From 81ad52d6ebf05f4fe55be1c0b805aa9fcb55e7cf Mon Sep 17 00:00:00 2001
From: Kevan Carstensen <kevan@isnotajoke.com>
Date: Sat, 20 Feb 2010 13:07:13 -0800
Subject: [PATCH] Change OphandleTable to use a deterministic clock, so we can
 test it

To test the changes for #577, we need a deterministic way to simulate
the passage of long periods of time. twisted.internet.task.Clock seems,
from my Googling, to be the way to go for this functionality. I changed
a few things so that OphandleTable would use twisted.internet.task.Clock
when testing:

  * WebishServer.__init___ now takes an optional 'clock' parameter,
  * which it passes to the root.Root instance it creates.
  * root.Root.__init__ now takes an optional 'clock' parameter, which it
    passes to the OphandleTable.__init__ method.
  * OphandleTable.__init__ now takes an optional 'clock' parameter. If
    it is provided, and it isn't None, its callLater method will be used
    to schedule ophandle expirations (as opposed to using
    reactor.callLater, which is what OphandleTable does normally).
  * The WebMixin object in test_web.py now sets a self.clock parameter,
    which is a twisted.internet.task.Clock that it feeds to the
    WebishServer it creates.

Tests using the WebMixin can control the passage of time in
OphandleTable by accessing self.clock.
---
 src/allmydata/test/test_web.py  |  8 ++++++--
 src/allmydata/web/operations.py | 12 ++++++++++--
 src/allmydata/web/root.py       |  6 ++++--
 src/allmydata/webish.py         |  9 +++++++--
 4 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/src/allmydata/test/test_web.py b/src/allmydata/test/test_web.py
index cd8b2e05..a7304c71 100644
--- a/src/allmydata/test/test_web.py
+++ b/src/allmydata/test/test_web.py
@@ -4,6 +4,7 @@ from StringIO import StringIO
 from twisted.application import service
 from twisted.trial import unittest
 from twisted.internet import defer, reactor
+from twisted.internet.task import Clock
 from twisted.web import client, error, http
 from twisted.python import failure, log
 from nevow import rend
@@ -119,7 +120,9 @@ class WebMixin(object):
         self.s = FakeClient()
         self.s.startService()
         self.staticdir = self.mktemp()
-        self.ws = webish.WebishServer(self.s, "0", staticdir=self.staticdir)
+        self.clock = Clock()
+        self.ws = webish.WebishServer(self.s, "0", staticdir=self.staticdir,
+                                      clock=self.clock)
         self.ws.setServiceParent(self.s)
         self.webish_port = port = self.ws.listener._port.getHost().port
         self.webish_url = "http://localhost:%d" % port
@@ -2873,7 +2876,8 @@ class Web(WebMixin, WebErrorMixin, testutil.StallMixin, unittest.TestCase):
             self.failUnless("finished" in data, res)
         d.addCallback(_check1)
         # the retain-for=0 will cause the handle to be expired very soon
-        d.addCallback(self.stall, 2.0)
+        d.addCallback(lambda ign:
+            self.clock.advance(2.0))
         d.addCallback(lambda ignored:
                       self.shouldHTTPError("test_ophandle_retainfor",
                                            404, "404 Not Found",
diff --git a/src/allmydata/web/operations.py b/src/allmydata/web/operations.py
index 7fbf8d27..8ee9f202 100644
--- a/src/allmydata/web/operations.py
+++ b/src/allmydata/web/operations.py
@@ -24,10 +24,15 @@ class OphandleTable(rend.Page, service.Service):
     UNCOLLECTED_HANDLE_LIFETIME = 4*DAY
     COLLECTED_HANDLE_LIFETIME = 1*DAY
 
-    def __init__(self):
+    def __init__(self, clock=None):
         # both of these are indexed by ophandle
         self.handles = {} # tuple of (monitor, renderer, when_added)
         self.timers = {}
+        # The tests will provide a deterministic clock
+        # (twisted.internet.task.Clock) that they can control so that
+        # they can test ophandle expiration. If this is provided, I'll
+        # use it schedule the expiration of ophandles.
+        self.clock = clock
 
     def stopService(self):
         for t in self.timers.values():
@@ -103,7 +108,10 @@ class OphandleTable(rend.Page, service.Service):
     def _set_timer(self, ophandle, when):
         if ophandle in self.timers and self.timers[ophandle].active():
             self.timers[ophandle].cancel()
-        t = reactor.callLater(when, self._release_ophandle, ophandle)
+        if self.clock:
+            t = self.clock.callLater(when, self._release_ophandle, ophandle)
+        else:
+            t = reactor.callLater(when, self._release_ophandle, ophandle)
         self.timers[ophandle] = t
 
     def _release_ophandle(self, ophandle):
diff --git a/src/allmydata/web/root.py b/src/allmydata/web/root.py
index ee1cd921..59ebfbdb 100644
--- a/src/allmydata/web/root.py
+++ b/src/allmydata/web/root.py
@@ -145,10 +145,12 @@ class Root(rend.Page):
     addSlash = True
     docFactory = getxmlfile("welcome.xhtml")
 
-    def __init__(self, client):
+    def __init__(self, client, clock=None):
         rend.Page.__init__(self, client)
         self.client = client
-        self.child_operations = operations.OphandleTable()
+        # If set, clock is a twisted.internet.task.Clock that the tests
+        # use to test ophandle expiration.
+        self.child_operations = operations.OphandleTable(clock)
         try:
             s = client.getServiceNamed("storage")
         except KeyError:
diff --git a/src/allmydata/webish.py b/src/allmydata/webish.py
index 57b84ca5..8442bb25 100644
--- a/src/allmydata/webish.py
+++ b/src/allmydata/webish.py
@@ -121,10 +121,15 @@ class MyRequest(appserver.NevowRequest):
 class WebishServer(service.MultiService):
     name = "webish"
 
-    def __init__(self, client, webport, nodeurl_path=None, staticdir=None):
+    def __init__(self, client, webport, nodeurl_path=None, staticdir=None,
+                                        clock=None):
         service.MultiService.__init__(self)
         # the 'data' argument to all render() methods default to the Client
-        self.root = root.Root(client)
+        # the 'clock' argument to root.Root is, if set, a
+        # twisted.internet.task.Clock that is provided by the unit tests
+        # so that they can test features that involve the passage of
+        # time in a deterministic manner.
+        self.root = root.Root(client, clock)
         self.buildServer(webport, nodeurl_path, staticdir)
         if self.root.child_operations:
             self.site.remember(self.root.child_operations, IOpHandleTable)
-- 
2.45.2