From a46395ecf932ea4e91ad047e92d1c70395e15673 Mon Sep 17 00:00:00 2001
From: rsc <devnull@localhost>
Date: Wed, 1 Oct 2003 02:53:00 +0000
Subject: More Darwin.

---
 src/lib9/rendez.c | 180 ------------------------------------------------------
 1 file changed, 180 deletions(-)
 delete mode 100644 src/lib9/rendez.c

(limited to 'src/lib9/rendez.c')

diff --git a/src/lib9/rendez.c b/src/lib9/rendez.c
deleted file mode 100644
index 320bd11a..00000000
--- a/src/lib9/rendez.c
+++ /dev/null
@@ -1,180 +0,0 @@
-/*
-     NAME
-          rendezvous - user level process synchronization
-
-     SYNOPSIS
-          ulong rendezvous(ulong tag, ulong value)
-
-     DESCRIPTION
-          The rendezvous system call allows two processes to synchro-
-          nize and exchange a value.  In conjunction with the shared
-          memory system calls (see segattach(2) and fork(2)), it
-          enables parallel programs to control their scheduling.
-
-          Two processes wishing to synchronize call rendezvous with a
-          common tag, typically an address in memory they share.  One
-          process will arrive at the rendezvous first; it suspends
-          execution until a second arrives.  When a second process
-          meets the rendezvous the value arguments are exchanged
-          between the processes and returned as the result of the
-          respective rendezvous system calls.  Both processes are
-          awakened when the rendezvous succeeds.
-
-          The set of tag values which two processes may use to
-          rendezvous-their tag space-is inherited when a process
-          forks, unless RFREND is set in the argument to rfork; see
-          fork(2).
-
-          If a rendezvous is interrupted the return value is ~0, so
-          that value should not be used in normal communication.
-
- * This simulates rendezvous with shared memory, pause, and SIGUSR1.
- */
-
-#include <signal.h>
-#include <lib9.h>
-
-enum
-{
-	VOUSHASH = 257,
-};
-
-typedef struct Vous Vous;
-struct Vous
-{
-	Vous *link;
-	Lock lk;
-	int pid;
-	ulong val;
-	ulong tag;
-};
-
-static void
-ign(int x)
-{
-	USED(x);
-}
-
-void /*__attribute__((constructor))*/
-ignusr1(void)
-{
-	signal(SIGUSR1, ign);
-}
-
-static Vous vouspool[2048];
-static int nvousused;
-static Vous *vousfree;
-static Vous *voushash[VOUSHASH];
-static Lock vouslock;
-
-static Vous*
-getvous(void)
-{
-	Vous *v;
-
-	if(vousfree){
-		v = vousfree;
-		vousfree = v->link;
-	}else if(nvousused < nelem(vouspool))
-		v = &vouspool[nvousused++];
-	else
-		abort();
-	return v;
-}
-
-static void
-putvous(Vous *v)
-{
-	lock(&vouslock);
-	v->link = vousfree;
-	vousfree = v;
-	unlock(&vouslock);
-}
-
-static Vous*
-findvous(ulong tag, ulong val, int pid)
-{
-	int h;
-	Vous *v, **l;
-
-	lock(&vouslock);
-	h = tag%VOUSHASH;
-	for(l=&voushash[h], v=*l; v; l=&(*l)->link, v=*l){
-		if(v->tag == tag){
-			*l = v->link;
-			unlock(&vouslock);
-			return v;
-		}
-	}
-	v = getvous();
-	v->pid = pid;
-	v->link = voushash[h];
-	v->val = val;
-	v->tag = tag;
-	lock(&v->lk);
-	voushash[h] = v;
-	unlock(&vouslock);
-	return v;
-}
-
-#define DBG 0
-ulong
-rendezvous(ulong tag, ulong val)
-{
-	int me, vpid;
-	ulong rval;
-	Vous *v;
-	sigset_t mask;
-
-	me = getpid();
-	v = findvous(tag, val, me);
-	if(v->pid == me){
-		if(DBG)fprint(2, "pid is %d tag %lux, sleeping\n", me, tag);
-		/*
-		 * No rendezvous partner was found; the next guy
-		 * through will find v and wake us, so we must go
-		 * to sleep.
-		 *
-		 * To go to sleep:
-		 *	1. disable USR1 signals.
-		 *	2. unlock v->lk (tells waker okay to signal us).
-		 *	3. atomically suspend and enable USR1 signals.
-		 *
-		 * The call to ignusr1() could be done once at 
-		 * process creation instead of every time through rendezvous.
-		 */
-		v->val = val;
-		ignusr1();
-		sigprocmask(SIG_SETMASK, NULL, &mask);
-		sigaddset(&mask, SIGUSR1);
-		sigprocmask(SIG_SETMASK, &mask, NULL);
-		sigdelset(&mask, SIGUSR1);
-		unlock(&v->lk);
-		sigsuspend(&mask);
-		rval = v->val;
-		if(DBG)fprint(2, "pid is %d, awake\n", me);
-		putvous(v);
-	}else{
-		/*
-		 * Found someone to meet.  Wake him:
-		 *
-		 *	A. lock v->lk (waits for him to get to his step 2)
-		 *	B. send a USR1
-		 *
-		 * He won't get the USR1 until he suspends, which
-		 * means it must wake him up (it can't get delivered
-		 * before he sleeps).
-		 */
-		vpid = v->pid;
-		lock(&v->lk);
-		rval = v->val;
-		v->val = val;
-		unlock(&v->lk);
-		if(kill(vpid, SIGUSR1) < 0){
-			if(DBG)fprint(2, "pid is %d, kill %d failed: %r\n", me, vpid);
-			abort();
-		}
-	}
-	return rval;
-}
-
-- 
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