perf_hooks: multiple fixes for Histogram

* The createHistogram(options) options weren't actually implemented
* Add a new count property that tracks the number of samples
* Adds BigInt options for relevant properties
* Adds add(other) method for RecordableHistogram
* Cleans up and expands tests
* Eliminates unnecessary ELDHistogram native class
* Improve/Simplify histogram transfer impl

Signed-off-by: James M Snell <jasnell@gmail.com>

perf_hooks: simplify Histogram constructor options

Signed-off-by: James M Snell <jasnell@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/41153
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

1 files changed, 34 insertions, 15 deletions

diff --git a/src/histogram-inl.h b/src/histogram-inl.h
index 18a1668512e..3b8712c8787 100644
--- a/src/histogram-inl.h
+++ b/src/histogram-inl.h
@@ -13,35 +13,49 @@ void Histogram::Reset() {
   Mutex::ScopedLock lock(mutex_);
   hdr_reset(histogram_.get());
   exceeds_ = 0;
+  count_ = 0;
   prev_ = 0;
 }
 
-int64_t Histogram::Min() {
+double Histogram::Add(const Histogram& other) {
+  Mutex::ScopedLock lock(mutex_);
+  count_ += other.count_;
+  exceeds_ += other.exceeds_;
+  if (other.prev_ > prev_)
+    prev_ = other.prev_;
+  return static_cast<double>(hdr_add(histogram_.get(), other.histogram_.get()));
+}
+
+size_t Histogram::Count() const {
+  Mutex::ScopedLock lock(mutex_);
+  return count_;
+}
+
+int64_t Histogram::Min() const {
   Mutex::ScopedLock lock(mutex_);
   return hdr_min(histogram_.get());
 }
 
-int64_t Histogram::Max() {
+int64_t Histogram::Max() const {
   Mutex::ScopedLock lock(mutex_);
   return hdr_max(histogram_.get());
 }
 
-double Histogram::Mean() {
+double Histogram::Mean() const {
   Mutex::ScopedLock lock(mutex_);
   return hdr_mean(histogram_.get());
 }
 
-double Histogram::Stddev() {
+double Histogram::Stddev() const {
   Mutex::ScopedLock lock(mutex_);
   return hdr_stddev(histogram_.get());
 }
 
-double Histogram::Percentile(double percentile) {
+int64_t Histogram::Percentile(double percentile) const {
   Mutex::ScopedLock lock(mutex_);
   CHECK_GT(percentile, 0);
   CHECK_LE(percentile, 100);
-  return static_cast<double>(
-      hdr_value_at_percentile(histogram_.get(), percentile));
+  return hdr_value_at_percentile(histogram_.get(), percentile);
 }
 
 template <typename Iterator>
@@ -51,26 +65,31 @@ void Histogram::Percentiles(Iterator&& fn) {
   hdr_iter_percentile_init(&iter, histogram_.get(), 1);
   while (hdr_iter_next(&iter)) {
     double key = iter.specifics.percentiles.percentile;
-    double value = static_cast<double>(iter.value);
-    fn(key, value);
+    fn(key, iter.value);
   }
 }
 
 bool Histogram::Record(int64_t value) {
   Mutex::ScopedLock lock(mutex_);
-  return hdr_record_value(histogram_.get(), value);
+  bool recorded = hdr_record_value(histogram_.get(), value);
+  if (!recorded)
+    exceeds_++;
+  else
+    count_++;
+  return recorded;
 }
 
 uint64_t Histogram::RecordDelta() {
   Mutex::ScopedLock lock(mutex_);
   uint64_t time = uv_hrtime();
-  uint64_t delta = 0;
+  int64_t delta = 0;
   if (prev_ > 0) {
+    CHECK_GE(time, prev_);
     delta = time - prev_;
-    if (delta > 0) {
-      if (!hdr_record_value(histogram_.get(), delta) && exceeds_ < 0xFFFFFFFF)
-        exceeds_++;
-    }
+    if (hdr_record_value(histogram_.get(), delta))
+      count_++;
+    else
+      exceeds_++;
   }
   prev_ = time;
   return delta;