From 559fe1daace8f48a8dc37906f840e9981b961415 Mon Sep 17 00:00:00 2001 From: wm4 Date: Sat, 26 Jul 2014 20:29:48 +0200 Subject: Add Plan 9-style barriers Plan 9 has a very interesting synchronization mechanism, the rendezvous() call. A good property of this is that you don't need to explicitly initialize and destroy a barrier object, unlike as with e.g. POSIX barriers (which are mandatory to begin with). Upon "meeting", they can exchange a value. This mechanism will be nice to synchronize certain stages of initialization between threads in the following commit. Unlike Plan 9 rendezvous(), this is not implemented with a hashtable, because that would require additional effort (especially if you want to make it actually scele). Unlike the Plan 9 variant, we use intptr_t instead of void* as type for the value, because I expect that we will be mostly passing a status code as value and not a pointer. Converting an integer to void* requires two cast (because the integer needs to be intptr_t), the other way around it's only one cast. We don't particularly care about performance in this case either. It's simply not important for our use-case. So a simple linked list is used for waiters, and on wakeup, all waiters are temporarily woken up. --- old-makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'old-makefile') diff --git a/old-makefile b/old-makefile index c5d8e6a223..a1d98e60ec 100644 --- a/old-makefile +++ b/old-makefile @@ -177,6 +177,7 @@ SOURCES = audio/audio.c \ input/keycodes.c \ misc/charset_conv.c \ misc/dispatch.c \ + misc/rendezvous.c \ misc/ring.c \ options/m_config.c \ options/m_option.c \ -- cgit v1.2.3