com.bigdata.service

Class EventReceiver

java.lang.Object

com.bigdata.service.EventReceiver

All Implemented Interfaces:

IEventReceivingService, IEventReportingService, Remote

Direct Known Subclasses:

DummyEventReportingService

public class EventReceiver
extends Object
implements IEventReceivingService, IEventReportingService

Class capable of receiving Events from remote services. Start events are maintained in a cache until their corresponding end event is received at which point they are propagated to an EventReceiver.EventBTree which is used for reporting purposes.

Author:

Bryan Thompson

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	EventReceiver.EventBTree A BTree whose keys are event start times and whose values are the serialized Events.

Field Summary

Fields

Modifier and Type	Field and Description
protected LinkedHashMap<UUID,Event>	eventCache Basically a ring buffer of events without a capacity limit and with random access by the event UUID.
protected long	eventHistoryMillis The maximum age of an Event that will be keep "on the books".
protected static org.apache.log4j.Logger	log Logs Events in a tab-delimited format @ INFO.
protected UnisolatedReadWriteIndex	ndx The completed events are removed from the eventCache and written onto the #eventBTree.

Constructor Summary

Constructors

Constructor and Description
EventReceiver(long eventHistoryMillis, EventReceiver.EventBTree eventBTree)

Method Summary

Methods

Modifier and Type	Method and Description
Lock	getWriteLock() Return the write lock for the EventReceiver.EventBTree.
protected void	logEvent(Event e) Logs the completed event using a tab-delimited format @ INFO on log.
void	notifyEvent(Event e) Accepts the event, either updates the existing event with the same UUID or adds the event to the set of recent events, and then prunes the set of recent events so that all completed events older than eventHistoryMillis are discarded.
protected void	pruneHistory(long now) Any completed events which are older (LT) than the cutoff point (now - eventHistoryMillis} are discarded.
long	rangeCount(long fromTime, long toTime) Reports the #of completed events that start in the given interval.
Iterator<Event>	rangeIterator(long fromTime, long toTime) Visits completed events that start in the given interval in order by their start time.

Methods inherited from class java.lang.Object

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

Field Detail

log

protected static final transient org.apache.log4j.Logger log

Logs Events in a tab-delimited format @ INFO.

Note: If you enable more detailed logging (DEBUG, etc). then that will get mixed up with your tab-delimited events log and you may have to filter it out before you can process the events log analytically.

eventHistoryMillis

protected final long eventHistoryMillis

The maximum age of an Event that will be keep "on the books". Events older than this are purged.

eventCache

protected final LinkedHashMap<UUID,Event> eventCache

Basically a ring buffer of events without a capacity limit and with random access by the event UUID. New events are added to the collection by notifyEvent(Event). That method also scans the head of the collection, purging any events that are older than the desired #of minutes of event history to retain.

Since this is a "linked" collection, the order of the events in the collection will always reflect their arrival time. This lets us scan the events in temporal order, filtering for desired criteria and makes it possible to prune the events in the buffer as new events arrive.

ndx

protected final UnisolatedReadWriteIndex ndx

The completed events are removed from the eventCache and written onto the #eventBTree. This is done in order to get the events out of memory and onto disk and to decouple the IEventReceivingService from the IEventReportingService.

Constructor Detail

EventReceiver

public EventReceiver(long eventHistoryMillis,
             EventReceiver.EventBTree eventBTree)

Parameters:

eventHistoryMillis - The maximum age of an Event that will be keep "on the books". Events older than this are purged. An error is logged if an event is purged before its end() event arrives. This generally indicates a code path where Event.end() is not getting called but could also indicate a disconnected client or service.

eventStore - A BTree used to record the completed events and to implement the IEventReportingService interface.

Method Detail

getWriteLock

public Lock getWriteLock()

Return the write lock for the EventReceiver.EventBTree.

notifyEvent

public void notifyEvent(Event e)
                 throws IOException

Accepts the event, either updates the existing event with the same UUID or adds the event to the set of recent events, and then prunes the set of recent events so that all completed events older than eventHistoryMillis are discarded.

An error is logged if an event is purged before its end() event arrives. This generally indicates a code path where Event.end() is not getting called but could also indicate a disconnected client or service.

Specified by:

notifyEvent in interface IEventReceivingService

Throws:

IOException

pruneHistory

protected void pruneHistory(long now)

Any completed events which are older (LT) than the cutoff point (now - eventHistoryMillis} are discarded.

logEvent

protected void logEvent(Event e)

Logs the completed event using a tab-delimited format @ INFO on log. Generally, log should be directed to a file for post-mortem analysis of the events, e.g., by importing the file into a worksheet, using a pivot table, etc.

rangeCount

public long rangeCount(long fromTime,
              long toTime)

Description copied from interface: IEventReportingService

Reports the #of completed events that start in the given interval.

Specified by:

rangeCount in interface IEventReportingService

Parameters:

fromTime - The first start time to be included.

toTime - The first start time to be excluded.

Returns:

The #of events whose start time is in that interval.

rangeIterator

public Iterator<Event> rangeIterator(long fromTime,
                            long toTime)

Description copied from interface: IEventReportingService

Visits completed events that start in the given interval in order by their start time.

Specified by:

rangeIterator in interface IEventReportingService