More powerful Options scheme

This prepares us for the addon configuration mechanism and gives us a more
flexible way to handle options changes. This changeset should spell the end of
the current anti-pattern in our codebase where we duplicate data out of options
onto the master when mutability is needed. From now on, Options can be the one
source of thruth.

- Change notifications
- Rollback on error

mitmproxy/console/master.py

@@ -20,6 +20,7 @@ from mitmproxy import controller
 from mitmproxy import exceptions
 from mitmproxy import flow
 from mitmproxy import script
+import mitmproxy.options
 from mitmproxy.console import flowlist
 from mitmproxy.console import flowview
 from mitmproxy.console import grideditor
@@ -175,7 +176,7 @@ class ConsoleState(flow.State):
         self.add_flow_setting(flow, "marked", marked)
 
 
-class Options(object):
+class Options(mitmproxy.options.Options):
     attributes = [
         "app",
         "app_domain",
@@ -210,13 +211,6 @@ class Options(object):
         "outfile",
     ]
 
-    def __init__(self, **kwargs):
-        for k, v in kwargs.items():
-            setattr(self, k, v)
-        for i in self.attributes:
-            if not hasattr(self, i):
-                setattr(self, i, None)
-
 
 class ConsoleMaster(flow.FlowMaster):
     palette = []

mitmproxy/dump.py

@@ -11,6 +11,7 @@ from mitmproxy import controller
 from mitmproxy import exceptions
 from mitmproxy import filt
 from mitmproxy import flow
+from mitmproxy import options
 from netlib import human
 from netlib import tcp
 from netlib import strutils
@@ -20,7 +21,7 @@ class DumpError(Exception):
     pass
 
 
-class Options(object):
+class Options(options.Options):
     attributes = [
         "app",
         "app_host",
@@ -53,13 +54,6 @@ class Options(object):
         "replay_ignore_host"
     ]
 
-    def __init__(self, **kwargs):
-        for k, v in kwargs.items():
-            setattr(self, k, v)
-        for i in self.attributes:
-            if not hasattr(self, i):
-                setattr(self, i, None)
-
 
 class DumpMaster(flow.FlowMaster):
 

mitmproxy/exceptions.py

@@ -95,3 +95,7 @@ class FlowReadException(ProxyException):
 
 class ControlException(ProxyException):
     pass
+
+
+class OptionsError(Exception):
+    pass

mitmproxy/options.py

@@ -0,0 +1,66 @@
+from __future__ import absolute_import, print_function, division
+
+import contextlib
+import blinker
+import pprint
+
+from mitmproxy import exceptions
+
+
+class Options(object):
+    """
+        .changed is a blinker Signal that triggers whenever options are
+        updated. If any handler in the chain raises an exceptions.OptionsError
+        exception, all changes are rolled back, the exception is suppressed,
+        and the .errored signal is notified.
+    """
+    attributes = []
+
+    def __init__(self, **kwargs):
+        self.__dict__["changed"] = blinker.Signal()
+        self.__dict__["errored"] = blinker.Signal()
+        self.__dict__["_opts"] = dict([(i, None) for i in self.attributes])
+        for k, v in kwargs.items():
+            self._opts[k] = v
+
+    @contextlib.contextmanager
+    def rollback(self):
+        old = self._opts.copy()
+        try:
+            yield
+        except exceptions.OptionsError as e:
+            # Notify error handlers
+            self.errored.send(self, exc=e)
+            # Rollback
+            self.__dict__["_opts"] = old
+            self.changed.send(self)
+
+    def __eq__(self, other):
+        return self._opts == other._opts
+
+    def __copy__(self):
+        return self.__class__(**self._opts)
+
+    def __getattr__(self, attr):
+        return self._opts[attr]
+
+    def __setattr__(self, attr, value):
+        if attr not in self._opts:
+            raise KeyError("No such option: %s" % attr)
+        with self.rollback():
+            self._opts[attr] = value
+            self.changed.send(self)
+
+    def get(self, k, d=None):
+        return self._opts.get(k, d)
+
+    def update(self, **kwargs):
+        for k in kwargs:
+            if k not in self._opts:
+                raise KeyError("No such option: %s" % k)
+        with self.rollback():
+            self._opts.update(kwargs)
+            self.changed.send(self)
+
+    def __repr__(self):
+        return pprint.pformat(self._opts)

mitmproxy/web/master.py

@@ -9,6 +9,7 @@ import tornado.ioloop
 from mitmproxy import controller
 from mitmproxy import exceptions
 from mitmproxy import flow
+from mitmproxy import options
 from mitmproxy.web import app
 from netlib.http import authentication
 
@@ -88,7 +89,7 @@ class WebState(flow.State):
         )
 
 
-class Options(object):
+class Options(options.Options):
     attributes = [
         "app",
         "app_domain",
@@ -124,14 +125,6 @@ class Options(object):
         "wsingleuser",
         "whtpasswd",
     ]
-
-    def __init__(self, **kwargs):
-        for k, v in kwargs.items():
-            setattr(self, k, v)
-        for i in self.attributes:
-            if not hasattr(self, i):
-                setattr(self, i, None)
-
     def process_web_options(self, parser):
         if self.wsingleuser or self.whtpasswd:
             if self.wsingleuser:

test/mitmproxy/test_options.py

@@ -0,0 +1,67 @@
+from __future__ import absolute_import, print_function, division
+import copy
+
+from mitmproxy import options
+from mitmproxy import exceptions
+from netlib.tutils import raises
+
+
+class TO(options.Options):
+    attributes = [
+        "one",
+        "two"
+    ]
+
+
+def test_options():
+    o = TO(two="three")
+    assert o.one is None
+    assert o.two == "three"
+    o.one = "one"
+    assert o.one == "one"
+    raises("no such option", setattr, o, "nonexistent", "value")
+    raises("no such option", o.update, nonexistent = "value")
+
+    rec = []
+
+    def sub(opts):
+        rec.append(copy.copy(opts))
+
+    o.changed.connect(sub)
+
+    o.one = "ninety"
+    assert len(rec) == 1
+    assert rec[-1].one == "ninety"
+
+    o.update(one="oink")
+    assert len(rec) == 2
+    assert rec[-1].one == "oink"
+
+
+def test_rollback():
+    o = TO(one="two")
+
+    rec = []
+
+    def sub(opts):
+        rec.append(copy.copy(opts))
+
+    recerr = []
+
+    def errsub(opts, **kwargs):
+        recerr.append(kwargs)
+
+    def err(opts):
+        if opts.one == "ten":
+            raise exceptions.OptionsError
+
+    o.changed.connect(sub)
+    o.changed.connect(err)
+    o.errored.connect(errsub)
+
+    o.one = "ten"
+    assert isinstance(recerr[0]["exc"], exceptions.OptionsError)
+    assert o.one == "two"
+    assert len(rec) == 2
+    assert rec[0].one == "ten"
+    assert rec[1].one == "two"