Dan Sugalski <[EMAIL PROTECTED]> wrote:
[ No Guarantees WRT data access }
... seems to indicate that even whole ops like add P,P,P are atomic.
Yep. They have to be, because they need to guarantee the integrity of the pmc structures and the data hanging off them (which includes buffer and string stuff)
But isn't that a contradiction? Or better: When even an opcode like above is atomic, that an access to a shared PerlNum should be guaranteed being atomic too.
Sure, but there's a *lot* more to user data integrity than atomic access to individual pieces. That's the least of the problem. The user data issue is one where you have multiple pieces being updated, or one piece being updated multiple times--that's the stuff we're not guaranteeing.
So, while we will make sure that storing a single value into a hash happens atomically, we won't guarantee that a series of stores into the hash, or a combination of loads and stores, or even a combination of reads and writes to a scalar, will happen atomically.
--
Dan
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Dan Sugalski even samurai
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