Change the Redis client patch to use prepend (#1743)

lib/ddtrace/contrib/redis/instrumentation.rb

@@ -0,0 +1,90 @@
+# typed: false
+require 'ddtrace/contrib/patcher'
+require 'ddtrace/contrib/redis/ext'
+require 'ddtrace/contrib/redis/configuration/resolver'
+
+module Datadog
+  module Contrib
+    module Redis
+      # Instrumentation for Redis
+      module Instrumentation
+        def self.included(base)
+          base.prepend(InstanceMethods)
+        end
+
+        # InstanceMethods - implementing instrumentation
+        module InstanceMethods
+          def call(*args, &block)
+            pin = Datadog::Pin.get_from(self)
+            return super unless pin && pin.tracer
+
+            response = nil
+            pin.tracer.trace(Datadog::Contrib::Redis::Ext::SPAN_COMMAND) do |span|
+              span.service = pin.service
+              span.span_type = Datadog::Contrib::Redis::Ext::TYPE
+              span.resource = get_command(args)
+              Datadog::Contrib::Redis::Tags.set_common_tags(self, span)
+
+              response = super
+            end
+
+            response
+          end
+
+          def call_pipeline(*args, &block)
+            pin = Datadog::Pin.get_from(self)
+            return super unless pin && pin.tracer
+
+            response = nil
+            pin.tracer.trace(Datadog::Contrib::Redis::Ext::SPAN_COMMAND) do |span|
+              span.service = pin.service
+              span.span_type = Datadog::Contrib::Redis::Ext::TYPE
+              commands = get_pipeline_commands(args)
+              span.resource = commands.join("\n")
+              span.set_metric Datadog::Contrib::Redis::Ext::METRIC_PIPELINE_LEN, commands.length
+              Datadog::Contrib::Redis::Tags.set_common_tags(self, span)
+
+              response = super
+            end
+
+            response
+          end
+
+          def datadog_pin
+            @datadog_pin ||= begin
+              pin = Datadog::Pin.new(
+                datadog_configuration[:service_name],
+                app: Ext::APP,
+                app_type: Datadog::Ext::AppTypes::DB,
+                tracer: -> { datadog_configuration[:tracer] }
+              )
+              pin.onto(self)
+            end
+          end
+
+          private
+
+          def get_command(args)
+            if datadog_configuration[:command_args]
+              Datadog::Contrib::Redis::Quantize.format_command_args(*args)
+            else
+              Datadog::Contrib::Redis::Quantize.get_verb(*args)
+            end
+          end
+
+          def get_pipeline_commands(args)
+            if datadog_configuration[:command_args]
+              args[0].commands.map { |c| Datadog::Contrib::Redis::Quantize.format_command_args(c) }
+            else
+              args[0].commands.map { |c| Datadog::Contrib::Redis::Quantize.get_verb(c) }
+            end
+          end
+
+          def datadog_configuration
+            Datadog.configuration[:redis, options]
+          end
+        end
+      end
+    end
+  end
+end

lib/ddtrace/contrib/redis/patcher.rb

@@ -23,92 +23,10 @@ def patch
           require 'ddtrace/ext/app_types'
           require 'ddtrace/contrib/redis/tags'
           require 'ddtrace/contrib/redis/quantize'
+          require 'ddtrace/contrib/redis/instrumentation'
 
-          patch_redis_client
+          ::Redis::Client.include(Instrumentation)
         end
-
-        # rubocop:disable Metrics/MethodLength
-        # rubocop:disable Metrics/BlockLength
-        # rubocop:disable Metrics/AbcSize
-        def patch_redis_client
-          ::Redis::Client.class_eval do
-            alias_method :call_without_datadog, :call
-            remove_method :call
-            def call(*args, &block)
-              pin = Datadog::Pin.get_from(self)
-              return call_without_datadog(*args, &block) unless pin && pin.tracer
-
-              response = nil
-              pin.tracer.trace(Datadog::Contrib::Redis::Ext::SPAN_COMMAND) do |span|
-                span.service = pin.service
-                span.span_type = Datadog::Contrib::Redis::Ext::TYPE
-                span.resource = get_command(args)
-                Datadog::Contrib::Redis::Tags.set_common_tags(self, span)
-
-                response = call_without_datadog(*args, &block)
-              end
-
-              response
-            end
-
-            alias_method :call_pipeline_without_datadog, :call_pipeline
-            remove_method :call_pipeline
-            def call_pipeline(*args, &block)
-              pin = Datadog::Pin.get_from(self)
-              return call_pipeline_without_datadog(*args, &block) unless pin && pin.tracer
-
-              response = nil
-              pin.tracer.trace(Datadog::Contrib::Redis::Ext::SPAN_COMMAND) do |span|
-                span.service = pin.service
-                span.span_type = Datadog::Contrib::Redis::Ext::TYPE
-                commands = get_pipeline_commands(args)
-                span.resource = commands.join("\n")
-                span.set_metric Datadog::Contrib::Redis::Ext::METRIC_PIPELINE_LEN, commands.length
-                Datadog::Contrib::Redis::Tags.set_common_tags(self, span)
-
-                response = call_pipeline_without_datadog(*args, &block)
-              end
-
-              response
-            end
-
-            def datadog_pin
-              @datadog_pin ||= begin
-                pin = Datadog::Pin.new(
-                  datadog_configuration[:service_name],
-                  app: Ext::APP,
-                  app_type: Datadog::Ext::AppTypes::DB,
-                  tracer: -> { datadog_configuration[:tracer] }
-                )
-                pin.onto(self)
-              end
-            end
-
-            private
-
-            def get_command(args)
-              if datadog_configuration[:command_args]
-                Datadog::Contrib::Redis::Quantize.format_command_args(*args)
-              else
-                Datadog::Contrib::Redis::Quantize.get_verb(*args)
-              end
-            end
-
-            def get_pipeline_commands(args)
-              if datadog_configuration[:command_args]
-                args[0].commands.map { |c| Datadog::Contrib::Redis::Quantize.format_command_args(c) }
-              else
-                args[0].commands.map { |c| Datadog::Contrib::Redis::Quantize.get_verb(c) }
-              end
-            end
-
-            def datadog_configuration
-              Datadog.configuration[:redis, options]
-            end
-          end
-        end
-        # rubocop:enable Metrics/MethodLength
-        # rubocop:enable Metrics/BlockLength
       end
     end
   end

spec/ddtrace/contrib/redis/patcher_spec.rb

@@ -0,0 +1,14 @@
+# typed: false
+require 'ddtrace/contrib/support/spec_helper'
+require 'ddtrace'
+
+RSpec.describe Datadog::Contrib::Redis::Patcher do
+  describe '.patch' do
+    it 'adds Instrumentation methods to ancestors of Redis class' do
+      described_class.patch
+
+      expect(Redis::Client.ancestors).to include(Datadog::Contrib::Redis::Instrumentation)
+      expect(Redis::Client.ancestors).to include(Datadog::Contrib::Redis::Instrumentation)
+    end
+  end
+end