uniqueness_checker.rb in services-0.2.9

- old
+ new
@@ -4,45 +4,90 @@
       KEY_PREFIX = %w(
         services
         uniqueness
       ).join(':')
 
+      ON_ERROR = %i(
+        fail
+        ignore
+        reschedule
+      )
+
+      MAX_RETRIES = 10
+      ONE_HOUR = 60 * 60
+
       def self.prepended(mod)
         mod.const_set :NotUniqueError, Class.new(mod::Error)
       end
 
-      def check_uniqueness!(*args)
-        if args.empty?
-          raise 'Could not find uniqueness args' unless defined?(@uniqueness_args)
-          args = @uniqueness_args
-        end
-        new_uniqueness_key = uniqueness_key(args)
-        if similar_service_id = Services.configuration.redis.get(new_uniqueness_key)
-          raise self.class::NotUniqueError, "Service #{self.class} with uniqueness args #{args} is not unique, a similar service is already running: #{similar_service_id}"
+      def check_uniqueness!(*args, on_error: :fail)
+        raise "on_error must be one of #{ON_ERROR.join(', ')}, but was #{on_error}" unless ON_ERROR.include?(on_error.to_sym)
+        raise 'Service args not found.' if @service_args.nil?
+        @uniqueness_args = args.empty? ? @service_args : args
+        new_uniqueness_key = uniqueness_key(@uniqueness_args)
+        raise "A uniqueness key with args #{@uniqueness_args.inspect} already exists." if @uniqueness_keys && @uniqueness_keys.include?(new_uniqueness_key)
+        if @similar_service_id = Services.configuration.redis.get(new_uniqueness_key)
+          case on_error.to_sym
+          when :ignore
+            false
+          when :fail
+            raise_non_unique_error
+          when :reschedule
+            error_count = (Services.configuration.redis.get(error_count_key) || 0).to_i
+            if error_count >= MAX_RETRIES
+              raise_non_unique_error
+            else
+              error_count += 1
+              self.class.perform_in retry_delay(error_count), @service_args
+              Services.configuration.redis.setex error_count_key, retry_delay(error_count) + ONE_HOUR, error_count
+              false
+            end
+          end
         else
           @uniqueness_keys ||= []
-          raise "A uniqueness key with args #{args.inspect} already exists." if @uniqueness_keys.include?(new_uniqueness_key)
           @uniqueness_keys << new_uniqueness_key
-          Services.configuration.redis.setex new_uniqueness_key, 60 * 60, @id
+          Services.configuration.redis.setex new_uniqueness_key, ONE_HOUR, @id
+          true
         end
       end
 
       def call(*args)
-        @uniqueness_args = args
+        @service_args = args
         super
       ensure
         Services.configuration.redis.del @uniqueness_keys unless @uniqueness_keys.nil? || @uniqueness_keys.empty?
+        Services.configuration.redis.del error_count_key
       end
 
       private
 
+      def raise_non_unique_error(retried = false)
+        message = "Service #{self.class} #{@id} with uniqueness args #{@uniqueness_args} is not unique, a similar service is already running: #{@similar_service_id}."
+        message << " The service has been retried #{MAX_RETRIES} times."
+        raise self.class::NotUniqueError, message
+      end
+
       def uniqueness_key(args)
         [
           KEY_PREFIX,
           self.class.to_s
         ].tap do |key|
           key << Digest::MD5.hexdigest(args.to_s) unless args.empty?
         end.join(':')
+      end
+
+      def error_count_key
+        [
+          KEY_PREFIX,
+          'errors',
+          self.class.to_s
+        ].tap do |key|
+          key << Digest::MD5.hexdigest(@service_args.to_s) unless @service_args.empty?
+        end.join(':')
+      end
+
+      def retry_delay(error_count)
+        (error_count ** 3) + 5
       end
     end
   end
 end