moonchen commented on code in PR #13754: URL: https://github.com/apache/trafficserver/pull/13754#discussion_r4233721951
########## plugins/stats_over_http/prometheus_render.cc: ########## @@ -0,0 +1,761 @@ +/** @file + + Render records in the Prometheus text format from a cache of translated names. + + @section license License + + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you 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 "prometheus_render.h" + +#include <algorithm> +#include <cerrno> +#include <charconv> +#include <cmath> +#include <cstdio> +#include <cstdlib> +#include <functional> +#include <limits> +#include <numeric> + +#include "prometheus_rules.h" +#include "tsutil/DbgCtl.h" +#include "tsutil/StringCompare.h" + +namespace +{ +DbgCtl dbg_ctl{"stats_over_http"}; + +bool +is_numeric(TSRecordDataType data_type) +{ + return data_type == TS_RECORDDATATYPE_COUNTER || data_type == TS_RECORDDATATYPE_INT || data_type == TS_RECORDDATATYPE_FLOAT; +} + +bool +is_digit(char c) +{ + return c >= '0' && c <= '9'; +} + +// Accepts a decimal number with an optional sign and exponent, Inf or Infinity with an optional sign, or NaN. The case of +// the letters does not matter. Rejects a number too large for a double. +bool +parse_number(const std::string &text, double &value) +{ + std::string_view body{text}; + + if (ts::iequals(body, "nan")) { + value = NAN; + return true; + } + if (!body.empty() && (body[0] == '+' || body[0] == '-')) { + body.remove_prefix(1); + } + if (!ts::iequals(body, "inf") && !ts::iequals(body, "infinity")) { + size_t i = 0; + size_t digits = 0; + + for (; i < body.size() && is_digit(body[i]); ++i) { + ++digits; + } + if (i < body.size() && body[i] == '.') { + for (++i; i < body.size() && is_digit(body[i]); ++i) { + ++digits; + } + } + if (digits == 0) { + return false; + } + if (i < body.size() && (body[i] == 'e' || body[i] == 'E')) { + size_t exponent = 0; + + if (++i < body.size() && (body[i] == '+' || body[i] == '-')) { + ++i; + } + for (; i < body.size() && is_digit(body[i]); ++i) { + ++exponent; + } + if (exponent == 0) { + return false; + } + } + if (i != body.size()) { + return false; + } + } + errno = 0; + value = std::strtod(text.c_str(), nullptr); + return !(errno == ERANGE && std::isinf(value)); +} + +// Appends @a value with the fewest significant digits, from @a min to @a max, that parse back to the same value. With +// @a single, the digits must parse back to the same float. NaN and the infinities get their Prometheus spellings. +void +append_number(std::string &out, double value, int min, int max, bool single) +{ + if (std::isnan(value)) { + out += "NaN"; + return; + } + if (std::isinf(value)) { + out += value > 0 ? "+Inf" : "-Inf"; + return; + } + + char buffer[32]; + int length = 0; + + for (int precision = min; precision <= max; ++precision) { + length = snprintf(buffer, sizeof(buffer), "%.*g", precision, value); + if (single ? std::strtof(buffer, nullptr) == static_cast<float>(value) : std::strtod(buffer, nullptr) == value) { + break; + } + } + out.append(buffer, length); +} + +std::string +join(const std::vector<std::string> &names) +{ + std::string result; + + for (const std::string &name : names) { + if (!result.empty()) { + result += ", "; + } + result += name; + } + return result; +} +} // namespace + +std::string_view +prometheus_type_name(PrometheusType type) +{ + switch (type) { + case PrometheusType::COUNTER: + return "counter"; + case PrometheusType::GAUGE: + return "gauge"; + case PrometheusType::UNTYPED: + break; + } + return "untyped"; +} + +void +prometheus_escape_label_value(std::string &out, std::string_view value) +{ + for (char c : value) { + switch (c) { + case '\\': + out += "\\\\"; + break; + case '"': + out += "\\\""; + break; + case '\n': + out += "\\n"; + break; + default: + out += c; + break; + } + } +} + +void +prometheus_escape_help_text(std::string &out, std::string_view text) +{ + for (char c : text) { + switch (c) { + case '\\': + out += "\\\\"; + break; + case '\n': + out += "\\n"; + break; + default: + out += c; + break; + } + } +} + +void +PrometheusRenderer::begin() +{ + ++_renders; + _position = 0; + _stats = {}; +} + +void +PrometheusRenderer::add(const char *name, TSRecordDataType data_type, const TSRecordData &datum) +{ + uint32_t const position = _position++; + uint32_t index; + + if (position < _slots.size() && _slots[position].name == name && _records[_slots[position].record].data_type == data_type) { + index = _slots[position].record; + } else { + index = find(name, data_type); + if (position < _slots.size()) { + _slots[position] = {name, index}; + } else { + _slots.push_back({name, index}); + } + } + + Record &record = _records[index]; + record.last_render = _renders; + record.datum = datum; + if (record.value == Value::TEXT_LABEL || record.value == Value::TEXT_NUMBER) { + // The string is valid only while TSRecordDump calls back. + _info[index].text.assign(datum.rec_string != nullptr ? datum.rec_string : ""); + } else if (record.value == Value::NONE && _info[index].invalid) { + ++_stats.dropped; + } +} + +uint32_t +PrometheusRenderer::find(const char *name, TSRecordDataType data_type) +{ + if (auto it = _by_pointer.find(name); it != _by_pointer.end() && _records[it->second].data_type == data_type) { + return it->second; + } + + auto [it, added] = _by_name.try_emplace(name, 0); + + if (added || _records[it->second].data_type != data_type) { + it->second = translate(it->first, data_type); + } + _by_pointer[name] = it->second; + return it->second; +} + +uint32_t +PrometheusRenderer::add_record(std::string_view name, TSRecordDataType data_type) +{ + auto const index = static_cast<uint32_t>(_records.size()); + + _records.emplace_back().data_type = data_type; + _info.emplace_back().name = name; + _writers.push_back({index, 0}); + return index; +} + +uint32_t +PrometheusRenderer::add_family(const std::string &name, std::string_view record_name, PrometheusType type, uint32_t record) +{ + auto [it, added] = _family_index.try_emplace(name, static_cast<uint32_t>(_families.size())); + + if (added) { + Family &family = _families.emplace_back(); + + _family_info.push_back({name, record}); + _reorder = true; + family.type = type; + if (_options.help) { + family.header.append("# HELP ").append(name).append(" "); + prometheus_escape_help_text(family.header, record_name); + family.header.append("\n"); + } + if (type != PrometheusType::UNTYPED) { + family.header.append("# TYPE ").append(name).append(" ").append(prometheus_type_name(type)).append("\n"); + } + } + return it->second; +} + +uint32_t +PrometheusRenderer::translate(std::string_view name, TSRecordDataType data_type) +{ + if (_options.rules != nullptr) { + return translate_rules(name, data_type); + } + + uint32_t const index = add_record(name, data_type); + + if (!is_numeric(data_type)) { + Dbg(dbg_ctl, "Prometheus supports only numeric values, skipping: %.*s", static_cast<int>(name.size()), name.data()); + } else if (PrometheusName translated = _options.namer(name, data_type); !translated.family.empty()) { + Record &record = _records[index]; + + record.value = Value::NUMBER; + record.type = translated.type; + _info[index].family = add_family(translated.family, name, translated.type, index); + + Family &family = _families[_info[index].family]; + + if (family.type != translated.type) { + Dbg(dbg_ctl, "Inconsistent types for metric family %s: %.*s is %s, the family is %s", translated.family.c_str(), + static_cast<int>(name.size()), name.data(), prometheus_type_name(translated.type).data(), + prometheus_type_name(family.type).data()); + } + record.prefix = std::move(translated.family); + if (!translated.labels.empty()) { + record.prefix.append("{").append(translated.labels).append("}"); + } + record.prefix += ' '; + family.members.push_back(index); Review Comment: This is the existing behavior on master: `prometheus_out_stat()` writes a separate HELP, TYPE and sample block for each record as `TSRecordDump` visits it, so two names that sanitize to the same string already produce the same series twice. This PR keeps that output for the formats without rules; it only groups those samples under one TYPE line. Deduplicating the flat formats changes their output for existing users, so it belongs in a separate change with an upgrade note. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
