From: daurnimator <quae@daurnimator.com>
Date: Tue, 15 Jul 2014 22:12:27 +0000 (-0400)
Subject: {luatz,doc}/gettime: Add ljsyscall as a source. Better docs.
X-Git-Url: https://git.madduck.net/etc/awesome.git/commitdiff_plain/98b26721ede0c7f2015bcf72ae8e61f100507de3

{luatz,doc}/gettime: Add ljsyscall as a source. Better docs.
---

diff --git a/doc/gettime.md b/doc/gettime.md
index 758be60..2e3ef35 100644
--- a/doc/gettime.md
+++ b/doc/gettime.md
@@ -2,10 +2,22 @@
 
 A module to get the current time.
 
+Uses the most precise method available (in order:)
 
-## `gettime ( )`
+  - Use [ljsyscall](http://www.myriabit.com/ljsyscall/) to access
+  	  - `clock_gettime(2)` called with `CLOCK_REALTIME`
+  	  - `gettimeofday(2)`
+  - [luasocket](http://w3.impa.br/~diego/software/luasocket/)'s `socket.gettime`
+  - [`os.time`](http://www.lua.org/manual/5.2/manual.html#pdf-os.time)
 
-Uses the most precise method available (in order:)
+## `source`
+
+The library/function currently in use.
+
+## `resolution`
+
+The smallest time resolution (in seconds) available from `gettime ( )` .
+
+## `gettime ( )`
 
-  - luasocket's `socket.gettime`
-  - `os.time`
+Returns the number of seconds since unix epoch (1970-01-01T00:00:00Z) as a lua number
diff --git a/luatz/gettime.lua b/luatz/gettime.lua
index a86829e..008e95c 100644
--- a/luatz/gettime.lua
+++ b/luatz/gettime.lua
@@ -1,10 +1,38 @@
 local _M = { }
 
-local has_socket , socket = pcall ( require , "socket" )
-if has_socket then
-	_M.gettime = socket.gettime
-else
-	_M.gettime = os.time
-end
+_M.source , _M.resolution , _M.gettime = (function()
+	local has_syscall , syscall = pcall ( require , "syscall" )
+	if has_syscall then
+		if syscall.clock_gettime then
+			local clock_id = syscall.c.CLOCK.REALTIME
+			local function timespec_to_number ( timespec )
+				return tonumber ( timespec.tv_sec ) + tonumber ( timespec.tv_nsec ) * 1e-9
+			end
+			return "syscall.clock_gettime(CLOCK_REALTIME)" ,
+				syscall.clock_getres and timespec_to_number ( syscall.clock_getres ( clock_id ) ) or 1e-9 ,
+				function ( )
+					return timespec_to_number ( syscall.clock_gettime ( clock_id ) )
+				end
+
+		elseif syscall.gettimeofday then
+			local function timeval_to_number ( timeval )
+				return tonumber ( timeval.tv_sec ) + tonumber ( timeval.tv_nsec ) * 1e-6
+			end
+			return "syscall.gettimeofday()" , 1e-6 ,
+				function ( )
+					return timeval_to_number ( syscall.gettimeofday ( ) )
+				end
+		end
+	end
+
+	local has_socket , socket = pcall ( require , "socket" )
+	if has_socket and socket.gettime then
+		-- on windows, this uses GetSystemTimeAsFileTime, which has resolution of 1e-7
+		-- on linux, this uses gettimeofday, which has resolution of 1e-6
+		return "socket.gettime()" , 1e-6 , socket.gettime
+	end
+
+	return "os.time()" , 1 , os.time
+end)()
 
 return _M