[#4017] Implement proper resource leak detection for CompositeByteBuf

Motivation:

CompositeByteBuf only implemented simple resource leak detection and how it was implemented was completly different to the way it was for ByteBuf. The other problem was that slice(), duplicate() and others would not return a resource leak enabled buffer.

Modifications:

- Proper implementation for all level of resource leak detection for CompositeByteBuf

Result:

Proper resource leak detection for CompositeByteBuf.

buffer/src/main/java/io/netty/buffer/AbstractByteBufAllocator.java

@@ -26,7 +26,7 @@
  */
 public abstract class AbstractByteBufAllocator implements ByteBufAllocator {
     private static final int DEFAULT_INITIAL_CAPACITY = 256;
-    private static final int DEFAULT_MAX_COMPONENTS = 16;
+    static final int DEFAULT_MAX_COMPONENTS = 16;
 
     protected static ByteBuf toLeakAwareBuffer(ByteBuf buf) {
         ResourceLeak leak;
@@ -48,6 +48,28 @@ protected static ByteBuf toLeakAwareBuffer(ByteBuf buf) {
         return buf;
     }
 
+    protected static CompositeByteBuf toLeakAwareBuffer(CompositeByteBuf buf) {
+        ResourceLeak leak;
+        switch (ResourceLeakDetector.getLevel()) {
+            case SIMPLE:
+                leak = AbstractByteBuf.leakDetector.open(buf);
+                if (leak != null) {
+                    buf = new SimpleLeakAwareCompositeByteBuf(buf, leak);
+                }
+                break;
+            case ADVANCED:
+            case PARANOID:
+                leak = AbstractByteBuf.leakDetector.open(buf);
+                if (leak != null) {
+                    buf = new AdvancedLeakAwareCompositeByteBuf(buf, leak);
+                }
+                break;
+            default:
+                break;
+        }
+        return buf;
+    }
+
     private final boolean directByDefault;
     private final ByteBuf emptyBuf;
 
@@ -178,7 +200,7 @@ public CompositeByteBuf compositeHeapBuffer() {
 
     @Override
     public CompositeByteBuf compositeHeapBuffer(int maxNumComponents) {
-        return new CompositeByteBuf(this, false, maxNumComponents);
+        return toLeakAwareBuffer(new CompositeByteBuf(this, false, maxNumComponents));
     }
 
     @Override
@@ -188,7 +210,7 @@ public CompositeByteBuf compositeDirectBuffer() {
 
     @Override
     public CompositeByteBuf compositeDirectBuffer(int maxNumComponents) {
-        return new CompositeByteBuf(this, true, maxNumComponents);
+        return toLeakAwareBuffer(new CompositeByteBuf(this, true, maxNumComponents));
     }
 
     private static void validate(int initialCapacity, int maxCapacity) {

buffer/src/main/java/io/netty/buffer/AbstractReferenceCountedByteBuf.java

@@ -44,7 +44,7 @@ protected AbstractReferenceCountedByteBuf(int maxCapacity) {
     }
 
     @Override
-    public final int refCnt() {
+    public int refCnt() {
         return refCnt;
     }
 
@@ -94,7 +94,7 @@ public ByteBuf retain(int increment) {
     }
 
     @Override
-    public final boolean release() {
+    public boolean release() {
         for (;;) {
             int refCnt = this.refCnt;
             if (refCnt == 0) {
@@ -112,7 +112,7 @@ public final boolean release() {
     }
 
     @Override
-    public final boolean release(int decrement) {
+    public boolean release(int decrement) {
         if (decrement <= 0) {
             throw new IllegalArgumentException("decrement: " + decrement + " (expected: > 0)");
         }