check_memory: add download-GET-slow, to simulate memory usage of a node feeding downloaded data via HTTP GET to a slow client

Makefile

@@ -181,6 +181,8 @@ check-memory: build
 	 $(PYTHON) src/allmydata/test/check_memory.py download
 	$(PP) \
 	 $(PYTHON) src/allmydata/test/check_memory.py download-GET
+	$(PP) \
+	 $(PYTHON) src/allmydata/test/check_memory.py download-GET-slow
 
 
 test-darcs-boringfile:

src/allmydata/test/check_memory.py

@@ -4,7 +4,7 @@ import os, shutil, sys, urllib
 from cStringIO import StringIO
 from twisted.internet import defer, reactor, protocol, error
 from twisted.application import service, internet
-from twisted.web.client import getPage, downloadPage
+from twisted.web import client as tw_client
 from allmydata import client, introducer_and_vdrive
 from allmydata.scripts import create_node
 from allmydata.util import testutil, fileutil
@@ -12,6 +12,50 @@ import foolscap
 from foolscap import eventual
 from twisted.python import log
 
+class StallableHTTPGetterDiscarder(tw_client.HTTPPageGetter):
+    full_speed_ahead = False
+    _bytes_so_far = 0
+    stalled = None
+    def handleResponsePart(self, data):
+        self._bytes_so_far += len(data)
+        if not self.factory.do_stall:
+            return
+        if self.full_speed_ahead:
+            return
+        if self._bytes_so_far > 1e6+100:
+            if not self.stalled:
+                print "STALLING"
+                self.transport.pauseProducing()
+                self.stalled = reactor.callLater(10.0, self._resume_speed)
+    def _resume_speed(self):
+        print "RESUME SPEED"
+        self.stalled = None
+        self.full_speed_ahead = True
+        self.transport.resumeProducing()
+    def handleResponseEnd(self):
+        if self.stalled:
+            print "CANCEL"
+            self.stalled.cancel()
+            self.stalled = None
+        return tw_client.HTTPPageGetter.handleResponseEnd(self)
+
+class StallableDiscardingHTTPClientFactory(tw_client.HTTPClientFactory):
+    protocol = StallableHTTPGetterDiscarder
+
+def discardPage(url, stall=False, *args, **kwargs):
+    """Start fetching the URL, but stall our pipe after the first 1MB.
+    Wait 10 seconds, then resume downloading (and discarding) everything.
+    """
+    # adapted from twisted.web.client.getPage . We can't just wrap or
+    # subclass because it provides no way to override the HTTPClientFactory
+    # that it creates.
+    scheme, host, port, path = tw_client._parse(url)
+    factory = StallableDiscardingHTTPClientFactory(url, *args, **kwargs)
+    factory.do_stall = stall
+    assert scheme == 'http'
+    reactor.connectTCP(host, port, factory)
+    return factory.deferred
+
 class SystemFramework(testutil.PollMixin):
     numnodes = 5
 
@@ -30,7 +74,7 @@ class SystemFramework(testutil.PollMixin):
         self.tub.setServiceParent(self.sparent)
         self.discard_shares = True
         self.mode = mode
-        if mode in ("download", "download-GET"):
+        if mode in ("download", "download-GET", "download-GET-slow"):
             self.discard_shares = False
         self.failed = False
 
@@ -272,13 +316,12 @@ this file are ignored.
         body = "\r\n".join(form) + "\r\n"
         headers = {"content-type": "multipart/form-data; boundary=%s" % sepbase,
                    }
-        return getPage(url, method="POST", postdata=body,
+        return tw_client.getPage(url, method="POST", postdata=body,
                                  headers=headers, followRedirect=False)
 
-    def GET_discard(self, urlpath):
-        # TODO: Slow
+    def GET_discard(self, urlpath, stall):
         url = self.webish_url + urlpath + "?filename=dummy-get.out"
-        return downloadPage(url, os.path.join(self.basedir, "dummy-get.out"))
+        return discardPage(url, stall)
 
     def _print_usage(self, res=None):
         d = self.control_rref.callRemote("get_memory_usage")
@@ -306,7 +349,7 @@ this file are ignored.
             data = "a" * size
             url = "/vdrive/global"
             d = self.POST(url, t="upload", file=("%d.data" % size, data))
-        elif self.mode in ("download", "download-GET"):
+        elif self.mode in ("download", "download-GET", "download-GET-slow"):
             # upload the data from a local peer, then have the
             # client-under-test download it.
             files[name] = self.create_data(name, size)
@@ -321,17 +364,26 @@ this file are ignored.
         return d
 
     def _do_download(self, res, size, uris):
-        if self.mode not in ("download", "download-GET"):
+        if self.mode not in ("download", "download-GET", "download-GET-slow"):
             return
         name = '%d' % size
+        print "downloading %s" % name
         uri = uris[name]
+
         if self.mode == "download":
             d = self.control_rref.callRemote("download_from_uri_to_file",
                                              uri, "dummy.out")
-        if self.mode == "download-GET":
+        elif self.mode == "download-GET":
             url = "/uri/%s" % uri
-            d = self.GET_discard(urllib.quote(url))
+            d = self.GET_discard(urllib.quote(url), stall=False)
+        elif self.mode == "download-GET-slow":
+            url = "/uri/%s" % uri
+            d = self.GET_discard(urllib.quote(url), stall=True)
 
+        def _complete(res):
+            print "downloaded %s" % name
+            return res
+        d.addCallback(_complete)
         return d
 
     def do_test(self):