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Improve exponential backoff of mdns service resolution retries #269

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Merged
balloob merged 1 commit into from
Feb 16, 2019
Merged

Improve exponential backoff of mdns service resolution retries #269

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5 changes: 5 additions & 0 deletions pychromecast/discovery.py
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,10 @@ def remove_service(self, zconf, typ, name):
_LOGGER.debug("remove_service %s, %s", typ, name)
service = self.services.pop(name, None)

if not service:
_LOGGER.debug("remove_service unknown %s, %s", typ, name)
return

if self.remove_callback:
self.remove_callback(name, service)

Expand All @@ -52,6 +56,7 @@ def add_service(self, zconf, typ, name):
tries += 1

if not service:
_LOGGER.debug("add_service failed to add %s, %s", typ, name)
return

def get_value(key):
Expand Down
21 changes: 13 additions & 8 deletions pychromecast/socket_client.py
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Original file line number Diff line number Diff line change
Expand Up @@ -245,6 +245,13 @@ def initialize_connection(self): # noqa: E501 pylint:disable=too-many-statement
# Dict keeping track of individual retry delay for each named service
retries = {}

def mdns_backoff(service, retry):
"""Exponentional backoff for service name mdns lookups."""
now = time.time()
retry['next_retry'] = now + retry['delay']
retry['delay'] = min(retry['delay']*2, 300)
retries[service] = retry

while not self.stop.is_set() and (tries is None or tries > 0): # noqa: E501 pylint:disable=too-many-nested-blocks
# Prune retries dict
retries = {key: retries[key] for key in self.services if (
Expand All @@ -254,6 +261,9 @@ def initialize_connection(self): # noqa: E501 pylint:disable=too-many-statement
now = time.time()
retry = retries.get(
service, {'delay': self.retry_wait, 'next_retry': now})
# If we're connecting to a named service, check if it's time
if service and now < retry['next_retry']:
continue
try:
self.socket = new_socket()
self.socket.settimeout(self.timeout)
Expand All @@ -263,8 +273,6 @@ def initialize_connection(self): # noqa: E501 pylint:disable=too-many-statement
# Resolve the service name. If service is None, we're
# connecting directly to a host name or IP-address
if service:
if now < retry['next_retry']:
continue
host = None
port = None
service_info = get_info_from_service(service,
Expand All @@ -284,12 +292,13 @@ def initialize_connection(self): # noqa: E501 pylint:disable=too-many-statement
self.port = port
else:
self.logger.debug(
"[%s:%s] failed to resolve service %s",
"[%s:%s] Failed to resolve service %s",
self.fn or self.host, self.port, service)
self._report_connection_status(
ConnectionStatus(
CONNECTION_STATUS_FAILED_RESOLVE,
NetworkAddress(service, None)))
mdns_backoff(service, retry)
# If zeroconf fails to receive the necessary data,
# try next service
continue
Expand Down Expand Up @@ -324,16 +333,12 @@ def initialize_connection(self): # noqa: E501 pylint:disable=too-many-statement
ConnectionStatus(CONNECTION_STATUS_FAILED,
NetworkAddress(self.host, self.port)))
if service is not None:
# Exponentional backoff for service name mdns lookups
now = time.time()
retry['next_retry'] = now + retry['delay']
retry_log_fun(
"[%s:%s] Failed to connect to service %s"
", retrying in %.1fs",
self.fn or self.host, self.port,
service, retry['delay'])
retry['delay'] = min(retry['delay']*2, 300)
retries[service] = retry
mdns_backoff(service, retry)
else:
retry_log_fun(
"[%s:%s] Failed to connect, retrying in %.1fs",
Expand Down