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/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ANDROID_FRAMETRACKER_H
#define ANDROID_FRAMETRACKER_H
#include <stddef.h>
#include <utils/Mutex.h>
#include <utils/Timers.h>
#include <utils/RefBase.h>
namespace android {
class String8;
class Fence;
// FrameTracker tracks information about the most recently rendered frames. It
// uses a circular buffer of frame records, and is *NOT* thread-safe -
// mutexing must be done at a higher level if multi-threaded access is
// possible.
//
// Some of the time values tracked may be set either as a specific timestamp
// or a fence. When a non-NULL fence is set for a given time value, the
// signal time of that fence is used instead of the timestamp.
class FrameTracker {
public:
// NUM_FRAME_RECORDS is the size of the circular buffer used to track the
// frame time history.
enum { NUM_FRAME_RECORDS = 128 };
enum { NUM_FRAME_BUCKETS = 7 };
FrameTracker();
// setDesiredPresentTime sets the time at which the current frame
// should be presented to the user under ideal (i.e. zero latency)
// conditions.
void setDesiredPresentTime(nsecs_t desiredPresentTime);
// setFrameReadyTime sets the time at which the current frame became ready
// to be presented to the user. For example, if the frame contents is
// being written to memory by some asynchronous hardware, this would be
// the time at which those writes completed.
void setFrameReadyTime(nsecs_t readyTime);
// setFrameReadyFence sets the fence that is used to get the time at which
// the current frame became ready to be presented to the user.
void setFrameReadyFence(const sp<Fence>& readyFence);
// setActualPresentTime sets the timestamp at which the current frame became
// visible to the user.
void setActualPresentTime(nsecs_t displayTime);
// setActualPresentFence sets the fence that is used to get the time
// at which the current frame became visible to the user.
void setActualPresentFence(const sp<Fence>& fence);
// setDisplayRefreshPeriod sets the display refresh period in nanoseconds.
// This is used to compute frame presentation duration statistics relative
// to this period.
void setDisplayRefreshPeriod(nsecs_t displayPeriod);
// advanceFrame advances the frame tracker to the next frame.
void advanceFrame();
// clearStats clears the tracked frame stats.
void clearStats();
// getStats gets the tracked frame stats.
void getStats(FrameStats* outStats) const;
// logAndResetStats dumps the current statistics to the binary event log
// and then resets the accumulated statistics to their initial values.
void logAndResetStats(const String8& name);
// dumpStats dump appends the current frame display time history to the result string.
void dumpStats(String8& result) const;
private:
struct FrameRecord {
FrameRecord() :
desiredPresentTime(0),
frameReadyTime(0),
actualPresentTime(0) {}
nsecs_t desiredPresentTime;
nsecs_t frameReadyTime;
nsecs_t actualPresentTime;
sp<Fence> frameReadyFence;
sp<Fence> actualPresentFence;
};
// processFences iterates over all the frame records that have a fence set
// and replaces that fence with a timestamp if the fence has signaled. If
// the fence is not signaled the record's displayTime is set to INT64_MAX.
//
// This method is const because although it modifies the frame records it
// does so in such a way that the information represented should not
// change. This allows it to be called from the dump method.
void processFencesLocked() const;
// updateStatsLocked updates the running statistics that are gathered
// about the frame times.
void updateStatsLocked(size_t newFrameIdx) const;
// resetFrameCounteresLocked sets all elements of the mNumFrames array to
// 0.
void resetFrameCountersLocked();
// logStatsLocked dumps the current statistics to the binary event log.
void logStatsLocked(const String8& name) const;
// isFrameValidLocked returns true if the data for the given frame index is
// valid and has all arrived (i.e. there are no oustanding fences).
bool isFrameValidLocked(size_t idx) const;
// mFrameRecords is the circular buffer storing the tracked data for each
// frame.
FrameRecord mFrameRecords[NUM_FRAME_RECORDS];
// mOffset is the offset into mFrameRecords of the current frame.
size_t mOffset;
// mNumFences is the total number of fences set in the frame records. It
// is incremented each time a fence is added and decremented each time a
// signaled fence is removed in processFences or if advanceFrame clobbers
// a fence.
//
// The number of fences is tracked so that the run time of processFences
// doesn't grow with NUM_FRAME_RECORDS.
int mNumFences;
// mNumFrames keeps a count of the number of frames with a duration in a
// particular range of vsync periods. Element n of the array stores the
// number of frames with duration in the half-inclusive range
// [2^n, 2^(n+1)). The last element of the array contains the count for
// all frames with duration greater than 2^(NUM_FRAME_BUCKETS-1).
int32_t mNumFrames[NUM_FRAME_BUCKETS];
// mDisplayPeriod is the display refresh period of the display for which
// this FrameTracker is gathering information.
nsecs_t mDisplayPeriod;
// mMutex is used to protect access to all member variables.
mutable Mutex mMutex;
};
}
#endif // ANDROID_FRAMETRACKER_H
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