# HG changeset patch
# User Akshat Kumar <seed@mail.nanosouffle.net>
# Date 1327700714 0
# Node ID 35f5add268d315f5d2e9dcfaf493411a0775c924
# Parent  65307256b5257902153f11edd174638b14e15b6d
nix: tsemacquire.
Forked a tsemacquire from semacquire,
leaving semacquire unchanged.
"For testing purposes only."

R=nix-dev, john, rminnich, nemo, ality
CC=nix-dev
http://codereview.appspot.com/5569056

Committer: John Floren <john@jfloren.net>

diff -r 65307256b525 -r 35f5add268d3 sys/include/libc.h
--- a/sys/include/libc.h	Fri Jan 27 18:54:26 2012 +0100
+++ b/sys/include/libc.h	Fri Jan 27 21:45:14 2012 +0000
@@ -683,6 +683,7 @@
 extern	long	semrelease(long*, long);
 extern	int	sleep(long);
 extern	int	stat(char*, uchar*, int);
+extern	int	tsemacquire(long*, ulong);
 extern	Waitmsg*	wait(void);
 extern	int	waitpid(void);
 extern	long	write(int, void*, long);
diff -r 65307256b525 -r 35f5add268d3 sys/src/libc/9syscall/sys.h
--- a/sys/src/libc/9syscall/sys.h	Fri Jan 27 18:54:26 2012 +0100
+++ b/sys/src/libc/9syscall/sys.h	Fri Jan 27 21:45:14 2012 +0000
@@ -56,4 +56,4 @@
 #define	ZIOPREAD		57
 #define	ZIOPWRITE		58
 #define	ZIOFREE		59
-
+#define	TSEMACQUIRE	60
diff -r 65307256b525 -r 35f5add268d3 sys/src/nix/port/syscallfmt.c
--- a/sys/src/nix/port/syscallfmt.c	Fri Jan 27 18:54:26 2012 +0100
+++ b/sys/src/nix/port/syscallfmt.c	Fri Jan 27 21:45:14 2012 +0000
@@ -247,6 +247,11 @@
 		i[0] = va_arg(list, int);
 		fmtprint(&fmt, "%#p %d", v, i[0]);
 		break;
+	case TSEMACQUIRE:
+		v = va_arg(list, int*);
+		l = va_arg(list, ulong);
+		fmtprint(&fmt, "%#p %ld", v, l);
+		break;
 	case SEMSLEEP:
 	case SEMWAKEUP:
 		v = va_arg(list, int*);
diff -r 65307256b525 -r 35f5add268d3 sys/src/nix/port/sysproc.c
--- a/sys/src/nix/port/sysproc.c	Fri Jan 27 18:54:26 2012 +0100
+++ b/sys/src/nix/port/sysproc.c	Fri Jan 27 21:45:14 2012 +0000
@@ -1185,13 +1185,59 @@
 		sleep(&phore, semawoke, &phore);
 		poperror();
 	}
+ 	semdequeue(s, &phore);
+ 	coherence();	/* not strictly necessary due to lock in semdequeue */
+ 	if(!phore.waiting)
+ 		semwakeup(s, addr, 1);
+	if(!acquired)
+		nexterror();
+	return 1;
+}
+
+/* Acquire semaphore or time-out */
+static int
+tsemacquire(Segment* s, int* addr, ulong ms)
+{
+	int acquired;
+	Sema phore;
+	int timedout;
+	ulong t;
+
+	if(canacquire(addr))
+		return 1;
+	if(ms == 0)
+		return 0;
+
+	acquired = 0;
+	timedout = 0;
+	semqueue(s, addr, &phore);
+	for(;;){
+		phore.waiting = 1;
+		coherence();
+		if(canacquire(addr)){
+			acquired = 1;
+			break;
+		}
+		if(waserror())
+			break;
+		t = m->ticks;
+		tsleep(&phore, semawoke, &phore, ms);
+		if(TK2MS(m->ticks-t) >= ms) {
+			timedout = 1;
+			poperror();
+			break;
+		}
+		ms -= TK2MS(m->ticks-t);
+		poperror();
+	}
 	semdequeue(s, &phore);
 	coherence();	/* not strictly necessary due to lock in semdequeue */
 	if(!phore.waiting)
 		semwakeup(s, addr, 1);
+	if(timedout)
+		return 0;
 	if(!acquired)
 		nexterror();
-
 	return 1;
 }
 
@@ -1220,6 +1266,30 @@
 }
 
 void
+systsemacquire(Ar0* ar0, va_list list)
+{
+	Segment *s;
+	int *addr, ms;
+
+	/*
+	 * int semacquire(long* addr, int block);
+	 * should be (and will be implemented below as) perhaps
+	 * int semacquire(int* addr, int block);
+	 */
+	addr = va_arg(list, int*);
+	addr = validaddr(addr, sizeof(int), 1);
+	evenaddr(PTR2UINT(addr));
+	ms = va_arg(list, int);
+
+	if((s = seg(up, PTR2UINT(addr), 0)) == nil)
+		error(Ebadarg);
+	if(*addr < 0)
+		error(Ebadarg);
+
+	ar0->i = tsemacquire(s, addr, ms);
+}
+
+void
 syssemrelease(Ar0* ar0, va_list list)
 {
 	Segment *s;
diff -r 65307256b525 -r 35f5add268d3 sys/src/nix/port/systab.c
--- a/sys/src/nix/port/systab.c	Fri Jan 27 18:54:26 2012 +0100
+++ b/sys/src/nix/port/systab.c	Fri Jan 27 21:45:14 2012 +0000
@@ -64,6 +64,7 @@
 extern void sysziopread(Ar0*, va_list);
 extern void sysziopwrite(Ar0*, va_list);
 extern void sysziofree(Ar0*, va_list);
+extern void systsemacquire(Ar0*, va_list);
 struct {
 	char*	n;
 	void (*f)(Ar0*, va_list);
@@ -127,6 +128,7 @@
 	[ZIOPREAD]	{ "Ziopread", sysziopread, { .l = -1 } },
 	[ZIOPWRITE]	{ "Ziopwrite", sysziopwrite, { .l = -1 } },
 	[ZIOFREE]	{ "Ziofree", sysziofree, { .i = -1 } },
+	[TSEMACQUIRE]	{ "Tsemacquire", systsemacquire, { .i = -1 } },
 };
 
 int nsyscall = nelem(systab);