[GHC] #13554: Allow the user to provide a C function that is called on each thread the RTS creates before running any Haskell code

[GHC]

#13554: Allow the user to provide a C function that is called on each thread the
RTS creates before running any Haskell code
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        Reporter:  dobenour          |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Runtime System    |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by fendor):

 Hi,

 As an API proposal:
 {{{
 data ThreadCallbackHandle

 data ThreadCallbacks =
   ThreadCallbacks
      { threadCreationCb :: IO ()
      , threadDestructionCb :: IO ()
      }

 -- function calls would be blocking until
 -- the callbacks have been executed on all threads.
 registerCallbacks :: ThreadCallbacks -> IO ThreadCallbackHandle
 unregisterCallbacks :: ThreadCallbackHandle -> IO ()

 }}}

 In this proposal, one can submit callbacks that are executed on thread
 creation or thread termination.
 These callbacks are also executed on every thread that is currently being
 executed, since it seems impossible to guarantee that no code execution
 migrates to threads that have not executed the callback functions.
 When registering new callbacks, the function should block, until it is
 guaranteed that every thread has executed the new callback function.

 Several calls to this function should save existing callbacks and execute
 all callback functions that have been supplied upon thread creation and
 termination.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13554#comment:5>
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