Rework org.eclipse.core.internal.utils.Cache with standard java

* Threadsafe implementation
* Instead of predefined cache size use SoftReferences.

Should avoid random NullPointerException in concurrent use:
#1411

Author: EcljpseB0T

resources/bundles/org.eclipse.core.resources.spysupport/src/org/eclipse/core/internal/resources/SpySupport.java

@@ -13,9 +13,9 @@
  *******************************************************************************/
 package org.eclipse.core.internal.resources;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Map;
 import java.util.Map.Entry;
-import org.eclipse.core.internal.utils.Cache;
 import org.eclipse.core.internal.watson.ElementTree;
 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.resources.ResourcesPlugin;
@@ -71,9 +71,4 @@ public static Object[] getElements(MarkerAttributeMap markerMap) {
 		}
 		return legacyElements.toArray();
 	}
-	public static boolean isContentDescriptionCached(File file) {
-		ResourceInfo info = file.getResourceInfo(false, false);
-		Cache.Entry entry = ((Workspace) ResourcesPlugin.getWorkspace()).getContentDescriptionManager().getCache().getEntry(file.getFullPath(), false);
-		return entry != null && info.getContentId() == entry.getTimestamp();
-	}
 }

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/resources/ContentDescriptionManager.java

@@ -35,6 +35,7 @@
 import org.eclipse.core.internal.events.ILifecycleListener;
 import org.eclipse.core.internal.events.LifecycleEvent;
 import org.eclipse.core.internal.utils.Cache;
+import org.eclipse.core.internal.utils.Cache.Entry;
 import org.eclipse.core.internal.utils.Messages;
 import org.eclipse.core.internal.utils.Policy;
 import org.eclipse.core.internal.watson.ElementTreeIterator;
@@ -235,7 +236,7 @@ public long skip(long n) throws IOException {
 
 	private static final String PT_CONTENTTYPES = "contentTypes"; //$NON-NLS-1$
 
-	private Cache cache;
+	private final Cache<IPath, IContentDescription> cache = new Cache<>();
 
 	private volatile byte cacheState;
 
@@ -269,7 +270,7 @@ synchronized void doFlushCache(final IProgressMonitor monitor, Set<IPath> toClea
 		try {
 			setCacheState(FLUSHING_CACHE);
 			// flush the MRU cache
-			cache.discardAll();
+			cache.clear();
 			SubMonitor subMonitor = SubMonitor.convert(monitor);
 			if (toClean.isEmpty()) {
 				// no project was added, must be a global flush
@@ -317,10 +318,6 @@ private void clearContentFlags(IPath root, final IProgressMonitor monitor) {
 			Policy.debug("Content type cache for " + root + " flushed in " + (System.currentTimeMillis() - flushStart) + " ms"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
 	}
 
-	Cache getCache() {
-		return cache;
-	}
-
 	/** Public so tests can examine it. */
 	public byte getCacheState() {
 		if (cacheState != 0) {
@@ -364,7 +361,7 @@ public IContentDescription getDescriptionFor(File file, ResourceInfo info, boole
 		if (getCacheState() == INVALID_CACHE) {
 			// discard the cache, so it can be used before the flush job starts
 			setCacheState(ABOUT_TO_FLUSH);
-			cache.discardAll();
+			cache.clear();
 			// the cache is not good, flush it
 			flushJob.schedule(1000);
 		}
@@ -390,10 +387,10 @@ public IContentDescription getDescriptionFor(File file, ResourceInfo info, boole
 		if (inSync) {
 			// tries to get a description from the cache
 			synchronized (this) {
-				Cache.Entry entry = cache.getEntry(file.getFullPath());
+				Entry<IContentDescription> entry = cache.getEntry(file.getFullPath());
 				if (entry != null && entry.getTimestamp() == getTimestamp(info))
 					// there was a description in the cache, and it was up to date
-					return (IContentDescription) entry.getCached();
+					return entry.getCached();
 			}
 		}
 
@@ -403,10 +400,10 @@ public IContentDescription getDescriptionFor(File file, ResourceInfo info, boole
 
 		synchronized (this) {
 			// tries to get a description from the cache
-			Cache.Entry entry = cache.getEntry(file.getFullPath());
+			Entry<IContentDescription> entry = cache.getEntry(file.getFullPath());
 			if (entry != null && inSync && entry.getTimestamp() == getTimestamp(info))
 				// there was a description in the cache, and it was up to date
-				return (IContentDescription) entry.getCached();
+				return entry.getCached();
 
 			if (getCacheState() != ABOUT_TO_FLUSH) {
 				// we are going to add an entry to the cache or update the resource info - remember that
@@ -427,14 +424,7 @@ public IContentDescription getDescriptionFor(File file, ResourceInfo info, boole
 				}
 			}
 			// we actually got a description filled by a describer (or a default description for a non-obvious type)
-			if (entry == null)
-				// there was no entry before - create one
-				entry = cache.addEntry(file.getFullPath(), newDescription, getTimestamp(info));
-			else {
-				// just update the existing entry
-				entry.setTimestamp(getTimestamp(info));
-				entry.setCached(newDescription);
-			}
+			entry = cache.addEntry(file.getFullPath(), newDescription, getTimestamp(info));
 			return newDescription;
 		}
 	}
@@ -470,7 +460,7 @@ public synchronized void invalidateCache(boolean flush, IProject project) {
 			try {
 				// discard the cache, so it can be used before the flush job starts
 				setCacheState(ABOUT_TO_FLUSH);
-				cache.discardAll();
+				cache.clear();
 			} catch (CoreException e) {
 				Policy.log(e.getStatus());
 			}
@@ -579,16 +569,14 @@ public void shutdown(IProgressMonitor monitor) throws CoreException {
 		IExtensionRegistry registry = Platform.getExtensionRegistry();
 		if (registry != null)
 			registry.removeRegistryChangeListener(this);
-		cache.dispose();
-		cache = null;
+		cache.clear();
 		flushJob.cancel();
 		flushJob = null;
 		projectContentTypes = null;
 	}
 
 	@Override
 	public void startup(IProgressMonitor monitor) throws CoreException {
-		cache = new Cache(100, 1000, 0.1);
 		projectContentTypes = new ProjectContentTypes(workspace);
 		getCacheState();
 		if (cacheState == FLUSHING_CACHE || cacheState == ABOUT_TO_FLUSH)

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/resources/ProjectContentTypes.java

@@ -15,15 +15,23 @@
  *******************************************************************************/
 package org.eclipse.core.internal.resources;
 
-import java.util.*;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
 import org.eclipse.core.internal.utils.Cache;
+import org.eclipse.core.internal.utils.Cache.Entry;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.ProjectScope;
-import org.eclipse.core.runtime.*;
+import org.eclipse.core.runtime.CoreException;
+import org.eclipse.core.runtime.IPath;
+import org.eclipse.core.runtime.Platform;
 import org.eclipse.core.runtime.content.IContentType;
 import org.eclipse.core.runtime.content.IContentTypeManager.ISelectionPolicy;
 import org.eclipse.core.runtime.content.IContentTypeMatcher;
-import org.eclipse.core.runtime.preferences.*;
+import org.eclipse.core.runtime.preferences.IEclipsePreferences;
+import org.eclipse.core.runtime.preferences.IScopeContext;
+import org.eclipse.core.runtime.preferences.InstanceScope;
 import org.osgi.service.prefs.BackingStoreException;
 import org.osgi.service.prefs.Preferences;
 
@@ -102,7 +110,7 @@ public IContentType[] select(IContentType[] candidates, boolean fileName, boolea
 
 	private static final String PREF_LOCAL_CONTENT_TYPE_SETTINGS = "enabled"; //$NON-NLS-1$
 	private static final Preferences PROJECT_SCOPE = Platform.getPreferencesService().getRootNode().node(ProjectScope.SCOPE);
-	private final Cache contentTypesPerProject;
+	private final Cache<String, Set<String>> contentTypesPerProject = new Cache<>();
 	private final Workspace workspace;
 
 	static boolean usesContentTypePreferences(String projectName) {
@@ -129,8 +137,6 @@ static boolean usesContentTypePreferences(String projectName) {
 
 	public ProjectContentTypes(Workspace workspace) {
 		this.workspace = workspace;
-		// keep cache small
-		this.contentTypesPerProject = new Cache(5, 30, 0.4);
 	}
 
 	/**
@@ -166,30 +172,22 @@ private IContentTypeMatcher createMatcher(Project project) {
 		return Platform.getContentTypeManager().getMatcher(projectContentTypeSelectionPolicy, projectContentTypeSelectionPolicy);
 	}
 
-	@SuppressWarnings({"unchecked"})
 	private Set<String> getAssociatedContentTypes(Project project) {
 		final ResourceInfo info = project.getResourceInfo(false, false);
 		if (info == null)
 			// the project has been deleted
 			return null;
 		final String projectName = project.getName();
 		synchronized (contentTypesPerProject) {
-			Cache.Entry entry = contentTypesPerProject.getEntry(projectName);
-			if (entry != null)
-				// we have an entry...
-				if (entry.getTimestamp() == info.getContentId())
-					// ...and it is not stale, so just return it
-					return (Set<String>) entry.getCached();
-			// no cached information found, have to collect associated content types
-			Set<String> result = collectAssociatedContentTypes(project);
-			if (entry == null)
-				// there was no entry before - create one
-				entry = contentTypesPerProject.addEntry(projectName, result, info.getContentId());
-			else {
-				// just update the existing entry
-				entry.setTimestamp(info.getContentId());
-				entry.setCached(result);
+			Entry<Set<String>> entry = contentTypesPerProject.getEntry(projectName);
+			int contentId = info.getContentId();
+			if (entry != null && entry.getTimestamp() == contentId) {
+				// use up-to-date cache
+				return entry.getCached();
 			}
+			// no up-to-date cached information found
+			Set<String> result = collectAssociatedContentTypes(project);
+			contentTypesPerProject.addEntry(projectName, result, contentId);
 			return result;
 		}
 	}