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Merged
SolidWallOfCode merged 1 commit into from
Feb 15, 2023
Merged

Histogram: rename members because Zwoop. #9417

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32 changes: 16 additions & 16 deletions include/tscpp/util/Histogram.h
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@

#pragma once

#include <stdint.h>
#include <cstdint>
#include <array>

namespace ts
Expand Down Expand Up @@ -65,17 +65,17 @@ template <auto R, auto S> class Histogram
/// Number of bits to split each base range in to span buckets.
static constexpr raw_type N_SPAN_BITS = S;
/// Number of buckets per span.
static constexpr raw_type N_SPAN_BUCKETS = 1 << N_SPAN_BITS;
static constexpr raw_type N_SPAN_BUCKETS = raw_type(1) << N_SPAN_BITS;
/// Mask to extract the local bucket index from a sample.
static constexpr raw_type SPAN_MASK = (1 << N_SPAN_BITS) - 1;
static constexpr raw_type SPAN_MASK = (raw_type(1) << N_SPAN_BITS) - 1;
/// Initial mask to find the MSB in the sample.
static constexpr raw_type MSB_MASK = 1 << (N_RANGE_BITS + N_SPAN_BITS - 1);
/// Total number of buckets - 1 for overflow and an extra range for less than @c LOWER_BOUND
static constexpr raw_type MSB_MASK = raw_type(1) << (N_RANGE_BITS + N_SPAN_BITS - 1);
/// Total number of buckets - 1 for overflow and an extra range for less than @c UNDERFLOW_BOUND
static constexpr raw_type N_BUCKETS = ((N_RANGE_BITS + 1) * N_SPAN_BUCKETS) + 1;
/// Samples less than this go in the underflow range.
static constexpr raw_type LOWER_BOUND = 1 << N_SPAN_BITS;
static constexpr raw_type UNDERFLOW_BOUND = raw_type(1) << N_SPAN_BITS;
/// Sample equal or greater than this go in the overflow bucket.
static constexpr raw_type UPPER_BOUND = 1 << (N_RANGE_BITS + N_SPAN_BITS + 1);
static constexpr raw_type OVERFLOW_BOUND = raw_type(1) << (N_RANGE_BITS + N_SPAN_BITS + 1);

/** Add @sample to the histogram.
*
Expand All @@ -97,12 +97,12 @@ template <auto R, auto S> class Histogram
*/
raw_type operator[](unsigned idx);

/** Lower bound for samples in bucket.
/** Minimum value for samples in bucket.
*
* @param idx Index of the bucket.
* @return The smallest sample value that will increment the bucket.
*/
static raw_type lower_bound(unsigned idx);
static raw_type min_for_bucket(unsigned idx);

/** Add counts from another histogram.
*
Expand Down Expand Up @@ -143,15 +143,15 @@ auto
Histogram<R, S>::operator()(raw_type sample) -> self_type &
{
int idx = N_BUCKETS - 1; // index of overflow bucket
if (sample < LOWER_BOUND) {
idx = sample; // sample -> bucket is identity in the underflow range.
} else if (sample < UPPER_BOUND) { // not overflow bucket.
idx -= N_SPAN_BUCKETS; // bottom bucket in the range.
auto mask = MSB_MASK; // Mask to probe for bit set.
if (sample < UNDERFLOW_BOUND) {
idx = sample; // sample -> bucket is identity in the underflow range.
} else if (sample < OVERFLOW_BOUND) { // not overflow bucket.
idx -= N_SPAN_BUCKETS; // bottom bucket in the range.
auto mask = MSB_MASK; // Mask to probe for bit set.
// Shift needed after finding the MSB to put the span bits in the LSBs.
unsigned normalize_shift_count = N_RANGE_BITS - 1;
// Walk the mask bit down until the MSB is found. Each span bumps down the bucket index
// and the shift for the span bits. An MSB will be found because @a sample >= @c LOWER_BOUND
// and the shift for the span bits. An MSB will be found because @a sample >= @c UNDERFLOW_BOUND
// The MSB is not before @c MSB_MASK because @a sample < @c UPPER_BOUND
while (0 == (sample & mask)) {
mask >>= 1;
Expand All @@ -166,7 +166,7 @@ Histogram<R, S>::operator()(raw_type sample) -> self_type &

template <auto R, auto S>
auto
Histogram<R, S>::lower_bound(unsigned idx) -> raw_type
Histogram<R, S>::min_for_bucket(unsigned idx) -> raw_type
{
auto range = idx / N_SPAN_BUCKETS;
raw_type base = 0; // minimum value for the range (not span!).
Expand Down
4 changes: 2 additions & 2 deletions iocore/eventsystem/UnixEventProcessor.cc
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Expand Up @@ -523,14 +523,14 @@ EventProcessor::start(int n_event_threads, size_t stacksize)
// Event loop timings.
for (Graph::raw_type id = 0; id < Graph::N_BUCKETS; ++id) {
snprintf(name, sizeof(name), "%s%zums", EThread::Metrics::LOOP_HISTOGRAM_STAT_STEM.data(),
static_cast<size_t>(EThread::Metrics::LOOP_HISTOGRAM_BUCKET_SIZE.count() * Graph::lower_bound(id)));
static_cast<size_t>(EThread::Metrics::LOOP_HISTOGRAM_BUCKET_SIZE.count() * Graph::min_for_bucket(id)));
RecRegisterRawStat(rsb, RECT_PROCESS, name, RECD_INT, RECP_NON_PERSISTENT, stat_idx++, NULL);
}

// plugin API timings
for (Graph::raw_type id = 0; id < Graph::N_BUCKETS; ++id) {
snprintf(name, sizeof(name), "%s%zums", EThread::Metrics::API_HISTOGRAM_STAT_STEM.data(),
static_cast<size_t>(EThread::Metrics::API_HISTOGRAM_BUCKET_SIZE.count() * Graph::lower_bound(id)));
static_cast<size_t>(EThread::Metrics::API_HISTOGRAM_BUCKET_SIZE.count() * Graph::min_for_bucket(id)));
RecRegisterRawStat(rsb, RECT_PROCESS, name, RECD_INT, RECP_NON_PERSISTENT, stat_idx++, NULL);
}

Expand Down
20 changes: 10 additions & 10 deletions src/tscore/unit_tests/test_Histogram.cc
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Expand Up @@ -35,22 +35,22 @@ TEST_CASE("Histogram Basic", "[libts][histogram]")
h(12);
REQUIRE(h[10] == 1);

REQUIRE(h.lower_bound(0) == 0);
REQUIRE(h.lower_bound(3) == 3);
REQUIRE(h.lower_bound(4) == 4);
REQUIRE(h.lower_bound(8) == 8);
REQUIRE(h.lower_bound(9) == 10);
REQUIRE(h.lower_bound(12) == 16);
REQUIRE(h.lower_bound(13) == 20);
REQUIRE(h.lower_bound(16) == 32);
REQUIRE(h.lower_bound(17) == 40);
REQUIRE(h.min_for_bucket(0) == 0);
REQUIRE(h.min_for_bucket(3) == 3);
REQUIRE(h.min_for_bucket(4) == 4);
REQUIRE(h.min_for_bucket(8) == 8);
REQUIRE(h.min_for_bucket(9) == 10);
REQUIRE(h.min_for_bucket(12) == 16);
REQUIRE(h.min_for_bucket(13) == 20);
REQUIRE(h.min_for_bucket(16) == 32);
REQUIRE(h.min_for_bucket(17) == 40);

for (auto x : {0, 1, 4, 6, 19, 27, 36, 409, 16000, 1097}) {
h(x);
}
REQUIRE(h[0] == 1);
REQUIRE(h[1] == 1);
REQUIRE(h[2] == 0);
REQUIRE(h[12] == 1); // sample 19 shoud be here.
REQUIRE(h[12] == 1); // sample 19 should be here.
REQUIRE(h[14] == 1); // sample 27 should be here.
};