def __init__(self, hosts, timeout):
self.hosts = [ (server, instance) for (server, port, instance) in hosts ]
self.ports = dict( ((server, instance), port) for (server, port, instance) in hosts )
self.timeout = float(timeout)
self.hash_ring = ConsistentHashRing(self.hosts)
self.connections = {}
self.last_failure = {}
# Create a connection pool for each host
for host in self.hosts:
self.connections[host] = set()
class CarbonLinkPool:
def __init__(self, hosts, timeout):
self.hosts = [ (server, instance) for (server, port, instance) in hosts ]
self.ports = dict( ((server, instance), port) for (server, port, instance) in hosts )
self.timeout = float(timeout)
self.hash_ring = ConsistentHashRing(self.hosts)
self.connections = {}
self.last_failure = {}
# Create a connection pool for each host
for host in self.hosts:
self.connections[host] = set()
def select_host(self, metric):
"Returns the carbon host that has data for the given metric"
return self.hash_ring.get_node(metric)
def get_connection(self, host):
# First try to take one out of the pool for this host
(server, instance) = host
port = self.ports[host]
connectionPool = self.connections[host]
try:
return connectionPool.pop()
except KeyError:
pass #nothing left in the pool, gotta make a new connection
log.cache("CarbonLink creating a new socket for %s" % str(host))
connection = socket.socket()
connection.settimeout(self.timeout)
try:
connection.connect( (server, port) )
except:
self.last_failure[host] = time.time()
raise
else:
connection.setsockopt( socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1 )
return connection
def query(self, metric):
request = dict(type='cache-query', metric=metric)
results = self.send_request(request)
log.cache("CarbonLink cache-query request for %s returned %d datapoints" % (metric, len(results)))
return results['datapoints']
def get_metadata(self, metric, key):
request = dict(type='get-metadata', metric=metric, key=key)
results = self.send_request(request)
log.cache("CarbonLink get-metadata request received for %s:%s" % (metric, key))
return results['value']
def set_metadata(self, metric, key, value):
request = dict(type='set-metadata', metric=metric, key=key, value=value)
results = self.send_request(request)
log.cache("CarbonLink set-metadata request received for %s:%s" % (metric, key))
return results
def send_request(self, request):
metric = request['metric']
serialized_request = pickle.dumps(request, protocol=-1)
len_prefix = struct.pack("!L", len(serialized_request))
request_packet = len_prefix + serialized_request
host = self.select_host(metric)
conn = self.get_connection(host)
try:
conn.sendall(request_packet)
result = self.recv_response(conn)
except:
self.last_failure[host] = time.time()
raise
else:
self.connections[host].add(conn)
if 'error' in result:
raise CarbonLinkRequestError(result['error'])
else:
return result
def recv_response(self, conn):
len_prefix = recv_exactly(conn, 4)
body_size = struct.unpack("!L", len_prefix)[0]
body = recv_exactly(conn, body_size)
return unpickle.loads(body)