let cls mirror AST be gc-able

java/java-psi-impl/src/com/intellij/psi/impl/compiled/ClsElementImpl.java

@@ -21,11 +21,14 @@ import com.intellij.lang.Language;
 import com.intellij.lang.java.JavaLanguage;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.util.Key;
+import com.intellij.openapi.util.Pair;
 import com.intellij.openapi.util.TextRange;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.psi.*;
 import com.intellij.psi.codeStyle.JavaCodeStyleSettingsFacade;
 import com.intellij.psi.impl.PsiElementBase;
+import com.intellij.psi.impl.smartPointers.AnchorTypeInfo;
+import com.intellij.psi.impl.smartPointers.SelfElementInfo;
 import com.intellij.psi.impl.source.SourceTreeToPsiMap;
 import com.intellij.psi.impl.source.tree.TreeElement;
 import com.intellij.psi.tree.IElementType;
@@ -44,7 +47,7 @@ public abstract class ClsElementImpl extends PsiElementBase implements PsiCompil
 
   private static final Logger LOG = Logger.getInstance("#com.intellij.psi.impl.compiled.ClsElementImpl");
 
-  private volatile PsiElement myMirror;
+  private volatile Pair<TextRange, AnchorTypeInfo> myMirror;
 
   @Override
   @NotNull
@@ -154,12 +157,9 @@ public abstract class ClsElementImpl extends PsiElementBase implements PsiCompil
 
   @Override
   public PsiElement getMirror() {
-    PsiElement mirror = myMirror;
-    if (mirror == null) {
-      ((ClsFileImpl)getContainingFile()).getMirror();
-      mirror = myMirror;
-    }
-    return mirror;
+    PsiFile mirrorFile = ((ClsFileImpl)getContainingFile()).getMirror().getContainingFile();
+    Pair<TextRange, AnchorTypeInfo> mirror = myMirror;
+    return mirror == null ? null : SelfElementInfo.findElementInside(mirrorFile, mirror.first, mirror.second);
   }
 
   @Override
@@ -268,7 +268,7 @@ public abstract class ClsElementImpl extends PsiElementBase implements PsiCompil
 
     PsiElement psi = element.getPsi();
     psi.putUserData(COMPILED_ELEMENT, this);
-    myMirror = psi;
+    myMirror = Pair.create(element.getTextRange(), AnchorTypeInfo.obtainInfo(psi, JavaLanguage.INSTANCE));
   }
 
   protected static <T extends  PsiElement> void setMirror(@Nullable T stub, @Nullable T mirror) throws InvalidMirrorException {

java/java-psi-impl/src/com/intellij/psi/impl/compiled/ClsFileImpl.java

@@ -42,7 +42,6 @@ import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.pom.java.LanguageLevel;
 import com.intellij.psi.*;
 import com.intellij.psi.compiled.ClassFileDecompilers;
-import com.intellij.psi.impl.CheckUtil;
 import com.intellij.psi.impl.DebugUtil;
 import com.intellij.psi.impl.JavaPsiImplementationHelper;
 import com.intellij.psi.impl.PsiFileEx;
@@ -76,6 +75,7 @@ import org.jetbrains.org.objectweb.asm.ClassReader;
 import org.jetbrains.org.objectweb.asm.Opcodes;
 
 import java.io.IOException;
+import java.lang.ref.Reference;
 import java.util.Collections;
 import java.util.Map;
 import java.util.Set;
@@ -99,7 +99,7 @@ public class ClsFileImpl extends ClsRepositoryPsiElement<PsiClassHolderFileStub>
   private final FileViewProvider myViewProvider;
   private final boolean myIsForDecompiling;
   private volatile SoftReference<StubTree> myStub;
-  private volatile TreeElement myMirrorFileElement;
+  private volatile Reference<TreeElement> myMirrorFileElement;
   private volatile ClsPackageStatementImpl myPackageStatement;
   private boolean myIsPhysical = true;
   private boolean myInvalidated;
@@ -382,10 +382,10 @@ public class ClsFileImpl extends ClsRepositoryPsiElement<PsiClassHolderFileStub>
 
   @Override
   public PsiElement getMirror() {
-    TreeElement mirrorTreeElement = myMirrorFileElement;
+    TreeElement mirrorTreeElement = SoftReference.dereference(myMirrorFileElement);
     if (mirrorTreeElement == null) {
       synchronized (myMirrorLock) {
-        mirrorTreeElement = myMirrorFileElement;
+        mirrorTreeElement = SoftReference.dereference(myMirrorFileElement);
         if (mirrorTreeElement == null) {
           VirtualFile file = getVirtualFile();
           PsiClass[] classes = getClasses();
@@ -417,7 +417,7 @@ public class ClsFileImpl extends ClsRepositoryPsiElement<PsiClassHolderFileStub>
           }
 
           ((PsiFileImpl)mirror).setOriginalFile(this);
-          myMirrorFileElement = mirrorTreeElement;
+          myMirrorFileElement = new SoftReference<TreeElement>(mirrorTreeElement);
         }
       }
     }

java/java-tests/testSrc/com/intellij/psi/ClsPsiTest.java

@@ -22,12 +22,17 @@ import com.intellij.openapi.util.io.IoTestUtil;
 import com.intellij.openapi.vfs.LocalFileSystem;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.pom.java.LanguageLevel;
+import com.intellij.psi.impl.compiled.ClsClassImpl;
+import com.intellij.psi.impl.compiled.ClsElementImpl;
 import com.intellij.psi.impl.compiled.ClsFileImpl;
 import com.intellij.psi.impl.compiled.ClsParameterImpl;
 import com.intellij.psi.impl.java.stubs.PsiMethodStub;
+import com.intellij.psi.impl.source.tree.java.ClassElement;
 import com.intellij.psi.search.GlobalSearchScope;
 import com.intellij.psi.util.PsiUtil;
+import com.intellij.testFramework.LeakHunter;
 import com.intellij.testFramework.LightIdeaTestCase;
+import com.intellij.util.GCUtil;
 import com.intellij.util.ObjectUtils;
 import com.intellij.util.indexing.FileBasedIndex;
 
@@ -436,4 +441,15 @@ public class ClsPsiTest extends LightIdeaTestCase {
     assertTrue(String.valueOf(clsFile), clsFile instanceof ClsFileImpl);
     return (PsiJavaFile)clsFile;
   }
+
+  public void testClsPsiDoesNotHoldStrongReferencesToMirrorAST() {
+    PsiClass dbl = getJavaFacade().findClass(Double.class.getName(), myScope);
+    assertNotNull(dbl);
+    int hash1 = ((ClsClassImpl)dbl).getMirror().hashCode();
+    assertEquals(dbl, ((ClsClassImpl)dbl).getMirror().getUserData(ClsElementImpl.COMPILED_ELEMENT));
+
+    GCUtil.tryGcSoftlyReachableObjects();
+    LeakHunter.checkLeak(dbl, ClassElement.class, element -> element.getPsi().getUserData(ClsElementImpl.COMPILED_ELEMENT) == dbl);
+    assertFalse(hash1 == ((ClsClassImpl)dbl).getMirror().hashCode());
+  }
 }