From 6d2e193373d660dbd96534c66eab181c5efd6b51 Mon Sep 17 00:00:00 2001
From: Bas Leijdekkers <basleijdekkers@gmail.com>
Date: Mon, 11 May 2015 11:09:49 +0200
Subject: [PATCH] IDEA-111282 (False positive on "while loop spins on field",
 where wait() is used)

---
 .../WhileLoopSpinsOnFieldInspection.java      | 20 +++++++++++++++++--
 .../WhileLoopSpinsOnField.java                | 14 +++++++++++++
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/threading/WhileLoopSpinsOnFieldInspection.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/threading/WhileLoopSpinsOnFieldInspection.java
index cbd9b479e970..b42eae42c1e7 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/threading/WhileLoopSpinsOnFieldInspection.java
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/threading/WhileLoopSpinsOnFieldInspection.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2012 Dave Griffith, Bas Leijdekkers
+ * Copyright 2003-2015 Dave Griffith, Bas Leijdekkers
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -74,12 +74,28 @@ public class WhileLoopSpinsOnFieldInspection extends BaseInspection {
       if (field == null) {
         return;
       }
-      if (body != null && VariableAccessUtils.variableIsAssigned(field, body)) {
+      if (body != null && (VariableAccessUtils.variableIsAssigned(field, body) ||
+                           containsWaitCall(body))) {
         return;
       }
       registerStatementError(statement);
     }
 
+    private boolean containsWaitCall(PsiElement element) {
+      final boolean[] result = new boolean[1];
+      element.accept(new JavaRecursiveElementWalkingVisitor() {
+        @Override
+        public void visitMethodCallExpression(PsiMethodCallExpression expression) {
+          super.visitMethodCallExpression(expression);
+          if (ThreadingUtils.isWaitCall(expression)) {
+            result[0] = true;
+            stopWalking();
+          }
+        }
+      });
+      return result[0];
+    }
+
     @Nullable
     private PsiField getFieldIfSimpleFieldComparison(PsiExpression condition) {
       condition = PsiUtil.deparenthesizeExpression(condition);
diff --git a/plugins/InspectionGadgets/test/com/siyeh/igtest/threading/while_loop_spins_on_field/WhileLoopSpinsOnField.java b/plugins/InspectionGadgets/test/com/siyeh/igtest/threading/while_loop_spins_on_field/WhileLoopSpinsOnField.java
index cbf00d8bef9f..23609319e27a 100644
--- a/plugins/InspectionGadgets/test/com/siyeh/igtest/threading/while_loop_spins_on_field/WhileLoopSpinsOnField.java
+++ b/plugins/InspectionGadgets/test/com/siyeh/igtest/threading/while_loop_spins_on_field/WhileLoopSpinsOnField.java
@@ -69,4 +69,18 @@ class WhileLoopSpinsOnField2
         }
     }
 }
+class WhileLoopSpinsOnFieldFalsePosDemo {
+    private boolean field = false;
 
+    public synchronized void setAndNotify() {
+        field = true;
+        this.notifyAll();
+    }
+
+    public synchronized void waitForStuff() throws InterruptedException {
+        // IDEA incorrectly reports "'while' loop spins on field" here:
+        while (!field) {    // <— this line
+            this.wait();    // this has the effect of synchronizing the field correctly
+        }
+    }
+}