Add threadgroup to manage timers and greenthreads.

Part of blueprint service-infrastructure

Change-Id: I40593b6ad13d99d9e63c8c04154a0dac5aced02e
Signed-off-by: Angus Salkeld <asalkeld@redhat.com>

1 files changed, 118 insertions, 0 deletions

diff --git a/openstack/common/threadgroup.py b/openstack/common/threadgroup.py
new file mode 100644
index 0000000..a9dfa5e
--- /dev/null
+++ b/openstack/common/threadgroup.py
@@ -0,0 +1,118 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2012 Red Hat, Inc.
+#
+#    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 os
+import sys
+
+from eventlet import event
+from eventlet import greenthread
+from eventlet import greenpool
+
+from openstack.common import loopingcall
+from openstack.common.gettextutils import _
+from openstack.common import log as logging
+
+
+LOG = logging.getLogger(__name__)
+
+
+def _thread_done(gt, *args, **kwargs):
+    args[0].thread_done(args[1])
+
+
+class Thread(object):
+    """
+    Wrapper around a greenthread, that holds a reference to
+    the ThreadGroup. The Thread will notify the ThreadGroup
+    when it has done so it can be removed from the threads
+    list.
+    """
+    def __init__(self, name, thread, group):
+        self.name = name
+        self.thread = thread
+        self.thread.link(_thread_done, group, self)
+
+    def stop(self):
+        self.thread.cancel()
+
+    def wait(self):
+        return self.thread.wait()
+
+
+class ThreadGroup():
+    """
+    The point of this class is to:
+    - keep track of timers and greenthreads (making it easier to stop them
+      when need be).
+    - provide an easy API to add timers.
+    """
+    def __init__(self, name, thread_pool_size=10):
+        self.name = name
+        self.pool = greenpool.GreenPool(thread_pool_size)
+        self.threads = []
+        self.timers = []
+
+    def add_timer(self, interval, callback, initial_delay=None,
+                  *args, **kwargs):
+        pulse = loopingcall.LoopingCall(callback, *args, **kwargs)
+        pulse.start(interval=interval,
+                    initial_delay=initial_delay)
+        self.timers.append(pulse)
+
+    def add_thread(self, callback, *args, **kwargs):
+        gt = self.pool.spawn(callback, *args, **kwargs)
+        th = Thread(callback.__name__, gt, self)
+        self.threads.append(th)
+
+    def thread_done(self, thread):
+        try:
+            thread.wait()
+        except Exception as ex:
+            LOG.exception(ex)
+        finally:
+            self.threads.remove(thread)
+
+    def stop(self):
+        current = greenthread.getcurrent()
+        for x in self.threads:
+            if x is current:
+                # don't kill the current thread.
+                continue
+            try:
+                x.stop()
+            except Exception as ex:
+                LOG.exception(ex)
+
+        for x in self.timers:
+            try:
+                x.stop()
+            except Exception as ex:
+                LOG.exception(ex)
+        self.timers = []
+
+    def wait(self):
+        for x in self.timers:
+            try:
+                x.wait()
+            except Exception as ex:
+                LOG.exception(ex)
+        current = greenthread.getcurrent()
+        for x in self.threads:
+            if x is current:
+                continue
+            try:
+                x.wait()
+            except Exception as ex:
+                LOG.exception(ex)