From fc58df907aac1177b1fd2ec43694fd492ce170da Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Niklas=20Hamb=C3=BCchen?= Date: Tue, 26 Apr 2022 16:34:57 +0200 Subject: libraries/base: docs: Explain relationshipt between `finalizeForeignPtr` and `*Conc*` creation Fixes https://gitlab.haskell.org/ghc/ghc/-/issues/21420 --- libraries/base/Foreign/Concurrent.hs | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'libraries/base/Foreign') diff --git a/libraries/base/Foreign/Concurrent.hs b/libraries/base/Foreign/Concurrent.hs index e197f798c3..94214d6b5b 100644 --- a/libraries/base/Foreign/Concurrent.hs +++ b/libraries/base/Foreign/Concurrent.hs @@ -38,11 +38,16 @@ newForeignPtr :: Ptr a -> IO () -> IO (ForeignPtr a) -- -- ^Turns a plain memory reference into a foreign object by -- associating a finalizer - given by the monadic operation - with the --- reference. The storage manager will start the finalizer, in a --- separate thread, some time after the last reference to the --- 'ForeignPtr' is dropped. There is no guarantee of promptness, and +-- reference. +-- +-- When finalization is triggered by GC, the storage manager will start the +-- finalizer, in a separate thread, some time after the last reference to the +-- @ForeignPtr@ is dropped. There is __no guarantee of promptness__, and -- in fact there is no guarantee that the finalizer will eventually --- run at all. +-- run at all for GC-triggered finalization. +-- +-- When finalization is triggered by explicitly calling @finalizeForeignPtr@, +-- the finalizer will run immediately on the current Haskell thread. -- -- Note that references from a finalizer do not necessarily prevent -- another object from being finalized. If A's finalizer refers to B -- cgit v1.2.1