def call(self, callee, callargs, policy, expiration=None, ondefer=None):
"""
invokes the callee with callargs through the cache, with the
given cache policy. This is the main user-space method. It
returns a CacheEntry instance. The entry will only be
guaranteed to have storage if policy.store is true.
"""
# the canonical name and cache key are needed both for
# retrieve and store; just get them once
debug("policy is %r", policy)
if expiration is not None:
expiration = time_convert(expiration)
args, kwargs = self._unpack_callargs(callargs)
if policy.defer and ondefer is None:
warnings.warn(
"cache policy DEFER in use without a deferral callback")
if policy.retrieve or policy.store:
cn = self.getCanonicalName(callee)
ck = self.getCacheKey((args, kwargs), False)
if policy.retrieve:
# has the callee changed since last checked?
self.validateCallable(callee, cn)
# get the cache entry if it exists
entry = self._retrieve(cn, ck)
if entry and policy.accept(entry):
entry.retrieved = time()
if policy.defer and ondefer:
ondefer(callee, callargs, expiration)
return entry
if policy.calculate or policy.defer:
val = callee(*args, **kwargs)
# the callee has a chance to determine the expiration by
# sending it out of band, through an "expiration"
# attribute. otherwise, value passed to this method will
# be used.
now = time()
expiration = getattr(callee, 'expiration', expiration) or 0
if expiration:
expiration = time_convert(expiration)
entry = CacheEntry(val,
created=now,
retrieved=now,
expiration=expiration)
else:
raise NotInCache, (callee, callargs)
if policy.store:
self._store(entry, cn, ck)
return entry
def _store(self, entry, canonicalName, cacheKey):
entry.stored=time.time()
p=self._path_for_name_and_key(canonicalName, cacheKey)
debug("cache path is %r", p)
dname=dirname(p)
try:
os.makedirs(dname)
except OSError, e:
if e.errno!=errno.EEXIST:
raise
def _store(self, entry, canonicalName, cacheKey):
entry.stored = time.time()
p = self._path_for_name_and_key(canonicalName, cacheKey)
debug("cache path is %r", p)
dname = dirname(p)
try:
os.makedirs(dname)
except OSError, e:
if e.errno != errno.EEXIST:
raise
def _store(self, entry, canonicalName, cacheKey):
entry.stored=time.time()
p=self._path_for_name_and_key(canonicalName, cacheKey)
debug("cache path is %r", p)
dname=dirname(p)
try:
os.makedirs(dname)
except OSError, e:
if e.errno!=errno.EEXIST:
if self.safe:
exception("error trying to create directory %s", dname)
else:
raise
def call(self,
callee,
callargs,
policy,
expiration=None,
ondefer=None):
"""
invokes the callee with callargs through the cache, with the
given cache policy. This is the main user-space method. It
returns a CacheEntry instance. The entry will only be
guaranteed to have storage if policy.store is true.
"""
# the canonical name and cache key are needed both for
# retrieve and store; just get them once
debug("policy is %r", policy)
if expiration is not None:
expiration=time_convert(expiration)
args, kwargs=self._unpack_callargs(callargs)
if policy.defer and ondefer is None:
warnings.warn("cache policy DEFER in use without a deferral callback")
if policy.retrieve or policy.store:
cn=self.getCanonicalName(callee)
ck=self.getCacheKey((args, kwargs), False)
if policy.retrieve:
# has the callee changed since last checked?
self.validateCallable(callee, cn)
# get the cache entry if it exists
entry=self._retrieve(cn, ck)
if entry and policy.accept(entry):
entry.retrieved=time()
if policy.defer and ondefer:
ondefer(callee, callargs, expiration)
return entry
if policy.calculate or policy.defer:
val=callee(*args, **kwargs)
# the callee has a chance to determine the expiration by
# sending it out of band, through an "expiration"
# attribute. otherwise, value passed to this method will
# be used.
now=time()
expiration=getattr(callee, 'expiration', expiration) or 0
if expiration:
expiration=time_convert(expiration)
entry=CacheEntry(val,
created=now,
retrieved=now,
expiration=expiration)
else:
raise NotInCache, (callee, callargs)
if policy.store:
self._store(entry, cn, ck)
return entry
