def _loop(msg_queue, response_queue, channels, archive_name):
"""Main server loop. Intended to be a Process target (and private to this
module). Accepts messages through its mailbox queue, and takes the
appropriate action based on the command and parameters contained within the
message.
Parameters
----------
msq_queue : Queue
Used for receiving inter-process communication.
response_queue : Queue
Used for pushing responses
channels : list of str
list of channel names in the underlying data table. Any records
written to the buffer are expected to have an entry for each
channel.
archive_name : str
sqlite database name
"""
buf = Buffer(channels=channels, archive_name=archive_name)
while True:
# Messages should be tuples with the structure:
# (command, params)
msg = msg_queue.get()
command, params = msg
if command == MSG_EXIT:
buf.cleanup(delete_archive=params)
response_queue.put(('exit', 'ok'))
break
elif command == MSG_PUT:
# params is the record to put
buf.append(params)
elif command == MSG_GET_ALL:
response_queue.put(buf.all())
elif command == MSG_COUNT:
response_queue.put(len(buf))
elif command == MSG_QUERY_SLICE:
row_start, row_end, field = params
log.debug("Sending query: %s", (row_start, row_end, field))
response_queue.put(buf.query(row_start, row_end, field))
elif command == MSG_QUERY:
# Generic query
filters, ordering, max_results = params
response_queue.put(buf.query_data(filters, ordering, max_results))
elif command == MSG_STARTED:
response_queue.put(('started', 'ok'))
elif command == MSG_DUMP_RAW_DATA:
buf.dump_raw_data(*params)
response_queue.put(('raw_data', 'ok'))
else:
log.debug("Error; message not understood: %s", msg)
def test_query_before_flush(self):
"""If a query is made before chunksize records have been written,
the data should still be available."""
n = 1000
channel_count = 25
channels = ["ch" + str(c) for c in range(channel_count)]
b = Buffer(channels=channels, chunksize=10000)
for i, d in enumerate(_mockdata(n, channel_count)):
timestamp = float(i)
b.append(Record(d, timestamp, None))
rows = b.query(start=b.start_time, field='timestamp')
self.assertEqual(len(rows), n)
self.assertEqual(len(b.all()), n)
b.cleanup()