From 0d3854b008677657711c70b854152f3d3583fc9e Mon Sep 17 00:00:00 2001
From: "W. Trevor King" <wking@drexel.edu>
Date: Wed, 19 May 2010 00:38:51 -0400
Subject: [PATCH] Fix a pickling problems with
 hooke.plugin.playlist.FilterCommand.

Pickle doesn't like functions that aren't defined the top level of
modules (such as NoteFilterCommand's old lambda filter_fn).  Add a
warning to that effect to the FilterCommand doc string, and rearrange
to encourage the use of methods (which are less likely to be defined
on the fly than functions).

Also:
  * Added pickle queue debugging code to hooke.hooke.  This isn't the
    first tiem I've had a pickling problem.  This code (when enabled),
    makes it easier for me to track down the failing code.
  * Fix a typo in hooke.hooke.HookeRunner.run (self.ui -> hooke.ui).
  * Remove a snip of trailing whitespace in hooke.hooke.
---
 hooke/hooke.py           | 36 ++++++++++++++++++++++++++++++++++--
 hooke/plugin/playlist.py | 26 ++++++++++++++++++--------
 2 files changed, 52 insertions(+), 10 deletions(-)

diff --git a/hooke/hooke.py b/hooke/hooke.py
index e8a0050..07d5d5a 100644
--- a/hooke/hooke.py
+++ b/hooke/hooke.py
@@ -22,6 +22,38 @@
 """Hooke - A force spectroscopy review & analysis tool.
 """
 
+if False: # Queue pickle error debugging code
+    """The Hooke class is passed back from the CommandEngine process
+    to the main process via a :class:`multiprocessing.queues.Queue`,
+    which uses :mod:`pickle` for serialization.  There are a number of
+    objects that are unpicklable, and the error messages are not
+    always helpful.  This block of code hooks you into the Queue's
+    _feed method so you can print out useful tidbits to help find the
+    particular object that is gumming up the pickle works.
+    """
+    import multiprocessing.queues
+    import sys
+    feed = multiprocessing.queues.Queue._feed
+    def new_feed (buffer, notempty, send, writelock, close):
+        def s(obj):
+            print 'SEND:', obj, dir(obj)
+            for a in dir(obj):
+                attr = getattr(obj, a)
+                #print '  ', a, attr, type(attr)
+            if obj.__class__.__name__ == 'Hooke':
+                # Set suspect attributes to None until you resolve the
+                # PicklingError.  Then fix whatever is breaking the
+                # pickling.
+                #obj.commands = None
+                #obj.drivers = None
+                #obj.plugins = None
+                #obj.ui = None
+                pass
+            sys.stdout.flush()
+            send(obj)
+        feed(buffer, notempty, s, writelock, close)
+    multiprocessing.queues.Queue._feed = staticmethod(new_feed)
+
 import multiprocessing
 import optparse
 import os.path
@@ -83,7 +115,7 @@ class HookeRunner (object):
         """
         ui_to_command,command_to_ui,command = self._setup_run(hooke)
         try:
-            self.ui.run(hooke.commands, ui_to_command, command_to_ui)
+            hooke.ui.run(hooke.commands, ui_to_command, command_to_ui)
         finally:
             hooke = self._cleanup_run(ui_to_command, command_to_ui, command)
         return hooke
@@ -106,7 +138,7 @@ class HookeRunner (object):
     def _setup_run(self, hooke):
         ui_to_command = multiprocessing.Queue()
         command_to_ui = multiprocessing.Queue()
-        manager = multiprocessing.Manager()        
+        manager = multiprocessing.Manager()
         command = multiprocessing.Process(name='command engine',
             target=hooke.command.run, args=(hooke, ui_to_command, command_to_ui))
         command.start()
diff --git a/hooke/plugin/playlist.py b/hooke/plugin/playlist.py
index 21a6419..dd6e626 100644
--- a/hooke/plugin/playlist.py
+++ b/hooke/plugin/playlist.py
@@ -260,8 +260,18 @@ class FilterCommand (Command):
     Removing lots of curves one at a time can be tedious.  With this
     command you can use a function `filter` to select the curves you
     wish to keep.
+
+    Notes
+    -----
+    There are issues with pickling functions bound to class
+    attributes, because the pickle module doesn't know where those
+    functions were originally defined (where it should point the
+    loader).  Because of this, subclasses with hard-coded filter
+    functions are encouraged to define their filter function as a
+    method of their subclass.  See, for example,
+    :meth:`NoteFilterCommand.filter`.
     """
-    def __init__(self, plugin, name='filter playlist', filter_fn=None):
+    def __init__(self, plugin, name='filter playlist'):
         super(FilterCommand, self).__init__(
             name=name,
             arguments=[
@@ -269,8 +279,7 @@ class FilterCommand (Command):
                 PlaylistNameArgument,
                 ],
             help=self.__doc__, plugin=plugin)
-        self.filter_fn = filter_fn
-        if filter_fn == None:
+        if not hasattr(self, 'filter'):
             self.arguments.append(
                 Argument(name='filter', type='function', optional=False,
                          help="""
@@ -279,10 +288,10 @@ Function returning `True` for "good" curves.
 """.strip()))
 
     def _run(self, hooke, inqueue, outqueue, params):
-        if self.filter_fn == None:
+        if not hasattr(self, 'filter'):
             filter_fn = params['filter']
         else:
-            filter_fn = self.filter_fn
+            filter_fn = self.filter
         p = params['playlist'].filter(filter_fn,
             hooke=hooke, inqueue=inqueue, outqueue=outqueue, params=params)
         hooke.playlists.add(p)
@@ -293,6 +302,7 @@ class NoteFilterCommand (FilterCommand):
     """
     def __init__(self, plugin):
         super(NoteFilterCommand, self).__init__(
-            plugin, name='note filter playlist',
-            filter_fn=lambda curve, hooke, inqueue, outqueue, params : \
-                'note' in curve.info and curve.info['note'] != None)
+            plugin, name='note filter playlist')
+
+    def filter(self, curve, hooke, inqueue, outqueue, params):
+        return 'note' in curve.info and curve.info['note'] != None
-- 
2.26.2