From c157502a9c65ad59cb8d83be59c264db03c3d2f8 Mon Sep 17 00:00:00 2001
From: Tim Simpson <tim.simpson@rackspace.com>
Date: Thu, 17 Oct 2013 14:39:55 -0500
Subject: [PATCH] Simulates events so run_tests.py executes 10x faster

This restores some functionality that had been removed earlier to use
a class from Oslo. It turns out making it work with the new Oslo RPC
manager code wasn't too hard, plus the new version is hopefully easier
to follow.

Change-Id: I18e4d06359f28605cd764a10ace791997f534ed7
Implements: blueprint bring-back-event-simulator
---
 run_tests.py                        |  2 +
 trove/tests/util/event_simulator.py | 60 +++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)
 create mode 100644 trove/tests/util/event_simulator.py

diff --git a/run_tests.py b/run_tests.py
index 3f3af39c5c..1b35e5d88d 100644
--- a/run_tests.py
+++ b/run_tests.py
@@ -82,6 +82,8 @@ def initialize_fakes(app):
     wsgi_intercept.add_wsgi_intercept('localhost',
                                       CONF.bind_port,
                                       wsgi_interceptor)
+    from trove.tests.util import event_simulator
+    event_simulator.monkey_patch()
 
 
 def parse_args_for_test_config():
diff --git a/trove/tests/util/event_simulator.py b/trove/tests/util/event_simulator.py
new file mode 100644
index 0000000000..f2af50c4b7
--- /dev/null
+++ b/trove/tests/util/event_simulator.py
@@ -0,0 +1,60 @@
+"""
+Simulates time itself to make the fake mode tests run even faster.
+"""
+
+
+pending_events = []
+sleep_entrance_count = 0
+
+
+def event_simulator_spawn_after(time_from_now_in_seconds, func, *args, **kw):
+    """Fakes events without doing any actual waiting."""
+    def __cb():
+        func(*args, **kw)
+    pending_events.append({"time": time_from_now_in_seconds, "func": __cb})
+
+
+def event_simulator_spawn(func, *args, **kw):
+    event_simulator_spawn_after(0, func, *args, **kw)
+
+
+def event_simulator_sleep(time_to_sleep):
+    """Simulates waiting for an event."""
+    global sleep_entrance_count
+    sleep_entrance_count += 1
+    time_to_sleep = float(time_to_sleep)
+    global pending_events
+    run_once = False  # Ensure simulator runs even if the sleep time is zero.
+    while not run_once or time_to_sleep > 0:
+        run_once = True
+        itr_sleep = 0.5
+        for i in range(len(pending_events)):
+            event = pending_events[i]
+            event["time"] = event["time"] - itr_sleep
+            if event["func"] is not None and event["time"] < 0:
+                # Call event, but first delete it so this function can be
+                # reentrant.
+                func = event["func"]
+                event["func"] = None
+                try:
+                    func()
+                except Exception:
+                    LOG.exception("Simulated event error.")
+        time_to_sleep -= itr_sleep
+    sleep_entrance_count -= 1
+    if sleep_entrance_count < 1:
+        # Clear out old events
+        pending_events = [event for event in pending_events
+                          if event["func"] is not None]
+
+
+def monkey_patch():
+    import time
+    time.sleep = event_simulator_sleep
+    import eventlet
+    from eventlet import greenthread
+    eventlet.sleep = event_simulator_sleep
+    greenthread.sleep = event_simulator_sleep
+    eventlet.spawn_after = event_simulator_spawn_after
+    eventlet.spawn_n = event_simulator_spawn
+    eventlet.spawn = NotImplementedError