io-sim-por: backport logging of MaskingState

Backport aa0fb5b11 to `IOSimPOR`.

Author: coot

io-sim/src/Control/Monad/IOSimPOR/Internal.hs

@@ -301,22 +301,24 @@ schedule thread@Thread{
         let thread' = thread { threadControl = ThreadControl (k x) ctl'
                              , threadMasking = maskst' }
         -- but if we're now unmasked, check for any pending async exceptions
-        deschedule Interruptable thread' simstate
+        trace <- deschedule Interruptable thread' simstate
+        return (SimTrace time tid tlbl (EventMask maskst') trace)
 
       CatchFrame _handler k ctl' -> do
         -- pop the control stack and continue
         let thread' = thread { threadControl = ThreadControl (k x) ctl' }
         schedule thread' simstate
 
     Throw e -> case unwindControlStack e thread of
-      Right thread0 -> do
+      Right thread0@Thread { threadMasking = maskst' } -> do
         -- We found a suitable exception handler, continue with that
         -- We record a step, in case there is no exception handler on replay.
         let thread'  = stepThread thread0
             control' = advanceControl (threadStepId thread0) control
             races'   = updateRacesInSimState thread0 simstate
         trace <- schedule thread' simstate{ races = races', control = control' }
-        return (SimTrace time tid tlbl (EventThrow e) trace)
+        return (SimTrace time tid tlbl (EventThrow e) $
+                SimTrace time tid tlbl (EventMask maskst') trace)
 
       Left isMain
         -- We unwound and did not find any suitable exception handler, so we
@@ -583,10 +585,12 @@ schedule thread@Thread{
                                                (runIOSim action')
                                                (MaskFrame k maskst ctl)
                            , threadMasking = maskst' }
-      case maskst' of
-        -- If we're now unmasked then check for any pending async exceptions
-        Unmasked -> deschedule Interruptable thread' simstate
-        _        -> schedule                 thread' simstate
+      trace <-
+        case maskst' of
+          -- If we're now unmasked then check for any pending async exceptions
+          Unmasked -> deschedule Interruptable thread' simstate
+          _        -> schedule                 thread' simstate
+      return (SimTrace time tid tlbl (EventMask maskst') trace)
 
     ThrowTo e tid' _ | tid' == tid -> do
       -- Throw to ourself is equivalent to a synchronous throw,