ca.odell.glazedlists.matchers
Class ThreadedMatcherEditor<E>
- MatcherEditor<E>
public class ThreadedMatcherEditor<E>
A MatcherEditor which decorates a source MatcherEditor with functionality.
Specifically, this MatcherEditor is meant to act as a buffer for
MatcherEvents to smooth out disparities between the rate at which
MatcherEvents are produced by the source MatcherEditor and the rate at
which they are consumed by registered MatcherEditorListeners.
Internally, a
ThreadedMatcherEditor
enqueues MatcherEvents as they
they are received from the source MatcherEditor. The MatcherEvents on the
queue are fired by another Thread as rapidly as the MatcherEditorListeners
can consume them. Two methods exist on this class which enable subclasses
to customize aspects of processing queued MatcherEvents:
-
executeMatcherEventQueueRunnable(Runnable)
is consulted when
a Thread must be selected to execute the given Runnable which will
drain the queue of MatcherEvents. Subclasses may override to
customize which Thread is used.
-
coalesceMatcherEvents(List)
is used to compress
many enqueued MatcherEvents into a single representative
MatcherEvent. This implies a contract between all registered
MatcherEditorListeners and this ThreadedMatcherEditor
that
guarantees that processing the coalesced MatcherEvent is equivalent
to processing all MatcherEvents sequentially.
Typical usage patterns of ThreadedMatcherEditor resemble:
MatcherEditor threadedMatcherEditor = new ThreadedMatcherEditor(new AnyMatcherEditor());
FilterList filterList = new FilterList(new BasicEventList(), threadedMatcherEditor);
ThreadedMatcherEditor(MatcherEditor source) - Creates a ThreadedMatcherEditor which wraps the given
source .
|
protected Event | coalesceMatcherEvents(List> matcherEvents) - This method implements the strategy for coalescing many queued
MatcherEvents into a single representative MatcherEvent.
|
protected void | executeMatcherEventQueueRunnable(Runnable runnable) - This method executes the given
runnable on a Thread.
|
Matcher | getMatcher() - Returns the current Matcher specified by the source
MatcherEditor .
|
ThreadedMatcherEditor
public ThreadedMatcherEditor(MatcherEditor source)
Creates a ThreadedMatcherEditor which wraps the given source
.
MatcherEvents fired from the source
will be enqueued within
this MatcherEditor until they are processed on an alternate Thread.
source
- the MatcherEditor to wrap with buffering functionality
coalesceMatcherEvents
protected Event coalesceMatcherEvents(List> matcherEvents)
This method implements the strategy for coalescing many queued
MatcherEvents into a single representative MatcherEvent. Listeners which
process the MatcherEvent returned from this method should match the state
that would exist if each of the
matcherEvents
were fired
sequentially. In general, any group of
matcherEvents
can be
succesfully coalesced as a single MatcherEvent with a type of
changed
, however, this method's default implementation
uses a few heuristics to do more intelligent coalescing in order to
gain speed improvements:
- if
matcherEvents
ends in a MatcherEvent which is a
MatcherEditor.Event.MATCH_ALL
or MatcherEditor.Event.MATCH_NONE
type, the last MatcherEvent is returned, regardless of previous
MatcherEvents
- if
matcherEvents
only contains a series of
monotonically constraining MatcherEvents, the final MatcherEvent
is returned
- if
matcherEvents
only contains a series of
monotonically relaxing MatcherEvents, the final MatcherEvent is
returned
- if
matcherEvents
contains both constraining and
relaxing MatcherEvents, the final MatcherEvent is returned with
its type as MatcherEditor.Event.CHANGED
Note that
1, 2,
and
3
above merely represent
safe optimizations of the type of MatcherEvent that can be returned.
It could also have been returned as a MatcherEvent with a type of
MatcherEditor.Event.CHANGED
and be assumed to work correctly, though
potentially less efficiently, since it is a more generic type of change.
Subclasses with the ability to fire precise MatcherEvents with fine grain
types (i.e.
relaxed
or
constrained
) when
coalescing
matcherEvents
in situations not recounted above
may do so by overiding this method.
matcherEvents
- an array of MatcherEvents recorded in the order
they were received from the source MatcherEditor
- a single MatcherEvent which, when fired, will result in the
same state as if all
matcherEvents
had been fired
sequentially
executeMatcherEventQueueRunnable
protected void executeMatcherEventQueueRunnable(Runnable runnable)
This method executes the given runnable
on a Thread. The
particular Thread chosen to execute the Runnable is left as an
implementation detail. By default, a new Thread named
MatcherQueueThread
is constructed to execute the
runnable
each time this method is called. Subclasses may
override this method to use any Thread selection strategy they wish.
runnable
- a Runnable to execute on an alternate Thread
Glazed Lists, Copyright © 2003-2006 publicobject.com, O'Dell Engineering.
Documentation build by pbuilder at 2007-12-21 23:49