authorgravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2019-05-04 15:16:39-04:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2019-05-04 15:16:39-04:00
log09cbcf8841a0b80cdbdf40c2b48acccbaa945ce8
treededa8f8f46e2033b1f6c3d19d8e2b52ae1fab9e6
parent70a9ee3dd68d8ed28a9fd2dc29f6c88fee5d789e
signaturelock-open Commit is signed but in an unrecognized format.

std lib sleep APIs: add doc comments and no @intCast

The sleep APIs are now documented as having spurious wakeups and no precision of timing guaranteed. They also cannot fail. This commit makes the entire range of u64 legal values to pass to std.os.time.sleep and std.os.time.posixSleep. Values that do not fit in the native system APIs will cause a sleep for the longest possible duration and then be handled as a spurious wakeup.

1 files changed, 12 insertions(+), 21 deletions(-)

std/os/time.zig+12-21
...@@ -13,44 +13,35 @@ const posix = std.os.posix;...@@ -13,44 +13,35 @@ const posix = std.os.posix;
1313
14pub const epoch = @import("epoch.zig");14pub const epoch = @import("epoch.zig");
1515
16/// Sleep for the specified duration16/// Spurious wakeups are possible and no precision of timing is guaranteed.
17pub fn sleep(nanoseconds: u64) void {17pub fn sleep(nanoseconds: u64) void {
18 switch (builtin.os) {18 switch (builtin.os) {
19 Os.linux, Os.macosx, Os.ios, Os.freebsd, Os.netbsd => {19 Os.linux, Os.macosx, Os.ios, Os.freebsd, Os.netbsd => {
20 const s = nanoseconds / ns_per_s;20 const s = nanoseconds / ns_per_s;
21 const ns = nanoseconds % ns_per_s;21 const ns = nanoseconds % ns_per_s;
22 posixSleep(@intCast(u63, s), @intCast(u63, ns));22 posixSleep(s, ns);
23 },23 },
24 Os.windows => {24 Os.windows => {
25 const ns_per_ms = ns_per_s / ms_per_s;25 const ns_per_ms = ns_per_s / ms_per_s;
26 const milliseconds = nanoseconds / ns_per_ms;26 const milliseconds = nanoseconds / ns_per_ms;
27 windows.Sleep(@intCast(windows.DWORD, milliseconds));27 const ms_that_will_fit = std.math.cast(windows.DWORD, milliseconds) catch std.math.maxInt(windows.DWORD);
28 windows.Sleep(ms_that_will_fit);
28 },29 },
29 else => @compileError("Unsupported OS"),30 else => @compileError("Unsupported OS"),
30 }31 }
31}32}
3233
33pub fn posixSleep(seconds: u63, nanoseconds: u63) void {34/// Spurious wakeups are possible and no precision of timing is guaranteed.
34 var req: posix.timespec = undefined;35pub fn posixSleep(seconds: u64, nanoseconds: u64) void {
36 var req = posix.timespec{
37 .tv_sec = std.math.cast(isize, seconds) catch std.math.maxInt(isize),
38 .tv_nsec = std.math.cast(isize, nanoseconds) catch std.math.maxInt(isize),
39 };
35 var rem: posix.timespec = undefined;40 var rem: posix.timespec = undefined;
36
37 var req_sec = seconds;
38 var req_nsec = nanoseconds;
39
40 while (true) {41 while (true) {
41 req.tv_sec = math.min(math.maxInt(isize), req_sec);
42 req.tv_nsec = @intCast(isize, req_nsec);
43
44 req_sec -= @intCast(u63, req.tv_sec);
45 req_nsec = 0;
46
47 const ret_val = posix.nanosleep(&req, &rem);42 const ret_val = posix.nanosleep(&req, &rem);
48 const err = posix.getErrno(ret_val);43 const err = posix.getErrno(ret_val);
49 switch (err) {44 switch (err) {
50 0 => {
51 // If there's still time to wait keep running the loop
52 if (req_sec == 0 and req_nsec == 0) return;
53 },
54 posix.EFAULT => unreachable,45 posix.EFAULT => unreachable,
55 posix.EINVAL => {46 posix.EINVAL => {
56 // Sometimes Darwin returns EINVAL for no reason.47 // Sometimes Darwin returns EINVAL for no reason.
...@@ -58,10 +49,10 @@ pub fn posixSleep(seconds: u63, nanoseconds: u63) void {...@@ -58,10 +49,10 @@ pub fn posixSleep(seconds: u63, nanoseconds: u63) void {
58 return;49 return;
59 },50 },
60 posix.EINTR => {51 posix.EINTR => {
61 req_sec += @intCast(u63, rem.tv_sec);52 req = rem;
62 req_nsec = @intCast(u63, rem.tv_nsec);
63 continue;53 continue;
64 },54 },
55 // This prong handles success as well as unexpected errors.
65 else => return,56 else => return,
66 }57 }
67 }58 }