dont assume subscription names, you may have many for the same topic for fanout

Author: glytch

README.md

@@ -18,16 +18,14 @@ And then execute:
 
 ### Conventions
 
-- Subscription names follow the format `"#{topic_name}-subscription"`
 - Messages are hashes
-- Message hashes are encoded to JSON for transport and decoded back to hashes when reading
 
 ### Receiving Messages
 
 ```ruby
 reader = Hover::PubSub::Reader.new(
   project_id: ENV['GCP_PUBSUB_PROJECT_ID'],
-  topic_names: ['list', 'of', 'topic', 'names'],
+  subscription_names: ['list', 'of', 'subscription', 'names'],
   ack_deadline: 30
 )
 
@@ -38,12 +36,9 @@ end
 
 A `Reader` instance has a `#read` instance method that takes a block. The block is responsible for processing each message. If the block returns true, processing is considered successful and the message is acknowledged and deleted. If the block returns false the message goes back to the queue for another reader to attempt processing again. 
 
-When the `#read` method is called a thread is created for each topic subscription. And all subscriptions are read from concurrently. It is safe to have more than one reader reading at the same time. With that you can scale up the number of active readers as the number of messages needing to be processed grows.
-
-`#read` does not yield the [received message](https://googleapis.dev/ruby/google-cloud-pubsub/latest/Google/Cloud/PubSub/ReceivedMessage.html) objects to your block. It assumes your messages are JSON strings and decodes them and returns the decoded object. 
-
-`Reader` assumes your subscription names follow the pattern `"#{topic_name}-subscription"`.
+When the `#read` method is called a thread is created for each subscription. And all subscriptions are read from concurrently. It is safe to have more than one reader reading at the same time. With that you can scale up the number of active readers as the number of messages needing to be processed grows.
 
+`#read` does not yield the [received message](https://googleapis.dev/ruby/google-cloud-pubsub/latest/Google/Cloud/PubSub/ReceivedMessage.html) objects to your block. It assumes your messages are JSON strings and decodes them and returns the decoded object.
 
 ### Publishing Messages
 

lib/hover/pub_sub/reader.rb

@@ -6,25 +6,21 @@
 module Hover
   module PubSub
     class Reader
-      def self.subscription_name(topic_name)
-        "#{topic_name}-subscription"
-      end
-
       def self.parse_message(message)
         json = message.data
         JSON.parse(json)
       end
 
-      def initialize(project_id:, topic_names:, ack_deadline:)
+      def initialize(project_id:, subscription_names:, ack_deadline:)
         @project_id = project_id
-        @topic_names = topic_names
+        @subscription_names = subscription_names
         @ack_deadline = ack_deadline
       end
 
       def read
-        for_each_new_message do |topic_name, message|
+        for_each_new_message do |subscription_name, message|
           parsed_message = self.class.parse_message(message)
-          processed_successfully = yield(topic_name, parsed_message).eql?(true)
+          processed_successfully = yield(subscription_name, parsed_message).eql?(true)
 
           delete message if processed_successfully
         end
@@ -33,10 +29,10 @@ def read
       private
 
       def for_each_new_message
-        threads = subscriptions.map do |topic_name, subscription|
+        threads = subscriptions.map do |subscription_name, subscription|
           Thread.new do
             subscription.pull(immediate: false).each do |message|
-              yield(topic_name, message)
+              yield(subscription_name, message)
             end
           end
         end
@@ -50,18 +46,10 @@ def delete(message)
       end
 
       def subscriptions
-        @topic_names.map.with_object({}) do |topic_name, hash|
-          project.topic(topic_name, skip_lookup: true)
-
-          hash[topic_name] = subscription(topic_name)
-        end
-      end
-
-      def subscription(topic_name)
-        name = self.class.subscription_name(topic_name)
-
-        project.subscription(name, skip_lookup: true).tap do |subscription|
-          subscription.deadline = @ack_deadline
+        @subscription_names.map.with_object({}) do |name, hash|
+          hash[name] = project.subscription(name, skip_lookup: true).tap do |subscription|
+            subscription.deadline = @ack_deadline
+          end
         end
       end
 

spec/hover/pub_sub/reader_spec.rb

@@ -31,7 +31,7 @@
     let(:instance) do
       described_class.new(
         project_id: @pubsub_project_id,
-        topic_names: [topic_name],
+        subscription_names: [subscription_name],
         ack_deadline: 1
       )
     end
@@ -55,8 +55,8 @@
         expect(messages.size).to eq(1)
         expect(messages.first).to eq(sent_message)
 
-        instance.read do |topic_name, message|
-          raise "No messages expected got #{message.inspect} on topic #{topic_name}"
+        instance.read do |subscription_name, message|
+          raise "No messages expected got #{message.inspect} on subscriptions #{subscription_name}"
         end
       end
     end