Package org.apache.hadoop.ipc

Class FairCallQueue<E extends Schedulable>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractQueue<E>

org.apache.hadoop.ipc.FairCallQueue<E>

All Implemented Interfaces:

Iterable<E>, Collection<E>, BlockingQueue<E>, Queue<E>

public class FairCallQueue<E extends Schedulable>
extends AbstractQueue<E>
implements BlockingQueue<E>

A queue with multiple levels for each priority.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	IPC_CALLQUEUE_PRIORITY_LEVELS_DEFAULT	Deprecated.
static final String	IPC_CALLQUEUE_PRIORITY_LEVELS_KEY	Deprecated.
static final org.slf4j.Logger	LOG

Constructor Summary

Constructors

Constructor	Description
FairCallQueue(int priorityLevels, int capacity, String ns, boolean serverFailOverEnabled, Configuration conf)
FairCallQueue(int priorityLevels, int capacity, String ns, int[] capacityWeights, boolean serverFailOverEnabled, Configuration conf)	Create a FairCallQueue.
FairCallQueue(int priorityLevels, int capacity, String ns, Configuration conf)

Method Summary

Modifier and Type	Method	Description
boolean	add(E e)	Add, put, and offer follow the same pattern: 1.
int	drainTo(Collection<? super E> c)
int	drainTo(Collection<? super E> c, int maxElements)	drainTo defers to each sub-queue.
long[]	getOverflowedCalls()
int[]	getQueueSizes()
boolean	isServerFailOverEnabled()
Iterator<E>	iterator()	Iterator is not implemented, as it is not needed.
boolean	offer(E e)
boolean	offer(E e, long timeout, TimeUnit unit)
E	peek()	Peek, like poll, provides no strict consistency.
E	poll()	poll() provides no strict consistency: it is possible for poll to return null even though an element is in the queue.
E	poll(long timeout, TimeUnit unit)
void	put(E e)
int	remainingCapacity()	Returns maximum remaining capacity.
void	setMultiplexer(RpcMultiplexer newMux)
int	size()	Size returns the sum of all sub-queue sizes, so it may be greater than capacity.
E	take()

Methods inherited from class java.util.AbstractQueue

addAll, clear, element, remove

Methods inherited from class java.util.AbstractCollection

contains, containsAll, isEmpty, remove, removeAll, retainAll, toArray, toArray, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.concurrent.BlockingQueue

contains, remove

Methods inherited from interface java.util.Collection

addAll, clear, containsAll, equals, hashCode, isEmpty, parallelStream, removeAll, removeIf, retainAll, spliterator, stream, toArray, toArray, toArray

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface java.util.Queue

element, remove

Field Details

IPC_CALLQUEUE_PRIORITY_LEVELS_DEFAULT

@Deprecated
public static final int IPC_CALLQUEUE_PRIORITY_LEVELS_DEFAULT

Deprecated.

See Also:

• Constant Field Values

IPC_CALLQUEUE_PRIORITY_LEVELS_KEY

@Deprecated
public static final String IPC_CALLQUEUE_PRIORITY_LEVELS_KEY

Deprecated.

See Also:

• Constant Field Values

LOG

public static final org.slf4j.Logger LOG

Constructor Details

FairCallQueue

@VisibleForTesting
public FairCallQueue(int priorityLevels,
 int capacity,
 String ns,
 Configuration conf)

FairCallQueue

@VisibleForTesting
public FairCallQueue(int priorityLevels,
 int capacity,
 String ns,
 boolean serverFailOverEnabled,
 Configuration conf)

FairCallQueue

public FairCallQueue(int priorityLevels,
 int capacity,
 String ns,
 int[] capacityWeights,
 boolean serverFailOverEnabled,
 Configuration conf)

Create a FairCallQueue.

Parameters:

priorityLevels - the total size of all multi-level queue priority policies

capacity - the total size of all sub-queues

ns - the prefix to use for configuration

capacityWeights - the weights array for capacity allocation among subqueues

serverFailOverEnabled - whether or not to enable callqueue overflow trigger failover for stateless servers when RPC call queue is filled

conf - the configuration to read from Notes: Each sub-queue has a capacity of `capacity / numSubqueues`. The first or the highest priority sub-queue has an excess capacity of `capacity % numSubqueues`

Method Details

add

public boolean add(E e)

Add, put, and offer follow the same pattern: 1. Get the assigned priorityLevel from the call by scheduler 2. Get the nth sub-queue matching this priorityLevel 3. delegate the call to this sub-queue. But differ in how they handle overflow: - Add will move on to the next queue, throw on last queue overflow - Put will move on to the next queue, block on last queue overflow - Offer does not attempt other queues on overflow

Specified by:

add in interface BlockingQueue<E extends Schedulable>

Specified by:

add in interface Collection<E extends Schedulable>

Specified by:

add in interface Queue<E extends Schedulable>

Overrides:

add in class AbstractQueue<E extends Schedulable>

put

public void put(E e)
         throws InterruptedException

Specified by:

put in interface BlockingQueue<E extends Schedulable>

Throws:

InterruptedException

offer

public boolean offer(E e,
 long timeout,
 TimeUnit unit)
              throws InterruptedException

Specified by:

offer in interface BlockingQueue<E extends Schedulable>

Throws:

InterruptedException

offer

public boolean offer(E e)

Specified by:

offer in interface BlockingQueue<E extends Schedulable>

Specified by:

offer in interface Queue<E extends Schedulable>

take

public E take()
       throws InterruptedException

Specified by:

take in interface BlockingQueue<E extends Schedulable>

Throws:

InterruptedException

poll

public E poll(long timeout,
 TimeUnit unit)
       throws InterruptedException

Specified by:

poll in interface BlockingQueue<E extends Schedulable>

Throws:

InterruptedException

poll

public E poll()

poll() provides no strict consistency: it is possible for poll to return null even though an element is in the queue.

Specified by:

poll in interface Queue<E extends Schedulable>

peek

public E peek()

Peek, like poll, provides no strict consistency.

Specified by:

peek in interface Queue<E extends Schedulable>

size

public int size()

Size returns the sum of all sub-queue sizes, so it may be greater than capacity. Note: size provides no strict consistency, and should not be used to control queue IO.

Specified by:

size in interface Collection<E extends Schedulable>

Specified by:

size in class AbstractCollection<E extends Schedulable>

iterator

public Iterator<E> iterator()

Iterator is not implemented, as it is not needed.

Specified by:

iterator in interface Collection<E extends Schedulable>

Specified by:

iterator in interface Iterable<E extends Schedulable>

Specified by:

iterator in class AbstractCollection<E extends Schedulable>

drainTo

public int drainTo(Collection<? super E> c,
 int maxElements)

drainTo defers to each sub-queue. Note that draining from a FairCallQueue to another FairCallQueue will likely fail, since the incoming calls may be scheduled differently in the new FairCallQueue. Nonetheless this method is provided for completeness.

Specified by:

drainTo in interface BlockingQueue<E extends Schedulable>

drainTo

public int drainTo(Collection<? super E> c)

Specified by:

drainTo in interface BlockingQueue<E extends Schedulable>

remainingCapacity

public int remainingCapacity()

Returns maximum remaining capacity. This does not reflect how much you can ideally fit in this FairCallQueue, as that would depend on the scheduler's decisions.

Specified by:

remainingCapacity in interface BlockingQueue<E extends Schedulable>

getQueueSizes

public int[] getQueueSizes()

getOverflowedCalls

public long[] getOverflowedCalls()

setMultiplexer

@VisibleForTesting
public void setMultiplexer(RpcMultiplexer newMux)

isServerFailOverEnabled

@VisibleForTesting
public boolean isServerFailOverEnabled()