1 files changed, 78 insertions, 0 deletions
diff --git a/keystone/common/environment/__init__.py b/keystone/common/environment/__init__.py
new file mode 100644
index 00000000..ac93e24f
--- /dev/null
+++ b/keystone/common/environment/__init__.py
@@ -0,0 +1,78 @@
+import functools
+import os
+
+from keystone.common import config
+from keystone.common import logging
+
+CONF = config.CONF
+LOG = logging.getLogger(__name__)
+
+
+__all__ = ['Server', 'httplib', 'subprocess']
+
+_configured = False
+
+Server = None
+httplib = None
+subprocess = None
+
+
+def configure_once(name):
+    """Ensure that environment configuration is only run once.
+
+    If environment is reconfigured in the same way then it is ignored.
+    It is an error to attempt to reconfigure environment in a different way.
+    """
+    def decorator(func):
+        @functools.wraps(func)
+        def wrapper(*args, **kwargs):
+            global _configured
+            if _configured:
+                if _configured == name:
+                    return
+                else:
+                    raise SystemError("Environment has already been "
+                                      "configured as %s" % _configured)
+
+            LOG.info(_("Environment configured as: %s"), name)
+            _configured = name
+            return func(*args, **kwargs)
+
+        return wrapper
+    return decorator
+
+
+@configure_once('eventlet')
+def use_eventlet(monkeypatch_thread=None):
+    global httplib, subprocess, Server
+
+    # This must be set before the initial import of eventlet because if
+    # dnspython is present in your environment then eventlet monkeypatches
+    # socket.getaddrinfo() with an implementation which doesn't work for IPv6.
+    os.environ['EVENTLET_NO_GREENDNS'] = 'yes'
+
+    import eventlet
+    from eventlet.green import httplib as _httplib
+    from eventlet.green import subprocess as _subprocess
+    from keystone.common.environment import eventlet_server
+
+    if monkeypatch_thread is None:
+        monkeypatch_thread = not os.getenv('STANDARD_THREADS')
+
+    eventlet.patcher.monkey_patch(all=False, socket=True, time=True,
+                                  thread=monkeypatch_thread)
+
+    Server = eventlet_server.Server
+    httplib = _httplib
+    subprocess = _subprocess
+
+
+@configure_once('stdlib')
+def use_stdlib():
+    global httplib, subprocess
+
+    import httplib as _httplib
+    import subprocess as _subprocess
+
+    httplib = _httplib
+    subprocess = _subprocess