Move interval to Rate and Gauge metrics, make sure it is not nil and …

…positive

lib/datadog/core/telemetry/metric.rb

@@ -7,39 +7,38 @@ module Telemetry
       module Metric
         # Base class for all metric types
         class Base
-          attr_reader :name, :tags, :values, :common, :interval
+          attr_reader :name, :tags, :values, :common
 
           # @param name [String] metric name
           # @param tags [Array<String>|Hash{String=>String}] metric tags as hash of array of "tag:val" strings
           # @param common [Boolean] true if the metric is common for all languages, false for Ruby-specific metric
-          # @param interval [Integer] metrics aggregation interval in seconds
-          def initialize(name, tags: {}, common: true, interval: nil)
+          def initialize(name, tags: {}, common: true)
             @name = name
             @values = []
             @tags = tags_to_array(tags)
             @common = common
-            @interval = interval
           end
 
           def id
             @id ||= "#{type}::#{name}::#{tags.join(',')}"
           end
 
-          def track(value); end
+          def track(value)
+            raise NotImplementedError, 'method must be implemented in subclasses'
+          end
 
-          def type; end
+          def type
+            raise NotImplementedError, 'method must be implemented in subclasses'
+          end
 
           def to_h
-            # @type var res: Hash[Symbol, untyped]
-            res = {
+            {
               metric: name,
               points: values,
               type: type,
               tags: tags,
               common: common
             }
-            res[:interval] = interval if interval
-            res
           end
 
           private
@@ -51,6 +50,29 @@ def tags_to_array(tags)
           end
         end
 
+        # Base class for metrics that require aggregation interval
+        class IntervalMetric < Base
+          attr_reader :interval
+
+          # @param name [String] metric name
+          # @param tags [Array<String>|Hash{String=>String}] metric tags as hash of array of "tag:val" strings
+          # @param common [Boolean] true if the metric is common for all languages, false for Ruby-specific metric
+          # @param interval [Integer] metrics aggregation interval in seconds
+          def initialize(name, interval:, tags: {}, common: true)
+            raise ArgumentError, 'interval must be a positive number' if interval.nil? || interval <= 0
+
+            super(name, tags: tags, common: common)
+
+            @interval = interval
+          end
+
+          def to_h
+            res = super
+            res[:interval] = interval
+            res
+          end
+        end
+
         # Count metric adds up all the submitted values in a time interval. This would be suitable for a
         # metric tracking the number of website hits, for instance.
         class Count < Base
@@ -84,7 +106,7 @@ def track(value)
         # A gauge type takes the last value reported during the interval. This type would make sense for tracking RAM or
         # CPU usage, where taking the last value provides a representative picture of the host’s behavior during the time
         # interval.
-        class Gauge < Base
+        class Gauge < IntervalMetric
           TYPE = 'gauge'
 
           def type
@@ -104,10 +126,10 @@ def track(value)
 
         # The rate type takes the count and divides it by the length of the time interval. This is useful if you’re
         # interested in the number of hits per second.
-        class Rate < Base
+        class Rate < IntervalMetric
           TYPE = 'rate'
 
-          def initialize(name, tags: {}, common: true, interval: nil)
+          def initialize(name, interval:, tags: {}, common: true)
             super
 
             @value = 0.0
@@ -119,15 +141,7 @@ def type
 
           def track(value = 1.0)
             @value += value
-
-            rate =
-              if interval && interval.positive?
-                @value / interval
-              else
-                0.0
-              end
-
-            @values = [[Time.now.to_i, rate]]
+            @values = [[Time.now.to_i, @value / interval]]
             nil
           end
         end

sig/datadog/core/telemetry/metric.rbs

@@ -22,8 +22,6 @@ module Datadog
 
           @common: bool
 
-          @interval: Integer?
-
           attr_reader name: String
 
           attr_reader tags: Array[String]
@@ -32,9 +30,8 @@ module Datadog
 
           attr_reader common: bool
 
-          attr_reader interval: Integer?
 
-          def initialize: (String name, ?tags: tags_input, ?common: bool, ?interval: Integer?) -> void
+          def initialize: (String name, ?tags: tags_input, ?common: bool) -> void
 
           def id: () -> String
 
@@ -49,6 +46,14 @@ module Datadog
           def tags_to_array: (tags_input tags) -> Array[String]
         end
 
+        class IntervalMetric < Base
+          @interval: Integer
+
+          attr_reader interval: Integer
+
+          def initialize: (String name, ?tags: tags_input, ?common: bool, interval: Integer) -> void
+        end
+
         class Count < Base
           TYPE: "count"
 
@@ -64,24 +69,22 @@ module Datadog
           def track: (input_value value) -> void
         end
 
-        class Gauge < Base
+        class Gauge < IntervalMetric
           TYPE: "gauge"
 
           def type: () -> "gauge"
 
           def track: (input_value value) -> void
         end
 
-        class Rate < Base
+        class Rate < IntervalMetric
           @value: Float
 
           @values: Array[metric_value]
           attr_reader values: Array[metric_value]
 
           TYPE: "rate"
 
-          def initialize: (String name, ?tags: tags_input, ?common: bool, ?interval: Integer?) -> void
-
           def type: () -> "rate"
 
           def track: (?input_value value) -> void

spec/datadog/core/telemetry/metric_spec.rb

@@ -16,7 +16,6 @@
       is_expected.to have_attributes(
         name: name,
         tags: ['tag1:val1', 'tag2:val2'],
-        interval: nil,
         common: true,
         values: []
       )
@@ -198,8 +197,8 @@
       context 'interval is nil' do
         let(:interval) { nil }
 
-        it 'sets rate to zero' do
-          expect { track }.to change { metric.values }.from([]).to([[now, 0.0]])
+        it 'raises error' do
+          expect { metric }.to raise_error(ArgumentError, 'interval must be a positive number')
         end
       end
     end
@@ -235,7 +234,6 @@
       is_expected.to have_attributes(
         name: name,
         tags: ['tag1:val1', 'tag2:val2'],
-        interval: nil,
         common: true,
         values: []
       )