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=== modified file 'src/client/frame_clock.cpp'
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--- src/client/frame_clock.cpp	2016-11-29 08:00:45 +0000
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+++ src/client/frame_clock.cpp	2017-05-01 07:03:11 +0000
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@@ -31,6 +31,7 @@
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FrameClock::FrameClock(FrameClock::GetCurrentTime gct)
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FrameClock::FrameClock(FrameClock::GetCurrentTime gct)
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    : get_current_time{gct}
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    : get_current_time{gct}
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    , config_changed{false}
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    , config_changed{false}
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    , phase{0}
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    , period{0}
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    , period{0}
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    , resync_callback{std::bind(&FrameClock::fallback_resync_callback, this)}
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    , resync_callback{std::bind(&FrameClock::fallback_resync_callback, this)}
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{
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{
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@@ -61,7 +62,7 @@
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    return period != period.zero() ? now - (now % period) : now;
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    return period != period.zero() ? now - (now % period) : now;
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}
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}
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PosixTimestamp FrameClock::next_frame_after(PosixTimestamp prev) const
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PosixTimestamp FrameClock::next_frame_after(PosixTimestamp when) const
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{
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{
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    Lock lock(mutex);
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    Lock lock(mutex);
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    /*
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    /*
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@@ -70,7 +71,12 @@
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     * it has no physical screen to sync to. Hence not throttled at all.
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     * it has no physical screen to sync to. Hence not throttled at all.
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     */
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     */
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    if (period == period.zero())
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    if (period == period.zero())
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        return prev;
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        return when;
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    /* Phase correction in case 'when' isn't in phase: */
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    auto const prev = when - ((when % period) - phase);
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    /* Verify it's been corrected: */
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    assert(prev % period == phase);
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    /*
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    /*
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     * Regardless of render times and scheduling delays, we should always
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     * Regardless of render times and scheduling delays, we should always
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@@ -109,6 +115,8 @@
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        auto const server_frame = resync_callback();
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        auto const server_frame = resync_callback();
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        lock.lock();
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        lock.lock();
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        phase = server_frame % period;
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        /*
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        /*
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         * Avoid mismatches (which will throw) and ensure we're always
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         * Avoid mismatches (which will throw) and ensure we're always
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         * comparing timestamps of the same clock ID. This means our result
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         * comparing timestamps of the same clock ID. This means our result
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=== modified file 'src/client/frame_clock.h'
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--- src/client/frame_clock.h	2016-12-15 08:15:54 +0000
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+++ src/client/frame_clock.h	2017-05-01 07:03:11 +0000
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@@ -52,10 +52,10 @@
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    /**
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    /**
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     * Return the next timestamp to sleep_until, which comes after the last one
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     * Return the next timestamp to sleep_until, which comes after the last one
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     * that was slept till. On the first frame you can just provide an
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     * that was slept till (or more generally after time 'when'). On the first
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     * uninitialized timestamp.
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     * frame you can just provide an uninitialized timestamp.
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     */
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     */
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    time::PosixTimestamp next_frame_after(time::PosixTimestamp prev) const;
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    time::PosixTimestamp next_frame_after(time::PosixTimestamp when) const;
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private:
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private:
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    time::PosixTimestamp fallback_resync_callback() const;
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    time::PosixTimestamp fallback_resync_callback() const;
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@@ -64,6 +64,7 @@
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    mutable std::mutex mutex;  // Protects below fields:
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    mutable std::mutex mutex;  // Protects below fields:
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    mutable bool config_changed;
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    mutable bool config_changed;
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    mutable std::chrono::nanoseconds phase;
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    std::chrono::nanoseconds period;
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    std::chrono::nanoseconds period;
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    ResyncCallback resync_callback;
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    ResyncCallback resync_callback;
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};
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};
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=== modified file 'tests/unit-tests/client/test_frame_clock.cpp'
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--- tests/unit-tests/client/test_frame_clock.cpp	2017-03-13 08:12:52 +0000
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+++ tests/unit-tests/client/test_frame_clock.cpp	2017-05-01 07:03:11 +0000
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@@ -116,6 +116,33 @@
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    EXPECT_EQ(one_frame, e - d);
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    EXPECT_EQ(one_frame, e - d);
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}
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}
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TEST_F(FrameClockTest, interval_is_perfectly_smooth_despite_parameter_jitter)
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{
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    FrameClock clock(with_fake_time);
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    clock.set_period(one_frame);
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    PosixTimestamp a;
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    auto b = clock.next_frame_after(a);
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    fake_sleep_until(b);
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    fake_sleep_for(one_frame/13);  // short render time
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    auto c = clock.next_frame_after(b + 3ms);
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    EXPECT_EQ(one_frame, c - b);
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    fake_sleep_until(c);
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    fake_sleep_for(one_frame/7);  // short render time
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    auto d = clock.next_frame_after(c + 1ms);
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    EXPECT_EQ(one_frame, d - c);
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    fake_sleep_until(d);
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    fake_sleep_for(one_frame/5);  // short render time
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    auto e = clock.next_frame_after(d + 7ms);
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    EXPECT_EQ(one_frame, e - d);
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}
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TEST_F(FrameClockTest, long_render_time_is_recoverable_without_decimation)
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TEST_F(FrameClockTest, long_render_time_is_recoverable_without_decimation)
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{
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{
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    FrameClock clock(with_fake_time);
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    FrameClock clock(with_fake_time);
Status:	Merged
Merged at revision:	4170
Proposed branch:	lp:~vanvugt/mir/generalise-next_frame_after
Merge into:	lp:mir
Diff against target:	107 lines (+41/-5) 3 files modified src/client/frame_clock.cpp (+10/-2) src/client/frame_clock.h (+4/-3) tests/unit-tests/client/test_frame_clock.cpp (+27/-0)
To merge this branch:	bzr merge lp:~vanvugt/mir/generalise-next_frame_after
Related bugs:	Link a bug report
Reviewer	Review Type	Date Requested	Status
Mir CI Bot	continuous-integration		Needs Fixing on 2017-05-17
Alan Griffiths		2017-05-01	Approve on 2017-05-16
Review via email: mp+323450@code.launchpad.net