org.apache.solr.cloud

Class DistributedQueue

java.lang.Object

org.apache.solr.cloud.DistributedQueue

Direct Known Subclasses:

OverseerTaskQueue

public class DistributedQueue
extends Object

A distributed queue. Optimized for single-consumer, multiple-producer: if there are multiple consumers on the same ZK queue, the results should be correct but inefficient

Constructor Summary

Constructors

Constructor and Description
DistributedQueue(SolrZkClient zookeeper, String dir)
DistributedQueue(SolrZkClient zookeeper, String dir, Overseer.Stats stats)

Method Summary

Modifier and Type	Method and Description
Overseer.Stats	getStats()
void	offer(byte[] data) Inserts data into queue.
byte[]	peek() Returns the data at the first element of the queue, or null if the queue is empty.
byte[]	peek(boolean block) Returns the data at the first element of the queue, or null if the queue is empty and block is false.
byte[]	peek(long wait) Returns the data at the first element of the queue, or null if the queue is empty after wait ms.
byte[]	poll() Attempts to remove the head of the queue and return it.
byte[]	remove() Attempts to remove the head of the queue and return it.
byte[]	take() Removes the head of the queue and returns it, blocks until it succeeds.

Methods inherited from class java.lang.Object

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

Constructor Detail

DistributedQueue

public DistributedQueue(SolrZkClient zookeeper,
                        String dir)

DistributedQueue

public DistributedQueue(SolrZkClient zookeeper,
                        String dir,
                        Overseer.Stats stats)

Method Detail

peek

public byte[] peek()
            throws org.apache.zookeeper.KeeperException,
                   InterruptedException

Returns the data at the first element of the queue, or null if the queue is empty.

Returns:

data at the first element of the queue, or null.

Throws:

org.apache.zookeeper.KeeperException

InterruptedException

peek

public byte[] peek(boolean block)
            throws org.apache.zookeeper.KeeperException,
                   InterruptedException

Returns the data at the first element of the queue, or null if the queue is empty and block is false.

Parameters:

block - if true, blocks until an element enters the queue

Returns:

data at the first element of the queue, or null.

Throws:

org.apache.zookeeper.KeeperException

InterruptedException

peek

public byte[] peek(long wait)
            throws org.apache.zookeeper.KeeperException,
                   InterruptedException

Returns the data at the first element of the queue, or null if the queue is empty after wait ms.

Parameters:

wait - max wait time in ms.

Returns:

data at the first element of the queue, or null.

Throws:

org.apache.zookeeper.KeeperException

InterruptedException

poll

public byte[] poll()
            throws org.apache.zookeeper.KeeperException,
                   InterruptedException

Attempts to remove the head of the queue and return it. Returns null if the queue is empty.

Returns:

Head of the queue or null.

Throws:

org.apache.zookeeper.KeeperException

InterruptedException

remove

public byte[] remove()
              throws NoSuchElementException,
                     org.apache.zookeeper.KeeperException,
                     InterruptedException

Attempts to remove the head of the queue and return it.

Returns:

The former head of the queue

Throws:

NoSuchElementException

org.apache.zookeeper.KeeperException

InterruptedException

take

public byte[] take()
            throws org.apache.zookeeper.KeeperException,
                   InterruptedException

Removes the head of the queue and returns it, blocks until it succeeds.

Returns:

The former head of the queue

Throws:

org.apache.zookeeper.KeeperException

InterruptedException

offer

public void offer(byte[] data)
           throws org.apache.zookeeper.KeeperException,
                  InterruptedException

Inserts data into queue. Successfully calling this method does NOT guarantee that the element will be immediately available in the in-memory queue. In particular, calling this method on an empty queue will not necessarily cause poll() to return the offered element. Use a blocking method if you must wait for the offered element to become visible.

Throws:

org.apache.zookeeper.KeeperException

InterruptedException

getStats

public Overseer.Stats getStats()