Add some private projects

soundcloud/soundcloud_problem_statement/ruby/main.rb

@@ -0,0 +1,106 @@
+require 'set'
+require 'socket'
+
+EVENT_PORT = 9090
+CLIENT_PORT = 9099
+
+client_pool = {}
+seq_no_to_message = {}
+follow_registry = {}
+last_seq_no = 0
+
+thread1 = Thread.new do
+  puts("Listening for events on #{EVENT_PORT}")
+  server = TCPServer.open(EVENT_PORT)
+  loop do
+    Thread.fork(server.accept) do |event_socket|
+      event_socket.each_line do |payload|
+        puts("Message received: #{payload}")
+
+        payload_parts = payload.split('|')
+        seq_no_to_message[payload_parts[0].to_i] = payload_parts
+
+        while seq_no_to_message[last_seq_no + 1]
+          next_message = seq_no_to_message[last_seq_no + 1]
+          next_payload = next_message.join('|')
+
+          seq_no = next_message[0].to_i
+          kind = next_message[1].strip
+
+          case kind
+          when 'F'
+            from_user_id = next_message[2].to_i
+            to_user_id = next_message[3].to_i
+
+            followers = follow_registry[to_user_id] || Set.new
+            followers << from_user_id
+            follow_registry[to_user_id] = followers
+
+            socket = client_pool[to_user_id]
+            if socket
+              socket.puts(next_payload)
+              socket.flush
+            end
+
+          when 'U'
+            from_user_id = next_message[2].to_i
+            to_user_id = next_message[3].to_i
+
+            followers = follow_registry[to_user_id] || Set.new
+            followers.delete(from_user_id)
+            follow_registry[to_user_id] = followers
+
+          when 'P'
+            to_user_id = next_message[3].to_i
+
+            socket = client_pool[to_user_id]
+            if socket
+              socket.puts(next_payload)
+              socket.flush
+            end
+
+          when 'B'
+            client_pool.values.each do |socket|
+              socket.puts(next_payload)
+              socket.flush
+            end
+
+          when 'S'
+            from_user_id = next_message[2].to_i
+
+            followers = follow_registry[from_user_id] || Set.new
+            followers.each do |follower|
+              socket = client_pool[follower]
+
+              if socket
+                socket.puts(next_payload)
+                socket.flush
+              end
+            end
+          end
+
+          last_seq_no = seq_no
+        end
+      end
+      event_socket.close
+    end
+  end
+end
+
+thread2 = Thread.new do
+  puts("Listening for client requests on #{CLIENT_PORT}")
+  server = TCPServer.open(CLIENT_PORT)
+  loop do
+    Thread.fork(server.accept) do |socket|
+      user_id_string = socket.gets
+      if user_id_string
+        user_id = user_id_string.to_i
+        client_pool[user_id] = socket
+        puts("User connected: #{user_id} (#{client_pool.size} total)")
+      end
+    end
+  end
+end
+
+thread1.join
+thread2.join