def __init__(
self,
identifier = None, #name under which the cache file is stored. defaults to modulename.objname
environment = None, #object containing information regarding the dependencies on global state of the cached operation
operation = None, #function to be cached. note that the order of arguments is significant for key reuse
hierarchy = None, #key hierarchy; if and how args and kwargs are hierarchically ordered
validate = False, #validation mode. if enabled, all cache retrievals are checked against a recomputed function call.
deferred_timeout = 30, #time to wait before a deferred object is considered obsolete. compilation may take a long time; that said, it may also crash your process...
lock_timeout = 1, #time to wait before a lock is considered obsolete. the lock is needed for pure db transactions only; this makes once second a long time
environment_clear = True, #clear the cache upon connection with a novel environment key
connect_clear = False #clear the cache upon every connection
):
"""
if environment_clear is set to true, the cache is cleared
"""
if identifier: self.identifier = identifier
if operation: self.operation = operation
self.hierarchy = hierarchy
#add some essentials to the environment
import platform
globalenv = platform.architecture(), platform.python_version()
funcenv = inspect.getargspec(self.operation), inspect.getsource(self.operation)
self.environment = globalenv, funcenv, (environment if environment else self.environment())
estr, ehash = process_key(self.environment)
self.validate = validate
self.lock_timeout = lock_timeout
self.deferred_timeout = deferred_timeout
self.filename = os.path.join(cachepath, self.identifier)
self.shelve = Shelve(self.filename, autocommit = True)
self.lock = threading.Lock()
self.lock_file = lockfile.MkdirLockFile(self.filename, timeout = lock_timeout)
with self.lock, self.lock_file:
if connect_clear:
#this isnt right; we are now invalidating the precomputed envrowid of other processes...
self.shelve.clear() #need write lock here
#write environment key to database and obtain its unique rowid
try:
self.envrowid = self.shelve.getrowid(self.environment, estr, ehash)
except:
#connect to the db with a novel environment; probably wont change back again
if environment_clear:
self.shelve.clear() #need write lock here
self.shelve.setitem(self.environment, None, estr, ehash)
self.envrowid = self.shelve.getrowid(self.environment, estr, ehash)
def __init__(self, path):
self.path = path
self.lock = mkdirlockfile.MkdirLockFile(self.path, threaded=True)