NBLog add log scale to histograms
Bug: 36490717
Test: Log histograms, check that scale displayed is logarithmic
Change-Id: I10d5387ad9eef80e7994ccb8246347e1413e9058
diff --git a/media/libnbaio/NBLog.cpp b/media/libnbaio/NBLog.cpp
index 88bd981..adbbb74 100644
--- a/media/libnbaio/NBLog.cpp
+++ b/media/libnbaio/NBLog.cpp
@@ -948,7 +948,7 @@
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 @@
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 @@
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 @@
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, " ");
}
diff --git a/media/libnbaio/include/NBLog.h b/media/libnbaio/include/NBLog.h
index 2068a94..2893dc9 100644
--- a/media/libnbaio/include/NBLog.h
+++ b/media/libnbaio/include/NBLog.h
@@ -466,7 +466,7 @@
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.