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Synchronize the access to LRUCache #978

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9712044
Synchronize the access to LRUCache
ramele1907 Dec 18, 2024
8bc7a14
Implement a thread safe solution for computeIfAbsent
ramele1907 Feb 9, 2025
4167d94
Fix formatting
jonahgraham Feb 10, 2025
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58 changes: 44 additions & 14 deletions ...cdt/managedbuilder/language/settings/providers/AbstractLanguageSettingsOutputScanner.java
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,8 @@
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.function.Function;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

Expand Down Expand Up @@ -100,6 +102,11 @@ public abstract class AbstractLanguageSettingsOutputScanner extends LanguageSett
FIND_RESOURCES_CACHE_SIZE);
private HashMap<IProject, LRUCache<IPath, List<IResource>>> findPathInProjectCache = new HashMap<>();

private final ReentrantReadWriteLock findContainersForLocationURICacheLock = new ReentrantReadWriteLock();
private final ReentrantReadWriteLock findFilesForLocationURICacheLock = new ReentrantReadWriteLock();
private final ReentrantReadWriteLock findPathInProjectCacheLock = new ReentrantReadWriteLock();
private final ReentrantReadWriteLock findPathInFoldertCacheLock = new ReentrantReadWriteLock();

//String pathStr, URI baseURI -> URI
private static class MappedURIKey {
URI baseURI;
Expand Down Expand Up @@ -149,6 +156,9 @@ public boolean equals(Object obj) {
private LRUCache<URI, IPath> fileSystemLocationCache = new LRUCache<>(FIND_RESOURCES_CACHE_SIZE);
// Caches the result of new File(pathname).exists()
private LRUCache<IPath, Boolean> pathExistsCache = new LRUCache<>(FIND_RESOURCES_CACHE_SIZE);
private final ReentrantReadWriteLock mappedURICacheLock = new ReentrantReadWriteLock();
private final ReentrantReadWriteLock fileSystemLocationCacheLock = new ReentrantReadWriteLock();
private final ReentrantReadWriteLock pathExistsCacheLock = new ReentrantReadWriteLock();

/** @since 8.2 */
protected EFSExtensionProvider efsProvider = null;
Expand Down Expand Up @@ -792,8 +802,9 @@ private IResource findFileForLocationURI(URI uri, IProject preferredProject, boo
}
IResource sourceFile = null;

IResource[] resources = workspaceRootFindFilesForLocationURICache.computeIfAbsent(uri,
key -> ResourcesPlugin.getWorkspace().getRoot().findFilesForLocationURI(key));
IResource[] resources = threadSafeComputeIfAbsent(uri, workspaceRootFindFilesForLocationURICache,
key -> ResourcesPlugin.getWorkspace().getRoot().findFilesForLocationURI(key),
findFilesForLocationURICacheLock);
for (IResource rc : resources) {
if (!checkExistence || rc.isAccessible()) {
if (rc.getProject().equals(preferredProject)) {
Expand All @@ -815,8 +826,9 @@ private IResource findFileForLocationURI(URI uri, IProject preferredProject, boo
private IResource findContainerForLocationURI(URI uri, IProject preferredProject, boolean checkExistence) {
IResource resource = null;

IResource[] resources = workspaceRootFindContainersForLocationURICache.computeIfAbsent(uri,
key -> ResourcesPlugin.getWorkspace().getRoot().findContainersForLocationURI(key));
IResource[] resources = threadSafeComputeIfAbsent(uri, workspaceRootFindContainersForLocationURICache,
(key) -> ResourcesPlugin.getWorkspace().getRoot().findContainersForLocationURI(key),
findContainersForLocationURICacheLock);
for (IResource rc : resources) {
if ((rc instanceof IProject || rc instanceof IFolder) && (!checkExistence || rc.isAccessible())) { // treat IWorkspaceRoot as non-workspace path
if (rc.getProject().equals(preferredProject)) {
Expand Down Expand Up @@ -1011,7 +1023,7 @@ private static URI resolvePathFromBaseLocation(String pathStr0, IPath baseLocati
* @return {@link URI} of the resource
*/
private URI determineMappedURI(String pathStr, URI baseURI) {
return mappedURICache.computeIfAbsent(new MappedURIKey(baseURI, pathStr), key -> {
return threadSafeComputeIfAbsent(new MappedURIKey(baseURI, pathStr), mappedURICache, key -> {
URI uri = null;

if (baseURI == null) {
Expand Down Expand Up @@ -1040,16 +1052,17 @@ private URI determineMappedURI(String pathStr, URI baseURI) {
uri = org.eclipse.core.filesystem.URIUtil.toURI(pathStr);
}
return uri;
});
}, mappedURICacheLock);
}

/**
* Find all resources in the project which might be represented by relative path passed.
*/
private List<IResource> findPathInProject(IPath path, IProject project) {
LRUCache<IPath, List<IResource>> cache = findPathInProjectCache.computeIfAbsent(project,
key -> new LRUCache<>(FIND_RESOURCES_CACHE_SIZE));
return cache.computeIfAbsent(path, key -> findPathInFolder(path, project));
LRUCache<IPath, List<IResource>> cache = threadSafeComputeIfAbsent(project, findPathInProjectCache,
key -> new LRUCache<IPath, List<IResource>>(FIND_RESOURCES_CACHE_SIZE), findPathInProjectCacheLock);
return threadSafeComputeIfAbsent(path, cache, key -> findPathInFolder(path, project),
findPathInFoldertCacheLock);
}

/**
Expand Down Expand Up @@ -1157,8 +1170,7 @@ private IResource findBestFitInWorkspace(String parsedName) {
private IPath getFilesystemLocation(URI uri) {
if (uri == null)
return null;

return fileSystemLocationCache.computeIfAbsent(uri, (k) -> {
return threadSafeComputeIfAbsent(uri, fileSystemLocationCache, (k) -> {
String pathStr = efsProvider.getMappedPath(uri);
URI resUri = org.eclipse.core.filesystem.URIUtil.toURI(pathStr);

Expand All @@ -1175,7 +1187,7 @@ private IPath getFilesystemLocation(URI uri) {
}
}
return null;
});
}, fileSystemLocationCacheLock);
}

/**
Expand Down Expand Up @@ -1256,9 +1268,9 @@ private ICLanguageSettingEntry resolvePathEntryInFilesystem(AbstractOptionParser
IPath location = getFilesystemLocation(uri);
if (location != null) {
String loc = location.toString();
boolean exists = pathExistsCache.computeIfAbsent(location, (s) -> {
boolean exists = threadSafeComputeIfAbsent(location, pathExistsCache, (s) -> {
return new File(loc).exists();
});
}, pathExistsCacheLock);
if (exists) {
return optionParser.createEntry(loc, loc, flag);
}
Expand Down Expand Up @@ -1415,4 +1427,22 @@ public boolean equals(Object obj) {
return true;
}

private static <K, V> V threadSafeComputeIfAbsent(K key, HashMap<K, V> cacheMap,
Function<? super K, ? extends V> mappingFunction, ReentrantReadWriteLock rwLock) {
rwLock.readLock().lock();
V value = cacheMap.get(key);
rwLock.readLock().unlock();
if (value != null) {
return value;
}

rwLock.writeLock().lock();
value = cacheMap.get(key);
if (value == null) {
value = cacheMap.computeIfAbsent(key, mappingFunction);
}
rwLock.writeLock().unlock();

return value;
}
}
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