Introduce multi matching engine server setup

lib/rex/book/trade_tracker.rb

@@ -1,28 +1,28 @@
 module Rex
   module Book
-    # Trade Tracker implemented as a simple ring buffer
     class TradeTracker
-      include Enumerable
       DEFAULT_TRADE_HISTORY_LIMIT = 200
 
       attr_reader :trades
 
       def initialize(limit: DEFAULT_TRADE_HISTORY_LIMIT)
         @limit = limit
-        @trades = Array.new(limit)
-        @current_id = -1
+        @trades = []
       end
 
       def add(trade)
-        @current_id += 1
-        idx = (@current_id % @limit)
-        @trades[idx] = trade
+        @trades.push(trade)
+        cap
       end
 
-      def each(&block)
-        (([@current_id - @limit, 0].max)..@current_id ).each do |id|
-          yield @trades[id % @limit]
-        end
+      def fetch_trades(limit)
+        @trades.last(limit)
+      end
+
+      private
+
+      def cap
+        @trades = @trades.last(@limit)
       end
     end
   end

lib/rex/server.rb

@@ -2,6 +2,7 @@
 
 require "json-schema"
 
+require_relative "server/publisher"
 require_relative "server/messages"
 
 require_relative "server/request_schemas"
@@ -14,6 +15,7 @@ require_relative "server/websocket_server"
 
 require_relative "server/json_message_serializer"
 require_relative "server/simple_server_setup"
+require_relative "server/multi_matching_engine_server_setup"
 
 module Rex
   module Server

lib/rex/server/matching_engine.rb

@@ -4,12 +4,14 @@ module Rex
       def initialize(inbox, outbox,
         order_book: Rex::Book::LimitOrderBook.new,
         limit_volume_tracker: Rex::Book::LimitVolumeTracker.new,
-        trade_tracker: Rex::Book::TradeTracker.new)
+        trade_tracker: Rex::Book::TradeTracker.new,
+        id: 1)
         @inbox = inbox
         @outbox = outbox
         @order_book = order_book
         @limit_volume_tracker = limit_volume_tracker
         @trade_tracker = trade_tracker
+        @id = id
       end
 
       def start
@@ -50,7 +52,7 @@ module Rex
       end
 
       def fetch_trades(user_id)
-        @trade_tracker.each do |trade|
+        @trade_tracker.fetch_trades(50).each do |trade|
           @outbox.push(
             Messages::TradeFetchEvent.new(
               trade.id,

lib/rex/server/multi_matching_engine_server_setup.rb

@@ -0,0 +1,63 @@
+module Rex
+  module Server
+    # Implementation of a simple one node server setup
+    #
+    # Setups/Starts
+    #
+    # - a message processor to parse and forward
+    #   messages to the matching engine
+    # - a matching engine instance to process any order book related
+    #   messages
+    # - a websocket server to accept websocket base connections and
+    #   process incoming messages
+    class MultiMatchingEngineServerSetup
+      def initialize(host, port)
+        matching_engine_inbox_pipe = EventMachine::Channel.new
+
+        matching_engine_out_channels = Hash[(1..3).map { |i| [i, EventMachine::Channel.new] }]
+
+        @matching_engines = matching_engine_out_channels.map do |id,channel|
+          MatchingEngine.new(
+            matching_engine_inbox_pipe,
+            channel,
+            id: id
+          )
+        end
+
+        matching_engine_published_channel = EventMachine::Channel.new
+        @publisher = Publisher.new(matching_engine_out_channels.values, matching_engine_published_channel)
+
+
+        message_processor_inflow_pipe = EventMachine::Channel.new
+        message_broker = MessageBroker.new(JsonMessageSerializer.new)
+
+        @message_processor = Rex::Server::MessageProcessor.new(
+          matching_engine_inbox_pipe,
+          matching_engine_published_channel,
+          message_broker,
+          message_processor_inflow_pipe
+        )
+
+        @websocket_server = Rex::Server::WebsocketServer.new(
+          message_broker,
+          message_processor_inflow_pipe,
+          host: host,
+          port: port
+        )
+      end
+
+      def start
+        @message_processor.start
+        @publisher.start
+        @matching_engines.each(&:start)
+        @websocket_server.start
+      end
+
+      def stop
+        @matching_engines.each(&:stop)
+        @message_processor.stop
+        @websocket_server.stop
+      end
+    end
+  end
+end

lib/rex/server/publisher.rb

@@ -0,0 +1,33 @@
+module Rex
+  module Server
+    class Publisher
+      def initialize(inputs, output)
+        @inputs = inputs
+        @output = output
+        @buffer = Hash.new { |hash,key| hash[key] = [] }
+      end
+
+      def start
+        @input_subscription_ids = @inputs.each_with_index.map do |input,idex|
+          input.subscribe do |message|
+            process_message(message, idex)
+          end
+        end
+      end
+
+      def process_message(message, index)
+        @buffer[index].push(message)
+
+        first_values =  @buffer.map { |_,v| v.first }.compact
+        return if first_values.length != @inputs.length
+
+        if first_values.compact.all? { |val| val == first_values[0] }
+          @output.push(first_values[0])
+          @buffer.each do |key,_|
+            @buffer[key].shift
+          end
+        end
+     end
+    end
+  end
+end

lib/rex/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Rex
-  VERSION = "0.1.1"
+  VERSION = "0.1.0"
 end

rex.gemspec

@@ -12,7 +12,7 @@ Gem::Specification.new do |spec|
   spec.description = "A simple limit order book with a matching engine implementation"
   spec.homepage = "https://git.timkaechele.me/timkaechele/rex"
   spec.required_ruby_version = ">= 2.6.0"
-  spec.licenses = ["AGPL-3.0-only"]
+
   spec.metadata["homepage_uri"] = spec.homepage
 
   # Specify which files should be added to the gem when it is released.
@@ -28,10 +28,10 @@ Gem::Specification.new do |spec|
 
   spec.add_dependency "rbtree", "~> 0.4.6"
 
-  spec.add_dependency "eventmachine", "~> 1.2"
-  spec.add_dependency "em-websocket", "~> 0.5"
+  spec.add_runtime_dependency "eventmachine", "~> 1.2"
+  spec.add_runtime_dependency "em-websocket", "~> 0.5"
 
-  spec.add_dependency "json-schema", "~> 4"
+  spec.add_runtime_dependency "json-schema", "~> 4"
   # For more information and examples about making a new gem, check out our
   # guide at: https://bundler.io/guides/creating_gem.html
 end

spec/book/trade_tracker_spec.rb

@@ -15,10 +15,10 @@ RSpec.describe Rex::Book::TradeTracker do
     end
   end
 
-  describe "#each" do
+  describe "#fetch_trades" do
     let(:n) { 3 }
     it "returns only the last n trades" do
-      expect(instance.to_a).to eq([10, 11])
+      expect(instance.fetch_trades(1)).to eq([11])
     end
   end
 end