From 6b0afa3ab612efef3d7c5cfa1710052b92ed9585 Mon Sep 17 00:00:00 2001
From: Ricardo Dias <rdias@suse.com>
Date: Tue, 13 Mar 2018 08:38:36 +0000
Subject: [PATCH] mgr/dashboard: Support for handler priorities in
 NotificationQueue

Signed-off-by: Ricardo Dias <rdias@suse.com>
---
 .../mgr/dashboard/tests/test_notification.py  | 25 ++++++++++++++++---
 src/pybind/mgr/dashboard/tools.py             | 24 +++++++++++++-----
 2 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/src/pybind/mgr/dashboard/tests/test_notification.py b/src/pybind/mgr/dashboard/tests/test_notification.py
index 151c8a59ed4..b421e1eb212 100644
--- a/src/pybind/mgr/dashboard/tests/test_notification.py
+++ b/src/pybind/mgr/dashboard/tests/test_notification.py
@@ -10,15 +10,20 @@ from ..tools import NotificationQueue
 
 
 class Listener(object):
+    # pylint: disable=too-many-instance-attributes
     def __init__(self):
-        NotificationQueue.register(self.log_type1, 'type1')
+        NotificationQueue.register(self.log_type1, 'type1', priority=90)
         NotificationQueue.register(self.log_type2, 'type2')
         NotificationQueue.register(self.log_type1_3, ['type1', 'type3'])
-        NotificationQueue.register(self.log_all)
+        NotificationQueue.register(self.log_all, priority=50)
         self.type1 = []
+        self.type1_ts = []
         self.type2 = []
+        self.type2_ts = []
         self.type1_3 = []
+        self.type1_3_ts = []
         self.all = []
+        self.all_ts = []
 
         # these should be ignored by the queue
         NotificationQueue.register(self.log_type1, 'type1')
@@ -26,22 +31,30 @@ class Listener(object):
         NotificationQueue.register(self.log_all)
 
     def log_type1(self, val):
+        self.type1_ts.append(time.time())
         self.type1.append(val)
 
     def log_type2(self, val):
+        self.type2_ts.append(time.time())
         self.type2.append(val)
 
     def log_type1_3(self, val):
+        self.type1_3_ts.append(time.time())
         self.type1_3.append(val)
 
     def log_all(self, val):
+        self.all_ts.append(time.time())
         self.all.append(val)
 
     def clear(self):
         self.type1 = []
+        self.type1_ts = []
         self.type2 = []
+        self.type2_ts = []
         self.type1_3 = []
+        self.type1_3_ts = []
         self.all = []
+        self.all_ts = []
 
 
 class NotificationQueueTest(unittest.TestCase):
@@ -69,6 +82,12 @@ class NotificationQueueTest(unittest.TestCase):
         self.assertEqual(self.listener.type1_3, [1, 3])
         self.assertEqual(self.listener.all, [1, 2, 3])
 
+        # validate priorities
+        self.assertLess(self.listener.type1_3_ts[0], self.listener.all_ts[0])
+        self.assertLess(self.listener.all_ts[0], self.listener.type1_ts[0])
+        self.assertLess(self.listener.type2_ts[0], self.listener.all_ts[1])
+        self.assertLess(self.listener.type1_3_ts[1], self.listener.all_ts[2])
+
     def test_notifications2(self):
         NotificationQueue.start_queue()
         for i in range(0, 600):
@@ -77,7 +96,7 @@ class NotificationQueueTest(unittest.TestCase):
                 time.sleep(0.002)
             NotificationQueue.new_notification(typ, i)
         NotificationQueue.stop()
-        for i in range(0, 500):
+        for i in range(0, 600):
             typ = i % 3 + 1
             if typ == 1:
                 self.assertIn(i, self.listener.type1)
diff --git a/src/pybind/mgr/dashboard/tools.py b/src/pybind/mgr/dashboard/tools.py
index b138454cb23..115d7737f1d 100644
--- a/src/pybind/mgr/dashboard/tools.py
+++ b/src/pybind/mgr/dashboard/tools.py
@@ -612,7 +612,14 @@ class NotificationQueue(threading.Thread):
         logger.debug("notification queue stopped")
 
     @classmethod
-    def register(cls, func, n_types=None):
+    def _registered_handler(cls, func, n_types):
+        for _, reg_func in cls._listeners[n_types]:
+            if reg_func == func:
+                return True
+        return False
+
+    @classmethod
+    def register(cls, func, n_types=None, priority=1):
         """Registers function to listen for notifications
 
         If the second parameter `n_types` is omitted, the function in `func`
@@ -620,17 +627,21 @@ class NotificationQueue(threading.Thread):
 
         Args:
             func (function): python function ex: def foo(val)
-            n_types (str|list): the single type to listen, or a list of notification types
+            n_types (str|list): the single type to listen, or a list of types
+            priority (int): the priority level (1=max, +inf=min)
         """
         with cls._lock:
             if not n_types:
-                cls._listeners[cls._ALL_TYPES_].add(func)
+                if not cls._registered_handler(func, cls._ALL_TYPES_):
+                    cls._listeners[cls._ALL_TYPES_].add((priority, func))
                 return
             if isinstance(n_types, str):
-                cls._listeners[n_types].add(func)
+                if not cls._registered_handler(func, n_types):
+                    cls._listeners[n_types].add((priority, func))
             elif isinstance(n_types, list):
                 for typ in n_types:
-                    cls._listeners[typ].add(func)
+                    if not cls._registered_handler(func, typ):
+                        cls._listeners[typ].add((priority, func))
             else:
                 raise Exception("n_types param is neither a string nor a list")
 
@@ -647,8 +658,9 @@ class NotificationQueue(threading.Thread):
             with cls._lock:
                 listeners = list(cls._listeners[notify_type])
                 listeners.extend(cls._listeners[cls._ALL_TYPES_])
+            listeners.sort(key=lambda lis: lis[0])
             for listener in listeners:
-                listener(notify_value)
+                listener[1](notify_value)
 
     def run(self):
         logger.debug("notification queue started")
-- 
2.39.5