Add delete action

Instead of moving the queues which is prone to errors and to
leave broken queues, we can simply delete the queues wich are
empty and they will be recreated in less than a second and
the proper balincing done to them.

This allows us to be blazing fast with minimal impact and without
having to doo too much.

Wont remove the code from the move part yet, that will come in a
different PR

main.py

@@ -36,6 +36,9 @@
 class ConfigNotFound(Exception):
     pass
 
+class NoMoreQueues(Exception):
+    pass
+
 
 class QueueBalancer:
     class SignalHandler:
@@ -48,6 +51,7 @@ def __call__(self, signum, frame):
             exit(0)
 
     def __init__(self):
+        self.action = "delete"
         self.retries = 6  # this number * self.wait_time == total number to wait for the check to expire
         signal.signal(signal.SIGINT, self.SignalHandler())
         self.log = logging.getLogger(__name__)
@@ -90,6 +94,7 @@ def __init__(self):
         self.nodes_url = "{}/api/nodes".format(full_host)
         self.queues_url = "{}/api/queues/{}".format(full_host, vhost)
         self.queue_status_url = self.queues_url + "/{}"
+        self.queue_delete_url = self.queues_url + "/{}"
         self.policy_url = "{}/api/policies/{}".format(full_host, vhost) + "/{}"
         self.sync_url = "{}/api/queues/{}".format(full_host, vhost) + "/{}/actions"
 
@@ -259,7 +264,26 @@ def prepare(self):
         # fill the destination pool
         self.fill_queue_with_destination_nodes(distribution)
 
-    def move_queue(self):
+    def delete_queue(self, queue_name):
+        response = self.conn.delete(self.queue_delete_url.format(queue_name), params={"if-empty": "true"}, timeout=5)
+        self.log.debug("Response to delete queue {}: {}".format(queue_name, response.status_code))
+
+    def delete_queue_action(self):
+        start = time.time()
+        try:
+            # pop queue from the overloaded pool
+            queue = self.queue_pool.pop()
+        except IndexError:
+            self.log.info("No more queues in the overloaded pool")
+            self.semaphore.release()
+            raise NoMoreQueues()
+
+        self.delete_queue(queue)
+        sleep(self.wait_time)
+        self.log.info("Finished deleting queue {}. It took {} seconds".format(queue, time.time() - start))
+        self.semaphore.release()
+
+    def move_queue_action(self):
         start = time.time()
         try:
             # pop queue from the overloaded pool
@@ -290,12 +314,20 @@ def go(self):
         self.prepare()
         self.log.debug("Queue pool has {} items".format(len(self.queue_pool)))
         self.log.debug("Destination pool has {} items".format(len(self.destiny_pool)))
+        self.log.info("Running action {}".format(self.action))
         # start threading here
-        while len(self.queue_pool) > 0 or len(self.destiny_pool) > 0:
-            self.semaphore.acquire()
-            t = threading.Thread(target=self.move_queue)
-            self.log.debug("Starting new thread: {}".format(t.getName()))
-            t.start()
+        if self.action == "delete":
+            while len(self.queue_pool) > 0:
+                self.semaphore.acquire()
+                t = threading.Thread(target=self.delete_queue_action)
+                self.log.debug("Starting new thread: {}".format(t.getName()))
+                t.start()
+        elif self.action == "move":
+            while len(self.queue_pool) > 0 or len(self.destiny_pool) > 0:
+                self.semaphore.acquire()
+                t = threading.Thread(target=self.move_queue_action)
+                self.log.debug("Starting new thread: {}".format(t.getName()))
+                t.start()
 
         # some housekeeping, if we dont have anymore queues to move that's ok but there may still be
         # threads doing some work, so find and join them so we wait for them to finish
@@ -305,7 +337,7 @@ def go(self):
             self.log.info("Waiting for thread {} to finish".format(t.getName()))
             t.join()
 
-        self.log.info("Finished moving queues. It took {} seconds".format(time.time() - start))
+        self.log.info("Finished action {} on queues. It took {} seconds".format(self.action, time.time() - start))
 
 
 if __name__ == '__main__':