Class: RBTracer

Inherits:
Object
  • Object
show all
Defined in:
lib/rbtrace/rbtracer.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(pid) ⇒ RBTracer

Create a new tracer

pid - The String of Fixnum process id

Returns a tracer.



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# File 'lib/rbtrace/rbtracer.rb', line 32

def initialize(pid)
  begin
    raise ArgumentError unless pid
    @pid = pid.to_i
    raise ArgumentError unless @pid > 0
    Process.kill(0, @pid)
  rescue TypeError, ArgumentError
    raise ArgumentError, 'pid required'
  rescue Errno::ESRCH
    raise ArgumentError, 'invalid pid'
  rescue Errno::EPERM
    raise ArgumentError, 'could not signal process, are you running as root?'
  end

  path = "/tmp/rbtrace-#{@pid}.sock"
  @sock = Socket.new Socket::AF_UNIX, Socket::SOCK_DGRAM, 0
  @sockaddr = Socket.pack_sockaddr_un(path)
  @sock.bind(@sockaddr)
  FileUtils.chmod 0666, path
  at_exit{ FileUtils.rm(path) if File.exists?(path) }

  5.times do
    signal
    sleep 0.15 # wait for process to create msgqs

    @qo = MsgQ.msgget(-@pid, 0666)

    break if @qo > -1
  end

  if @qo == -1
    raise ArgumentError, 'pid is not listening for messages, did you `require "rbtrace"`'
  end

  @klasses = {}
  @methods = {}
  @tracers = Hash.new{ |h,k|
    h[k] = {
      :query => nil,
      :times => [],
      :names => [],
      :exprs => {},
      :last => false,
      :arglist => false
    }
  }
  @max_nesting = @last_nesting = @nesting = 0
  @last_tracer = nil

  @timeout = 5

  @out = STDOUT
  @out.sync = true
  @prefix = '  '
  @printed_newline = true

  @show_time = false
  @show_duration = true
  @watch_slow = false

  attach
end

Instance Attribute Details

#out ⇒ Object

Public: The IO where tracing output is written (default: STDOUT).



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# File 'lib/rbtrace/rbtracer.rb', line 13

def out
  @out
end

#pid ⇒ Object (readonly)

Public: The Fixnum pid of the traced process.



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# File 'lib/rbtrace/rbtracer.rb', line 10

def pid
  @pid
end

#prefix ⇒ Object

The String prefix used on nested method calls (default: ' ').



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# File 'lib/rbtrace/rbtracer.rb', line 19

def prefix
  @prefix
end

#show_duration ⇒ Object

The Boolean flag for showing how long method calls take (default: true).



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# File 'lib/rbtrace/rbtracer.rb', line 22

def show_duration
  @show_duration
end

#show_time ⇒ Object

The Boolean flag for showing the timestamp when method calls start (default: false).



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# File 'lib/rbtrace/rbtracer.rb', line 25

def show_time
  @show_time
end

#timeout ⇒ Object

Public: The timeout before giving up on attaching/detaching to a process.



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# File 'lib/rbtrace/rbtracer.rb', line 16

def timeout
  @timeout
end

Instance Method Details

#add(methods, slow = false) ⇒ Object

Add tracers for the given list of methods.

methods - The String or Array of method selectors to trace.

Returns nothing.



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# File 'lib/rbtrace/rbtracer.rb', line 169

def add(methods, slow=false)
  Array(methods).each do |func|
    func = func.strip
    next if func.empty?

    if func =~ /^(.+?)\((.+)\)$/
      name, args = $1, $2
      args = args.split(',').map{ |a| a.strip }
    end

    send_cmd(:add, name || func, slow)

    if args and args.any?
      args.each do |arg|
        if (err = valid_syntax?(arg)) != true
          raise ArgumentError, "#{err.class} for expression #{arg.inspect} in method #{func.inspect}"
        end
        if arg =~ /^@/ and arg !~ /^@[_a-z][_a-z0-9]+$/i
          # arg[0]=='@' means ivar, but if this is an expr
          # we can hack a space in front so it gets eval'd instead
          arg = " #{arg}"
        end
        send_cmd(:addexpr, arg)
      end
    end
  end
end

#add_slow(methods) ⇒ Object

Restrict slow tracing to a specific list of methods.

methods - The String or Array of method selectors.

Returns nothing.



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# File 'lib/rbtrace/rbtracer.rb', line 160

def add_slow(methods)
  add(methods, true)
end

#attach ⇒ Object

Attach to the process.

Returns nothing.



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# File 'lib/rbtrace/rbtracer.rb', line 200

def attach
  send_cmd(:attach, Process.pid)
  if wait('to attach'){ @attached == true }
    STDERR.puts "*** attached to process #{pid}"
  else
    raise ArgumentError, 'process already being traced?'
  end
end

#detach ⇒ Object

Detach from the traced process.

Returns nothing.



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# File 'lib/rbtrace/rbtracer.rb', line 212

def detach
  begin
    send_cmd(:detach)
  rescue Errno::ESRCH
  end

  newline

  if wait('to detach cleanly'){ @attached == false }
    newline
    STDERR.puts "*** detached from process #{pid}"
  else
    newline
    STDERR.puts "*** could not detach cleanly from process #{pid}"
  end
rescue Errno::EINVAL, Errno::EIDRM
  newline
  STDERR.puts "*** process #{pid} is gone"
  # STDERR.puts "*** #{$!.inspect}"
  # STDERR.puts $!.backtrace.join("\n  ")
rescue Interrupt, SignalException
  retry
end

#devmode ⇒ Object

Turn on dev mode.

Returns nothing.



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# File 'lib/rbtrace/rbtracer.rb', line 115

def devmode
  send_cmd(:devmode)
end

#eval(code) ⇒ Object

Evaluate some ruby code.

Returns the String result.



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# File 'lib/rbtrace/rbtracer.rb', line 134

def eval(code)
  if (err = valid_syntax?(code)) != true
    raise ArgumentError, "#{err.class} for expression #{code.inspect}"
  end

  send_cmd(:eval, code)

  if wait('for eval response', 15){ !!@eval_result }
    @eval_result
  else
    STDERR.puts '*** timed out waiting for eval response'
  end
end

#firehose ⇒ Object

Turn on the firehose (show all method calls).

Returns nothing.



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# File 'lib/rbtrace/rbtracer.rb', line 108

def firehose
  send_cmd(:firehose)
end

#fork ⇒ Object

Fork the process and return the copy's pid.

Returns a Fixnum pid.



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# File 'lib/rbtrace/rbtracer.rb', line 122

def fork
  send_cmd(:fork)
  if wait('for fork', 30){ !!@forked_pid }
    @forked_pid
  else
    STDERR.puts '*** timed out waiting for fork'
  end
end

#gc ⇒ Object

Turn on GC tracing.

Returns nothing.



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# File 'lib/rbtrace/rbtracer.rb', line 151

def gc
  send_cmd(:gc)
end

#puts(arg = nil) ⇒ Object 



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# File 'lib/rbtrace/rbtracer.rb', line 263

def puts(arg=nil)
  @printed_newline = true
  arg ? @out.puts(arg) : @out.puts
end

#recv_lines ⇒ Object

Process events from the traced process, without blocking if there is nothing to do. This is a useful way to drain the buffer so messages do not accumulate in kernel land.

Returns nothing.



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# File 'lib/rbtrace/rbtracer.rb', line 256

def recv_lines
  50.times do
    break unless line = recv_cmd(false)
    process_line(line)
  end
end

#recv_loop ⇒ Object

Process events from the traced process.

Returns nothing.



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# File 'lib/rbtrace/rbtracer.rb', line 239

def recv_loop
  while true
    # block until a message arrives
    process_line(recv_cmd)

    # process any remaining messages
    recv_lines
  end
rescue Errno::EINVAL, Errno::EIDRM
  # process went away
end

#watch(msec, cpu_only = false) ⇒ Object

Watch for method calls slower than a threshold.

msec - The Fixnum threshold in milliseconds

Returns nothing.



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# File 'lib/rbtrace/rbtracer.rb', line 100

def watch(msec, cpu_only=false)
  @watch_slow = true
  send_cmd(cpu_only ? :watchcpu : :watch, msec)
end