Add nanosecond resolution support on unixes to jl_gettimeofday and time()

NEWS.md

@@ -73,6 +73,7 @@ New library features
 * `tempname` can now take a suffix string to allow the file name to include a suffix and include that suffix in
   the uniquing checking ([#53474])
 * `RegexMatch` objects can now be used to construct `NamedTuple`s and `Dict`s ([#50988])
+* `time()` now has up to nanosecond resolution on Unix based platforms. ([#45023])
 
 Standard library changes
 ------------------------
@@ -116,6 +117,9 @@ Standard library changes
 Deprecated or removed
 ---------------------
 
+* `Libc.TimeVal` is deprecated in favor of `Libc.TimeSpec`, which (generally) has higher resolution.
+  This deprecation follows the deprecation of `gettimeofday` in libc. ([#45023])
+
 External dependencies
 ---------------------
 

base/deprecated.jl

@@ -397,3 +397,15 @@ end
 @deprecate invpermute!!(a, p::AbstractVector{<:Integer}) invpermute!(a, p) false
 
 # END 1.11 deprecations
+
+# BEGIN 1.12 deprecations
+
+@deprecate splat(x) Splat(x) false
+# When removing this, also remove the struct & its constructor in Libc
+function Libc.TimeVal()
+    Base.depwarn("`TimeVal()` is deprecated, use `TimeSpec()` and convert to microseconds manually or move to the higher precision directly instead.", :TimeVal)
+    convert(Libc.TimeVal, Libc.TimeSpec())
+end
+
+# END 1.12 deprecations
+

base/libc.jl

@@ -176,13 +176,20 @@ struct TimeVal
    usec::Int64
 end
 
-function TimeVal()
-    tv = Ref{TimeVal}()
-    status = ccall(:jl_gettimeofday, Cint, (Ref{TimeVal},), tv)
+struct TimeSpec
+   sec::Int64
+   nsec::Int64
+end
+
+function TimeSpec()
+    ts = Ref{TimeSpec}()
+    status = ccall(:jl_gettimeofday, Cint, (Ref{TimeSpec},), ts)
     status != 0 && error("unable to determine current time: ", status)
-    return tv[]
+    return ts[]
 end
 
+Base.convert(::Type{TimeVal}, ts::TimeSpec) = TimeVal(ts.sec, div(ts.nsec, 1000))
+
 """
     TmStruct([seconds])
 
@@ -280,7 +287,7 @@ time(tm::TmStruct) = Float64(ccall(:mktime, Int, (Ref{TmStruct},), tm))
 """
     time() -> Float64
 
-Get the system time in seconds since the epoch, with fairly high (typically, microsecond) resolution.
+Get the system time in seconds since the epoch. Resolution is system dependent and limited to milliseconds on windows, with (up to) nanosecond resolution on other platforms.
 """
 time() = ccall(:jl_clock_now, Float64, ())
 

src/support/timefuncs.c

@@ -7,7 +7,7 @@
 #if defined(_OS_WINDOWS_)
 #include <sys/timeb.h>
 #else
-#include <sys/time.h>
+#include <time.h>
 #include <sys/select.h>
 #endif
 
@@ -23,12 +23,13 @@ JL_DLLEXPORT int jl_gettimeofday(struct jl_timeval *jtv)
     struct __timeb64 tb;
     errno_t code = _ftime64_s(&tb);
     jtv->sec = tb.time;
-    jtv->usec = tb.millitm * 1000;
+    jtv->nsec = tb.millitm * 1000000;
 #else
-    struct timeval tv;
-    int code = gettimeofday(&tv, NULL);
-    jtv->sec = tv.tv_sec;
-    jtv->usec = tv.tv_usec;
+    struct timespec ts;
+    int code = clock_gettime(CLOCK_REALTIME, &ts);
+    // TODO: warn/error on EINVAL/EOVERFLOW?
+    jtv->sec = ts.tv_sec;
+    jtv->nsec = ts.tv_nsec;
 #endif
     return code;
 }
@@ -37,7 +38,7 @@ JL_DLLEXPORT double jl_clock_now(void)
 {
     struct jl_timeval now;
     jl_gettimeofday(&now);
-    return now.sec + now.usec * 1e-6;
+    return now.sec + now.nsec * 1e-9;
 }
 
 void sleep_ms(int ms)

src/support/timefuncs.h

@@ -9,7 +9,7 @@ extern "C" {
 
 struct jl_timeval {
     int64_t sec;    /* seconds */
-    int64_t usec;   /* microseconds */
+    int64_t nsec;   /* nanoseconds */
 };
 
 JL_DLLEXPORT int jl_gettimeofday(struct jl_timeval *jtv);

stdlib/Dates/src/conversions.jl

@@ -66,9 +66,9 @@ Return a `DateTime` corresponding to the user's system time including the system
 locale.
 """
 function now()
-    tv = Libc.TimeVal()
-    tm = Libc.TmStruct(tv.sec)
-    return DateTime(tm.year + 1900, tm.month + 1, tm.mday, tm.hour, tm.min, tm.sec, div(tv.usec, 1000))
+    ts = Libc.TimeSpec()
+    tm = Libc.TmStruct(ts.sec)
+    return DateTime(tm.year + 1900, tm.month + 1, tm.mday, tm.hour, tm.min, tm.sec, div(ts.nsec, 1_000_000))
 end
 
 """