def from_environment(cls, max_pool_size=4):
"""Generate a ``pymemcache.Client`` from an environment variable.
This class method looks for the ``MEMCACHED_HOSTS`` environment
variable and, if it is set, parses the value as a space delimited list of
hostnames, optionally with ports. For example:
"localhost"
"localhost:11211"
"1.1.1.1:11211 2.2.2.2:11211 3.3.3.3:11211"
Returns:
Optional[MemcacheCache]: A :class:`MemcacheCache` instance or
:data:`None`, if ``MEMCACHED_HOSTS`` is not set in the
environment.
"""
hosts_string = os.environ.get("MEMCACHED_HOSTS")
if not hosts_string:
return None
hosts = [
cls._parse_host_string(host_string.strip())
for host_string in hosts_string.split()
]
if not max_pool_size:
max_pool_size = 1
if len(hosts) == 1:
client = pymemcache.PooledClient(hosts[0],
max_pool_size=max_pool_size)
else:
client = pymemcache.HashClient(hosts,
use_pooling=True,
max_pool_size=max_pool_size)
return cls(client)
def from_environment(cls,
max_pool_size=4,
strict_read=False,
strict_write=True):
"""Generate a ``pymemcache.Client`` from an environment variable.
This class method looks for the ``MEMCACHED_HOSTS`` environment
variable and, if it is set, parses the value as a space delimited list of
hostnames, optionally with ports. For example:
"localhost"
"localhost:11211"
"1.1.1.1:11211 2.2.2.2:11211 3.3.3.3:11211"
Args:
max_pool_size (int): Size of connection pool to be used by client. If set to
``0`` or ``1``, connection pooling will not be used. Default: ``4``
strict_read (bool): If :data:`False`, connection errors during read
operations will be logged with a warning and treated as cache misses,
but will not raise an exception in the application, with connection
errors during reads being treated as cache misses. If :data:`True`,
connection errors will be raised as exceptions in the application.
Default: :data:`False`.
strict_write (bool): If :data:`False`, connection errors during write
operations will be logged with a warning, but will not raise an
exception in the application. If :data:`True`, connection errors during
write will be raised as exceptions in the application. Because write
operations involve cache invalidation, setting this to :data:`False` may
allow other clients to retrieve stale data from the cache. If there is
a connection error, an internal flag will be set to clear the cache the
next time any method is called on this object, to try and minimize the
opportunity for clients to read stale data from the cache. Default:
:data:`True`.
Returns:
Optional[MemcacheCache]: A :class:`MemcacheCache` instance or
:data:`None`, if ``MEMCACHED_HOSTS`` is not set in the
environment.
"""
hosts_string = os.environ.get("MEMCACHED_HOSTS")
if not hosts_string:
return None
hosts = [
cls._parse_host_string(host_string.strip())
for host_string in hosts_string.split()
]
if not max_pool_size:
max_pool_size = 1
if len(hosts) == 1:
client = pymemcache.PooledClient(hosts[0],
max_pool_size=max_pool_size)
else:
client = pymemcache.HashClient(hosts,
use_pooling=True,
max_pool_size=max_pool_size)
return cls(client, strict_read=strict_read, strict_write=strict_write)