Class: PryTimetravel

Inherits:
Object
  • Object
show all
Defined in:
lib/pry-timetravel.rb

Class Method Summary collapse

Class Method Details

.dlog(msg) ⇒ Object 



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# File 'lib/pry-timetravel.rb', line 10

def dlog(msg)
  if ENV["TIMETRAVEL_DEBUG"]
    File.open("meta.log", 'a') do |file|
      file.puts("#{Time.now} [#{$$}] #{msg}")
    end
  end
end

.enter_suspended_animation ⇒ Object 



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# File 'lib/pry-timetravel.rb', line 26

def enter_suspended_animation
  dlog("Installing SIGCONT trap")
  old_sigcont_handler = Signal.trap('CONT') do
    dlog("Got a SIGCONT")
  end

  dlog("Installing SIGEXIT trap")
  old_sigexit_handler = Signal.trap('EXIT') do
    dlog("got EXIT")
    Kernel.exit! true
  end

  dlog("Stopping myself")
  Process.kill 'SIGSTOP', $$
  dlog("Back from SIGSTOP!")

  @snap_tree = JSON.parse(File.read("/tmp/timetravel_#{$root_parent}.json"))

  dlog("Returning to old SIGCONT")
  Signal.trap('CONT', old_sigcont_handler || "DEFAULT")

  dlog("Returning to old SIGEXIT")
  Signal.trap('EXIT', old_sigexit_handler || "DEFAULT")
end

.restore_root_snapshot ⇒ Object 



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# File 'lib/pry-timetravel.rb', line 161

def restore_root_snapshot
  restore_snapshot(@timetravel_root) if @timetravel_root
end

.restore_snapshot(target, target_pid = nil, count = 1) ⇒ Object 



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# File 'lib/pry-timetravel.rb', line 134

def restore_snapshot(target, target_pid = nil, count = 1)
  dlog("Thinking about time travel... $$");

  if target_pid.nil? && @snap_tree && ! @snap_tree[$$.to_s].nil?
    count = 1 if count < 1
    target_pid = @snap_tree[$$.to_s]["previous"]
    @snap_tree[$$.to_s]["file"] = target.eval('__FILE__')
    @snap_tree[$$.to_s]["line"] = target.eval('__LINE__')
  else
    target_pid = target_pid
  end

  if target_pid
    dlog("ME #{$$}: I found a target pid #{target_pid}! TIME TRAVEL TIME")

    File.open("/tmp/timetravel_#{$root_parent}.json", 'w') do |f|
      f.puts @snap_tree.to_json
    end

    Process.kill 'SIGCONT', target_pid
    enter_suspended_animation
  else
    dlog("I was unable to time travel. Maybe it is a myth.");
    puts "No previous snapshot found."
  end
end

.snapshot(target, parent = -> {}, child = -> {}) ⇒ Object 



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# File 'lib/pry-timetravel.rb', line 74

def snapshot(target, parent = -> {}, child = -> {})

  # We need a root-parent to keep the shell happy
  if ! $root_parent
    start_root_parent
  end

  @timetravel_root ||= $$
  @snap_tree ||= {
    $$.to_s => {
      "file" => target.eval('__FILE__'),
      "line" => target.eval('__LINE__'),
    }
  }

  parent_pid = $$
  child_pid = fork

  if child_pid

    dlog("I am parent #{parent_pid}: I have a child pid #{child_pid}")
    enter_suspended_animation

    # Perform child operation
    child.()

  else

    child_pid = $$
    dlog("I am child #{child_pid}: I have a parent pid #{parent_pid}")

    @snap_tree[child_pid.to_s] = {
      "previous" => parent_pid,
      "file" => target.eval('__FILE__'),
      "line" => target.eval('__LINE__'),
    }

    # Perform parent operation
    parent.()

  end
end

.snapshot_list(target, indent = "", node = @timetravel_root.to_s) ⇒ Object 



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# File 'lib/pry-timetravel.rb', line 117

def snapshot_list(target, indent = "", node = @timetravel_root.to_s)
  # @snap_tree && @snap_tree.keys.join(" ")
  return unless node && node != ""

  # This shouldn't be here
  @snap_tree[$$.to_s]["file"] = target.eval('__FILE__')
  @snap_tree[$$.to_s]["line"] = target.eval('__LINE__')

  out = "#{indent}#{node} #{@snap_tree[node]["file"]} #{@snap_tree[node]["line"]} #{ node == $$.to_s ? '***' : ''}\n"
  @snap_tree.keys.select { |n|
    @snap_tree[n]["previous"] == node.to_i
  }.each do |n|
    out += snapshot_list(target, indent + "  ", n)
  end
  out
end

.start_root_parent ⇒ Object 



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# File 'lib/pry-timetravel.rb', line 51

def start_root_parent
  $root_parent = $$
  child_pid = fork
  if child_pid
    Signal.trap('INT') do
      dlog("root-parent got INT, ignoring")
    end
    Signal.trap('USR1') do
      dlog("root-parent got USR1, exiting")
      FileUtils.rm("/tmp/timetravel_#{$root_parent}.json")
      Kernel.exit! true
    end
    dlog "Root parent waiting on #{child_pid}"
    #  sleep
    #  Process.waitall
    Process.waitpid child_pid
    #  Process.waitpid 0
    dlog "Root parent exiting after wait"
    FileUtils.rm("/tmp/timetravel_#{$root_parent}.json")
    Kernel.exit! true
  end
end