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| author | Simon Marlow <marlowsd@gmail.com> | 2016-08-30 20:55:10 +0100 |
|---|---|---|
| committer | Simon Marlow <marlowsd@gmail.com> | 2016-09-12 08:33:24 +0100 |
| commit | 454033b54e2f7eef2354cc9d7ae7e7cba4dff09a (patch) | |
| tree | 3577ed7b0b42e2acff1502673e1ee474fba31319 /rts/Prelude.h | |
| parent | 0e7ccf6d233c66b23a60de4e35e039f78ea3e162 (diff) | |
| download | haskell-454033b54e2f7eef2354cc9d7ae7e7cba4dff09a.tar.gz | |
Add hs_try_putmvar()
Summary:
This is a fast, non-blocking, asynchronous, interface to tryPutMVar that
can be called from C/C++.
It's useful for callback-based C/C++ APIs: the idea is that the callback
invokes hs_try_putmvar(), and the Haskell code waits for the callback to
run by blocking in takeMVar.
The callback doesn't block - this is often a requirement of
callback-based APIs. The callback wakes up the Haskell thread with
minimal overhead and no unnecessary context-switches.
There are a couple of benchmarks in
testsuite/tests/concurrent/should_run. Some example results comparing
hs_try_putmvar() with using a standard foreign export:
./hs_try_putmvar003 1 64 16 100 +RTS -s -N4 0.49s
./hs_try_putmvar003 2 64 16 100 +RTS -s -N4 2.30s
hs_try_putmvar() is 4x faster for this workload (see the source for
hs_try_putmvar003.hs for details of the workload).
An alternative solution is to use the IO Manager for this. We've tried
it, but there are problems with that approach:
* Need to create a new file descriptor for each callback
* The IO Manger thread(s) become a bottleneck
* More potential for things to go wrong, e.g. throwing an exception in
an IO Manager callback kills the IO Manager thread.
Test Plan: validate; new unit tests
Reviewers: niteria, erikd, ezyang, bgamari, austin, hvr
Subscribers: thomie
Differential Revision: https://phabricator.haskell.org/D2501
Diffstat (limited to 'rts/Prelude.h')
| -rw-r--r-- | rts/Prelude.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/rts/Prelude.h b/rts/Prelude.h index ae1e9cb266..58de23013b 100644 --- a/rts/Prelude.h +++ b/rts/Prelude.h @@ -24,6 +24,7 @@ * modules these names are defined in. */ +PRELUDE_CLOSURE(ghczmprim_GHCziTuple_Z0T_closure); PRELUDE_CLOSURE(ghczmprim_GHCziTypes_True_closure); PRELUDE_CLOSURE(ghczmprim_GHCziTypes_False_closure); PRELUDE_CLOSURE(base_GHCziPack_unpackCString_closure); @@ -87,6 +88,7 @@ PRELUDE_INFO(base_GHCziWord_W64zh_con_info); PRELUDE_INFO(base_GHCziStable_StablePtr_static_info); PRELUDE_INFO(base_GHCziStable_StablePtr_con_info); +#define Unit_closure DLL_IMPORT_DATA_REF(ghczmprim_GHCziTuple_Z0T_closure) #define True_closure DLL_IMPORT_DATA_REF(ghczmprim_GHCziTypes_True_closure) #define False_closure DLL_IMPORT_DATA_REF(ghczmprim_GHCziTypes_False_closure) #define unpackCString_closure DLL_IMPORT_DATA_REF(base_GHCziPack_unpackCString_closure) |