STSPG-2256: Dynamic Hermes Weights

Author: scootklein

.ruby-gemset

@@ -1 +1 @@
-hermes
+status-page

lib/hermes/deliverer.rb

@@ -82,7 +82,7 @@ def aggregate_weight_for_type(type, filter: [])
       }
 
       # then sum up all of the weights across our providers
-      providers.map(&:weight).inject(0, :+)
+      providers.count == 1 ? 1 : providers.map(&:weight).inject(0, :+)
     end
 
     def weighted_provider_for_type(type, filter: [])
@@ -99,6 +99,8 @@ def weighted_provider_for_type(type, filter: [])
         filter.empty? || filter.include?(provider_instance.class)
       }
 
+      return providers.first if providers.count == 1
+
       # if we end up with an empty list we're in trouble
       raise ProviderNotFoundError, "Empty provider list found for type:#{type} filter:#{filter}" unless providers.any?
 

lib/providers/provider.rb

@@ -10,7 +10,7 @@ def required_credentials(*args)
       end
     end
 
-    attr_reader :deliverer, :defaults, :credentials, :weight
+    attr_reader :deliverer, :defaults, :credentials
 
     def initialize(deliverer, options = {})
 
@@ -20,7 +20,7 @@ def initialize(deliverer, options = {})
       @deliverer = deliverer
       @defaults = (options[:defaults] || {}).symbolize_keys
       @credentials = (options[:credentials] || {}).symbolize_keys
-      @weight = options[:weight].to_i
+      @weight = options[:weight] || 0
 
       # required credentials should hard stop if they aren't being met
       if self.class._required_credentials.try(:any?)
@@ -32,8 +32,8 @@ def initialize(deliverer, options = {})
       end
 
       # provider weights need to be 0 (disabled), or greater than 0 to show as active
-      unless @weight >= 0
-        raise(InvalidWeightError, "Provider name:#{common_name} has invalid weight:#{@weight}")
+      unless self.weight >= 0
+        raise(InvalidWeightError, "Provider name:#{common_name} has invalid weight:#{self.weight}")
       end
     end
 
@@ -52,6 +52,15 @@ def default(key)
       end
     end
 
+    def weight
+      if @weight.is_a?(Fixnum)
+        @weight.to_i
+      elsif @weight.is_a?(Class)
+        @weight_determiner ||= @weight.new(common_name)
+        @weight_determiner.weight
+      end
+    end
+
     def send_message(rails_message)
       raise ProviderInterfaceError.new("this is an abstract method and must be defined in the subclass")
     end

test/dummy/lib/hermes/non_compliant_provider.rb

@@ -1,5 +1,5 @@
 module Hermes
-  class NonCompliantProvider < Provider    
+  class NonCompliantProvider < Provider
     # don't define this so we can test the enforcement of it being defined :)
     # def send_message(rails_message)
     # end