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Diffstat (limited to 'src/mongo/db/stats/operation_latency_histogram.cpp')
| -rw-r--r-- | src/mongo/db/stats/operation_latency_histogram.cpp | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/src/mongo/db/stats/operation_latency_histogram.cpp b/src/mongo/db/stats/operation_latency_histogram.cpp new file mode 100644 index 00000000000..3b55b18af5a --- /dev/null +++ b/src/mongo/db/stats/operation_latency_histogram.cpp @@ -0,0 +1,171 @@ +/** + * Copyright (C) 2016 MongoDB Inc. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU Affero General Public License, version 3, + * as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + * + * As a special exception, the copyright holders give permission to link the + * code of portions of this program with the OpenSSL library under certain + * conditions as described in each individual source file and distribute + * linked combinations including the program with the OpenSSL library. You + * must comply with the GNU Affero General Public License in all respects + * for all of the code used other than as permitted herein. If you modify + * file(s) with this exception, you may extend this exception to your + * version of the file(s), but you are not obligated to do so. If you do not + * wish to do so, delete this exception statement from your version. If you + * delete this exception statement from all source files in the program, + * then also delete it in the license file. + */ + +#include "mongo/platform/basic.h" + +#include "mongo/db/stats/operation_latency_histogram.h" + +#include <algorithm> + +#include "mongo/bson/bsonobjbuilder.h" +#include "mongo/db/namespace_string.h" +#include "mongo/platform/bits.h" + +namespace mongo { + +const std::array<uint64_t, OperationLatencyHistogram::kMaxBuckets> + OperationLatencyHistogram::kLowerBounds = {0, + 2, + 4, + 8, + 16, + 32, + 64, + 128, + 256, + 512, + 1024, + 2048, + 3072, + 4096, + 6144, + 8192, + 12288, + 16384, + 24576, + 32768, + 49152, + 65536, + 98304, + 131072, + 196608, + 262144, + 393216, + 524288, + 786432, + 1048576, + 1572864, + 2097152, + 4194304, + 8388608, + 16777216, + 33554432, + 67108864, + 134217728, + 268435456, + 536870912, + 1073741824, + 2147483648, + 4294967296, + 8589934592, + 17179869184, + 34359738368, + 68719476736, + 137438953472, + 274877906944, + 549755813888, + 1099511627776}; + +void OperationLatencyHistogram::_append(const HistogramData& data, + const char* key, + BSONObjBuilder* builder) const { + + BSONObjBuilder histogramBuilder(builder->subobjStart(key)); + BSONArrayBuilder arrayBuilder(histogramBuilder.subarrayStart("histogram")); + for (int i = 0; i < kMaxBuckets; i++) { + if (data.buckets[i] == 0) + continue; + BSONObjBuilder entryBuilder(arrayBuilder.subobjStart()); + entryBuilder.append("micros", static_cast<long long>(kLowerBounds[i])); + entryBuilder.append("count", static_cast<long long>(data.buckets[i])); + entryBuilder.doneFast(); + } + + arrayBuilder.doneFast(); + histogramBuilder.append("latency", static_cast<long long>(data.sum)); + histogramBuilder.append("ops", static_cast<long long>(data.entryCount)); + histogramBuilder.doneFast(); +} + +void OperationLatencyHistogram::append(BSONObjBuilder* builder) const { + _append(_reads, "reads", builder); + _append(_writes, "writes", builder); + _append(_commands, "commands", builder); +} + +// Computes the log base 2 of value, and checks for cases of split buckets. +int OperationLatencyHistogram::_getBucket(uint64_t value) { + // Zero is a special case since log(0) is undefined. + if (value == 0) { + return 0; + } + + int log2 = 63 - countLeadingZeros64(value); + // Half splits occur in range [2^11, 2^21) giving 10 extra buckets. + if (log2 < 11) { + return log2; + } else if (log2 < 21) { + int extra = log2 - 11; + // Split value boundary is at (2^n + 2^(n+1))/2 = 2^n + 2^(n-1). + // Which corresponds to (1ULL << log2) | (1ULL << (log2 - 1)) + // Which is equivalent to the following: + uint64_t splitBoundary = 3ULL << (log2 - 1); + if (value >= splitBoundary) { + extra++; + } + return log2 + extra; + } else { + // Add all of the extra 10 buckets. + return std::min(log2 + 10, kMaxBuckets - 1); + } +} + +void OperationLatencyHistogram::_incrementData(uint64_t latency, int bucket, HistogramData* data) { + data->buckets[bucket]++; + data->entryCount++; + data->sum += latency; +} + +void OperationLatencyHistogram::increment(uint64_t latency, Command::ReadWriteType type) { + int bucket = _getBucket(latency); + switch (type) { + case Command::ReadWriteType::kRead: + _incrementData(latency, bucket, &_reads); + break; + case Command::ReadWriteType::kWrite: + _incrementData(latency, bucket, &_writes); + break; + case Command::ReadWriteType::kCommand: + _incrementData(latency, bucket, &_commands); + break; + default: + MONGO_UNREACHABLE; + } +} + +} // namespace mongo |