Package org.osgi.util.pushstream

Class ThresholdPushbackPolicy<T,U extends BlockingQueue<PushEvent<? extends T>>>

java.lang.Object

org.osgi.util.pushstream.ThresholdPushbackPolicy<T,U>

Type Parameters:

T - The type of objects in the PushEvent

U - The type of the Queue used in the user specified buffer

All Implemented Interfaces:

PushbackPolicy<T,U>

public final class ThresholdPushbackPolicy<T,U extends BlockingQueue<PushEvent<? extends T>>>
extends Object
implements PushbackPolicy<T,U>

Provides a configurable PushbackPolicy implementation that returns zero back pressure until the buffer fills beyond the supplied threshold. Once the threshold is reached back pressure is returned based on the supplied parameters.

The starting level of the back pressure once the threshold is exceeded is defined using the initial parameter. Additional back pressure is applied for each queued item over the threshold. The amount of this additional back pressure is defined by the increment parameter.

The following common use cases are supported:

• The increment size can be zero, returning the initial value as a fixed back pressure after the threshold is exceeded.
• The initial value can be zero, returning a linearly increasing back pressure from zero once the threshold is exceeded

Since:

1.1

Method Summary

Modifier and Type	Method	Description
static <T, U extends BlockingQueue<PushEvent<? extends T>>> ThresholdPushbackPolicy<T,U>	createIncrementalThresholdPushbackPolicy(int threshold, long increment)	A simple configuration, where the increment size is used as the initial back pressure.
static <T, U extends BlockingQueue<PushEvent<? extends T>>> ThresholdPushbackPolicy<T,U>	createSimpleThresholdPushbackPolicy(int threshold)	A simple configuration with an initial back pressure of one and and increase increment size of one.
static <T, U extends BlockingQueue<PushEvent<? extends T>>> ThresholdPushbackPolicy<T,U>	createThresholdPushbackPolicy(int threshold, long initial, long increment)	Provides a ThresholdPushbackPolicy with an individual configuration for all possible parameters.
long	pushback(U queue)	Given the current state of the queue, determine the level of back pressure that should be applied

Methods inherited from class java.lang.Object

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

Method Details

createSimpleThresholdPushbackPolicy

public static <T,
U extends BlockingQueue<PushEvent<? extends T>>>
ThresholdPushbackPolicy<T,U> createSimpleThresholdPushbackPolicy(int threshold)

A simple configuration with an initial back pressure of one and and increase increment size of one.

Parameters:

threshold - the queue size limit after which back pressure will be applied

Returns:

a new ThresholdPushbackPolicy

Throws:

IllegalArgumentException - if any of the given values is lower then zero

See Also:

• createThresholdPushbackPolicy(int threshold, long initial, long increment)

createIncrementalThresholdPushbackPolicy

public static <T,
U extends BlockingQueue<PushEvent<? extends T>>>
ThresholdPushbackPolicy<T,U> createIncrementalThresholdPushbackPolicy(int threshold,
 long increment)

A simple configuration, where the increment size is used as the initial back pressure.

Parameters:

increment - the increments in which the pressure increases

threshold - the queue size limit after which back pressure will be applied

Returns:

a new ThresholdPushbackPolicy

Throws:

IllegalArgumentException - if any of the given values is lower then zero

See Also:

• createThresholdPushbackPolicy(int threshold, long initial, long increment)

createThresholdPushbackPolicy

public static <T,
U extends BlockingQueue<PushEvent<? extends T>>>
ThresholdPushbackPolicy<T,U> createThresholdPushbackPolicy(int threshold,
 long initial,
 long increment)

Provides a ThresholdPushbackPolicy with an individual configuration for all possible parameters.

Parameters:

increment - the increments in which the pressure increases.

initial - the initial back pressure which defines the floor after the threshold is exceeded

threshold - the queue size limit after which back pressure will be applied

Returns:

a new ThresholdPushbackPolicy

Throws:

IllegalArgumentException - if any of the given values is lower then zero

pushback

public long pushback(U queue)
              throws Exception

Description copied from interface: PushbackPolicy

Given the current state of the queue, determine the level of back pressure that should be applied

Specified by:

pushback in interface PushbackPolicy<T,U extends BlockingQueue<PushEvent<? extends T>>>

Returns:

a back pressure value in nanoseconds

Throws:

Exception