Chaching results of findClasses in JavaElementFinder

Quieries to this method appear very high in the profile when there are many exceptions in the console

compiler/jet.as.java.psi/src/org/jetbrains/jet/asJava/JavaElementFinder.java

@@ -26,7 +26,12 @@ import com.intellij.psi.PsiElementFinder;
 import com.intellij.psi.PsiManager;
 import com.intellij.psi.PsiPackage;
 import com.intellij.psi.search.GlobalSearchScope;
+import com.intellij.psi.util.CachedValue;
+import com.intellij.psi.util.CachedValueProvider;
+import com.intellij.psi.util.CachedValuesManager;
+import com.intellij.psi.util.PsiModificationTracker;
 import com.intellij.util.SmartList;
+import com.intellij.util.containers.SLRUCache;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.codegen.NamespaceCodegen;
@@ -59,6 +64,8 @@ public class JavaElementFinder extends PsiElementFinder implements JavaPsiFacade
     private final PsiManager psiManager;
     private final LightClassGenerationSupport lightClassGenerationSupport;
 
+    private final CachedValue<SLRUCache<FindClassesRequest, PsiClass[]>> findClassesCache;
+
     public JavaElementFinder(
             @NotNull Project project,
             @NotNull LightClassGenerationSupport lightClassGenerationSupport
@@ -66,6 +73,25 @@ public class JavaElementFinder extends PsiElementFinder implements JavaPsiFacade
         this.project = project;
         this.psiManager = PsiManager.getInstance(project);
         this.lightClassGenerationSupport = lightClassGenerationSupport;
+        this.findClassesCache = CachedValuesManager.getManager(project).createCachedValue(
+            new CachedValueProvider<SLRUCache<FindClassesRequest, PsiClass[]>>() {
+                @Nullable
+                @Override
+                public Result<SLRUCache<FindClassesRequest, PsiClass[]>> compute() {
+                    return new Result<SLRUCache<FindClassesRequest, PsiClass[]>>(
+                            new SLRUCache<FindClassesRequest, PsiClass[]>(30, 10) {
+                                @NotNull
+                                @Override
+                                public PsiClass[] createValue(FindClassesRequest key) {
+                                    return doFindClasses(key.fqName, key.scope);
+                                }
+                            },
+                            PsiModificationTracker.OUT_OF_CODE_BLOCK_MODIFICATION_COUNT
+                    );
+                }
+            },
+            false
+        );
     }
 
     @Override
@@ -77,6 +103,13 @@ public class JavaElementFinder extends PsiElementFinder implements JavaPsiFacade
     @NotNull
     @Override
     public PsiClass[] findClasses(@NotNull String qualifiedNameString, @NotNull GlobalSearchScope scope) {
+        SLRUCache<FindClassesRequest, PsiClass[]> value = findClassesCache.getValue();
+        synchronized (value) {
+            return value.get(new FindClassesRequest(qualifiedNameString, scope));
+        }
+    }
+
+    private PsiClass[] doFindClasses(String qualifiedNameString, GlobalSearchScope scope) {
         if (!QualifiedNamesUtil.isValidJavaFqName(qualifiedNameString)) {
             return PsiClass.EMPTY_ARRAY;
         }
@@ -199,5 +232,35 @@ public class JavaElementFinder extends PsiElementFinder implements JavaPsiFacade
 
         return answer.toArray(new PsiClass[answer.size()]);
     }
+
+    private static class FindClassesRequest {
+        private final String fqName;
+        private final GlobalSearchScope scope;
+
+        private FindClassesRequest(@NotNull String fqName, @NotNull GlobalSearchScope scope) {
+            this.fqName = fqName;
+            this.scope = scope;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+
+            FindClassesRequest request = (FindClassesRequest) o;
+
+            if (!fqName.equals(request.fqName)) return false;
+            if (!scope.equals(request.scope)) return false;
+
+            return true;
+        }
+
+        @Override
+        public int hashCode() {
+            int result = fqName.hashCode();
+            result = 31 * result + (scope.hashCode());
+            return result;
+        }
+    }
 }