org.apache.flink.streaming.api.windowing.policy

Class TimeEvictionPolicy<DATA>

java.lang.Object

org.apache.flink.streaming.api.windowing.policy.TimeEvictionPolicy<DATA>

Type Parameters:

DATA - The type of the incoming data points which are processed by this policy.

All Implemented Interfaces:

Serializable, Cloneable, ActiveEvictionPolicy<DATA>, CloneableEvictionPolicy<DATA>, EvictionPolicy<DATA>

public class TimeEvictionPolicy<DATA>
extends Object
implements ActiveEvictionPolicy<DATA>, CloneableEvictionPolicy<DATA>

This eviction policy evicts all elements which are older then a specified time. The time is measured using a given Timestamp implementation. A point in time is always represented as long. Therefore, the granularity can be set as long value as well.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
TimeEvictionPolicy(long granularity, TimestampWrapper<DATA> timestampWrapper) This eviction policy evicts all elements which are older than a specified time.

Method Summary

Modifier and Type	Method and Description
TimeEvictionPolicy<DATA>	clone() This method should return an exact copy of the object it belongs to including the current object state.
boolean	equals(Object other)
TimestampWrapper<DATA>	getTimeStampWrapper()
long	getWindowSize()
int	notifyEviction(DATA datapoint, boolean triggered, int bufferSize) Proves if and how many elements should be deleted from the element buffer.
int	notifyEvictionWithFakeElement(Object datapoint, int bufferSize) Proves if and how many elements should be deleted from the element buffer.
String	toString()

Methods inherited from class java.lang.Object

finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

TimeEvictionPolicy

public TimeEvictionPolicy(long granularity,
                          TimestampWrapper<DATA> timestampWrapper)

This eviction policy evicts all elements which are older than a specified time. The time is measured using a given Timestamp implementation. A point in time is always represented as long. Therefore, the granularity can be set as long value as well. If this value is set to 2 the policy will evict all elements which are older as 2. while (time(firstInBuffer)

Parameters:

granularity - The granularity of the eviction. If this value is set to 2 the policy will evict all elements which are older as 2(if (time(X)

timestampWrapper - The TimestampWrapper to measure the time with. This can be either user defined of provided by the API.

Method Detail

notifyEvictionWithFakeElement

public int notifyEvictionWithFakeElement(Object datapoint,
                                         int bufferSize)

Description copied from interface: ActiveEvictionPolicy

Proves if and how many elements should be deleted from the element buffer. The eviction takes place after the trigger and after the call to the UDF. This method is only called with fake elements. Note: Fake elements are always considered as triggered. Therefore this method does not have a triggered parameter.

Specified by:

notifyEvictionWithFakeElement in interface ActiveEvictionPolicy<DATA>

Parameters:

datapoint - the current fake data point

bufferSize - the current size of the buffer (only real elements are counted)

Returns:

the number of elements to delete from the buffer (only real elements are counted)

notifyEviction

public int notifyEviction(DATA datapoint,
                          boolean triggered,
                          int bufferSize)

Description copied from interface: EvictionPolicy

Proves if and how many elements should be deleted from the element buffer. The eviction takes place after the trigger and after the call to the UDF but before the adding of the new data point.

Specified by:

notifyEviction in interface EvictionPolicy<DATA>

Parameters:

datapoint - data point the data point which arrived

triggered - Information whether the UDF was triggered or not

bufferSize - The current size of the element buffer at the operator

Returns:

The number of elements to be deleted from the buffer

clone

public TimeEvictionPolicy<DATA> clone()

Description copied from interface: CloneableEvictionPolicy

This method should return an exact copy of the object it belongs to including the current object state.

Specified by:

clone in interface CloneableEvictionPolicy<DATA>

Overrides:

clone in class Object

Returns:

a copy of this object

equals

public boolean equals(Object other)

Overrides:

equals in class Object

getWindowSize

public long getWindowSize()

toString

public String toString()

Overrides:

toString in class Object

getTimeStampWrapper

public TimestampWrapper<DATA> getTimeStampWrapper()