move ThreadOptions into its own module

ki/ki.cabal

@@ -95,6 +95,7 @@ library
     Ki.Internal.Scope
     Ki.Internal.Thread
     Ki.Internal.ThreadAffinity
+    Ki.Internal.ThreadOptions
 
 test-suite tests
   import: component

ki/src/Ki.hs

@@ -48,8 +48,9 @@ import Ki.Internal.Scope
     fork_,
     scoped,
   )
-import Ki.Internal.Thread (Thread, ThreadOptions (..), await, defaultThreadOptions)
+import Ki.Internal.Thread (Thread, await)
 import Ki.Internal.ThreadAffinity (ThreadAffinity (..))
+import Ki.Internal.ThreadOptions (ThreadOptions (..), defaultThreadOptions)
 
 -- $introduction
 --

ki/src/Ki/Internal/Scope.hs

@@ -61,7 +61,8 @@ import Ki.Internal.IO
   )
 import Ki.Internal.NonblockingSTM
 import Ki.Internal.Propagating (Tid, peelOffPropagating, propagate, pattern PropagatingFrom)
-import Ki.Internal.Thread (Thread, ThreadOptions (..), defaultThreadOptions, forkWithAffinity, makeThread)
+import Ki.Internal.Thread (Thread, forkWithAffinity, makeThread)
+import Ki.Internal.ThreadOptions (ThreadOptions (..), defaultThreadOptions)
 
 -- | A scope.
 --
@@ -159,8 +160,8 @@ scoped action = do
         atomically do
           -- Block until we haven't committed to starting any threads. Without this, we may create a thread concurrently
           -- with closing its scope, and not grab its thread id to throw an exception to.
-          n <- readTVar statusVar
-          assert (n >= 0) (guard (n == 0))
+          starting <- readTVar statusVar
+          assert (starting >= 0) (guard (starting == 0))
           -- Indicate that this scope is closing, so attempts to create a new thread within it will throw ScopeClosing
           -- (as if the calling thread was a parent of this scope, which it should be, and we threw it a ScopeClosing
           -- ourselves).
@@ -185,7 +186,8 @@ scoped action = do
       -- Block until all children have terminated; this relies on children respecting the async exception, which they
       -- must, for correctness. Otherwise, a thread could indeed outlive the scope in which it's created, which is
       -- definitely not structured concurrency!
-      blockUntilEmpty childrenVar
+      children <- readTVar childrenVar
+      guard (IntMap.Lazy.null children)
       -- Record the scope as closed (from closing), so subsequent attempts to use it will throw a runtime exception
       writeTVar statusVar Closed
 
@@ -292,19 +294,14 @@ unrecordChild childrenVar childId = do
 -- | Wait until all threads created within a scope terminate.
 awaitAll :: Scope -> STM ()
 awaitAll Scope {childrenVar, statusVar} = do
-  blockUntilEmpty childrenVar
-  n <- readTVar statusVar
-  case n of
-    Open -> guard (n == 0)
+  children <- readTVar childrenVar
+  guard (IntMap.Lazy.null children)
+  status <- readTVar statusVar
+  case status of
+    Open -> guard (status == 0)
     Closing -> retry -- block until closed
     Closed -> pure ()
 
--- Block until an IntMap becomes empty.
-blockUntilEmpty :: TVar (IntMap a) -> STM ()
-blockUntilEmpty var = do
-  x <- readTVar var
-  guard (IntMap.Lazy.null x)
-
 -- | Create a child thread to execute an action within a scope.
 --
 -- /Note/: The child thread does not mask asynchronous exceptions, regardless of the parent thread's masking state. To

ki/src/Ki/Internal/Thread.hs

@@ -3,15 +3,12 @@ module Ki.Internal.Thread
     makeThread,
     await,
     forkWithAffinity,
-    ThreadOptions (..),
-    defaultThreadOptions,
   )
 where
 
 import Control.Concurrent (ThreadId, forkOS)
-import Control.Exception (BlockedIndefinitelyOnSTM (..), MaskingState (..))
+import Control.Exception (BlockedIndefinitelyOnSTM (..))
 import GHC.Conc (STM)
-import Ki.Internal.ByteCount (ByteCount)
 import Ki.Internal.IO (forkIO, forkOn, tryEitherSTM)
 import Ki.Internal.ThreadAffinity (ThreadAffinity (..))
 
@@ -58,62 +55,6 @@ forkWithAffinity = \case
   Capability n -> forkOn n
   OsThread -> Control.Concurrent.forkOS
 
--- |
---
--- [@affinity@]:
---
---     The affinity of a thread. A thread can be unbound, bound to a specific capability, or bound to a specific OS
---     thread.
---
---     Default: 'Unbound'
---
--- [@allocationLimit@]:
---
---     The maximum number of bytes a thread may allocate before it is delivered an
---     'Control.Exception.AllocationLimitExceeded' exception. If caught, the thread is allowed to allocate an additional
---     100kb (tunable with @+RTS -xq@) to perform any necessary cleanup actions; if exceeded, the thread is delivered
---     another.
---
---     Default: @Nothing@ (no limit)
---
--- [@label@]:
---
---     The label of a thread, visible in the [event log](https://downloads.haskell.org/ghc/latest/docs/html/users_guide/runtime_control.html#rts-eventlog) (@+RTS -l@).
---
---     Default: @""@ (no label)
---
--- [@maskingState@]:
---
---     The masking state a thread is created in. To unmask, use 'GHC.IO.unsafeUnmask'.
---
---     Default: @Unmasked@
-data ThreadOptions = ThreadOptions
-  { affinity :: ThreadAffinity,
-    allocationLimit :: Maybe ByteCount,
-    label :: String,
-    maskingState :: MaskingState
-  }
-  deriving stock (Eq, Show)
-
--- | Default thread options.
---
--- @
--- 'Ki.ThreadOptions'
---   { 'Ki.affinity' = 'Ki.Unbound'
---   , 'Ki.allocationLimit' = Nothing
---   , 'Ki.label' = ""
---   , 'Ki.maskingState' = 'Unmasked'
---   }
--- @
-defaultThreadOptions :: ThreadOptions
-defaultThreadOptions =
-  ThreadOptions
-    { affinity = Unbound,
-      allocationLimit = Nothing,
-      label = "",
-      maskingState = Unmasked
-    }
-
 -- | Wait for a thread to terminate.
 await :: Thread a -> STM a
 await =

ki/src/Ki/Internal/ThreadOptions.hs

@@ -0,0 +1,65 @@
+module Ki.Internal.ThreadOptions
+  ( ThreadOptions (..),
+    defaultThreadOptions,
+  )
+where
+
+import Control.Exception (MaskingState (..))
+import Ki.Internal.ByteCount (ByteCount)
+import Ki.Internal.ThreadAffinity (ThreadAffinity (..))
+
+-- |
+--
+-- [@affinity@]:
+--
+--     The affinity of a thread. A thread can be unbound, bound to a specific capability, or bound to a specific OS
+--     thread.
+--
+--     Default: 'Unbound'
+--
+-- [@allocationLimit@]:
+--
+--     The maximum number of bytes a thread may allocate before it is delivered an
+--     'Control.Exception.AllocationLimitExceeded' exception. If caught, the thread is allowed to allocate an additional
+--     100kb (tunable with @+RTS -xq@) to perform any necessary cleanup actions; if exceeded, the thread is delivered
+--     another.
+--
+--     Default: @Nothing@ (no limit)
+--
+-- [@label@]:
+--
+--     The label of a thread, visible in the [event log](https://downloads.haskell.org/ghc/latest/docs/html/users_guide/runtime_control.html#rts-eventlog) (@+RTS -l@).
+--
+--     Default: @""@ (no label)
+--
+-- [@maskingState@]:
+--
+--     The masking state a thread is created in. To unmask, use 'GHC.IO.unsafeUnmask'.
+--
+--     Default: @Unmasked@
+data ThreadOptions = ThreadOptions
+  { affinity :: ThreadAffinity,
+    allocationLimit :: Maybe ByteCount,
+    label :: String,
+    maskingState :: MaskingState
+  }
+  deriving stock (Eq, Show)
+
+-- | Default thread options.
+--
+-- @
+-- 'Ki.ThreadOptions'
+--   { 'Ki.affinity' = 'Ki.Unbound'
+--   , 'Ki.allocationLimit' = Nothing
+--   , 'Ki.label' = ""
+--   , 'Ki.maskingState' = 'Unmasked'
+--   }
+-- @
+defaultThreadOptions :: ThreadOptions
+defaultThreadOptions =
+  ThreadOptions
+    { affinity = Unbound,
+      allocationLimit = Nothing,
+      label = "",
+      maskingState = Unmasked
+    }