| 2015-11-12 15:19:22 |
Andreas Pokorny |
description |
Calling clock_gettime behaves strangely with CLOCK_MONOTONIC CLOCK_MONOTONIC_RAW or CLOCK_MONOTONIC_BOOTTIME depending on which process you are in. Whithin usc and unity8 we get a consistent stream of monotonic time updates. independet of suspends/wakeups. Within a process like unity8-dash it seems to work until after the first suspend then the current time of CLOCK_REALTIME is returned.
This can be observed through input receiver traces in mir/unity8 and unity8-dash.
Steps to reproduce - take the current released version of mir :
http://bazaar.launchpad.net/~mir-team/mir/0.17/view/head:/3rd_party/android-input/android/frameworks/native/libs/utils/Timers.cpp
Modify
// we don't support the clocks here.
struct timeval t;
t.tv_sec = t.tv_usec = 0;
gettimeofday(&t, NULL);
return std::chrono::nanoseconds(t.tv_sec)*1000000000LL + std::chrono::nanoseconds(t.tv_usec)*1000LL;
into:
struct timespec t;
t.tv_sec = t.tv_nsec = 0;
clock_gettime(CLOCK_MONOTONIC, &t);
return std::chrono::nanoseconds(t.tv_sec*1000000000LL) +
std::chrono::nanoseconds(t.tv_nsec);
Then enable mirs input traces in /usr/share/upstart/sessions/unity8-dash.conf
i.e. add:
export MIR_CLIENT_INPUT_RECEIVER_REPORT=log
and for comparison you could do something similar in /usr/share/upstart/sessions/unity8.conf
You should get traces like:
[1447315263.459656] <DEBUG> input-receiver: Received event:touch_event(when=71864404480 (-88787157.149558 ms ago), from=0, touch = {{id=0, action=change, tool=finger, x=328.545, y=504.624, pressure=0.275735, major=7.98521, minor=0, size=0}, modifiers=1)
The timestamp at the beginning of the trace is gettimeofday(), but look at the "when=" part - this is the 'current time' androids input resampling believes it is.
Then after the wakeup you should see:
[1447315273.639723] <DEBUG> input-receiver: Received event:touch_event(when=1447404060779907704 (-88787140.-356826 ms ago), from=0, touch = {{id=0, action=down, tool=finger, x=416.229, y=593.339, pressure=0.291054, major=11.9778, minor=0, size=0}, modifiers=1)
when= is now closer to gettimeofday.. |
If we try to change the input platforms to also use CLOCK_MONOTONIC (or std::chrono::steady_clock) in mir we also need to change unity8. Otherwise input resampling will get confused by the large difference in time stamps and long press calculation will fail.
Mir should provide an interface to the clock used for user input event time stamps - both server and client side. |
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