try-catch for null reference in Transfer

src/DotNetty.Common/ThreadLocalPool.cs

@@ -236,98 +236,109 @@ internal void Add(DefaultHandle handle)
  // transfer as many items as we can from this queue to the stack, returning true if any were transferred
  internal bool Transfer(Stack dst)
  {
- Link head = this.head?.link;
- if (head == null)
+ try
  {
- return false;
- }
-
- if (head.ReadIndex == LinkCapacity)
- {
- if (head.next == null)
+ Link head = this.head?.link;
+ if (head == null)
  {
  return false;
  }
- this.head.link = head = head.next;
- }
 
- int srcStart = head.ReadIndex;
- int srcEnd = head.WriteIndex;
- int srcSize = srcEnd - srcStart;
- if (srcSize == 0)
- {
- return false;
- }
+ if (head.ReadIndex == LinkCapacity)
+ {
+ if (head.next == null)
+ {
+ return false;
+ }
 
- if (dst?.elements == null)
- {
- return false;
- }
-
- int dstSize = dst.size;
- int expectedCapacity = dstSize + srcSize;
+ this.head.link = head = head.next;
+ }
 
- if (expectedCapacity > dst.elements.Length)
- {
- int actualCapacity = dst.IncreaseCapacity(expectedCapacity);
- srcEnd = Math.Min(srcStart + actualCapacity - dstSize, srcEnd);
- }
+ int srcStart = head.ReadIndex;
+ int srcEnd = head.WriteIndex;
+ int srcSize = srcEnd - srcStart;
+ if (srcSize == 0)
+ {
+ return false;
+ }
 
- if (srcStart != srcEnd)
- {
- DefaultHandle[] srcElems = head.elements;
- DefaultHandle[] dstElems = dst.elements;
- int newDstSize = dstSize;
- if (head.elements == null)
+ if (dst?.elements == null)
  {
  return false;
  }
-
- for (int i = srcStart; i < srcEnd; i++)
+
+ int dstSize = dst.size;
+ int expectedCapacity = dstSize + srcSize;
+
+ if (expectedCapacity > dst.elements.Length)
  {
- DefaultHandle element = srcElems[i];
- if (element == null)
+ int actualCapacity = dst.IncreaseCapacity(expectedCapacity);
+ srcEnd = Math.Min(srcStart + actualCapacity - dstSize, srcEnd);
+ }
+
+ if (srcStart != srcEnd)
+ {
+ DefaultHandle[] srcElems = head.elements;
+ DefaultHandle[] dstElems = dst.elements;
+ int newDstSize = dstSize;
+ if (head.elements == null)
  {
  return false;
  }
- 
- if (element.recycleId == 0)
+
+ for (int i = srcStart; i < srcEnd; i++)
  {
- element.recycleId = element.lastRecycledId;
+ DefaultHandle element = srcElems[i];
+ if (element == null)
+ {
+ return false;
+ }
+
+ if (element.recycleId == 0)
+ {
+ element.recycleId = element.lastRecycledId;
+ }
+ else if (element.recycleId != element.lastRecycledId)
+ {
+ throw new InvalidOperationException("recycled already");
+ }
+
+ srcElems[i] = null;
+
+ if (dst.DropHandle(element))
+ {
+ // Drop the object.
+ continue;
+ }
+
+ element.Stack = dst;
+ dstElems[newDstSize++] = element;
  }
- else if (element.recycleId != element.lastRecycledId)
+
+ if (srcEnd == LinkCapacity && head.next != null)
  {
- throw new InvalidOperationException("recycled already");
+ // Add capacity back as the Link is GCed.
+ this.head.ReclaimSpace(LinkCapacity);
+ this.head.link = head.next;
  }
- srcElems[i] = null;
 
- if (dst.DropHandle(element))
+ head.ReadIndex = srcEnd;
+ if (dst.size == newDstSize)
  {
- // Drop the object.
- continue;
+ return false;
  }
- element.Stack = dst;
- dstElems[newDstSize++] = element;
- }
 
- if (srcEnd == LinkCapacity && head.next != null)
- {
- // Add capacity back as the Link is GCed.
- this.head.ReclaimSpace(LinkCapacity);
- this.head.link = head.next;
+ dst.size = newDstSize;
+ return true;
  }
-
- head.ReadIndex = srcEnd;
- if (dst.size == newDstSize)
+ else
  {
+ // The destination stack is full already.
  return false;
  }
- dst.size = newDstSize;
- return true;
  }
- else
+ catch (NullReferenceException)
  {
- // The destination stack is full already.
  return false;
  }
  }