[HADOOP-11221] JAVA specification for hashcode does not enforce it to be non-negative, but IdentityHashStore assumes System.identityHashCode() is non-negative

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.1
• Fix Version/s: 2.6.0
• Component/s: util
• Hadoop Flags: Reviewed
• Assignee: Jinghui Wang
• Reporter: Jinghui Wang
• Created: 23/Oct/14 18:18
• Updated: 01/Dec/14 03:10
• Resolved: 30/Oct/14 18:02

Description

The following code snippet shows that IdentityHashStore assumes the hashCode is always non-negative.

   private void putInternal(Object k, Object v) {
     int hash = System.identityHashCode(k);
     final int numEntries = buffer.length / 2;
     int index = hash % numEntries;
	 ...
   }
   
  private int getElementIndex(K k) {
     ...
     final int numEntries = buffer.length / 2;
     int hash = System.identityHashCode(k);
     int index = hash % numEntries;
     int firstIndex = index;
     ...
  }