Initial commit: API preview for metrics and adapters

Author: Envek

.gitignore

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+/.bundle/
+/.yardoc
+/_yardoc/
+/coverage/
+/doc/
+/pkg/
+/spec/reports/
+/tmp/
+Gemfile.lock
+
+# rspec failure tracking
+.rspec_status

.rspec

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+--format documentation
+--color
+--require spec_helper

.rubocop.yml

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+---
+require:
+- rubocop-rspec
+
+AllCops:
+  TargetRubyVersion: 2.3
+
+Metrics/BlockLength:
+  Exclude:
+  - "Gemfile"
+  - "spec/**/*"
+
+Style/BracesAroundHashParameters:
+  EnforcedStyle: context_dependent
+
+Style/StringLiterals:
+  EnforcedStyle: double_quotes
+
+# Allow to use let!
+RSpec/LetSetup:
+  Enabled: false
+
+RSpec/MultipleExpectations:
+  Enabled: false
+
+Bundler/OrderedGems:
+  Enabled: false
+
+Style/TrailingCommaInArguments:
+  Description: 'Checks for trailing comma in argument lists.'
+  StyleGuide: 'https://github.com/bbatsov/ruby-style-guide#no-trailing-params-comma'
+  Enabled: true
+  EnforcedStyleForMultiline: consistent_comma
+
+Style/TrailingCommaInArrayLiteral:
+  Description: 'Checks for trailing comma in array literals.'
+  StyleGuide: 'https://github.com/bbatsov/ruby-style-guide#no-trailing-array-commas'
+  Enabled: true
+  EnforcedStyleForMultiline: consistent_comma
+
+Style/TrailingCommaInHashLiteral:
+  Description: 'Checks for trailing comma in hash literals.'
+  StyleGuide: 'https://github.com/bbatsov/ruby-style-guide#no-trailing-array-commas'
+  Enabled: true
+  EnforcedStyleForMultiline: consistent_comma
+

.travis.yml

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+---
+sudo: false
+language: ruby
+cache: bundler
+rvm:
+- 2.5.1
+- 2.4.4
+- 2.3.7
+before_install: gem install bundler -v 1.16.5

.yardopts

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+--plugin dry-initializer

Gemfile

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+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+git_source(:github) { |repo_name| "https://github.com/#{repo_name}" }
+
+# Specify your gem's dependencies in evil-metrics.gemspec
+gemspec
+
+group :development, :test do
+  gem "pry"
+  gem "pry-byebug", platform: :mri
+
+  gem "rubocop"
+  gem "rubocop-rspec"
+end

LICENSE.txt

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+The MIT License (MIT)
+
+Copyright (c) 2018 Andrey Novikov
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

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+# Evil::Metrics
+
+**This software is Work in Progress: features will appear and disappear, API will be changed, your feedback is always welcome!** 
+
+Extensible solution for easy setup of monitoring in your Ruby apps.
+
+## Installation
+
+Most of the time you don't need to add this gem to your Gemfile directly (unless you're only collecting your custom metrics):
+
+```ruby
+gem 'evil-metrics'
+# Then add monitoring system adapter, e.g.:
+# gem 'evil-metrics-prometheus'
+```
+
+And then execute:
+
+    $ bundle
+
+## Usage
+
+ 1. Declare your metrics:
+
+    ```ruby
+    Evil::Metrics.configure do
+      group :your_app
+    
+      counter   :bells_rang_count, "Total number of bells being rang"
+      gauge     :whistles_active,  "Number of whistles ready to whistle"
+      histogram :whistle_runtime,  "How long whistles are being active", unit: :seconds
+    end
+    ```
+    
+ 2. Access metric in your app and use it!
+ 
+    ```ruby
+    def ring_the_bell(id)
+      bell = Bell.find(id)
+      bell.ring!
+      Evil::Metrics.your_app_bells_rang_count.increment({bell_size: bell.size}, by: 1)
+    end
+
+    def whistle!
+      Evil::Metrics.your_app_whistle_runtime.measure do
+        # Run your code
+      end
+    end
+    ```
+    
+ 3. Setup collecting of metrics that do not tied to specific events in you application. E.g.: reporting your app's current state
+    ```ruby
+    Evil::Metrics.configure do
+      # This block will be executed periodically few times in a minute
+      # (by timer or external request depending on adapter you're using) 
+      # Keep it fast and simple!
+      collect do
+        your_app_whistles_active.set({}, Whistle.where(state: :active).count
+      end
+    end
+    ```
+
+  4. See the docs for the adapter you're using
+  5. Enjoy!
+
+## Roadmap (aka TODO or Help wanted)
+
+ - Ability to change metric settings for individual adapters
+ 
+   ```rb
+   histogram :foo, comment: "say what?" do
+     adapter :prometheus do
+       buckets [0.01, 0.5, …, 60, 300, 3600]
+     end
+   end
+   ```
+   
+ - Ability to route some metrics only for given adapter:
+ 
+   ```rb
+   adapter :prometheus do
+     include_group :sidekiq
+   end
+   ```
+
+
+
+## Development
+
+After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
+
+To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
+
+## Contributing
+
+Bug reports and pull requests are welcome on GitHub at https://github.com/evil-metrics/evil-metrics.
+
+## License
+
+The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).

Rakefile

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+# frozen_string_literal: true
+
+require "bundler/gem_tasks"
+require "rspec/core/rake_task"
+
+RSpec::Core::RakeTask.new(:spec)
+
+task default: :spec

bin/console

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+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "bundler/setup"
+require "evil/metrics"
+
+# You can add fixtures and/or initialization code here to make experimenting
+# with your gem easier. You can also use a different console, if you like.
+
+require "pry"
+Pry.start

bin/setup

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+#!/usr/bin/env bash
+set -euo pipefail
+IFS=$'\n\t'
+set -vx
+
+bundle install
+
+# Do any other automated setup that you need to do here

evil-metrics.gemspec

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+# frozen_string_literal: true
+
+lib = File.expand_path("lib", __dir__)
+$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+require "evil/metrics/version"
+
+Gem::Specification.new do |spec|
+  spec.name          = "evil-metrics"
+  spec.version       = Evil::Metrics::VERSION
+  spec.authors       = ["Andrey Novikov"]
+  spec.email         = ["[email protected]"]
+
+  spec.summary       = "Extensible framework for collecting metric for your Ruby application"
+  spec.description   = <<~DESCRIPTION
+    Collect statistics about how your application is performing with ease. \
+    Export metrics to various monitoring systems.
+  DESCRIPTION
+  spec.homepage      = "https://github.com/evil-metrics/evil-metrics"
+  spec.license       = "MIT"
+
+  spec.files         = `git ls-files -z`.split("\x0").reject do |f|
+    f.match(%r{^(test|spec|features)/})
+  end
+  spec.bindir        = "exe"
+  spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
+  spec.require_paths = ["lib"]
+
+  spec.add_dependency "concurrent-ruby"
+  spec.add_dependency "dry-initializer"
+
+  spec.add_development_dependency "bundler", "~> 1.16"
+  spec.add_development_dependency "rake", "~> 12.0"
+  spec.add_development_dependency "rspec", "~> 3.0"
+  spec.add_development_dependency "yard"
+  spec.add_development_dependency "yard-dry-initializer"
+end

lib/evil/metrics.rb

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+# frozen_string_literal: true
+
+require "concurrent"
+
+require "evil/metrics/version"
+require "evil/metrics/dsl"
+
+module Evil
+  module Metrics
+    include DSL
+
+    cattr_reader :metrics,    default: Concurrent::Hash.new
+    cattr_reader :adapters,   default: Concurrent::Hash.new
+    cattr_reader :collectors, default: Concurrent::Array.new
+
+    class << self
+      # @param [Symbol] name
+      # @param [BaseAdapter] instance
+      def register_adapter(name, instance)
+        adapters[name] = instance
+        # NOTE: Pretty sure there is race condition
+        metrics.each do |_, metric|
+          instance.register!(metric)
+        end
+      end
+    end
+  end
+end

lib/evil/metrics/base_adapter.rb

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+# frozen_string_literal: true
+
+module Evil
+  module Metrics
+    class BaseAdapter
+      def register!(metric)
+        case metric
+        when Counter   then register_counter!(metric)
+        when Gauge     then register_gauge!(metric)
+        when Histogram then register_histogram!(metric)
+        else raise "#{metric.class} is unknown metric type"
+        end
+      end
+
+      def register_counter!(_metric)
+        raise NotImplementedError, "#{self.class} doesn't support counters as metric type!"
+      end
+
+      def perform_counter_increment!(_counter, _tags, _increment)
+        raise NotImplementedError, "#{self.class} doesn't support incrementing counters"
+      end
+
+      def register_gauge!(_metric)
+        raise NotImplementedError, "#{self.class} doesn't support gauges as metric type!"
+      end
+
+      def perform_gauge_set!(_metric, _tags, _value)
+        raise NotImplementedError, "#{self.class} doesn't support setting gauges"
+      end
+
+      def register_histogram!(_metric)
+        raise NotImplementedError, "#{self.class} doesn't support histograms as metric type!"
+      end
+
+      def perform_histogram_measure!(_metric, _tags, _value)
+        raise NotImplementedError, "#{self.class} doesn't support measuring histograms"
+      end
+    end
+  end
+end

lib/evil/metrics/counter.rb

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+# frozen_string_literal: true
+
+module Evil
+  module Metrics
+    # Growing-only counter
+    class Counter < Metric
+      def increment(tags, by: 1)
+        values[tags] += by
+        ::Evil::Metrics.adapters.each do |_, adapter|
+          adapter.perform_counter_increment!(self, tags, by)
+        end
+        values[tags]
+      end
+
+      def values
+        @values ||= Concurrent::Hash.new(0)
+      end
+    end
+  end
+end