/*******************************************************************************
* Copyright (c) 2005, 2015 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.jface.viewers.deferred;
import java.util.Comparator;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.NullProgressMonitor;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.viewers.AcceptAllFilter;
import org.eclipse.jface.viewers.IFilter;
import org.eclipse.jface.viewers.deferred.ConcurrentTableUpdator.Range;
/**
* Contains the algorithm for performing background sorting and filtering in a virtual
* table. This is the real implementation for <code>DeferredContentProvider</code>.
* However, this class will work with anything that implements <code>AbstractVirtualTable</code>
* rather than being tied to a <code>TableViewer</code>.
*
* <p>
* This is package visibility since it currently only needs to be used in one place,
* but it could potentially be made public if there was a need to use the same background
* sorting algorithm for something other than a TableViewer.
* </p>
*
* <p>
* Information flow is like this:
* </p>
* <ol>
* <li>IConcurrentModel sends unordered elements to BackgroundContentProvider (in a background thread)</li>
* <li>BackgroundContentProvider sorts, filters, and sends element/index pairs to
* ConcurrentTableUpdator (in a background thread)</li>
* <li>ConcurrentTableUpdator batches the updates and sends them to an AbstractVirtualTable
* (in the UI thread)</li>
* </ol>
*
* <p>
* Internally, sorting is done using a <code>LazySortedCollection</code>. This data structure
* allows the content provider to locate and sort the visible range without fully sorting
* all elements in the table. It also supports fast cancellation, allowing the visible range
* to change in the middle of a sort without discarding partially-sorted information from
* the previous range.
* </p>
*
* @since 3.1
*/
/* package */ final class BackgroundContentProvider {
/**
* Sorting message string
*/
private static final String SORTING = JFaceResources.getString("Sorting"); //$NON-NLS-1$
/**
* Table limit. -1 if unlimited
*/
private int limit = -1;
/**
* Model that is currently providing input to this content provider.
*/
private IConcurrentModel model;
/**
* Current sort order
*/
private volatile Comparator sortOrder;
/**
* True iff the content provider has
*/
private volatile IFilter filter = AcceptAllFilter.getInstance();
/**
* Queued changes
*/
private ChangeQueue changeQueue = new ChangeQueue();
/**
* Listener that gets callbacks from the model
*/
private IConcurrentModelListener listener = new IConcurrentModelListener() {
@Override
public void add(Object[] added) {
BackgroundContentProvider.this.add(added);
}
@Override
public void remove(Object[] removed) {
BackgroundContentProvider.this.remove(removed);
}
@Override
public void setContents(Object[] newContents) {
BackgroundContentProvider.this.setContents(newContents);
}
@Override
public void update(Object[] changed) {
BackgroundContentProvider.this.update(changed);
}
};
/**
* Object that posts updates to the UI thread. Must synchronize on
* sortMutex when accessing.
*/
private ConcurrentTableUpdator updator;
private IProgressMonitor sortingProgressMonitor = new NullProgressMonitor();
private Thread sortThread = null;
private volatile FastProgressReporter sortMon = new FastProgressReporter();
private volatile Range range = new Range(0,0);
/**
* Creates a new background content provider
*
* @param table table that will receive updates
* @param model data source
* @param sortOrder initial sort order
*/
public BackgroundContentProvider(AbstractVirtualTable table,
IConcurrentModel model, Comparator sortOrder) {
updator = new ConcurrentTableUpdator(table);
this.model = model;
this.sortOrder = sortOrder;
model.addListener(listener);
}
/**
* Cleans up this content provider, detaches listeners, frees up memory, etc.
* Must be the last public method called on this object.
*/
public void dispose() {
cancelSortJob();
updator.dispose();
model.removeListener(listener);
}
/**
* Force a refresh. Asks the model to re-send its complete contents.
*/
public void refresh() {
if (updator.isDisposed()) {
return;
}
model.requestUpdate(listener);
}
/**
* Called from sortJob. Sorts the elements defined by sortStart and sortLength.
* Schedules a UI update when finished.
*
* @param mon monitor where progress will be reported
*/
private void doSort(IProgressMonitor mon) {
// Workaround for some weirdness in the Jobs framework: if you cancel a monitor
// for a job that has ended and reschedule that same job, it will start
// the job with a monitor that is already cancelled. We can workaround this by
// removing all references to the progress monitor whenever the job terminates,
// but this would require additional synchronize blocks (which are slow) and more
// complexity. Instead, we just un-cancel the monitor at the start of each job.
mon.setCanceled(false);
mon.beginTask(SORTING, 100);
// Create a LazySortedCollection
Comparator order = sortOrder;
IFilter f = filter;
LazySortedCollection collection = new LazySortedCollection(order);
// Fill it in with all existing known objects
Object[] knownObjects = updator.getKnownObjects();
for (Object object : knownObjects) {
if (object != null) {
collection.add(object);
}
}
boolean dirty = false;
int prevSize = knownObjects.length;
updator.setTotalItems(prevSize);
// Start processing changes
while(true) {
// If the sort order has changed, build a new LazySortedCollection with
// the new comparator
if (order != sortOrder) {
dirty = true;
order = sortOrder;
// Copy all elements from the old collection to the new one
LazySortedCollection newCollection = new LazySortedCollection(order);
Object[] items = collection.getItems(false);
for (int j = 0; j < items.length && order == sortOrder; j++) {
Object item = items[j];
newCollection.add(item);
}
// If the sort order changed again, re-loop
if (order != sortOrder) {
continue;
}
collection = newCollection;
continue;
}
// If the filter has changed
if (f != filter) {
dirty = true;
f = filter;
Object[] items = collection.getItems(false);
// Remove any items that don't pass the new filter
for (int j = 0; j < items.length && f == filter; j++) {
Object toTest = items[j];
if (!f.select(toTest)) {
collection.remove(toTest);
}
}
continue;
}
// If there are pending changes, process one of them
if (!changeQueue.isEmpty()) {
dirty = true;
ChangeQueue.Change next = changeQueue.dequeue();
switch(next.getType()) {
case ChangeQueue.ADD: {
filteredAdd(collection, next.getElements(), f);
break;
}
case ChangeQueue.REMOVE: {
Object[] toRemove = next.getElements();
flush(toRemove, collection);
collection.removeAll(toRemove);
break;
}
case ChangeQueue.UPDATE: {
Object[] items = next.getElements();
for (Object item : items) {
if (collection.contains(item)) {
// TODO: write a collection.update(...) method
collection.remove(item);
collection.add(item);
updator.clear(item);
}
}
break;
}
case ChangeQueue.SET: {
Object[] items = next.getElements();
collection.clear();
filteredAdd(collection, items, f);
break;
}
}
continue;
}
int totalElements = collection.size();
if (limit != -1) {
if (totalElements > limit) {
totalElements = limit;
}
}
if (totalElements != prevSize) {
prevSize = totalElements;
// Send the total items to the updator ASAP -- the user may want
// to scroll to a different section of the table, which would
// cause our sort range to change and cause this job to get cancelled.
updator.setTotalItems(totalElements);
dirty = true;
}
// Terminate loop
if (!dirty) {
break;
}
try {
ConcurrentTableUpdator.Range updateRange = updator.getVisibleRange();
sortMon = new FastProgressReporter();
range = updateRange;
int sortStart = updateRange.start;
int sortLength = updateRange.length;
if (limit != -1) {
collection.retainFirst(limit, sortMon);
}
sortLength = Math.min(sortLength, totalElements - sortStart);
sortLength = Math.max(sortLength, 0);
Object[] objectsOfInterest = new Object[sortLength];
collection.getRange(objectsOfInterest, sortStart, true, sortMon);
// Send the new elements to the table
for (int i = 0; i < sortLength; i++) {
Object object = objectsOfInterest[i];
updator.replace(object, sortStart + i);
}
objectsOfInterest = new Object[collection.size()];
collection.getFirst(objectsOfInterest, true, sortMon);
// Send the new elements to the table
for (int i = 0; i < totalElements; i++) {
Object object = objectsOfInterest[i];
updator.replace(object, i);
}
} catch (InterruptedException e) {
continue;
}
dirty = false;
}
mon.done();
}
/**
* @param collection
* @param toAdd
*/
private static void filteredAdd(LazySortedCollection collection, Object[] toAdd, IFilter filter) {
if (filter != AcceptAllFilter.getInstance()) {
for (Object object : toAdd) {
if (filter.select(object)) {
collection.add(object);
}
}
} else {
collection.addAll(toAdd);
}
}
/**
* Sets the sort order for this content provider
*
* @param sorter sort order
*/
public void setSortOrder(Comparator sorter) {
Assert.isNotNull(sorter);
this.sortOrder = sorter;
sortMon.cancel();
refresh();
}
/**
* Sets the filter for this content provider
*
* @param toSet filter to set
*/
public void setFilter(IFilter toSet) {
Assert.isNotNull(toSet);
this.filter = toSet;
sortMon.cancel();
refresh();
}
/**
* Sets the maximum table size. Based on the current sort order,
* the table will be truncated if it grows beyond this size.
* Using a limit improves memory usage and performance, and is
* strongly recommended for large tables.
*
* @param limit maximum rows to show in the table or -1 if unbounded
*/
public void setLimit(int limit) {
this.limit = limit;
refresh();
}
/**
* Returns the maximum table size or -1 if unbounded
*
* @return the maximum number of rows in the table or -1 if unbounded
*/
public int getLimit() {
return limit;
}
/**
* Checks if currently visible range has changed, and triggers and update
* and resort if necessary. Must be called in the UI thread, typically
* within a SWT.SetData callback.
* @param includeIndex the index that should be included in the visible range.
*/
public void checkVisibleRange(int includeIndex) {
updator.checkVisibleRange(includeIndex);
ConcurrentTableUpdator.Range newRange = updator.getVisibleRange();
ConcurrentTableUpdator.Range oldRange = range;
// If we're in the middle of processing an invalid range, cancel the sort
if (newRange.start != oldRange.start || newRange.length != oldRange.length) {
sortMon.cancel();
}
}
/**
* This lock protects the two boolean variables sortThreadStarted and resortScheduled.
*/
private Object lock = new Object();
/**
* true if the sort thread is running
*/
private boolean sortThreadStarted = false;
/**
* true if we need to sort
*/
private boolean sortScheduled = false;
private final class SortThread extends Thread {
private SortThread(String name) {
super(name);
}
@Override
public void run() {
loop: while (true) {
synchronized (lock) {
sortScheduled = false;
}
try {
// this is the main work
doSort(sortingProgressMonitor);
} catch (Exception ex) {
// ignore
}
synchronized (lock) {
if (sortScheduled) {
continue loop;
}
sortThreadStarted = false;
break loop;
}
}
}
}
/**
* Must be called whenever the model changes. Dirties this object and triggers a sort
* if necessary.
*/
private void makeDirty() {
synchronized (lock) {
sortMon.cancel();
// request sorting
sortScheduled = true;
if (!sortThreadStarted) {
sortThreadStarted = true;
sortThread = new SortThread(SORTING);
sortThread.setDaemon(true);
sortThread.setPriority(Thread.NORM_PRIORITY - 1);
sortThread.start();
}
}
}
/**
* Cancels any sort in progress. Note that we try to use the
* FastProgresReporter if possible since this is more responsive than
* canceling the sort job. However, it is not a problem to cancel in both
* ways.
*/
private void cancelSortJob() {
sortMon.cancel();
sortingProgressMonitor.setCanceled(true);
}
/**
* Called when new elements are added to the model.
*
* @param toAdd
* newly added elements
*/
private void add(Object[] toAdd) {
changeQueue.enqueue(ChangeQueue.ADD, toAdd);
makeDirty();
}
/**
* Called with the complete contents of the model
*
* @param contents new contents of the model
*/
private void setContents(Object[] contents) {
changeQueue.enqueue(ChangeQueue.SET, contents);
makeDirty();
}
/**
* Called when elements are removed from the model
*
* @param toRemove elements removed from the model
*/
private void remove(Object[] toRemove) {
changeQueue.enqueue(ChangeQueue.REMOVE, toRemove);
makeDirty();
refresh();
}
/**
* Notifies the updator that the given elements have changed
*
* @param toFlush changed elements
* @param collection collection of currently-known elements
*/
private void flush(Object[] toFlush, LazySortedCollection collection) {
for (Object item : toFlush) {
if (collection.contains(item)) {
updator.clear(item);
}
}
}
/**
* Called when elements in the model change
*
* @param items changed items
*/
private void update(Object[] items) {
changeQueue.enqueue(ChangeQueue.UPDATE, items);
makeDirty();
}
}