[JAY-737] Allow the retrieval of total metrics for the indexes

CHANGELOG.md

@@ -15,6 +15,11 @@ Please mark backwards incompatible changes with an exclamation mark at the start
   when `active_support/core_ext/string` hadn't been loaded.
 
 ### Added
+- The `#totals` method to `Elasticsearch::Stats::Index`, this gives the caller
+  access to the index's total metrics.
+- The `Elasticsearch::Stats::Index::Totals` class. The class contains information
+  about an index's total metrics, for example, total number of documents, total
+  size, etc.
 - The `#settings` method to the `Elasticsearch::Index` class. This gives the
   caller access to the index's settings.
 - The `Elasticsearch::Indices::Settings::Blocks` class. The class encapsulates

lib/jay_api/elasticsearch/stats/index.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require_relative 'index/totals'
+
 module JayAPI
   module Elasticsearch
     class Stats
@@ -13,6 +15,17 @@ def initialize(name, data)
           @name = name
           @data = data
         end
+
+        # @return [JayAPI::Elasticsearch::Stats::Index::Totals] Information
+        #   about the index's total metrics.
+        # @raise [KeyError] If the given data doesn't have a +total+ key.
+        def totals
+          @totals ||= ::JayAPI::Elasticsearch::Stats::Index::Totals.new(data.fetch('total'))
+        end
+
+        private
+
+        attr_reader :data
       end
     end
   end

lib/jay_api/elasticsearch/stats/index/totals.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+module JayAPI
+  module Elasticsearch
+    class Stats
+      class Index
+        # Contains information about an index's totals (docs, used space, etc).
+        class Totals
+          # @param [Hash] data The data under the index's +total+ key.
+          def initialize(data)
+            @data = data
+          end
+
+          # @return [Integer] The total number of documents in the index.
+          def docs_count
+            @docs_count ||= docs.fetch('count')
+          end
+
+          # @return [Integer] The total number of deleted documents in the index.
+          def deleted_docs
+            @deleted_docs ||= docs.fetch('deleted')
+          end
+
+          # @return [Float] A number between 0 and 1 that represents the ratio
+          #   of between deleted documents and total documents in the index.
+          def deleted_ratio
+            @deleted_ratio ||= calculate_deleted_ratio
+          end
+
+          private
+
+          attr_reader :data
+
+          # @return [Hash] The information about the documents in the index.
+          #   Looks something like this:
+          #
+          #   { "count" => 530626, "deleted" => 11 }
+          #
+          # @raise [KeyError] If the given data doesn't have a +docs+ key.
+          def docs
+            @docs ||= data.fetch('docs')
+          end
+
+          # @return [Float] A number between 0 and 1 that represents the ratio
+          #   of between deleted documents and total documents in the index.
+          def calculate_deleted_ratio
+            if docs_count.zero?
+              return deleted_docs.zero? ? 0.0 : 1.0
+            end
+
+            deleted_docs / docs_count.to_f
+          end
+        end
+      end
+    end
+  end
+end

spec/jay_api/elasticsearch/stats/index/totals_spec.rb

@@ -0,0 +1,124 @@
+# frozen_string_literal: true
+
+require 'jay_api/elasticsearch/stats/index/totals'
+
+RSpec.describe JayAPI::Elasticsearch::Stats::Index::Totals do
+  subject(:totals) { described_class.new(data) }
+
+  let(:docs) do
+    { 'count' => 530_626, 'deleted' => 11 }
+  end
+
+  let(:data) do
+    {
+      'docs' => docs,
+      'store' => { 'size_in_bytes' => 1_001_425_875, 'reserved_in_bytes' => 0 },
+      'flush' => { 'total' => 25, 'periodic' => 0, 'total_time_in_millis' => 1924 },
+      'warmer' => { 'current' => 0, 'total' => 30, 'total_time_in_millis' => 0 },
+      'completion' => { 'size_in_bytes' => 0 }
+    }
+  end
+
+  shared_examples_for '#docs' do
+    context "when the data doesn't have a 'docs' key" do
+      let(:data) { super().except('docs') }
+
+      it 'raises a KeyError' do
+        expect { method_call }.to raise_error(
+          KeyError, 'key not found: "docs"'
+        )
+      end
+    end
+  end
+
+  shared_examples_for '#docs_count' do
+    it_behaves_like '#docs'
+
+    context "when the data doesn't contain the total number of documents" do
+      let(:docs) { super().except('count') }
+
+      it 'raises a KeyError' do
+        expect { method_call }.to raise_error(
+          KeyError, 'key not found: "count"'
+        )
+      end
+    end
+  end
+
+  describe '#docs_count' do
+    subject(:method_call) { totals.docs_count }
+
+    it_behaves_like '#docs_count'
+
+    it 'returns the expected number of documents' do
+      expect(method_call).to eq(530_626)
+    end
+  end
+
+  shared_examples_for '#deleted_docs' do
+    it_behaves_like '#docs'
+
+    context "when the data doesn't contain the number of deleted documents" do
+      let(:docs) { super().except('deleted') }
+
+      it 'raises a KeyError' do
+        expect { method_call }.to raise_error(
+          KeyError, 'key not found: "deleted"'
+        )
+      end
+    end
+  end
+
+  describe '#deleted_docs' do
+    subject(:method_call) { totals.deleted_docs }
+
+    it_behaves_like '#deleted_docs'
+
+    it 'returns the expected number of deleted documents' do
+      expect(method_call).to eq(11)
+    end
+  end
+
+  describe '#deleted_ratio' do
+    subject(:method_call) { totals.deleted_ratio }
+
+    it_behaves_like '#docs_count'
+    it_behaves_like '#deleted_docs'
+
+    context 'when the index has no documents' do
+      let(:docs) { super().merge('count' => 0) }
+
+      context 'when the index has no deleted documents' do
+        let(:docs) { super().merge('deleted' => 0) }
+
+        it 'returns 0' do
+          expect(method_call).to be_zero
+        end
+      end
+
+      context 'when the index has deleted documents' do
+        it 'returns 1' do
+          expect(method_call).to be(1.0)
+        end
+      end
+    end
+
+    context 'when the index has documents' do
+      context 'when the index has no deleted documents' do
+        let(:docs) { super().merge('deleted' => 0) }
+
+        it 'returns 0' do
+          expect(method_call).to be_zero
+        end
+      end
+
+      context 'when the index has deleted documents' do
+        let(:docs) { super().merge('deleted' => 10_636) }
+
+        it 'returns the expected ratio' do
+          expect(method_call).to be_within(0.0001).of(0.02)
+        end
+      end
+    end
+  end
+end

spec/jay_api/elasticsearch/stats/index_spec.rb

@@ -6,7 +6,20 @@
   subject(:index) { described_class.new(name, data) }
 
   let(:name) { 'xyz01_integration_tests' }
-  let(:data) { {} }
+
+  let(:data) do
+    {
+      'uuid' => 'rouPqkZMSrKHY5bzL7OhTA',
+      'primaries' => {
+        'docs' => { 'count' => 265_313, 'deleted' => 0 },
+        'store' => { 'size_in_bytes' => 497_335_237, 'reserved_in_bytes' => 0 }
+      },
+      'total' => {
+        'docs' => { 'count' => 530_626, 'deleted' => 11 },
+        'store' => { 'size_in_bytes' => 1_001_425_875, 'reserved_in_bytes' => 0 }
+      }
+    }
+  end
 
   describe '#initialize' do
     subject(:method_call) { index }
@@ -16,4 +29,45 @@
       expect(index.name).to be(name)
     end
   end
+
+  describe '#totals' do
+    subject(:method_call) { index.totals }
+
+    let(:totals_hash) do
+      {
+        'docs' => { 'count' => 530_626, 'deleted' => 11 },
+        'store' => { 'size_in_bytes' => 1_001_425_875, 'reserved_in_bytes' => 0 }
+      }
+    end
+
+    let(:totals) do
+      instance_double(
+        JayAPI::Elasticsearch::Stats::Index::Totals
+      )
+    end
+
+    before do
+      allow(JayAPI::Elasticsearch::Stats::Index::Totals)
+        .to receive(:new).and_return(totals)
+    end
+
+    context "when the index's data doesn't contain the totals information" do
+      let(:data) { super().except('total') }
+
+      it 'raises a KeyError' do
+        expect { method_call }.to raise_error(
+          KeyError, 'key not found: "total"'
+        )
+      end
+    end
+
+    it 'creates a new instance of the Totals class with the expected Hash' do
+      expect(JayAPI::Elasticsearch::Stats::Index::Totals).to receive(:new).with(totals_hash)
+      method_call
+    end
+
+    it 'returns the instance of the Totals class' do
+      expect(method_call).to be(totals)
+    end
+  end
 end