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// Copyright 2021 gRPC authors.
//
// 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.
#include <grpc/support/port_platform.h>
#include "src/core/lib/debug/histogram_view.h"
namespace grpc_core {
double HistogramView::Count() const {
double sum = 0;
for (int i = 0; i < num_buckets; i++) {
sum += buckets[i];
}
return sum;
}
double HistogramView::ThresholdForCountBelow(double count_below) const {
double lower_bound;
double upper_bound;
int upper_idx;
// find the lowest bucket that gets us above count_below
double count_so_far = 0.0;
int lower_idx = 0;
for (; lower_idx < num_buckets; lower_idx++) {
count_so_far += static_cast<double>(buckets[lower_idx]);
if (count_so_far >= count_below) {
break;
}
}
if (count_so_far == count_below) {
// this bucket hits the threshold exactly... we should be midway through
// any run of zero values following the bucket
for (upper_idx = lower_idx + 1; upper_idx < num_buckets; upper_idx++) {
if (buckets[upper_idx]) {
break;
}
}
return (bucket_boundaries[lower_idx] + bucket_boundaries[upper_idx]) / 2.0;
} else {
// treat values as uniform throughout the bucket, and find where this value
// should lie
lower_bound = bucket_boundaries[lower_idx];
upper_bound = bucket_boundaries[lower_idx + 1];
return upper_bound - (upper_bound - lower_bound) *
(count_so_far - count_below) /
static_cast<double>(buckets[lower_idx]);
}
}
double HistogramView::Percentile(double p) const {
const double count = Count();
if (count == 0) return 0.0;
return ThresholdForCountBelow(count * p / 100.0);
}
} // namespace grpc_core
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