fix kushaldas#18 - create a manager class to view tasks and delete queue

Created a manager class which will help user
to view tasks of a given queue and also will
allow user to delete a given queue

retask/__init__.py

@@ -1,3 +1,4 @@
 from .exceptions import (RetaskException, ConnectionError)
 from .task import Task
 from .queue import Queue, Job
+from .manager import Manager

retask/manager.py

@@ -0,0 +1,138 @@
+"""
+retask Manager implementation
+
+"""
+
+import json
+import redis
+import uuid
+import six
+from .task import Task
+from .exceptions import ConnectionError
+
+class Manager(object):
+    """
+    Returns the ``Manager`` object. If the user
+    passes optional config dictionary with details for Redis
+    server, it will connect to that instance. By default it connects
+    to the localhost.
+
+    """
+    def __init__(self, config=None):
+        specified_config = config or {}
+        self.config = {
+            'host': 'localhost',
+            'port': 6379,
+            'db': 0,
+            'password': None,
+        }
+        self.config.update(specified_config)
+        self.rdb = None
+        self.connected = False
+
+    def connect(self):
+        """
+        Creates the connection with the redis server.
+        Return ``True`` if the connection works, else returns
+        ``False``. It does not take any arguments.
+
+        :return: ``Boolean`` value
+
+        .. note::
+
+           After creating the ``Manager`` object the user should call
+           the ``connect`` method to create the connection.
+
+        .. doctest::
+
+           >>> from retask import Manager
+           >>> manager = Manager()
+           >>> manager.connect()
+           True
+
+        """
+        config = self.config
+        self.rdb = redis.Redis(config['host'], config['port'], config['db'],\
+                              config['password'])
+        try:
+            info = self.rdb.info()
+            self.connected = True
+        except redis.ConnectionError:
+            return False
+
+        return True
+
+    def tasks(self, queue):
+        """
+        Returns a list of :class:`~retask.task.Task` objects from the given queue.
+        Returns ``None`` if the queue is empty.
+
+        :return: list of :class:`~retask.task.Task` objects from the given queue
+
+        If the queue is not connected then it will raise
+        :class:`retask.ConnectionError`
+
+        .. doctest::
+
+           >>> from retask import Queue
+           >>> from retask import Manager
+           >>> q = Queue('test')
+           >>> q.connect()
+           True
+           >>> manager = Manager()
+           >>> manager.connect()
+           True
+           >>> manager.tasks(q)
+           [Task({'name': 'Kushal'})]
+
+        """
+        if not self.connected:
+            raise ConnectionError('Queue is not connected')
+
+        queue_name = queue._name
+        queue_length = self.rdb.llen(queue_name)
+
+        if queue_length == 0:
+            return None
+
+        queue_tasks = self.rdb.lrange(queue_name, 0, queue_length)
+        for index, queue_task in enumerate(queue_tasks):
+            if isinstance(queue_task, six.binary_type):
+                queue_task = six.text_type(queue_task, 'utf-8', errors = 'replace')
+            task = Task()
+            task.__dict__ = json.loads(queue_task)
+            queue_tasks[index] = task
+        return queue_tasks
+
+    def delete(self, queue):
+        """
+        Deletes a given queue.
+        Return ``True`` if the queue exists and is deleted
+        ``False``. If no such queue exists
+
+        :return: ``Boolean`` value
+
+        .. doctest::
+
+           >>> from retask import Manager
+           >>> manager = Manager()
+           >>> manager.connect()
+           True
+           >>> q = Queue('example')
+           >>> q.connect()
+           True
+           >>> manager.delete(q)
+           True
+           >>> manager.delete(q)
+           False
+
+        """
+        if not self.connected:
+            raise ConnectionError('Queue is not connected')
+
+        queue_name = queue._name
+        status = self.rdb.delete(queue_name)
+
+        if status == 0:
+            return False
+        return True