def perform_readahead(config, redis_client):
""" The heart of the readahead script.
:param config: dict, tscached level of config.
:param redis_client: redis.StrictRedis
:return: void
"""
lock = become_leader(config, redis_client)
if not lock:
logging.info('Could not become leader; exiting.')
return
try:
redis_keys = list(redis_client.smembers(SHADOW_LIST))
logging.info('Found %d KQuery keys in the shadow list' % len(redis_keys))
for kq in kquery.KQuery.from_cache(redis_keys, redis_client):
last_ts = kq.cached_data['last_add_data'] # unix timestamp, seconds
mins_in_past = (last_ts / 60) - 5 # add 5m of margin
# all that really matters is that end_ values are unset.
kairos_time_range = {'start_relative': {'unit': 'minutes', 'value': str(mins_in_past)}}
# throw away the diagnostic mode info for the moment.
kq_resp, _ = cache_calls.process_cache_hit(config, redis_client, kq, kairos_time_range)
size = kq_resp.get('sample_size', -1)
logging.debug('Processed KQuery %s; sample size now at %d' % (kq.redis_key, size))
except BackendQueryFailure as e:
logging.error('BackendQueryFailure: %s' % e.message)
except redis.exceptions.RedisError as e:
logging.error('RedisError: ' + e.message)
release_leader(lock, redis_client)
def handle_query():
try:
if request.method == 'POST':
payload = json.loads(request.data) # dict
else:
payload = json.loads(request.args.get('query'))
except:
err = 'Cannot deserialize JSON payload.'
logging.error(err)
return json.dumps({'error': err}), 500
config = app.config['tscached']
logging.info('Query')
redis_client = getRedisClient()
kairos_time_range = populate_time_range(payload)
ret_data = {'queries': []}
overall_cache_mode = None
# HTTP request may contain one or more kqueries
for kquery in KQuery.from_request(payload, redis_client):
try:
# get whatever is in redis for this kquery
kq_result = kquery.get_cached()
# readahead shadow load support
process_for_readahead(config, redis_client, kquery.get_key(),
request.referrer, request.headers)
if kq_result:
kq_resp, cache_mode = process_cache_hit(
config, redis_client, kquery, kairos_time_range)
else:
kq_resp = cold(config, redis_client, kquery, kairos_time_range)
cache_mode = 'cold_miss'
except BackendQueryFailure as e:
# KairosDB is broken so we fail fast.
logging.error('BackendQueryFailure: %s' % e.message)
return json.dumps({'error': e.message}), 500
except redis.exceptions.RedisError as e:
# Redis is broken, so we pretend it's a cache miss. This will eat any further exceptions.
logging.error('RedisError: ' + e.message)
kq_resp = cold(config, redis_client, kquery, kairos_time_range)
cache_mode = 'cold_proxy'
ret_data['queries'].append(kq_resp)
if not overall_cache_mode:
overall_cache_mode = cache_mode
elif cache_mode != overall_cache_mode:
overall_cache_mode = 'mixed'
return json.dumps(ret_data), 200, {
'Content-Type': 'application/json',
'X-tscached-mode': overall_cache_mode
}
def handle_query():
try:
if request.method == 'POST':
payload = json.loads(request.data) # dict
else:
payload = json.loads(request.args.get('query'))
except:
err = 'Cannot deserialize JSON payload.'
logging.error(err)
return json.dumps({'error': err}), 500
config = app.config['tscached']
logging.info('Query')
redis_client = redis.StrictRedis(host=config['redis']['host'], port=config['redis']['port'])
kairos_time_range = populate_time_range(payload)
ret_data = {'queries': []}
overall_cache_mode = None
# HTTP request may contain one or more kqueries
for kquery in KQuery.from_request(payload, redis_client):
try:
# get whatever is in redis for this kquery
kq_result = kquery.get_cached()
# readahead shadow load support
process_for_readahead(config, redis_client, kquery.get_key(), request.referrer,
request.headers)
if kq_result:
kq_resp, cache_mode = process_cache_hit(config, redis_client, kquery, kairos_time_range)
else:
kq_resp = cold(config, redis_client, kquery, kairos_time_range)
cache_mode = 'cold_miss'
except BackendQueryFailure as e:
# KairosDB is broken so we fail fast.
logging.error('BackendQueryFailure: %s' % e.message)
return json.dumps({'error': e.message}), 500
except redis.exceptions.RedisError as e:
# Redis is broken, so we pretend it's a cache miss. This will eat any further exceptions.
logging.error('RedisError: ' + e.message)
kq_resp = cold(config, redis_client, kquery, kairos_time_range)
cache_mode = 'cold_proxy'
ret_data['queries'].append(kq_resp)
if not overall_cache_mode:
overall_cache_mode = cache_mode
elif cache_mode != overall_cache_mode:
overall_cache_mode = 'mixed'
return json.dumps(ret_data), 200, {'Content-Type': 'application/json', 'X-tscached-mode': overall_cache_mode}