time: add sleep

clock_nanosleep with EINTR restart from the kernel remainder.

lib/time/time.ww

@@ -1,8 +1,8 @@
 // time — clocks, instants, durations. Mirrors Hare's lib/time
 // (ref/hare/time/duration.ha, instant.ha, arithm.ha,
-// +linux/functions.ha). Calendar / date / strftime / timezone /
+// +linux/functions.ha). Calendar / date / strftime / timezone live in
-// sleep live in separate Hare modules and graduate when callers /
+// separate Hare modules
-// supporting stdlib arrive.
+// and graduate when callers / supporting stdlib arrive.
 //
 // `duration` is a NAMED alias of i64 (lib/math/random precedent
 // at lib/math/random/random.ww:8); ww treats NAMED as a newtype,
@@ -13,8 +13,10 @@
 package time;
 
 @symbol("rt_syscall") fn syscall2(num: i64, a: i64, b: i64) i64;
+@symbol("rt_syscall") fn syscall4(num: i64, a: i64, b: i64, c: i64, d: i64) i64;
 
 def SYS_CLOCK_GETTIME: i64 = 228;
+def SYS_CLOCK_NANOSLEEP: i64 = 230;
 
 // ref/hare/time/duration.ha:6. 290y representable range.
 export type duration = i64;
@@ -56,6 +58,26 @@ export fn now(c: clock) instant = {
 	return i;
 };
 
+// ref/hare/time/+linux/functions.ha:40-58 and
+// ref/hare/sys/+linux/syscalls.ha:524-536. WW has no default parameters,
+// so the Hare clock argument is explicit. The raw syscall reports -EINTR;
+// restarting with the kernel-written remainder keeps the requested delay.
+export fn sleep(d: duration, c: clock) void = {
+	let ns: i64 = d: i64;
+	let sec: i64 = second: i64;
+	let req: instant;
+	req.sec = ns / sec;
+	req.nsec = ns % sec;
+	for (true) {
+		let rem: instant;
+		let rc: i64 = syscall4(SYS_CLOCK_NANOSLEEP,
+		    (c as i32): i64, 0i64, (&req): i64, (&rem): i64);
+		if (rc == 0i64) { return; };
+		if (rc != -4i64) { abort("time.sleep: clock_nanosleep failed"); };
+		req = rem;
+	};
+};
+
 // ref/hare/time/arithm.ha:9. Adds duration to instant. The
 // negative-duration branch normalises nsec into [0, second).
 export fn add(i: instant, x: duration) instant = {

lib/time/timetest.ww

@@ -157,3 +157,12 @@ import time;
 	assert(!(time.compare(a, b) != -1i8));
 	assert(!(time.compare(b, a) !=  1i8));
 };
+
+@test fn sleepmonotonic() void = {
+	let before: time.instant = time.now(time.clock.monotonic);
+	time.sleep((5i64 * (time.millisecond: i64)): time.duration,
+	    time.clock.monotonic);
+	let after: time.instant = time.now(time.clock.monotonic);
+	let elapsed: i64 = time.diff(before, after): i64;
+	assert(!(elapsed < 5i64 * (time.millisecond: i64)));
+};