[HARMONY-6652] Synchronized setter method but non-synchronized similarly-name getter method in DragSourceContextr.java

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 6.0M1
• Component/s: Classlib
• Environment: Windows XP
• Assignee: Unassigned
• Reporter: Wendy Feng
• Created: 19/Sep/10 02:19
• Updated: 19/Sep/10 02:19

Description

I found some unsafe synchronization in DragSourceContextr.java as follow:

public class DragSourceContext implements DragSourceListener,
DragSourceMotionListener, Serializable{
...
public Cursor getCursor()

{ return cursor; }

public synchronized void setCursor(Cursor c) {
cursor = c;

defaultCursor = (cursor == null);
if (defaultCursor)

{ updateCurrentCursor(sourceAction, lastTargetAction, lastStatus); }

else

{ peer.setCursor(cursor); }

}
...
}

in the above code, cursor is a field variable but not declared volatile. getCursor() method is not synchronized while setCursor(Cursor c) is. Unless the fields are declared volatile, the Java Memory Model doesn't guarantee up-to-date field value visible to threads in the absent of synchronization. Caller of unsynchronized getter method could read stale or inconsistent values, which could cause serious problems.

Consequence:
Threads can read a stale cursor value in the absence of synchronization.

It is more safer to Synchronize getScheduledExecutionTime() method.