Simplify shutdown logic for Connection

* Use a QSocketNotifier listening to stdin to determine when the parent
  process has detached.

lib/capybara/webkit/connection.rb

@@ -52,27 +52,7 @@ module Capybara::Webkit
     end
 
     def open_pipe
-      _, @pipe_stdout, @pipe_stderr, @wait_thr = Open3.popen3(SERVER_PATH)
-      register_shutdown_hook
-    end
-
-    def register_shutdown_hook
-      @owner_pid = Process.pid
-      at_exit do
-        if Process.pid == @owner_pid
-          kill_process
-        end
-      end
-    end
-
-    def kill_process
-      if RUBY_PLATFORM =~ /mingw32/
-        Process.kill(9, @pid)
-      else
-        Process.kill("INT", @pid)
-      end
-    rescue Errno::ESRCH
-      # This just means that the webkit_server process has already ended
+      @pipe_stdin, @pipe_stdout, @pipe_stderr, @wait_thr = Open3.popen3(SERVER_PATH)
     end
 
     def discover_port

spec/connection_spec.rb

@@ -2,6 +2,27 @@ require 'spec_helper'
 require 'capybara/webkit/connection'
 
 describe Capybara::Webkit::Connection do
+  it "kills the process when the parent process dies", skip_on_windows: true, skip_on_jruby: true do
+    read_io, write_io = IO.pipe
+
+    fork_pid = fork do
+      read_io.close
+      connection = Capybara::Webkit::Connection.new
+      write_io.write(connection.pid)
+      write_io.close
+      Process.wait(connection.pid)
+    end
+
+    write_io.close
+
+    webkit_pid = read_io.read.to_i
+    webkit_pid.should be > 1
+    read_io.close
+    Process.kill(9, fork_pid)
+    sleep 1
+    expect { Process.getpgid(webkit_pid) }.to raise_error Errno::ESRCH
+  end
+
   it "boots a server to talk to" do
     url = "http://#{@rack_server.host}:#{@rack_server.port}/"
     connection.puts "Visit"

src/StdinNotifier.cpp

@@ -0,0 +1,16 @@
+#include "StdinNotifier.h"
+
+#include <QTcpServer>
+
+StdinNotifier::StdinNotifier(QObject *parent) : QObject(parent) {
+  m_notifier = new QSocketNotifier(fileno(stdin), QSocketNotifier::Read, this);
+  connect(m_notifier, SIGNAL(activated(int)), this, SLOT(notifierActivated()));
+}
+
+void StdinNotifier::notifierActivated() {
+  std::string line;
+  std::getline(std::cin, line);
+  if (std::cin.eof()) {
+    emit eof();
+  }
+}

src/StdinNotifier.h

@@ -0,0 +1,20 @@
+#include <QObject>
+
+class QSocketNotifier;
+
+class StdinNotifier : public QObject {
+  Q_OBJECT
+
+  public:
+    StdinNotifier(QObject *parent = 0);
+
+  public slots:
+    void notifierActivated();
+
+  signals:
+    void eof();
+
+  private:
+    QSocketNotifier *m_notifier;
+};
+

src/main.cpp

@@ -1,5 +1,6 @@
 #include "Server.h"
 #include "IgnoreDebugOutput.h"
+#include "StdinNotifier.h"
 #include <QApplication>
 #include <iostream>
 #ifdef Q_OS_UNIX
@@ -19,6 +20,9 @@ int main(int argc, char **argv) {
   app.setOrganizationName("thoughtbot, inc");
   app.setOrganizationDomain("thoughtbot.com");
 
+  StdinNotifier notifier;
+  QObject::connect(&notifier, SIGNAL(eof()), &app, SLOT(quit()));
+
   ignoreDebugOutput();
   Server server(0);
 

src/webkit_server.pro

@@ -75,7 +75,8 @@ HEADERS = \
   JavascriptCommand.h \
   FindXpath.h \
   NetworkReplyProxy.h \
-  IgnoreDebugOutput.h
+  IgnoreDebugOutput.h \
+  StdinNotifier.h
 
 SOURCES = \
   GoForward.cpp \
@@ -147,7 +148,8 @@ SOURCES = \
   JavascriptCommand.cpp \
   FindXpath.cpp \
   NetworkReplyProxy.cpp \
-  IgnoreDebugOutput.cpp
+  IgnoreDebugOutput.cpp \
+  StdinNotifier.cpp
 
 RESOURCES = webkit_server.qrc
 QT += network