org.dataone.cn.batch.logging.type

Class ReadEventCounterCache

java.lang.Object

org.dataone.cn.batch.logging.type.ReadEventCounterCache

public class ReadEventCounterCache
extends Object

The ReadEventCounterCache is used for detecting "double-clicks" by a user, as defined by Project Counter (see page 7 of https://www.projectcounter.org/wp-content/uploads/2016/03/Technical-pdf.pdf) The default constructor uses the Project Counter standard of 30 seconds to detect double-clicks, but provides a parameterized constructor for flexibility and testing purposes.

The cache is specifically designed to be self-pruning by removing events older than the double-click window from the cache when a newer event is added. In order to be self-pruning, it depends on new etnries to be added in chronological order, but does not enforce it. The method isLaterOrSameAsLatestCachedTime is provided for users wishing to take action on out-of-order even entry.

Cache pruning is improved over the naive implementation by maintenance of a housekeeping map structure organized by DateTime to eliminate the need to search for items to remove, as well as limiting pruning to when later log entries are encountered (although millisecond precision of times might limit the usefulness of this approach)

Author:

rnahf

Field Summary

Fields

Modifier and Type	Field and Description
protected Map<String,org.joda.time.DateTime>	idMap
static int	STANDARD_COUNTER_INTERVAL_PDF
protected Map<org.joda.time.DateTime,HashSet<String>>	timeMap

Constructor Summary

Constructors

Constructor and Description
ReadEventCounterCache() Creates a ReadEventCounterCache with the standard double-click window of 30 seconds.
ReadEventCounterCache(int timeWindowSeconds) Creates a ReadEventCounterCache with the specified double-click / repeatVisit time window.

Method Summary

Modifier and Type	Method and Description
boolean	contains(String eventKey) A method to determine if an eventKey is present in the cache.
boolean	isLaterOrSameAsLatestCachedTime(org.joda.time.DateTime testValue) Useful for checking that log Entries are being processed in chronological order.
boolean	isRepeatVisit(String eventKey, org.joda.time.DateTime value) Used to determine if an event is a repeatVisit.
int	pruneOutdatedCacheEntries() Removes items from the cache that are more than the configured seconds older than the latest time in the cache.
void	putEvent(String eventKey, org.joda.time.DateTime value) Puts a read event into the cache, with the same add / replace semantics as Map.put.
int	size() gets the number of IDs in the Cache

Methods inherited from class java.lang.Object

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

Field Detail

idMap

protected Map<String,org.joda.time.DateTime> idMap

timeMap

protected Map<org.joda.time.DateTime,HashSet<String>> timeMap

STANDARD_COUNTER_INTERVAL_PDF

public static final int STANDARD_COUNTER_INTERVAL_PDF

See Also:

Constant Field Values

Constructor Detail

ReadEventCounterCache

public ReadEventCounterCache()

Creates a ReadEventCounterCache with the standard double-click window of 30 seconds.

ReadEventCounterCache

public ReadEventCounterCache(int timeWindowSeconds)

Creates a ReadEventCounterCache with the specified double-click / repeatVisit time window.

Parameters:

timeWindowSeconds -

Method Detail

size

public int size()

gets the number of IDs in the Cache

Returns:

contains

public boolean contains(String eventKey)

A method to determine if an eventKey is present in the cache.

Parameters:

eventKey -

Returns:

isLaterOrSameAsLatestCachedTime

public boolean isLaterOrSameAsLatestCachedTime(org.joda.time.DateTime testValue)

Useful for checking that log Entries are being processed in chronological order.

Parameters:

testValue -

Returns:

isRepeatVisit

public boolean isRepeatVisit(String eventKey,
                             org.joda.time.DateTime value)

Used to determine if an event is a repeatVisit. Does not change the cache.

Parameters:

eventKey -

value -

Returns:

putEvent

public void putEvent(String eventKey,
                     org.joda.time.DateTime value)

Puts a read event into the cache, with the same add / replace semantics as Map.put. Updates housekeeping structures and triggers cache cleanup if the time value is later than exists in the cache.

Parameters:

eventKey -

value -

pruneOutdatedCacheEntries

public int pruneOutdatedCacheEntries()

Removes items from the cache that are more than the configured seconds older than the latest time in the cache.

Returns:

the number of items pruned