Improve progress reporting in ClasspathContainerState

Updated the run method to drain the workQueue into a local list at the
start. This allows for an accurate count of pending tasks and prevents
the performance penalty of calling ConcurrentLinkedQueue.size() (which
is O(n)) inside the loop.

Removed the repeated monitor.setWorkRemaining(WORK) call inside the
loop, which was causing the progress bar to reset and appear stuck.

Implemented logic to estimate work: count * 2 ticks are allocated
initially (assuming 1 tick for checking and 1 tick for potential
update). This seems a bit too much for the classpath update in my test
environment but is much better then before and it is difficult to judge
how long the classpath update will actually take.

Updated monitor.worked(1) to happen for every processed request.

Adjusted the remaining work for the final phase (setProjectContainers)
based on the actual number of projects requiring updates.

In a small / fast environment you may want to a Thread.sleep() to the
loop, in my client environment with > 900 bundles the process is not
much better visible.

Author: vogella

ui/org.eclipse.pde.core/src/org/eclipse/pde/internal/core/ClasspathContainerState.java

@@ -78,7 +78,6 @@ public void resourceChanged(IResourceChangeEvent event) {
 	 */
 	private static final class UpdateClasspathsJob extends Job {
 
-		private static final int WORK = 10_000;
 		private final Queue<UpdateRequest> workQueue = new ConcurrentLinkedQueue<>();
 
 		/**
@@ -98,15 +97,25 @@ public boolean belongsTo(Object family) {
 
 		@Override
 		protected IStatus run(IProgressMonitor jobMonitor) {
-			SubMonitor monitor = SubMonitor.convert(jobMonitor, PDECoreMessages.PluginModelManager_1, WORK);
-			PluginModelManager.getInstance().initialize(monitor.split(10));
+			SubMonitor monitor = SubMonitor.convert(jobMonitor, PDECoreMessages.PluginModelManager_1, 100);
+			PluginModelManager.getInstance().initialize(monitor.split(1));
 			PluginModelManager modelManager = PluginModelManager.getInstance();
 			Map<IJavaProject, IClasspathContainer> updateProjects = new LinkedHashMap<>();
 			Map<IProject, IStatus> errorsPerProject = new LinkedHashMap<>();
+
+			java.util.List<UpdateRequest> requests = new java.util.ArrayList<>();
 			UpdateRequest request;
-			while (!monitor.isCanceled() && (request = workQueue.poll()) != null) {
-				monitor.setWorkRemaining(WORK);
-				IProject project = request.project();
+			while ((request = workQueue.poll()) != null) {
+				requests.add(request);
+			}
+			int count = requests.size();
+			monitor.setWorkRemaining(count * 2);
+
+			for (UpdateRequest req : requests) {
+				if (monitor.isCanceled()) {
+					break;
+				}
+				IProject project = req.project();
 				if (project.exists() && project.isOpen()) {
 					monitor.subTask(project.getName());
 					IPluginModelBase model = modelManager.findModel(project);
@@ -115,17 +124,17 @@ protected IStatus run(IProgressMonitor jobMonitor) {
 						try {
 							IClasspathEntry[] entries = ClasspathComputer.computeClasspathEntries(model,
 									javaProject.getProject());
-							if (!isUpToDate(project, entries, request.container())) {
+							if (!isUpToDate(project, entries, req.container())) {
 								updateProjects.put(javaProject, PDEClasspathContainerSaveHelper.containerOf(entries));
 								errorsPerProject.remove(project);
 								saveState(project, entries);
 							}
 						} catch (CoreException e) {
 							errorsPerProject.put(project, e.getStatus());
 						}
-						monitor.worked(1);
 					}
 				}
+				monitor.worked(1);
 			}
 			if (monitor.isCanceled()) {
 				return Status.CANCEL_STATUS;
@@ -151,7 +160,8 @@ protected IStatus run(IProgressMonitor jobMonitor) {
 					i++;
 				}
 				try {
-					setProjectContainers(javaProjects, container, monitor);
+					monitor.setWorkRemaining(n);
+					setProjectContainers(javaProjects, container, monitor.split(n));
 				} catch (JavaModelException e) {
 					return e.getStatus();
 				}