Replace childprocess gem

lib/screen-recorder.rb

@@ -1,4 +1,3 @@
-require 'childprocess'
 require 'logger'
 require 'os'
 require 'streamio-ffmpeg'
@@ -80,4 +79,5 @@ def self.logger
 require 'screen-recorder/common'
 require 'screen-recorder/screenshot'
 require 'screen-recorder/desktop'
-require 'screen-recorder/window'
+require 'screen-recorder/window'
+require 'screen-recorder/process'

lib/screen-recorder/common.rb

@@ -4,7 +4,7 @@ module ScreenRecorder
   #
   # @api private
   class Common
-    PROCESS_TIMEOUT = 5 # Seconds to wait for ffmpeg to quit
+    PROCESS_TIMEOUT = 10 # Seconds to wait for ffmpeg to quit
 
     attr_reader :options, :video
 
@@ -21,7 +21,7 @@ def initialize(input:, output:, advanced: {})
     #
     def start
       ScreenRecorder.logger.debug 'Starting recorder...'
-      @video   = nil # New file
+      @video = nil # New file
       @process = start_ffmpeg
       ScreenRecorder.logger.info 'Recording...'
       @process
@@ -32,12 +32,11 @@ def start
     #
     def stop
       ScreenRecorder.logger.debug 'Stopping ffmpeg...'
-      exit_code = stop_ffmpeg
-      return if exit_code == 1 # recording failed
-
+      @process.stop
       ScreenRecorder.logger.debug 'Stopped ffmpeg.'
-      ScreenRecorder.logger.info 'Recording complete.'
-      @video = prepare_video unless exit_code == 1
+      ScreenRecorder.logger.info 'Preparing video...'
+      @video = prepare_video
+      ScreenRecorder.logger.info 'Recording ready.'
     end
 
     #
@@ -58,7 +57,7 @@ def discard
     # the given options.
     #
     def start_ffmpeg
-      process = execute_command(ffmpeg_command, options.log)
+      process = execute_command(ffmpeg_command)
       sleep(1.5) # Takes ~1.5s to initialize ffmpeg
       # Check if it exited unexpectedly
       if process.exited?
@@ -69,17 +68,6 @@ def start_ffmpeg
       process
     end
 
-    #
-    # Sends 'q' to the ffmpeg binary to gracefully stop the process.
-    # Forcefully terminates it if it takes more than 5s.
-    #
-    def stop_ffmpeg
-      @process.io.stdin.puts 'q' # Gracefully exit ffmpeg
-      @process.io.stdin.close
-      @log_file.close
-      wait_for_process_exit(@process)
-    end
-
     #
     # Runs ffprobe on the output video file and returns
     # a FFMPEG::Movie object.
@@ -139,47 +127,14 @@ def lines_from_log(position = :last, count = 2)
 
     #
     # Executes the given command and outputs to the
-    # optional logfile
     #
-    def execute_command(cmd, logfile = nil)
+    def execute_command(cmd)
       ScreenRecorder.logger.debug "Executing command: #{cmd}"
-      process        = new_process(cmd)
-      process.duplex = true
-      if logfile
-        @log_file         = File.new(logfile, 'w+')
-        process.io.stdout = process.io.stderr = @log_file
-        @log_file.sync    = true
-      end
-      process.start
-      process
-    end
-
-    #
-    # Calls Childprocess.new with OS specific arguments
-    # to start the given process.
-    #
-    def new_process(process)
-      ChildProcess.posix_spawn = true if RUBY_PLATFORM == 'java' # Support JRuby.
-      if OS.windows?
-        ChildProcess.new('cmd.exe', '/c', process)
-      else
-        ChildProcess.new('sh', '-c', process)
-      end
-    end
-
-    #
-    # Waits for given process to exit.
-    # Forcefully kills the process if it does not exit within 5 seconds.
-    # Returns exit code.
-    #
-    def wait_for_process_exit(process)
-      process.poll_for_exit(PROCESS_TIMEOUT)
-      process.exit_code # 0
-    rescue ChildProcess::TimeoutError
-      ScreenRecorder.logger.error 'ffmpeg failed to stop. Force killing it...'
-      process.stop # Tries increasingly harsher methods to kill the process.
-      ScreenRecorder.logger.error 'Forcefully killed ffmpeg. Recording failed!'
-      1
+      @process = ScreenRecorder::Process.build(cmd)
+      @process.detach = true
+      @process.io = options.log
+      @process.start
+      @process
     end
   end
 end

lib/screen-recorder/process.rb

@@ -0,0 +1,112 @@
+# frozen_string_literal: true
+
+module ScreenRecorder
+  #
+  # @api private
+  #
+  # @since 1.7.0
+  #
+  # Original from https://github.com/SeleniumHQ/selenium/blob/trunk/rb/lib/selenium/webdriver/common/child_process.rb
+  class Process
+    TimeoutError = Class.new(StandardError)
+
+    SIGTERM = 'TERM'
+    SIGKILL = 'KILL'
+
+    POLL_INTERVAL = 0.1
+
+    attr_accessor :detach, :pid
+    attr_writer :io
+
+    def self.build(*command)
+      new(*command)
+    end
+
+    def initialize(*command)
+      @command = command
+      @detach = false
+      @pid = nil
+      @status = nil
+    end
+
+    def io
+      @io ||= ::IO.pipe
+    end
+
+    def start
+      options = { :in => io, %i[out err] => io }
+      options[:pgroup] = true unless OS.windows? # NOTE: this is a bug only in Windows 7
+
+      @pid = ::Process.spawn(*@command, options)
+      ScreenRecorder.logger.debug("  -> pid: #{@pid}")
+
+      ::Process.detach(@pid) if detach
+    end
+
+    def stop(timeout = 3)
+      return unless @pid
+      return if exited?
+
+      ScreenRecorder.logger.debug("Sending TERM to process: #{@pid}")
+      terminate(-@pid)
+      poll_for_exit(timeout)
+
+      ScreenRecorder.logger.debug("  -> stopped #{@pid}")
+    rescue TimeoutError, Errno::EINVAL
+      ScreenRecorder.logger.debug("    -> sending KILL to process: #{@pid}")
+      kill(@pid)
+      wait
+      ScreenRecorder.logger.debug("      -> killed #{@pid}")
+    end
+
+    def alive?
+      @pid && !exited?
+    end
+
+    def exited?
+      return false unless @pid
+
+      ScreenRecorder.logger.debug("Checking if #{@pid} is exited:")
+      _, @status = waitpid2(@pid, ::Process::WNOHANG | ::Process::WUNTRACED) if @status.nil?
+      return false if @status.nil?
+
+      exit_code = @status.exitstatus || @status.termsig
+      ScreenRecorder.logger.debug("  -> exit code is #{exit_code.inspect}")
+
+      !!exit_code
+    end
+
+    def poll_for_exit(timeout)
+      ScreenRecorder.logger.debug("Polling #{timeout} seconds for exit of #{@pid}")
+
+      end_time = Time.now + timeout
+      sleep POLL_INTERVAL until exited? || Time.now > end_time
+
+      raise TimeoutError, "  ->  #{@pid} still alive after #{timeout} seconds" unless exited?
+    end
+
+    def wait
+      return if exited?
+
+      _, @status = waitpid2(@pid)
+    end
+
+    private
+
+    def terminate(pid)
+      ::Process.kill(SIGTERM, pid)
+    end
+
+    def kill(pid)
+      ::Process.kill(SIGKILL, pid)
+    rescue Errno::ECHILD, Errno::ESRCH
+      # already dead
+    end
+
+    def waitpid2(pid, flags = 0)
+      ::Process.waitpid2(pid, flags)
+    rescue Errno::ECHILD
+      # already dead
+    end
+  end # Process
+end # Common

screen-recorder.gemspec

@@ -29,7 +29,6 @@ Gem::Specification.new do |spec|
 
   spec.require_paths = ['lib']
 
-  spec.add_dependency 'childprocess', '>= 1.0', '< 5.0' # Roughly match Selenium
   spec.add_dependency 'os', '~> 1.0'
   spec.add_dependency 'streamio-ffmpeg', '~> 3.0'
 end

spec/spec_helper.rb

@@ -9,6 +9,7 @@
 require 'screen-recorder'
 require 'watir'
 require 'webdrivers'
+require 'pry-byebug'
 
 RSpec.configure do |config|
   # Enable flags like --only-failures and --next-failure
@@ -30,7 +31,7 @@
   config.after do |example|
     if example.exception
       # Print error from ffmpeg.log
-      log_file = `ls | grep *.log`.strip
+      log_file = 'ffmpeg.log'
       File.open(log_file).readlines.last(10).join('\n') { puts "FFMPEG error: #{f}" } if log_file
     end