From e6749fcfe11141d6499a5820e39211b21d6ad070 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Thu, 12 Apr 2018 16:27:00 +0700
Subject: [PATCH] ConstantExpressionVisitor: decrease memory pressure

1. Use weak-referenced keys as it's unnecessary for cached constant values to live longer than any other reference (if PsiElement disappeared everywhere except constant expression cache, no reason to keep it in constant expression cache either)
2. Replace PsiClassReferenceType (as class literal value) as it keeps the strong reference to the surrounding PsiFile, so until the whole constant expression cache is invalidated (e.g. on PSI change) we don't free any file containing xyz.class expression.
---
 .../intellij/psi/impl/ConstantExpressionVisitor.java | 12 ++++++++++--
 .../psi/impl/JavaConstantExpressionEvaluator.java    |  2 +-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/java/java-psi-impl/src/com/intellij/psi/impl/ConstantExpressionVisitor.java b/java/java-psi-impl/src/com/intellij/psi/impl/ConstantExpressionVisitor.java
index 4e2a1ebfdbbd..0c53e114b46d 100644
--- a/java/java-psi-impl/src/com/intellij/psi/impl/ConstantExpressionVisitor.java
+++ b/java/java-psi-impl/src/com/intellij/psi/impl/ConstantExpressionVisitor.java
@@ -16,16 +16,17 @@
 package com.intellij.psi.impl;
 
 import com.intellij.psi.*;
+import com.intellij.psi.impl.source.PsiClassReferenceType;
 import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.ClassUtil;
 import com.intellij.psi.util.ConstantEvaluationOverflowException;
 import com.intellij.psi.util.ConstantExpressionUtil;
-import java.util.HashMap;
 import com.intellij.util.containers.StringInterner;
 import gnu.trove.THashSet;
 import org.jetbrains.annotations.Nullable;
 
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentMap;
@@ -507,7 +508,14 @@ class ConstantExpressionVisitor extends JavaElementVisitor implements PsiConstan
 
   @Override
   public void visitClassObjectAccessExpression(PsiClassObjectAccessExpression expression) {
-    myResult = expression.getOperand().getType();
+    PsiType type = expression.getOperand().getType();
+    if (type instanceof PsiClassReferenceType) {
+      PsiClass aClass = ((PsiClassReferenceType)type).resolve();
+      if (aClass != null) {
+        type = JavaPsiFacade.getElementFactory(expression.getProject()).createType(aClass, ((PsiClassReferenceType)type).getParameters());
+      }
+    }
+    myResult = type;
   }
 
   @Override public void visitReferenceExpression(PsiReferenceExpression expression) {
diff --git a/java/java-psi-impl/src/com/intellij/psi/impl/JavaConstantExpressionEvaluator.java b/java/java-psi-impl/src/com/intellij/psi/impl/JavaConstantExpressionEvaluator.java
index dea9c8b1fc43..a8c083d6ead7 100644
--- a/java/java-psi-impl/src/com/intellij/psi/impl/JavaConstantExpressionEvaluator.java
+++ b/java/java-psi-impl/src/com/intellij/psi/impl/JavaConstantExpressionEvaluator.java
@@ -89,7 +89,7 @@ public class JavaConstantExpressionEvaluator extends JavaRecursiveElementWalking
   }
 
   private static final CachedValueProvider<ConcurrentMap<PsiElement,Object>> PROVIDER = () -> {
-    ConcurrentMap<PsiElement, Object> value = ContainerUtil.createConcurrentSoftMap();
+    ConcurrentMap<PsiElement, Object> value = ContainerUtil.createConcurrentWeakMap();
     return CachedValueProvider.Result.create(value, PsiModificationTracker.MODIFICATION_COUNT);
   };