shithub: mc

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Fix condvars to use requeue.

    The docs are wrong. Fuck.

--- a/lib/thread/condvar+linux.myr

+++ b/lib/thread/condvar+linux.myr

@@ -32,9 +32,14 @@

 	mtxunlock(mtx)

 	sys.futex(&cond._seq, sys.Futexwait | sys.Futexpriv, seq, Zptr, Zptr, 0)

-	/* We need to atomically set the mutex to contended */

+	/*

+	We need to atomically set the mutex to contended. This allows us to

+	pass responsibility for waking up the potential other waiters on to the

+	unlocker of the mutex.

+	*/

 	while xchg(&mtx._state, Contended) != Unlocked

-		sys.futex(&mtx._state, sys.Futexwait | sys.Futexpriv, Contended, Zptr, Zptr, 0)

+		sys.futex(&mtx._state, sys.Futexwait | sys.Futexpriv, \

+			Contended, Zptr, Zptr, 0)

 	;;

 }

@@ -45,6 +50,13 @@

 const condbroadcast = {cond : cond#

 	xadd(&cond._seq, 1)

-	sys.futex(&cond._seq, sys.Futexwake | sys.Futexpriv, 0x7fffffff, Zptr, Zptr, 0)

+	/*

+	The futex docs seem to be broken -- the timeout parameter seems to be

+	used for the number of threads to move, and is not ignored when

+	requeueing

+	*/

+	sys.futex(&cond._seq, sys.Futexcmprequeue | sys.Futexpriv, \

+		1, 0x7fffffff castto(sys.timespec#), \

+		&cond._mtx._state, cond._seq)

 }

--- a/lib/thread/test/condvar.myr

+++ b/lib/thread/test/condvar.myr

@@ -41,7 +41,6 @@

 	;;

 	thread.condbroadcast(&cv)

 	while nwoken != 100

-		std.put("{}\n", nwoken)

 		/* nothing */

 	;;

 	std.assert(nwoken == 100, "wrong thread count woken")