def test_dequeue_order(self):
""" Test the order that frames are returned by dequeue() method. """
dest = '/queue/foo'
frame1 = StompFrame('MESSAGE', headers={'message-id': 'id-1'}, body='message-1')
self.store.enqueue(dest, frame1)
frame2 = StompFrame('MESSAGE', headers={'message-id': 'id-2'}, body='message-2')
self.store.enqueue(dest, frame2)
frame3 = StompFrame('MESSAGE', headers={'message-id': 'id-3'}, body='message-3')
self.store.enqueue(dest, frame3)
assert self.store.has_frames(dest) == True
assert self.store.size(dest) == 3
# Perform some updates to change the expected order.
sess = meta.Session()
sess.execute(model.frames_table.update().where(model.frames_table.c.message_id=='id-1').values(queued=datetime.datetime(2010, 01, 01)))
sess.execute(model.frames_table.update().where(model.frames_table.c.message_id=='id-2').values(queued=datetime.datetime(2009, 01, 01)))
sess.execute(model.frames_table.update().where(model.frames_table.c.message_id=='id-3').values(queued=datetime.datetime(2004, 01, 01)))
sess.commit()
rframe1 = self.store.dequeue(dest)
assert frame3 == rframe1
rframe2 = self.store.dequeue(dest)
assert frame2 == rframe2
rframe3 = self.store.dequeue(dest)
assert frame1 == rframe3
assert self.store.has_frames(dest) == False
assert self.store.size(dest) == 0
def destinations(self):
"""
Provides a list of destinations (queue "addresses") available.
@return: A list of the detinations available.
@rtype: C{set}
"""
session = meta.Session()
sel = select([distinct(model.frames_table.c.destination)])
result = session.execute(sel)
return set([r[0] for r in result.fetchall()])
def has_frames(self, destination):
"""
Whether specified queue has any frames.
@param destination: The queue name (destinationination).
@type destination: C{str}
@return: Whether there are any frames in the specified queue.
@rtype: C{bool}
"""
session = meta.Session()
sel = select([model.frames_table.c.message_id
]).where(model.frames_table.c.destination == destination)
result = session.execute(sel)
first = result.fetchone()
return first is not None
def enqueue(self, destination, frame):
"""
Store message (frame) for specified destinationination.
@param destination: The destinationination queue name for this message (frame).
@type destination: C{str}
@param frame: The message (frame) to send to specified destinationination.
@type frame: C{stompclient.frame.Frame}
"""
session = meta.Session()
message_id = frame.headers.get('message-id')
if not message_id:
raise ValueError("Cannot queue a frame without message-id set.")
ins = model.frames_table.insert().values(message_id=message_id,
destination=destination,
frame=frame)
session.execute(ins)
session.commit()
def size(self, destination):
"""
Size of the queue for specified destination.
@param destination: The queue destination (e.g. /queue/foo)
@type destination: C{str}
@return: The number of frames in specified queue.
@rtype: C{int}
"""
session = meta.Session()
sel = select([func.count(model.frames_table.c.message_id)
]).where(model.frames_table.c.destination == destination)
result = session.execute(sel)
first = result.fetchone()
if not first:
return 0
else:
return int(first[0])
def dequeue(self, destination):
"""
Removes and returns an item from the queue (or C{None} if no items in queue).
@param destination: The queue name (destinationination).
@type destination: C{str}
@return: The first frame in the specified queue, or C{None} if there are none.
@rtype: C{stompclient.frame.Frame}
"""
session = meta.Session()
try:
selstmt = select(
[model.frames_table.c.message_id, model.frames_table.c.frame])
selstmt = selstmt.where(
model.frames_table.c.destination == destination)
selstmt = selstmt.order_by(model.frames_table.c.queued,
model.frames_table.c.sequence)
result = session.execute(selstmt)
first = result.fetchone()
if not first:
return None
delstmt = model.frames_table.delete().where(
model.frames_table.c.message_id == first[
model.frames_table.c.message_id])
session.execute(delstmt)
frame = first[model.frames_table.c.frame]
except:
session.rollback()
raise
else:
session.commit()
return frame
