Check whether the socket file exists before connecting.

By removing the socket file when the browser process of Atom quits and
checking it's existence before trying to connect it, we can greatly
reduce the startup time of the first instance of Atom.

src/atom-application.coffee

@@ -82,11 +82,15 @@ class AtomApplication
     process.env['NODE_PATH'] = resourcePaths.join path.delimiter
 
   sendArgumentsToExistingProcess: (pidToKillWhenClosed, callback) ->
+    if not fs.existsSync(@socketPath)
+      callback(false)
+      return
+
     client = net.connect {path: @socketPath}, (args...) =>
       client.write(JSON.stringify({@pathsToOpen, pidToKillWhenClosed}))
       callback(true)
 
-    client.on 'error', (args...) -> callback(false)
+    client.on 'error', (error) -> console.log(error); callback(false)
 
   listenForArgumentsFromNewProcess: ->
     fs.unlinkSync @socketPath if fs.existsSync(@socketPath)
@@ -155,6 +159,10 @@ class AtomApplication
     app.on 'window-all-closed', ->
       app.quit()
 
+    # Clean the socket file when quit normally.
+    app.on 'will-quit', =>
+      fs.unlinkSync @socketPath if fs.existsSync(@socketPath)
+
     ipc.on 'close-without-confirm', (processId, routingId) ->
       window = BrowserWindow.fromProcessIdAndRoutingId processId, routingId
       window.removeAllListeners 'close'