Methods for managing VIMs, SDNs

[osm/NBI.git] / osm_nbi / msglocal.py

diff --git a/osm_nbi/msglocal.py b/osm_nbi/msglocal.py
index a19c5c3..337321f 100644 (file)
--- a/osm_nbi/msglocal.py
+++ b/osm_nbi/msglocal.py
@@ -3,9 +3,16 @@ import os
 import yaml
 import asyncio
 from msgbase import MsgBase, MsgException
+from time import sleep
 
 __author__ = "Alfonso Tierno <alfonso.tiernosepulveda@telefonica.com>"
 
+"""
+This emulated kafka bus by just using a shared file system. Usefull for testing or devops.
+One file is used per topic. Only one producer and one consumer is allowed per topic. Both consumer and producer 
+access to the same file. e.g. same volume if running with docker.
+One text line per message is used in yaml format
+"""
 
 class MsgLocal(MsgBase):
 
@@ -14,6 +21,7 @@ class MsgLocal(MsgBase):
         self.path = None
         # create a different file for each topic
         self.files = {}
+        self.buffer = {}
 
     def connect(self, config):
         try:
@@ -41,55 +49,63 @@ class MsgLocal(MsgBase):
         Insert a message into topic
         :param topic: topic
         :param key: key text to be inserted
-        :param msg: value object to be inserted
+        :param msg: value object to be inserted, can be str, object ...
         :return: None or raises and exception
         """
         try:
             if topic not in self.files:
                 self.files[topic] = open(self.path + topic, "a+")
-            yaml.safe_dump({key: msg}, self.files[topic], default_flow_style=True)
+            yaml.safe_dump({key: msg}, self.files[topic], default_flow_style=True, width=20000)
             self.files[topic].flush()
         except Exception as e:  # TODO refine
             raise MsgException(str(e))
 
-    def read(self, topic):
+    def read(self, topic, blocks=True):
+        """
+        Read from one or several topics. it is non blocking returning None if nothing is available
+        :param topic: can be str: single topic; or str list: several topics
+        :param blocks: indicates if it should wait and block until a message is present or returns None
+        :return: topic, key, message; or None if blocks==True
+        """
         try:
-            msg = ""
-            if topic not in self.files:
-                self.files[topic] = open(self.path + topic, "a+")
-                # ignore previous content
-                for line in self.files[topic]:
-                    if not line.endswith("\n"):
-                        msg = line
-            msg += self.files[topic].readline()
-            if not msg.endswith("\n"):
-                return None
-            msg_dict = yaml.load(msg)
-            assert len(msg_dict) == 1
-            for k, v in msg_dict.items():
-                return k, v
+            if isinstance(topic, (list, tuple)):
+                topic_list = topic
+            else:
+                topic_list = (topic, )
+            while True:
+                for single_topic in topic_list:
+                    if single_topic not in self.files:
+                        self.files[single_topic] = open(self.path + single_topic, "a+")
+                        self.buffer[single_topic] = ""
+                    self.buffer[single_topic] += self.files[single_topic].readline()
+                    if not self.buffer[single_topic].endswith("\n"):
+                        continue
+                    msg_dict = yaml.load(self.buffer[single_topic])
+                    self.buffer[single_topic] = ""
+                    assert len(msg_dict) == 1
+                    for k, v in msg_dict.items():
+                        return single_topic, k, v
+                if not blocks:
+                    return None
+                sleep(2)
         except Exception as e:  # TODO refine
             raise MsgException(str(e))
 
-    async def aioread(self, topic, loop=None):
+    async def aioread(self, topic, loop):
+        """
+        Asyncio read from one or several topics. It blocks
+        :param topic: can be str: single topic; or str list: several topics
+        :param loop: asyncio loop
+        :return: topic, key, message
+        """
         try:
-            msg = ""
-            if not loop:
-                loop = asyncio.get_event_loop()
-            if topic not in self.files:
-                self.files[topic] = open(self.path + topic, "a+")
-                # ignore previous content
-                for line in self.files[topic]:
-                    if not line.endswith("\n"):
-                        msg = line
             while True:
-                msg += self.files[topic].readline()
-                if msg.endswith("\n"):
-                    break
+                msg = self.read(topic, blocks=False)
+                if msg:
+                    return msg
                 await asyncio.sleep(2, loop=loop)
-            msg_dict = yaml.load(msg)
-            assert len(msg_dict) == 1
-            for k, v in msg_dict.items():
-                return k, v
+        except MsgException:
+            raise
         except Exception as e:  # TODO refine
             raise MsgException(str(e))
+