Merge branch 'master' of git.clinicalfuture.com:arvados

[arvados.git] / services / api / app / middlewares / rack_socket.rb

diff --git a/services/api/app/middlewares/rack_socket.rb b/services/api/app/middlewares/rack_socket.rb
index 7fcba83cfc6effc56adf775dc1726bbdc54f30f0..795df4a7fc0e1b1b77c94d3d29d92bff77b99fd7 100644 (file)
--- a/services/api/app/middlewares/rack_socket.rb
+++ b/services/api/app/middlewares/rack_socket.rb
@@ -1,38 +1,86 @@
+require 'rack'
+require 'faye/websocket'
+require 'eventmachine'
 
-  require 'faye/websocket'
+# A Rack middleware to handle inbound websocket connection requests and hand
+# them over to the faye websocket library.
+class RackSocket
 
-  class RackSocket
+  DEFAULT_ENDPOINT  = '/websocket'
 
-    DEFAULT_ENDPOINT  = '/websocket'
-
-    def initialize(app = nil, options = nil)
-      @app = app if app.respond_to?(:call)
-      @options = [app, options].grep(Hash).first || {}
-      @endpoint = @options[:mount] || DEFAULT_ENDPOINT
-    end
-
-    def call env
-      request = Rack::Request.new(env)
-      if request.path_info == @endpoint and Faye::WebSocket.websocket?(env)
-        ws = Faye::WebSocket.new(env)
+  # Stop EventMachine on signal, this should give it a chance to to unwind any
+  # open connections.
+  def die_gracefully_on_signal
+    Signal.trap("INT") { EM.stop }
+    Signal.trap("TERM") { EM.stop }
+  end
 
-        ws.on :message do |event|
-          puts "got #{event.data}"
-          ws.send(event.data)
-        end
+  # Create a new RackSocket handler
+  # +app+  The next layer of the Rack stack.
+  #
+  # Accepts options:
+  # +:handler+ (Required) A class to handle new connections.  #initialize will
+  # call handler.new to create the actual handler instance object.  When a new
+  # websocket connection is established, #on_connect on the handler instance
+  # object will be called with the new connection.
+  #
+  # +:mount+ The HTTP request path that will be recognized for websocket
+  # connect requests, defaults to '/websocket'.
+  #
+  # +:websocket_only+  If true, the server will only handle websocket requests,
+  # and all other requests will result in an error.  If false, unhandled
+  # non-websocket requests will be passed along on to 'app' in the usual Rack
+  # way.
+  def initialize(app = nil, options = nil)
+    @app = app if app.respond_to?(:call)
+    @options = [app, options].grep(Hash).first || {}
+    @endpoint = @options[:mount] || DEFAULT_ENDPOINT
+    @websocket_only = @options[:websocket_only] || false
 
-        ws.on :close do |event|
-          p [:close, event.code, event.reason]
-          ws = nil
+    # from https://gist.github.com/eatenbyagrue/1338545#file-eventmachine-rb
+    if defined?(PhusionPassenger)
+      PhusionPassenger.on_event(:starting_worker_process) do |forked|
+        # for passenger, we need to avoid orphaned threads
+        if forked && EM.reactor_running?
+          EM.stop
         end
-
-        # Return async Rack response
-        ws.rack_response
-      else
-        @app.call env
+        Thread.new {
+          EM.run
+        }
+        die_gracefully_on_signal
       end
+    else
+      # faciliates debugging
+      Thread.abort_on_exception = true
+      # just spawn a thread and start it up
+      Thread.new {
+        EM.run
+      }
     end
 
+    # Create actual handler instance object from handler class.
+    @handler = @options[:handler].new
   end
 
+  # Handle websocket connection request, or pass on to the next middleware
+  # supplied in +app+ initialize (unless +:websocket_only+ option is true, in
+  # which case return an error response.)
+  # +env+ the Rack environment with information about the request.
+  def call env
+    request = Rack::Request.new(env)
+    if request.path_info == @endpoint and Faye::WebSocket.websocket?(env)
+      ws = Faye::WebSocket.new(env)
+
+      # Notify handler about new connection
+      @handler.on_connect ws
+
+      # Return async Rack response
+      ws.rack_response
+    elsif not @websocket_only
+      @app.call env
+    else
+      [406, {"Content-Type" => "text/plain"}, ["Only websocket connections are permitted on this port."]]
+    end
+  end
 
+end