[GHC] #4001: Implement an atomic readMVar

[GHC]

#4001: Implement an atomic readMVar
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        Reporter:           |            Owner:  ezyang
  simonmar                  |           Status:  closed
            Type:  task     |        Milestone:  7.6.2
        Priority:  low      |          Version:  6.12.2
       Component:  Runtime  |         Keywords:
  System                    |     Architecture:  Unknown/Multiple
      Resolution:  fixed    |       Difficulty:  Moderate (less than a day)
Operating System:           |       Blocked By:
  Unknown/Multiple          |  Related Tickets:
 Type of failure:           |
  None/Unknown              |
       Test Case:           |
        Blocking:           |
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Changes (by ezyang):

 * status:  new => closed
 * resolution:   => fixed


Comment:

 {{{
 commit 70e20631742e516c6a11c3c112fbd5b4a08c15ac
 Author: Edward Z. Yang <ezyang at mit.edu>
 Date:   Mon Jul 8 11:03:35 2013 -0700

     Implement atomicReadMVar, fixing #4001.

     We add the invariant to the MVar blocked threads queue that
     threads blocked on an atomic read are always at the front of
     the queue.  This invariant is easy to maintain, since takers
     are only ever added to the end of the queue.

     Signed-off-by: Edward Z. Yang <ezyang at mit.edu>

 commit 1cb6aee7fd81175fe0af81146e878aaf7cda87d2
 Author: Edward Z. Yang <ezyang at mit.edu>
 Date:   Fri Jun 14 14:21:02 2013 -0700

     Tests for atomicReadMVar.

     Signed-off-by: Edward Z. Yang <ezyang at mit.edu>

 commit c464def32f8ba65927ecfcbe34a5f06c21774ecc
 Author: Edward Z. Yang <ezyang at mit.edu>
 Date:   Fri Jun 14 14:19:58 2013 -0700

     Add atomicReadMVar to Control.Concurrent.MVar and friends.

     Also renumber thread statuses as necessary.

     Signed-off-by: Edward Z. Yang <ezyang at mit.edu>
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4001#comment:21>
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