cleanup terminal console iopub handling

ensures IOPub for a given cell is handled before drawing the next prompt.

Follows logic elsewhere using `status=idle` to signal end of output for a given cell.
Prior to this, early execute reply could result in some output being printed after the prompt for the next input.

IPython/terminal/console/interactiveshell.py

@@ -1,464 +1,480
 # -*- coding: utf-8 -*-
 """terminal client to the IPython kernel
 
 """
 #-----------------------------------------------------------------------------
 # Copyright (C) 2013 The IPython Development Team
 #
 # Distributed under the terms of the BSD License. The full license is in
 # the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 from __future__ import print_function
 
 import bdb
 import signal
 import os
 import sys
 import time
 import subprocess
 from io import BytesIO
 import base64
 
 from Queue import Empty
 
 try:
     from contextlib import nested
 except:
     from IPython.utils.nested_context import nested
 
 from IPython.core import page
 from IPython.utils.warn import warn, error
 from IPython.utils import io
 from IPython.utils.traitlets import List, Enum, Any, Instance, Unicode
 from IPython.utils.tempdir import NamedFileInTemporaryDirectory
 
 from IPython.terminal.interactiveshell import TerminalInteractiveShell
 from IPython.terminal.console.completer import ZMQCompleter
 
 
 class ZMQTerminalInteractiveShell(TerminalInteractiveShell):
     """A subclass of TerminalInteractiveShell that uses the 0MQ kernel"""
     _executing = False
+    _execution_state = Unicode('')
+    _current_msg_id = Unicode('')
 
     image_handler = Enum(('PIL', 'stream', 'tempfile', 'callable'),
                          config=True, help=
         """
         Handler for image type output.  This is useful, for example,
         when connecting to the kernel in which pylab inline backend is
         activated.  There are four handlers defined.  'PIL': Use
         Python Imaging Library to popup image; 'stream': Use an
         external program to show the image.  Image will be fed into
         the STDIN of the program.  You will need to configure
         `stream_image_handler`; 'tempfile': Use an external program to
         show the image.  Image will be saved in a temporally file and
         the program is called with the temporally file.  You will need
         to configure `tempfile_image_handler`; 'callable': You can set
         any Python callable which is called with the image data.  You
         will need to configure `callable_image_handler`.
         """
     )
 
     stream_image_handler = List(config=True, help=
         """
         Command to invoke an image viewer program when you are using
         'stream' image handler.  This option is a list of string where
         the first element is the command itself and reminders are the
         options for the command.  Raw image data is given as STDIN to
         the program.
         """
     )
 
     tempfile_image_handler = List(config=True, help=
         """
         Command to invoke an image viewer program when you are using
         'tempfile' image handler.  This option is a list of string
         where the first element is the command itself and reminders
         are the options for the command.  You can use {file} and
         {format} in the string to represent the location of the
         generated image file and image format.
         """
     )
 
     callable_image_handler = Any(config=True, help=
         """
         Callable object called via 'callable' image handler with one
         argument, `data`, which is `msg["content"]["data"]` where
         `msg` is the message from iopub channel.  For exmaple, you can
         find base64 encoded PNG data as `data['image/png']`.
         """
     )
 
     mime_preference = List(
         default_value=['image/png', 'image/jpeg', 'image/svg+xml'],
         config=True, allow_none=False, help=
         """
         Preferred object representation MIME type in order.  First
         matched MIME type will be used.
         """
     )
 
     manager = Instance('IPython.kernel.KernelManager')
     client = Instance('IPython.kernel.KernelClient')
     def _client_changed(self, name, old, new):
         self.session_id = new.session.session
     session_id = Unicode()
 
     def init_completer(self):
         """Initialize the completion machinery.
 
         This creates completion machinery that can be used by client code,
         either interactively in-process (typically triggered by the readline
         library), programatically (such as in test suites) or out-of-prcess
         (typically over the network by remote frontends).
         """
         from IPython.core.completerlib import (module_completer,
                                                magic_run_completer, cd_completer)
         
         self.Completer = ZMQCompleter(self, self.client)
         
 
         self.set_hook('complete_command', module_completer, str_key = 'import')
         self.set_hook('complete_command', module_completer, str_key = 'from')
         self.set_hook('complete_command', magic_run_completer, str_key = '%run')
         self.set_hook('complete_command', cd_completer, str_key = '%cd')
 
         # Only configure readline if we truly are using readline.  IPython can
         # do tab-completion over the network, in GUIs, etc, where readline
         # itself may be absent
         if self.has_readline:
             self.set_readline_completer()
     
     def run_cell(self, cell, store_history=True):
         """Run a complete IPython cell.
         
         Parameters
         ----------
         cell : str
           The code (including IPython code such as %magic functions) to run.
         store_history : bool
           If True, the raw and translated cell will be stored in IPython's
           history. For user code calling back into IPython's machinery, this
           should be set to False.
         """
         if (not cell) or cell.isspace():
             return
 
         if cell.strip() == 'exit':
             # explicitly handle 'exit' command
             return self.ask_exit()
 
-        self._executing = True
         # flush stale replies, which could have been ignored, due to missed heartbeats
         while self.client.shell_channel.msg_ready():
             self.client.shell_channel.get_msg()
         # shell_channel.execute takes 'hidden', which is the inverse of store_hist
         msg_id = self.client.shell_channel.execute(cell, not store_history)
-        while not self.client.shell_channel.msg_ready() and self.client.is_alive():
+        self._current_msg_id = msg_id
+        
+        # first thing is wait for any side effects (output, stdin, etc.)
+        self._executing = True
+        self._execution_state = "busy"
+        while self._execution_state != 'idle' and self.client.is_alive():
+            print (self._execution_state)
             try:
-                self.handle_stdin_request(timeout=0.05)
+                self.handle_stdin_request(msg_id, timeout=0.05)
             except Empty:
                 # display intermediate print statements, etc.
-                self.handle_iopub()
+                self.handle_iopub(msg_id)
+                pass
+        
+        # after all of that is done, wait for the execute reply
+        while self.client.is_alive():
+            try:
+                self.handle_execute_reply(msg_id, timeout=0.05)
+            except Empty:
                 pass
-        if self.client.shell_channel.msg_ready():
-            self.handle_execute_reply(msg_id)
+            else:
+                break
         self._executing = False
 
     #-----------------
     # message handlers
     #-----------------
 
-    def handle_execute_reply(self, msg_id):
-        msg = self.client.shell_channel.get_msg()
+    def handle_execute_reply(self, msg_id, timeout=None):
+        msg = self.client.shell_channel.get_msg(block=False, timeout=timeout)
         if msg["parent_header"].get("msg_id", None) == msg_id:
             
-            self.handle_iopub()
+            self.handle_iopub(msg_id)
             
             content = msg["content"]
             status = content['status']
             
             if status == 'aborted':
                 self.write('Aborted\n')
                 return
             elif status == 'ok':
                 # print execution payloads as well:
                 for item in content["payload"]:
                     text = item.get('text', None)
                     if text:
                         page.page(text)
                
             elif status == 'error':
                 for frame in content["traceback"]:
                     print(frame, file=io.stderr)
             
             self.execution_count = int(content["execution_count"] + 1)
 
 
-    def handle_iopub(self):
-        """ Method to procces subscribe channel's messages
+    def handle_iopub(self, msg_id):
+        """ Method to process subscribe channel's messages
 
-           This method reads a message and processes the content in different
-           outputs like stdout, stderr, pyout and status
+           This method consumes and processes messages on the IOPub channel,
+           such as stdout, stderr, pyout and status.
 
-           Arguments:
-           sub_msg:  message receive from kernel in the sub socket channel
-                     capture by kernel manager.
+           It only displays output that is caused by the given msg_id
         """
         while self.client.iopub_channel.msg_ready():
             sub_msg = self.client.iopub_channel.get_msg()
             msg_type = sub_msg['header']['msg_type']
             parent = sub_msg["parent_header"]
-            if (not parent) or self.session_id == parent['session']:
+            if (not parent) or msg_id == parent['msg_id']:
                 if msg_type == 'status' :
-                    if sub_msg["content"]["execution_state"] == "busy" :
-                        pass
+                    state = self._execution_state = sub_msg["content"]["execution_state"]
+                    # idle messages mean an individual sequence is complete,
+                    # so break out of consumption to allow other things to take over.
+                    if state == 'idle':
+                        break
 
                 elif msg_type == 'stream' :
                     if sub_msg["content"]["name"] == "stdout":
                         print(sub_msg["content"]["data"], file=io.stdout, end="")
                         io.stdout.flush()
                     elif sub_msg["content"]["name"] == "stderr" :
                         print(sub_msg["content"]["data"], file=io.stderr, end="")
                         io.stderr.flush()
 
                 elif msg_type == 'pyout':
                     self.execution_count = int(sub_msg["content"]["execution_count"])
                     format_dict = sub_msg["content"]["data"]
                     self.handle_rich_data(format_dict)
                     # taken from DisplayHook.__call__:
                     hook = self.displayhook
                     hook.start_displayhook()
                     hook.write_output_prompt()
                     hook.write_format_data(format_dict)
                     hook.log_output(format_dict)
                     hook.finish_displayhook()
 
                 elif msg_type == 'display_data':
                     self.handle_rich_data(sub_msg["content"]["data"])
 
+
     _imagemime = {
         'image/png': 'png',
         'image/jpeg': 'jpeg',
         'image/svg+xml': 'svg',
     }
 
     def handle_rich_data(self, data):
         for mime in self.mime_preference:
             if mime in data and mime in self._imagemime:
                 self.handle_image(data, mime)
                 return
 
     def handle_image(self, data, mime):
         handler = getattr(
             self, 'handle_image_{0}'.format(self.image_handler), None)
         if handler:
             handler(data, mime)
 
     def handle_image_PIL(self, data, mime):
         if mime not in ('image/png', 'image/jpeg'):
             return
         import PIL.Image
         raw = base64.decodestring(data[mime].encode('ascii'))
         img = PIL.Image.open(BytesIO(raw))
         img.show()
 
     def handle_image_stream(self, data, mime):
         raw = base64.decodestring(data[mime].encode('ascii'))
         imageformat = self._imagemime[mime]
         fmt = dict(format=imageformat)
         args = [s.format(**fmt) for s in self.stream_image_handler]
         with open(os.devnull, 'w') as devnull:
             proc = subprocess.Popen(
                 args, stdin=subprocess.PIPE,
                 stdout=devnull, stderr=devnull)
             proc.communicate(raw)
 
     def handle_image_tempfile(self, data, mime):
         raw = base64.decodestring(data[mime].encode('ascii'))
         imageformat = self._imagemime[mime]
         filename = 'tmp.{0}'.format(imageformat)
         with nested(NamedFileInTemporaryDirectory(filename),
                     open(os.devnull, 'w')) as (f, devnull):
             f.write(raw)
             f.flush()
             fmt = dict(file=f.name, format=imageformat)
             args = [s.format(**fmt) for s in self.tempfile_image_handler]
             subprocess.call(args, stdout=devnull, stderr=devnull)
 
     def handle_image_callable(self, data, mime):
         self.callable_image_handler(data)
 
-    def handle_stdin_request(self, timeout=0.1):
+    def handle_stdin_request(self, msg_id, timeout=0.1):
         """ Method to capture raw_input
         """
         msg_rep = self.client.stdin_channel.get_msg(timeout=timeout)
         # in case any iopub came while we were waiting:
-        self.handle_iopub()
-        if self.session_id == msg_rep["parent_header"].get("session"):
+        self.handle_iopub(msg_id)
+        if msg_id == msg_rep["parent_header"].get("msg_id"):
             # wrap SIGINT handler
             real_handler = signal.getsignal(signal.SIGINT)
             def double_int(sig,frame):
                 # call real handler (forwards sigint to kernel),
                 # then raise local interrupt, stopping local raw_input
                 real_handler(sig,frame)
                 raise KeyboardInterrupt
             signal.signal(signal.SIGINT, double_int)
             
             try:
                 raw_data = raw_input(msg_rep["content"]["prompt"])
             except EOFError:
                 # turn EOFError into EOF character
                 raw_data = '\x04'
             except KeyboardInterrupt:
                 sys.stdout.write('\n')
                 return
             finally:
                 # restore SIGINT handler
                 signal.signal(signal.SIGINT, real_handler)
             
             # only send stdin reply if there *was not* another request
             # or execution finished while we were reading.
             if not (self.client.stdin_channel.msg_ready() or self.client.shell_channel.msg_ready()):
                 self.client.stdin_channel.input(raw_data)
 
     def mainloop(self, display_banner=False):
         while True:
             try:
                 self.interact(display_banner=display_banner)
                 #self.interact_with_readline()                
                 # XXX for testing of a readline-decoupled repl loop, call
                 # interact_with_readline above
                 break
             except KeyboardInterrupt:
                 # this should not be necessary, but KeyboardInterrupt
                 # handling seems rather unpredictable...
                 self.write("\nKeyboardInterrupt in interact()\n")
     
     def wait_for_kernel(self, timeout=None):
         """method to wait for a kernel to be ready"""
         tic = time.time()
         self.client.hb_channel.unpause()
         while True:
             self.run_cell('1', False)
             if self.client.hb_channel.is_beating():
                 # heart failure was not the reason this returned
                 break
             else:
                 # heart failed
                 if timeout is not None and (time.time() - tic) > timeout:
                     return False
         return True
     
     def interact(self, display_banner=None):
         """Closely emulate the interactive Python console."""
 
         # batch run -> do not interact
         if self.exit_now:
             return
 
         if display_banner is None:
             display_banner = self.display_banner
         
         if isinstance(display_banner, basestring):
             self.show_banner(display_banner)
         elif display_banner:
             self.show_banner()
 
         more = False
         
         # run a non-empty no-op, so that we don't get a prompt until
         # we know the kernel is ready. This keeps the connection
         # message above the first prompt.
         if not self.wait_for_kernel(3):
             error("Kernel did not respond\n")
             return
         
         if self.has_readline:
             self.readline_startup_hook(self.pre_readline)
             hlen_b4_cell = self.readline.get_current_history_length()
         else:
             hlen_b4_cell = 0
         # exit_now is set by a call to %Exit or %Quit, through the
         # ask_exit callback.
 
         while not self.exit_now:
             if not self.client.is_alive():
                 # kernel died, prompt for action or exit
 
                 action = "restart" if self.manager else "wait for restart"
                 ans = self.ask_yes_no("kernel died, %s ([y]/n)?" % action, default='y')
                 if ans:
                     if self.manager:
                         self.manager.restart_kernel(True)
                     self.wait_for_kernel(3)
                 else:
                     self.exit_now = True
                 continue
             try:
                 # protect prompt block from KeyboardInterrupt
                 # when sitting on ctrl-C
                 self.hooks.pre_prompt_hook()
                 if more:
                     try:
                         prompt = self.prompt_manager.render('in2')
                     except Exception:
                         self.showtraceback()
                     if self.autoindent:
                         self.rl_do_indent = True
                     
                 else:
                     try:
                         prompt = self.separate_in + self.prompt_manager.render('in')
                     except Exception:
                         self.showtraceback()
                 
                 line = self.raw_input(prompt)
                 if self.exit_now:
                     # quick exit on sys.std[in|out] close
                     break
                 if self.autoindent:
                     self.rl_do_indent = False
                     
             except KeyboardInterrupt:
                 #double-guard against keyboardinterrupts during kbdint handling
                 try:
                     self.write('\nKeyboardInterrupt\n')
                     source_raw = self.input_splitter.source_raw_reset()[1]
                     hlen_b4_cell = self._replace_rlhist_multiline(source_raw, hlen_b4_cell)
                     more = False
                 except KeyboardInterrupt:
                     pass
             except EOFError:
                 if self.autoindent:
                     self.rl_do_indent = False
                     if self.has_readline:
                         self.readline_startup_hook(None)
                 self.write('\n')
                 self.exit()
             except bdb.BdbQuit:
                 warn('The Python debugger has exited with a BdbQuit exception.\n'
                      'Because of how pdb handles the stack, it is impossible\n'
                      'for IPython to properly format this particular exception.\n'
                      'IPython will resume normal operation.')
             except:
                 # exceptions here are VERY RARE, but they can be triggered
                 # asynchronously by signal handlers, for example.
                 self.showtraceback()
             else:
                 self.input_splitter.push(line)
                 more = self.input_splitter.push_accepts_more()
                 if (self.SyntaxTB.last_syntax_error and
                     self.autoedit_syntax):
                     self.edit_syntax_error()
                 if not more:
                     source_raw = self.input_splitter.source_raw_reset()[1]
                     hlen_b4_cell = self._replace_rlhist_multiline(source_raw, hlen_b4_cell)
                     self.run_cell(source_raw)
                 
 
         # Turn off the exit flag, so the mainloop can be restarted if desired
         self.exit_now = False