From a0ed6ec06ca605ed39b601355daedace93828032 Mon Sep 17 00:00:00 2001
From: Xiaoyan Lin <linxiaoyan18@gmail.com>
Date: Tue, 8 May 2018 11:09:16 -0700
Subject: [PATCH] Fix the error message in ReferenceCounted.release (#7921)

Motivation:

When a buffer is over-released, the current error message of `IllegalReferenceCountException` is `refCnt: XXX, increment: XXX`, which is confusing. The correct message should be `refCnt: XXX, decrement: XXX`.

Modifications:

Pass `-decrement` to create `IllegalReferenceCountException`.

Result:

The error message will be `refCnt: XXX, decrement: XXX` when a buffer is over-released.
---
 .../buffer/AbstractReferenceCountedByteBuf.java     |  2 +-
 .../buffer/AbstractReferenceCountedByteBufTest.java | 13 +++++++++++++
 .../io/netty/util/AbstractReferenceCounted.java     |  2 +-
 .../io/netty/util/AbstractReferenceCountedTest.java | 13 +++++++++++++
 4 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/buffer/src/main/java/io/netty/buffer/AbstractReferenceCountedByteBuf.java b/buffer/src/main/java/io/netty/buffer/AbstractReferenceCountedByteBuf.java
index d3058c0fb6..d624d855f4 100644
--- a/buffer/src/main/java/io/netty/buffer/AbstractReferenceCountedByteBuf.java
+++ b/buffer/src/main/java/io/netty/buffer/AbstractReferenceCountedByteBuf.java
@@ -97,7 +97,7 @@ public abstract class AbstractReferenceCountedByteBuf extends AbstractByteBuf {
         } else if (oldRef < decrement || oldRef - decrement > oldRef) {
             // Ensure we don't over-release, and avoid underflow.
             refCntUpdater.getAndAdd(this, decrement);
-            throw new IllegalReferenceCountException(oldRef, decrement);
+            throw new IllegalReferenceCountException(oldRef, -decrement);
         }
         return false;
     }
diff --git a/buffer/src/test/java/io/netty/buffer/AbstractReferenceCountedByteBufTest.java b/buffer/src/test/java/io/netty/buffer/AbstractReferenceCountedByteBufTest.java
index 48fe415332..dcc25b20cb 100644
--- a/buffer/src/test/java/io/netty/buffer/AbstractReferenceCountedByteBufTest.java
+++ b/buffer/src/test/java/io/netty/buffer/AbstractReferenceCountedByteBufTest.java
@@ -29,6 +29,7 @@ import java.nio.channels.ScatteringByteChannel;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 public class AbstractReferenceCountedByteBufTest {
 
@@ -55,6 +56,18 @@ public class AbstractReferenceCountedByteBufTest {
         referenceCounted.release(Integer.MAX_VALUE);
     }
 
+    @Test
+    public void testReleaseErrorMessage() {
+        AbstractReferenceCountedByteBuf referenceCounted = newReferenceCounted();
+        assertTrue(referenceCounted.release());
+        try {
+            referenceCounted.release(1);
+            fail("IllegalReferenceCountException didn't occur");
+        } catch (IllegalReferenceCountException e) {
+            assertEquals("refCnt: 0, decrement: 1", e.getMessage());
+        }
+    }
+
     @Test(expected = IllegalReferenceCountException.class)
     public void testRetainResurrect() {
         AbstractReferenceCountedByteBuf referenceCounted = newReferenceCounted();
diff --git a/common/src/main/java/io/netty/util/AbstractReferenceCounted.java b/common/src/main/java/io/netty/util/AbstractReferenceCounted.java
index 5fae9dca11..fe20f92a2e 100644
--- a/common/src/main/java/io/netty/util/AbstractReferenceCounted.java
+++ b/common/src/main/java/io/netty/util/AbstractReferenceCounted.java
@@ -84,7 +84,7 @@ public abstract class AbstractReferenceCounted implements ReferenceCounted {
         } else if (oldRef < decrement || oldRef - decrement > oldRef) {
             // Ensure we don't over-release, and avoid underflow.
             refCntUpdater.getAndAdd(this, decrement);
-            throw new IllegalReferenceCountException(oldRef, decrement);
+            throw new IllegalReferenceCountException(oldRef, -decrement);
         }
         return false;
     }
diff --git a/common/src/test/java/io/netty/util/AbstractReferenceCountedTest.java b/common/src/test/java/io/netty/util/AbstractReferenceCountedTest.java
index e004e5df7b..5af113490f 100644
--- a/common/src/test/java/io/netty/util/AbstractReferenceCountedTest.java
+++ b/common/src/test/java/io/netty/util/AbstractReferenceCountedTest.java
@@ -19,6 +19,7 @@ import org.junit.Test;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 public class AbstractReferenceCountedTest {
 
@@ -45,6 +46,18 @@ public class AbstractReferenceCountedTest {
         referenceCounted.release(Integer.MAX_VALUE);
     }
 
+    @Test
+    public void testReleaseErrorMessage() {
+        AbstractReferenceCounted referenceCounted = newReferenceCounted();
+        assertTrue(referenceCounted.release());
+        try {
+            referenceCounted.release(1);
+            fail("IllegalReferenceCountException didn't occur");
+        } catch (IllegalReferenceCountException e) {
+            assertEquals("refCnt: 0, decrement: 1", e.getMessage());
+        }
+    }
+
     @Test(expected = IllegalReferenceCountException.class)
     public void testRetainResurrect() {
         AbstractReferenceCounted referenceCounted = newReferenceCounted();