Re: [9front] etimer() assumes seconds together with APE

[ori@eigenstate.org]

> Dear list,
> 
> The function etimer(ulong key, int n) is used in libevent to get a timer 
> event every 'n' milliseconds. However, if APE is used, etimer() delivers 
> an event every 'n' second instead. The reason is that sleep() assumes 
> seconds in APE and milliseconds in Plan 9.
> 
> I am aware that combining Plan 9 libraries with APE is a bit risky.

Note, we've *designed* it to work: /sys/src/ape/lib/draw. This should
be fine.

> When I earlier wanted to use etimer() in the netsurf framebuffer driver, I 
> assumed it didn't work under APE, but I was not patient enough to wait 
> 1000 seconds, when I thought it would fire after one second.
> 
> Would this be considered a bug?

I'd call it a bug, yeah. It's a bit tricky to fix, since we share code
between native and ape-compatible draw -- it can be done with an ifdef,
but that's gross. Other approaches could be to add a compat.c file that
we link against in ape/libdraw.

I've got both approaches below:

diff -r 965e0f59464d sys/src/ape/lib/draw/ape.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sys/src/ape/lib/draw/ape.c	Tue May 12 08:37:35 2020 -0700
@@ -0,0 +1,17 @@
+#include <time.h>
+
+void
+_drawsleep(int ms)
+{
+	/*
+	 * This is gross. We need draw to compile under APE,
+	 * which defines sleep differently from plan 9.
+	 * Native sleep is in milliseconds, APE sleep is in
+	 * seconds. So we need to call different functions.
+	 */
+	struct timespec ts;
+	ts.tv_sec = ms/1000;
+	ts.tv_nsec = (ms%1000)*1000*1000;
+	while(ts.tv_sec != 0 && ts.tv_nsec != 0)
+		nanosleep(&ts, &ts);
+}
diff -r 965e0f59464d sys/src/ape/lib/draw/mkfile
--- a/sys/src/ape/lib/draw/mkfile	Sun May 10 22:51:40 2020 +0200
+++ b/sys/src/ape/lib/draw/mkfile	Tue May 12 08:37:35 2020 -0700
@@ -14,6 +14,7 @@
 	bytesperline.$O\
 	chan.$O\
 	cloadimage.$O\
+	ape.$O\
 	computil.$O\
 	creadimage.$O\
 	debug.$O\
diff -r 965e0f59464d sys/src/libdraw/event.c
--- a/sys/src/libdraw/event.c	Sun May 10 22:51:40 2020 +0200
+++ b/sys/src/libdraw/event.c	Tue May 12 08:37:35 2020 -0700
@@ -7,6 +7,8 @@
 typedef struct	Slave Slave;
 typedef struct	Ebuf Ebuf;
 
+extern void _drawsleep(int);
+
 struct Slave
 {
 	int	pid;
@@ -176,7 +178,7 @@
 		n = 1000;
 	t[0] = t[1] = Stimer - MAXSLAVE;
 	do
-		sleep(n);
+		_drawsleep(n);
 	while(write(epipe[1], t, 2) == 2);
 	t[0] = MAXSLAVE;
 	write(epipe[1], t, 1);
diff -r 965e0f59464d sys/src/libdraw/mkfile
--- a/sys/src/libdraw/mkfile	Sun May 10 22:51:40 2020 +0200
+++ b/sys/src/libdraw/mkfile	Tue May 12 08:37:35 2020 -0700
@@ -13,6 +13,7 @@
 	bytesperline.$O\
 	chan.$O\
 	cloadimage.$O\
+	plan9.$O\
 	computil.$O\
 	creadimage.$O\
 	debug.$O\
diff -r 965e0f59464d sys/src/libdraw/plan9.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sys/src/libdraw/plan9.c	Tue May 12 08:37:35 2020 -0700
@@ -0,0 +1,8 @@
+#include <u.h>
+#include <libc.h>
+
+static void
+_drawsleep(int ms)
+{
+	sleep(ms);
+}


===============================================================
Here's an alternative with ifdef:

diff -r 965e0f59464d sys/src/libdraw/event.c
--- a/sys/src/libdraw/event.c	Sun May 10 22:51:40 2020 +0200
+++ b/sys/src/libdraw/event.c	Tue May 12 08:29:57 2020 -0700
@@ -175,9 +175,23 @@
 	if(n <= 0)
 		n = 1000;
 	t[0] = t[1] = Stimer - MAXSLAVE;
-	do
+	do{
+		/*
+		 * This is gross. We need draw to compile under APE,
+		 * which defines sleep differently from plan 9.
+		 * Native sleep is in milliseconds, APE sleep is in
+		 * seconds. So we need to call different functions.
+		 */
+#ifdef _POSIX_SOURCE
+		struct timespec ts;
+		ts.tv_sec = n/1000;
+		ts.tv_nsec = (n%1000)*1000*1000;
+		while(ts.tv_sec != 0 && ts.tv_nsec != 0)
+			nanosleep(&ts, &ts);
+#else
 		sleep(n);
-	while(write(epipe[1], t, 2) == 2);
+#endif
+	}while(write(epipe[1], t, 2) == 2);
 	t[0] = MAXSLAVE;
 	write(epipe[1], t, 1);
 	_exits(0);