review request (URGENT): 7051206: JSR 292 method name SwitchPoint.isValid is misleading to unwary users; should be hasBeenInvalidated

[Vladimir Kozlov]

Looks good to me.

Vladimir

John Rose wrote:
> http://cr.openjdk.java.net/~jrose/7051206
> 
> This is a changed method name (and inverted sense), replacing 
> SwitchPoint.isValid.  Here's the updated javadoc:
> 
> 
>         hasBeenInvalidated
> 
> public boolean hasBeenInvalidated()
> 
> Determines if this switch point has been invalidated yet.
> 
> /Discussion:/ Because of the one-way nature of invalidation, once a 
> switch point begins to return true for |hasBeenInvalidated|, it will 
> always do so in the future. On the other hand, a valid switch point 
> visible to other threads may invalidated at any moment, due to a request 
> by another thread.
> 
> Since invalidation is a global and immediate operation, the execution of 
> this query, on a valid switchpoint, must be internally sequenced with 
> any other threads that could cause invalidation. This query may 
> therefore be expensive. The recommended way to build a boolean-valued 
> method handle which queries the invalidation state of a switch 
> point |s| is to call |s.guardWithTest| on |constant| 
> <file:///Users/jrose/Projects/davinci/patches/netbeans/meth/dist/javadoc/java/lang/invoke/MethodHandles.html#constant(java.lang.Class,%20java.lang.Object)> true 
> and false method handles.
> 
> Returns:
>     true if this switch point has been invalidated
> 
>