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Commit 4f03349c authored by Nicolas Roulet's avatar Nicolas Roulet
Browse files

NBLog add log scale to histograms 

Bug: 36490717
Test: Log histograms, check that scale displayed is logarithmic
Change-Id: I10d5387ad9eef80e7994ccb8246347e1413e9058
parent ad82aa66

media/libnbaio/NBLog.cpp

+31 −6
Original line number Diff line number Diff line
@@ -948,7 +948,7 @@ void NBLog::Reader::dump(int fd, size_t indent, NBLog::Reader::Snapshot &snapsho 
            for (auto hist = mHists.begin(); hist != mHists.end();) {

                if (hist->first.second == histEntry.author()) {

                    body.appendFormat("Histogram %X", (int)hist->first.first);

                    drawHistogram(&body, hist->second, indent + timestamp.size());

                    drawHistogram(&body, hist->second, true/*logScale*/, indent + timestamp.size());

                    hist = mHists.erase(hist);

                } else {

                    ++hist;
@@ -1150,13 +1150,37 @@ static std::map<int, int> buildBuckets(const std::vector<int64_t> &samples) { 
    return buckets;

}



static inline uint32_t log2(uint32_t x) {

    // This works for x > 0

    return 31 - __builtin_clz(x);

}



// TODO put this function in separate file. Make it return a std::string instead of modifying body

/*

Example output:

[54.234] Histogram flush - AudioOut_D:

Histogram 33640BF1

            [ 1][ 1][ 1][ 3][54][69][ 1][ 2][ 1]

        64|                      []

        32|                  []  []

        16|                  []  []

         8|                  []  []

         4|                  []  []

         2|______________[]__[]__[]______[]____

              4   5   6   8   9  10  11  13  15

Notice that all values that fall in the same row have the same height (65 and 127 are displayed

identically). That's why exact counts are added at the top.

*/

void NBLog::Reader::drawHistogram(String8 *body,

                                  const std::vector<int64_t> &samples,

                                  bool logScale,

                                  int indent,

                                  int maxHeight) {

    if (samples.size() <= 1) {

        return;

    }

    std::map<int, int> buckets = buildBuckets(samples);

    // TODO add option for log scale

    // TODO consider changing all ints to uint32_t or uint64_t

    static const char *underscores = "________________";

    static const char *spaces = "                ";
@@ -1172,7 +1196,7 @@ void NBLog::Reader::drawHistogram(String8 *body, 
            maxVal = it->second;

        }

    }

    int height = maxVal;

    int height = (logScale) ? log2(maxVal) + 1 : maxVal; // maxVal > 0, safe to call log2

    int leftPadding = widthOf(maxVal);

    int colWidth = std::max(std::max(widthOf(maxLabel) + 1, 3), leftPadding + 2);

    int scalingFactor = 1;
@@ -1192,11 +1216,12 @@ void NBLog::Reader::drawHistogram(String8 *body, 
    body->appendFormat("\n%*s", indent, " ");

    for (int row = height * scalingFactor; row > 0; row -= scalingFactor)

    {

        body->appendFormat("%*u|", leftPadding, row);

        int value = ((logScale) ? (1 << row) : row);

        body->appendFormat("%*u|", leftPadding, value);

        for (auto const &x : buckets) {

            body->appendFormat("%.*s%s", colWidth - 2,

                   (row == scalingFactor) ? underscores : spaces,

                   x.second < row ? ((row == scalingFactor) ? "__" : "  ") : "[]");

                   (row <= scalingFactor) ? underscores : spaces,

                   x.second < value ? ((row <= scalingFactor) ? "__" : "  ") : "[]");

        }

        body->appendFormat("\n%*s", indent, " ");

    }

media/libnbaio/include/NBLog.h

+1 −1
Original line number Diff line number Diff line
@@ -466,7 +466,7 @@ private: 
    virtual void handleAuthor(const AbstractEntry &fmtEntry, String8 *body) {}



    static void drawHistogram(String8 *body, const std::vector<int64_t> &samples,

                              int indent = 0, int maxHeight = 10);

                              bool logScale, int indent = 0, int maxHeight = 10);



    // Searches for the last entry of type <type> in the range [front, back)

    // back has to be entry-aligned. Returns nullptr if none enconuntered.