From 74cfca2ac8812f3c715deb5966dc09476db039cf Mon Sep 17 00:00:00 2001
From: peter <peter@jetbrains.com>
Date: Wed, 21 Dec 2016 09:09:21 +0100
Subject: [PATCH] lock-free stub.getPsi

---
 .../src/com/intellij/psi/stubs/StubBase.java  | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/platform/core-api/src/com/intellij/psi/stubs/StubBase.java b/platform/core-api/src/com/intellij/psi/stubs/StubBase.java
index c59265a4f91b..420c4918cce9 100644
--- a/platform/core-api/src/com/intellij/psi/stubs/StubBase.java
+++ b/platform/core-api/src/com/intellij/psi/stubs/StubBase.java
@@ -28,6 +28,7 @@ import com.intellij.util.ArrayFactory;
 import com.intellij.util.ArrayUtil;
 import com.intellij.util.ObjectUtils;
 import com.intellij.util.SmartList;
+import com.intellij.util.concurrency.AtomicFieldUpdater;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -39,6 +40,9 @@ public abstract class StubBase<T extends PsiElement> extends ObjectStubBase<Stub
   private final IStubElementType myElementType;
   private volatile T myPsi;
 
+  private static final AtomicFieldUpdater<StubBase, PsiElement> ourPsiUpdater =
+    AtomicFieldUpdater.forFieldOfType(StubBase.class, PsiElement.class);
+
   @SuppressWarnings("unchecked")
   protected StubBase(final StubElement parent, final IStubElementType elementType) {
     super(parent);
@@ -82,26 +86,15 @@ public abstract class StubBase<T extends PsiElement> extends ObjectStubBase<Stub
     myPsi = psi;
   }
 
-  public T getCachedPsi() {
-    return myPsi;
-  }
-
   @Override
   public T getPsi() {
     T psi = myPsi;
     if (psi != null) return psi;
 
-    synchronized (PsiLock.LOCK) {
-      psi = myPsi;
-      if (psi != null) return psi;
-      //noinspection unchecked
-      myPsi = psi = (T)getStubType().createPsi(this);
-    }
-
-    return psi;
+    psi = (T)getStubType().createPsi(this);
+    return ourPsiUpdater.compareAndSet(this, null, psi) ? psi : ObjectUtils.assertNotNull(myPsi);
   }
 
-
   @NotNull
   @Override
   public <E extends PsiElement> E[] getChildrenByType(@NotNull final IElementType elementType, E[] array) {