def process_queue(self, worker_id):
"""Continuously processes tasks on the queue."""
# Create a new logs instance (with its own httplib2 instance) so that
# there is a separate one for each thread.
logs = Logs("twitter-listener-worker-%s" % worker_id,
to_cloud=self.logs_to_cloud)
logs.debug("Started worker thread: %s" % worker_id)
while not self.stop_event.is_set():
try:
data = self.queue.get(block=True, timeout=QUEUE_TIMEOUT_S)
start_time = time()
self.handle_data(logs, data)
self.queue.task_done()
end_time = time()
qsize = self.queue.qsize()
logs.debug("Worker %s took %.f ms with %d tasks remaining." %
(worker_id, end_time - start_time, qsize))
except Empty:
logs.debug("Worker %s timed out on an empty queue." %
worker_id)
continue
except Exception:
# The main loop doesn't catch and report exceptions from
# background threads, so do that here.
logs.catch()
logs.debug("Stopped worker thread: %s" % worker_id)
class Main:
"""A wrapper for the main application logic and retry loop."""
def __init__(self):
self.logs = Logs(name="main", to_cloud=LOGS_TO_CLOUD)
self.twitter = Twitter(logs_to_cloud=LOGS_TO_CLOUD)
self.logs.info("I'm running")
self.twitter.test_tweet()
def twitter_callback(self, tweet):
"""Analyzes tweets, trades stocks, and tweets about it."""
# Initialize the Analysis, Logs, Trading, and Twitter instances inside
# the callback to create separate httplib2 instances per thread.
analysis = Analysis(logs_to_cloud=LOGS_TO_CLOUD)
logs = Logs(name="main-callback", to_cloud=LOGS_TO_CLOUD)
# Analyze the tweet.
companies = analysis.find_companies(tweet)
logs.info("Using companies: %s" % companies)
if not companies:
return
# Trade stocks.
trading = Trading(logs_to_cloud=LOGS_TO_CLOUD)
trading.make_trades(companies)
# Tweet about it.
twitter = Twitter(logs_to_cloud=LOGS_TO_CLOUD)
twitter.tweet(companies, tweet)
def run_session(self):
"""Runs a single streaming session. Logs and cleans up after
exceptions.
"""
self.logs.info("Starting new session.")
try:
self.twitter.start_streaming(self.twitter_callback)
except:
self.logs.catch()
finally:
self.twitter.stop_streaming()
self.logs.info("Ending session.")
def backoff(self, tries):
"""Sleeps an exponential number of seconds based on the number of
tries.
"""
delay = BACKOFF_STEP_S * pow(2, tries)
self.logs.warn("Waiting for %.1f seconds." % delay)
sleep(delay)
def run(self):
"""Runs the main retry loop with exponential backoff."""
tries = 0
while True:
# The session blocks until an error occurs.
self.run_session()
# Remember the first time a backoff sequence starts.
now = datetime.now()
if tries == 0:
self.logs.debug("Starting first backoff sequence.")
backoff_start = now
# Reset the backoff sequence if the last error was long ago.
if (now - backoff_start).total_seconds() > BACKOFF_RESET_S:
self.logs.debug("Starting new backoff sequence.")
tries = 0
backoff_start = now
# Give up after the maximum number of tries.
if tries >= MAX_TRIES:
self.logs.warn("Exceeded maximum retry count.")
break
# Wait according to the progression of the backoff sequence.
self.backoff(tries)
# Increment the number of tries for the next error.
tries += 1