def latest(self,n=25,timestamp=None):
"""most recent n bins from the given timestamp (defaults to now)"""
if timestamp is None:
timestamp = utcdtnow()
return self._ts_query(end_time=timestamp).\
order_by(desc(Bin.sample_time)).\
limit(n)
def changed(self, event, state=RUNNING, message=HEARTBEAT, ts=None, ttl=None):
"""call to record the event of a product state change"""
if event is not None:
self.event = event
if state is not None:
self.state = state
if message is not None:
self.message = message
if ts is None:
ts = utcdtnow()
self.ts = ts
# expiration semantics:
# if ttl is never set, never expire
# if ttl is set to FOREVER, no longer expire
# if ttl is set to an integer, expire in that many seconds
# if ttl is None, make no change to expiration time or ttl
if ttl is not None:
ttl = int(ttl)
if ttl==FOREVER:
self.ttl = None
else:
self.ttl = ttl
if self.ttl is not None:
self.expires = self.ts + timedelta(seconds=self.ttl)
else:
self.expires = None
def elapsed(self,timestamp=None):
"""time elapsed since latest bin at the given time (default now) (utc datetime).
returns a timedelta"""
if timestamp is None:
timestamp = utcdtnow()
latest = self.latest(1,timestamp)[0]
return timestamp - latest.sample_time
def nearest(self, n=1, timestamp=None):
"""nearest bin. timestamp must be a utc datetime, defaults to now"""
if timestamp is None:
timestamp = utcdtnow()
n_before = self._ts_query(end_time=timestamp).order_by(desc(Bin.sample_time)).limit(n).all()
min_date = datetime2utcdatetime(n_before[-1].sample_time)
max_date = timestamp + (timestamp - min_date)
n_after = self._ts_query(start_time=timestamp, end_time=max_date).order_by(Bin.sample_time).limit(n).all()
cand = list(n_before) + list(n_after)
return sorted(cand, key=lambda b: timestamp - datetime2utcdatetime(b.sample_time))[:n]
def ts_metric(ts_label, callback, start=None, end=None, s=None):
if s is None:
s = 86400
if end is None:
end = utcdtnow()
if start is None:
start = end - timedelta(seconds=s)
with Feed(session, ts_label) as feed:
result = []
for b in feed.time_range(start, end):
r = canonicalize_bin(ts_label, b)
r.update(callback(b))
result.append(r)
return Response(json.dumps(result), mimetype=MIME_JSON)
def expire(self, state=RUNNING, new_state=WAITING, event='expired', message=None, **kw):
"""allow products to expire whose most recent event is older
than their TTL allows"""
if state == new_state:
raise ValueError('state and new_state are both %s' % state)
now = utcdtnow()
n = 0
for p in self.session.query(Product).\
filter(and_(Product.ttl.isnot(None),Product.ttl!=FOREVER)).\
filter(Product.expires.isnot(None)).\
filter(now > Product.expires).\
with_lockmode('update'):
p.changed('expired', new_state)
n += 1
self.session.commit()
return n
def older_than(self, ago):
"""find all products whose events occurred longer than ago ago.
ago must be a datetime.timedelta"""
now = utcdtnow()
return self.session.query(Product).\
filter(Product.ts < now - ago)