def get(self):
key = "some key"
seconds = 5
memcache.set(key, "some value")
# [START memcache-delete]
memcache.delete(key, seconds) # clears cache
# write to persistent datastore
# Do not attempt to put new value in cache, first reader will do that
# [END memcache-delete]
self.response.content_type = 'text/html'
self.response.write('done')
python类delete()的实例源码
def ExpireAndLock(self, timeout):
"""Marks this entry as deleted and locks it for the expiration time.
Used to implement memcache's delete timeout behavior.
Args:
timeout: Parameter originally passed to memcache.delete or
memcache.delete_multi to control deletion timeout.
"""
self.will_expire = True
self.locked = True
self._SetExpiration(timeout)
def set_token(unique_key, token_str):
"""Saves the serialized auth token in the datastore.
The token is also stored in memcache to speed up retrieval on a cache hit.
Args:
unique_key: The unique name for this token as a string. It is up to your
code to ensure that this token value is unique in your application.
Previous values will be silently overwitten.
token_str: A serialized auth token as a string. I expect that this string
will be generated by gdata.gauth.token_to_blob.
Returns:
True if the token was stored sucessfully, False if the token could not be
safely cached (if an old value could not be cleared). If the token was
set in memcache, but not in the datastore, this function will return None.
However, in that situation an exception will likely be raised.
Raises:
Datastore exceptions may be raised from the App Engine SDK in the event of
failure.
"""
# First try to save in memcache.
result = memcache.set(unique_key, token_str)
# If memcache fails to save the value, clear the cached value.
if not result:
result = memcache.delete(unique_key)
# If we could not clear the cached value for this token, refuse to save.
if result == 0:
return False
# Save to the datastore.
if Token(key_name=unique_key, t=token_str).put():
return True
return None
def delete_token(unique_key):
# Clear from memcache.
memcache.delete(unique_key)
# Clear from the datastore.
Token(key_name=unique_key).delete()
def get_and_delete_user_messages(self):
"""
Get all of the messages for the current user; removing them.
"""
if self.facebook.uid:
key = 'messages:%s' % self.facebook.uid
if not hasattr(self, '_messages') or self._messages is None:
self._messages = memcache.get(key)
memcache.delete(key)
return self._messages
return None
def _expire_conversation(self):
memcache.delete(self._convo_mckey())
def post(self):
"""Handle modifying actions and/or redirect to GET page."""
next_param = {}
if self.request.get('action:flush'):
if memcache.flush_all():
next_param['message'] = 'Cache flushed, all keys dropped.'
else:
next_param['message'] = 'Flushing the cache failed. Please try again.'
elif self.request.get('action:display'):
next_param['key'] = self.request.get('key')
elif self.request.get('action:edit'):
next_param['edit'] = self.request.get('key')
elif self.request.get('action:delete'):
key = self.request.get('key')
result = memcache.delete(key)
if result == memcache.DELETE_NETWORK_FAILURE:
next_param['message'] = ('ERROR: Network failure, key "%s" not deleted.'
% key)
elif result == memcache.DELETE_ITEM_MISSING:
next_param['message'] = 'Key "%s" not in cache.' % key
elif result == memcache.DELETE_SUCCESSFUL:
next_param['message'] = 'Key "%s" deleted.' % key
else:
next_param['message'] = ('Unknown return value. Key "%s" might still '
'exist.' % key)
elif self.request.get('action:save'):
key = self.request.get('key')
value = self.request.get('value')
type_ = self.request.get('type')
next_param['key'] = key
try:
if self._SetValue(key, type_, value):
next_param['message'] = 'Key "%s" saved.' % key
else:
next_param['message'] = 'ERROR: Failed to save key "%s".' % key
except ValueError, e:
next_param['message'] = 'ERROR: Unable to encode value: %s' % e
elif self.request.get('action:cancel'):
next_param['key'] = self.request.get('key')
else:
next_param['message'] = 'Unknown action.'
next = self.request.path_url
if next_param:
next = '%s?%s' % (next, self._urlencode(next_param))
self.redirect(next)
def post(self):
"""Handle modifying actions and/or redirect to GET page."""
next_param = {}
if self.request.get('action:flush'):
if memcache.flush_all():
next_param['message'] = 'Cache flushed, all keys dropped.'
else:
next_param['message'] = 'Flushing the cache failed. Please try again.'
elif self.request.get('action:display'):
next_param['key'] = self.request.get('key')
elif self.request.get('action:edit'):
next_param['edit'] = self.request.get('key')
elif self.request.get('action:delete'):
key = self.request.get('key')
result = memcache.delete(key)
if result == memcache.DELETE_NETWORK_FAILURE:
next_param['message'] = ('ERROR: Network failure, key "%s" not deleted.'
% key)
elif result == memcache.DELETE_ITEM_MISSING:
next_param['message'] = 'Key "%s" not in cache.' % key
elif result == memcache.DELETE_SUCCESSFUL:
next_param['message'] = 'Key "%s" deleted.' % key
else:
next_param['message'] = ('Unknown return value. Key "%s" might still '
'exist.' % key)
elif self.request.get('action:save'):
key = self.request.get('key')
value = self.request.get('value')
type_ = self.request.get('type')
next_param['key'] = key
converter = self.FRIENDLY_TYPE_NAME_TO_CONVERTER[type_]
try:
memcache_value = converter.to_cache(value)
except ValueError as e:
next_param['message'] = 'ERROR: Failed to save key "%s": %s.' % (key, e)
else:
if self._set_memcache_value(key,
memcache_value,
converter.memcache_type):
next_param['message'] = 'Key "%s" saved.' % key
else:
next_param['message'] = 'ERROR: Failed to save key "%s".' % key
elif self.request.get('action:cancel'):
next_param['key'] = self.request.get('key')
else:
next_param['message'] = 'Unknown action.'
next = self.request.path_url
if next_param:
next = '%s?%s' % (next, self._urlencode(next_param))
self.redirect(next)
