Package com.wavefront.agent.queueing

Interface QueueFile

All Superinterfaces:

AutoCloseable, Closeable, Iterable<byte[]>

All Known Implementing Classes:

ConcurrentQueueFile, ConcurrentShardedQueueFile, TapeQueueFile

public interface QueueFile
extends Closeable, Iterable<byte[]>

Proxy-specific FIFO queue interface for storing byte[]. This allows us to potentially support multiple backing storages in the future.

Author:

[email protected]

Method Summary

Modifier and Type	Method	Description
default void	add(byte[] data)	Adds an element to the end of the queue.
void	add(byte[] data, int offset, int count)	Adds an element to the end of the queue.
long	availableBytes()	Returns the number of bytes available for adding new tasks without growing the file.
void	clear()	Clears this queue.
default boolean	isEmpty()	Checks whether this queue is empty.
byte[]	peek()	Reads the eldest element.
void	remove()	Removes the eldest element.
int	size()	Returns the number of elements in this queue.
long	storageBytes()	Returns the storage size (on-disk file size) in bytes.
long	usedBytes()	Returns the number of bytes used for data.

Methods inherited from interface java.io.Closeable

close

Methods inherited from interface java.lang.Iterable

forEach, iterator, spliterator

Method Detail

add

default void add(byte[] data)
          throws IOException

Adds an element to the end of the queue.

Parameters:

data - to copy bytes from

Throws:

IOException

add

void add(byte[] data,
         int offset,
         int count)
  throws IOException

Adds an element to the end of the queue.

Parameters:

data - to copy bytes from

offset - to start from in buffer

count - number of bytes to copy

Throws:

IndexOutOfBoundsException - if offset < 0 or count < 0, or if offset + count is bigger than the length of buffer.

IOException

clear

void clear()
    throws IOException

Clears this queue. Truncates the file to the initial size.

Throws:

IOException

isEmpty

default boolean isEmpty()

Checks whether this queue is empty.

Returns:

true if this queue contains no entries

peek

@Nullable
byte[] peek()
     throws IOException

Reads the eldest element. Returns null if the queue is empty.

Returns:

the eldest element.

Throws:

IOException

remove

void remove()
     throws IOException

Removes the eldest element.

Throws:

NoSuchElementException - if the queue is empty

IOException

size

int size()

Returns the number of elements in this queue.

storageBytes

long storageBytes()

Returns the storage size (on-disk file size) in bytes.

Returns:

file size in bytes.

usedBytes

long usedBytes()

Returns the number of bytes used for data.

Returns:

bytes used.

availableBytes

long availableBytes()

Returns the number of bytes available for adding new tasks without growing the file.

Returns:

bytes available.