#15980: unpin a mutable byte array -------------------------------------+------------------------------------- Reporter: andrewthad | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.6.3 Component: Compiler | Version: 8.6.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Sometimes, it necessary to allocate a mutable byte array as pinned. This commonly happens when the mutable byte array will immidiately be handed over to a `safe` FFI routine to be initialized. However, after it has been initialized, it might not be useful for it to be pinned anymore. If it's a little byte array, it may contribute to a fragmented heap. Even if it's large, the fact that the user explicitly asked pin it prohibits it from ever being added to a compact region (pinned bytearrays that were pinned simply because they are over 3KB can be added to compact regions). A workaround for either of these problems is to copy the pinned bytearray into an unpinned byte array afterwards. But that's kind of wasteful. Is it possible to have a primop {{{ unpinMutableByteArray :: MutableByteArray s -> State# s -> State# s }}} After this, the mutable byte array could be moved in memory. This would require `isMutableByteArrayPinned#` to undergo a similar transition as `sizeofMutableByteArray#` (which was superceeded by `getSizeofMutableByteArray#`) underwent. Is this possible? Or are pinned things allocated in a special place that makes unpinning impossible? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15980 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler