Type	Method	Description
void	add(T entry)	Add a task to the end of the queue
void	clear()	Empty and re-initialize the queue.
void	close()	Close the queue.
Long	getAvailableBytes()	Returns the total number of pre-allocated but unused bytes in the backing file.
T	peek()	Retrieve a task that is currently at the head of the queue.
void	remove()	Remove a task from the head of the queue.
int	size()	Returns a number of tasks currently in the queue.
Long	weight()	Returns the total weight of the queue (sum of weights of all tasks).

Methods inherited from interface java.lang.Iterable

forEach, iterator, spliterator

Method Detail

peek

@Nullable
T peek()

Retrieve a task that is currently at the head of the queue.

Returns:

task object

add

void add(@Nonnull
         T entry)
  throws IOException

Add a task to the end of the queue

Parameters:

entry - task

Throws:

IOException - IO exceptions caught by the storage engine

remove

void remove()
     throws IOException

Remove a task from the head of the queue. Requires peek() to be called first, otherwise an IllegalStateException is thrown.

Throws:

IOException - IO exceptions caught by the storage engine

clear

void clear()
    throws IOException

Empty and re-initialize the queue.

Throws:

IOException

size

int size()

Returns a number of tasks currently in the queue.

Returns:

number of tasks

close

void close()
    throws IOException

Close the queue. Should be invoked before a graceful shutdown.

Throws:

IOException

weight

@Nullable
Long weight()

Returns the total weight of the queue (sum of weights of all tasks).

Returns:

weight of the queue (null if unknown)

getAvailableBytes

@Nullable
Long getAvailableBytes()

Returns the total number of pre-allocated but unused bytes in the backing file. May return null if not applicable.

Returns:

total number of available bytes in the file or null