Difference between revisions of "minetest.get us time"

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(→‎Description: (last edit and this:) Information retrieved from lua_api.txt and from in-game testing.)
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Returns time with microsecond precision.  This does not seem to be strictly related to [[minetest.get_gametime|game time]] or [[timeofday|time of day]] in a meaningful way, but should be useful for taking differences in time measured during a single execution of the server.  For example, it can be useful for profiling mod performance.
 
Returns time with microsecond precision.  This does not seem to be strictly related to [[minetest.get_gametime|game time]] or [[timeofday|time of day]] in a meaningful way, but should be useful for taking differences in time measured during a single execution of the server.  For example, it can be useful for profiling mod performance.
  
−
== Example ==
+
== Examples ==
 
<source>
 
<source>
 
local t0_us = minetest.get_us_time();
 
local t0_us = minetest.get_us_time();
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local elapsed_time_in_seconds = (t1_us - t0_us)/1000000.0;
 
local elapsed_time_in_seconds = (t1_us - t0_us)/1000000.0;
 
</source>
 
</source>
 +
 +
minetest.get_us_time seems to works faster than os.clock:
 +
<source>[…]
 +
 +
local oclock = os.clock
 +
local ustime = minetest.get_us_time
 +
 +
local function test_os_clock()
 +
local t1 = oclock()
 +
local delay = tonumber(oclock() - t1)
 +
end
 +
 +
local function test_get_us_time()
 +
local t1 = ustime()
 +
local delay = (ustime() - t1) / 1000000
 +
end
 +
 +
local function apply_timer_tests()
 +
local oclock_count = benchmark_function(test_os_clock)
 +
local ustime_count = benchmark_function(test_get_us_time)
 +
print("test_os_clock: " .. oclock_count .. " s⁻¹")
 +
print("test_get_us_time: " .. ustime_count .. " s⁻¹")
 +
print("minetest.get_us_time is " .. ustime_count / oclock_count .. " times as fast as os.clock")
 +
end
 +
 +
apply_timer_tests()
 +
 +
minetest.register_node(":mo:timtest", {
 +
on_place = apply_timer_tests
 +
})
 +
 +
--[[ results:
 +
 +
Using minetest.get_us_time for measuring (see the benchmark function):
 +
 +
executing when loading:
 +
 +
test_os_clock: 1019720 s⁻¹
 +
test_get_us_time: 1843077.3333333 s⁻¹
 +
minetest.get_us_time is 1.8074347206423 times as fast as os.clock
 +
 +
 +
placing the node:
 +
 +
test_os_clock: 742641.66666667 s⁻¹
 +
test_get_us_time: 1772569.6666667 s⁻¹
 +
minetest.get_us_time is 2.3868438120673 times as fast as os.clock
 +
 +
test_os_clock: 824095 s⁻¹
 +
test_get_us_time: 1790176.6666667 s⁻¹
 +
minetest.get_us_time is 2.1722940518589 times as fast as os.clock
 +
 +
test_os_clock: 736386.33333333 s⁻¹
 +
test_get_us_time: 1769226.6666667 s⁻¹
 +
minetest.get_us_time is 2.4025794431275 times as fast as os.clock
 +
 +
 +
Using os.clock for measuring:
 +
 +
executing when loading:
 +
 +
test_os_clock: 801913.66666667 s⁻¹
 +
test_get_us_time: 1229572.3333333 s⁻¹
 +
minetest.get_us_time is 1.5332976409347 times as fast as os.clock
 +
 +
 +
placing the node:
 +
 +
test_os_clock: 326955 s⁻¹
 +
test_get_us_time: 642647.66666667 s⁻¹
 +
minetest.get_us_time is 1.9655538733669 times as fast as os.clock
 +
 +
test_os_clock: 475252 s⁻¹
 +
test_get_us_time: 844550.33333333 s⁻¹
 +
minetest.get_us_time is 1.7770579257601 times as fast as os.clock
 +
 +
test_os_clock: 296636 s⁻¹
 +
test_get_us_time: 574708.33333333 s⁻¹
 +
minetest.get_us_time is 1.9374193736881 times as fast as os.clock
 +
]]
 +
</source>
 +
benchmark_function from [[Lua_Optimization_Tips#Benchmarking]]
 +
 +
<br/>
  
 
[[Category:Methods]]
 
[[Category:Methods]]

Revision as of 16:45, 21 April 2016

Syntax

minetest.get_us_time()

Description

Returns time with microsecond precision. This does not seem to be strictly related to game time or time of day in a meaningful way, but should be useful for taking differences in time measured during a single execution of the server. For example, it can be useful for profiling mod performance.

Examples

local t0_us = minetest.get_us_time();
-- ...
local t1_us = minetest.get_us_time();
local elapsed_time_in_seconds = (t1_us - t0_us)/1000000.0;

minetest.get_us_time seems to works faster than os.clock: 

[…]

local oclock = os.clock
local ustime = minetest.get_us_time

local function test_os_clock()
	local t1 = oclock()
	local delay = tonumber(oclock() - t1)
end

local function test_get_us_time()
	local t1 = ustime()
	local delay = (ustime() - t1) / 1000000
end

local function apply_timer_tests()
	local oclock_count = benchmark_function(test_os_clock)
	local ustime_count = benchmark_function(test_get_us_time)
	print("test_os_clock: " .. oclock_count .. " s⁻¹")
	print("test_get_us_time: " .. ustime_count .. " s⁻¹")
	print("minetest.get_us_time is " .. ustime_count / oclock_count .. " times as fast as os.clock")
end

apply_timer_tests()

minetest.register_node(":mo:timtest", {
	on_place = apply_timer_tests
})

--[[ results:

Using minetest.get_us_time for measuring (see the benchmark function):

executing when loading:

test_os_clock: 1019720 s⁻¹
test_get_us_time: 1843077.3333333 s⁻¹
minetest.get_us_time is 1.8074347206423 times as fast as os.clock


placing the node:

test_os_clock: 742641.66666667 s⁻¹
test_get_us_time: 1772569.6666667 s⁻¹
minetest.get_us_time is 2.3868438120673 times as fast as os.clock

test_os_clock: 824095 s⁻¹
test_get_us_time: 1790176.6666667 s⁻¹
minetest.get_us_time is 2.1722940518589 times as fast as os.clock

test_os_clock: 736386.33333333 s⁻¹
test_get_us_time: 1769226.6666667 s⁻¹
minetest.get_us_time is 2.4025794431275 times as fast as os.clock


Using os.clock for measuring:

executing when loading:

test_os_clock: 801913.66666667 s⁻¹
test_get_us_time: 1229572.3333333 s⁻¹
minetest.get_us_time is 1.5332976409347 times as fast as os.clock


placing the node:

test_os_clock: 326955 s⁻¹
test_get_us_time: 642647.66666667 s⁻¹
minetest.get_us_time is 1.9655538733669 times as fast as os.clock

test_os_clock: 475252 s⁻¹
test_get_us_time: 844550.33333333 s⁻¹
minetest.get_us_time is 1.7770579257601 times as fast as os.clock

test_os_clock: 296636 s⁻¹
test_get_us_time: 574708.33333333 s⁻¹
minetest.get_us_time is 1.9374193736881 times as fast as os.clock
]]

benchmark_function from Lua_Optimization_Tips#Benchmarking


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