[WORKER] Implement new STATS request

STATS requests will now return usage information for each LB
defined on a device (TCP, HTTP, or both). This change introduces
a new StatisticsManager class for managing temporary storage of
HAProxy statistics to deal with the fact that its reported values
are reset on restart. Also add tests for the new class.

Removed the LBStatistics class since it wasn't necessary.

Change-Id: I56177a829650b2206ee855fdf4756ed52825e936

libra/worker/controller.py

@@ -21,7 +21,7 @@ from libra import __release__ as libra_release
 from libra.common.exc import DeletedStateError
 from libra.common.faults import BadRequest
 from libra.openstack.common import log
-from libra.worker.drivers.base import LoadBalancerDriver
+from libra.worker.drivers import base
 
 LOG = log.getLogger(__name__)
 
@@ -71,8 +71,7 @@ class LBaaSController(object):
             elif action == 'ARCHIVE':
                 return self._action_archive()
             elif action == 'STATS':
-                # TODO: Implement new STATS function
-                return self._action_ping()
+                return self._action_stats()
             elif action == 'PING':
                 return self._action_ping()
             elif action == 'DIAGNOSTICS':
@@ -203,15 +202,15 @@ class LBaaSController(object):
             if 'algorithm' in current_lb:
                 algo = current_lb['algorithm'].upper()
                 if algo == 'ROUND_ROBIN':
-                    algo = LoadBalancerDriver.ROUNDROBIN
+                    algo = base.LoadBalancerDriver.ROUNDROBIN
                 elif algo == 'LEAST_CONNECTIONS':
-                    algo = LoadBalancerDriver.LEASTCONN
+                    algo = base.LoadBalancerDriver.LEASTCONN
                 else:
                     LOG.error("Invalid algorithm: %s" % algo)
                     self.msg[self.RESPONSE_FIELD] = self.RESPONSE_FAILURE
                     return self.msg
             else:
-                algo = LoadBalancerDriver.ROUNDROBIN
+                algo = base.LoadBalancerDriver.ROUNDROBIN
 
             try:
                 self.driver.set_algorithm(current_lb['protocol'], algo)
@@ -451,26 +450,69 @@ class LBaaSController(object):
         """
 
         try:
-            stats = self.driver.get_status()
+            nodes = self.driver.get_status()
         except NotImplementedError:
             error = "Selected driver does not support PING action."
             LOG.error(error)
             self.msg[self.RESPONSE_FIELD] = self.RESPONSE_FAILURE
             self.msg[self.ERROR_FIELD] = error
         except DeletedStateError:
-            LOG.info("Invalid operation PING on a deleted LB")
+            error = "Invalid operation PING on a deleted LB."
+            LOG.error(error)
             self.msg['status'] = 'DELETED'
             self.msg[self.RESPONSE_FIELD] = self.RESPONSE_FAILURE
+            self.msg[self.ERROR_FIELD] = error
         except Exception as e:
             LOG.error("PING failed: %s, %s" % (e.__class__, e))
             self.msg[self.RESPONSE_FIELD] = self.RESPONSE_FAILURE
             self.msg[self.ERROR_FIELD] = str(e)
         else:
-            node_status = stats.node_status_map()
             self.msg['nodes'] = []
-            for node in node_status.keys():
-                self.msg['nodes'].append({'id': node,
-                                          'status': node_status[node]})
+            for node, status in nodes:
+                self.msg['nodes'].append({'id': node, 'status': status})
             self.msg[self.RESPONSE_FIELD] = self.RESPONSE_SUCCESS
 
         return self.msg
+
+    def _action_stats(self):
+        """
+        Get load balancer statistics
+
+        This type of request gets the number of bytes out for each load
+        balancer defined on the device. If both a TCP and HTTP load
+        balancer exist, we report on each in a single response.
+        """
+
+        try:
+            start, end, statistics = self.driver.get_statistics()
+        except NotImplementedError:
+            error = "Selected driver does not support STATS action."
+            LOG.error(error)
+            self.msg[self.RESPONSE_FIELD] = self.RESPONSE_FAILURE
+            self.msg[self.ERROR_FIELD] = error
+            return self.msg
+        except DeletedStateError:
+            error = "Invalid operation STATS on a deleted LB."
+            LOG.error(error)
+            self.msg['status'] = 'DELETED'
+            self.msg[self.RESPONSE_FIELD] = self.RESPONSE_FAILURE
+            self.msg[self.ERROR_FIELD] = error
+            return self.msg
+        except Exception as e:
+            LOG.error("STATS failed: %s, %s" % (e.__class__, e))
+            self.msg[self.RESPONSE_FIELD] = self.RESPONSE_FAILURE
+            self.msg[self.ERROR_FIELD] = str(e)
+            return self.msg
+
+        self.msg['utc_start'] = start
+        self.msg['utc_end'] = end
+        self.msg['loadBalancers'] = []
+
+        # We should have a list of tuples pairing the number of bytes
+        # out with the protocol/LB.
+        for proto, bytes_out in statistics:
+            self.msg['loadBalancers'].append({'protocol': proto,
+                                              'bytes_out': bytes_out})
+
+        self.msg[self.RESPONSE_FIELD] = self.RESPONSE_SUCCESS
+        return self.msg