Remove the psutil dependency (#6318)

* remove psutil and replace with resource

tests/test_phone_home.py

@@ -0,0 +1,51 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import resource
+
+import mock
+
+from synapse.app.homeserver import phone_stats_home
+
+from tests.unittest import HomeserverTestCase
+
+
+class PhoneHomeStatsTestCase(HomeserverTestCase):
+    def test_performance_frozen_clock(self):
+        """
+        If time doesn't move, don't error out.
+        """
+        past_stats = [
+            (self.hs.get_clock().time(), resource.getrusage(resource.RUSAGE_SELF))
+        ]
+        stats = {}
+        self.get_success(phone_stats_home(self.hs, stats, past_stats))
+        self.assertEqual(stats["cpu_average"], 0)
+
+    def test_performance_100(self):
+        """
+        1 second of usage over 1 second is 100% CPU usage.
+        """
+        real_res = resource.getrusage(resource.RUSAGE_SELF)
+        old_resource = mock.Mock(spec=real_res)
+        old_resource.ru_utime = real_res.ru_utime - 1
+        old_resource.ru_stime = real_res.ru_stime
+        old_resource.ru_maxrss = real_res.ru_maxrss
+
+        past_stats = [(self.hs.get_clock().time(), old_resource)]
+        stats = {}
+        self.reactor.advance(1)
+        self.get_success(phone_stats_home(self.hs, stats, past_stats))
+        self.assertApproximates(stats["cpu_average"], 100, tolerance=2.5)