caches: don't try to delete keys if there aren't any to delete.

- This is problematic for REDIS backend.

rhodecode/lib/rc_cache/utils.py

@@ -1,320 +1,322 b''
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2015-2018 RhodeCode GmbH
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License, version 3
 # (only), as published by the Free Software Foundation.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 # This program is dual-licensed. If you wish to learn more about the
 # RhodeCode Enterprise Edition, including its added features, Support services,
 # and proprietary license terms, please see https://rhodecode.com/licenses/
 import os
 import time
 import logging
 import functools
 import threading
 
 from dogpile.cache import CacheRegion
 from dogpile.cache.util import compat
 
 import rhodecode
 from rhodecode.lib.utils import safe_str, sha1
 from rhodecode.lib.utils2 import safe_unicode, str2bool
 from rhodecode.model.db import Session, CacheKey, IntegrityError
 
 from . import region_meta
 
 log = logging.getLogger(__name__)
 
 
 class RhodeCodeCacheRegion(CacheRegion):
 
     def conditional_cache_on_arguments(
             self, namespace=None,
             expiration_time=None,
             should_cache_fn=None,
             to_str=compat.string_type,
             function_key_generator=None,
             condition=True):
         """
         Custom conditional decorator, that will not touch any dogpile internals if
         condition isn't meet. This works a bit different than should_cache_fn
         And it's faster in cases we don't ever want to compute cached values
         """
         expiration_time_is_callable = compat.callable(expiration_time)
 
         if function_key_generator is None:
             function_key_generator = self.function_key_generator
 
         def decorator(fn):
             if to_str is compat.string_type:
                 # backwards compatible
                 key_generator = function_key_generator(namespace, fn)
             else:
                 key_generator = function_key_generator(namespace, fn, to_str=to_str)
 
             @functools.wraps(fn)
             def decorate(*arg, **kw):
                 key = key_generator(*arg, **kw)
 
                 @functools.wraps(fn)
                 def creator():
                     return fn(*arg, **kw)
 
                 if not condition:
                     return creator()
 
                 timeout = expiration_time() if expiration_time_is_callable \
                     else expiration_time
 
                 return self.get_or_create(key, creator, timeout, should_cache_fn)
 
             def invalidate(*arg, **kw):
                 key = key_generator(*arg, **kw)
                 self.delete(key)
 
             def set_(value, *arg, **kw):
                 key = key_generator(*arg, **kw)
                 self.set(key, value)
 
             def get(*arg, **kw):
                 key = key_generator(*arg, **kw)
                 return self.get(key)
 
             def refresh(*arg, **kw):
                 key = key_generator(*arg, **kw)
                 value = fn(*arg, **kw)
                 self.set(key, value)
                 return value
 
             decorate.set = set_
             decorate.invalidate = invalidate
             decorate.refresh = refresh
             decorate.get = get
             decorate.original = fn
             decorate.key_generator = key_generator
 
             return decorate
 
         return decorator
 
 
 def make_region(*arg, **kw):
     return RhodeCodeCacheRegion(*arg, **kw)
 
 
 def get_default_cache_settings(settings, prefixes=None):
     prefixes = prefixes or []
     cache_settings = {}
     for key in settings.keys():
         for prefix in prefixes:
             if key.startswith(prefix):
                 name = key.split(prefix)[1].strip()
                 val = settings[key]
                 if isinstance(val, basestring):
                     val = val.strip()
                 cache_settings[name] = val
     return cache_settings
 
 
 def compute_key_from_params(*args):
     """
     Helper to compute key from given params to be used in cache manager
     """
     return sha1("_".join(map(safe_str, args)))
 
 
 def key_generator(namespace, fn):
     fname = fn.__name__
 
     def generate_key(*args):
         namespace_pref = namespace or 'default'
         arg_key = compute_key_from_params(*args)
         final_key = "{}:{}_{}".format(namespace_pref, fname, arg_key)
 
         return final_key
 
     return generate_key
 
 
 def get_or_create_region(region_name, region_namespace=None):
     from rhodecode.lib.rc_cache.backends import FileNamespaceBackend
     region_obj = region_meta.dogpile_cache_regions.get(region_name)
     if not region_obj:
         raise EnvironmentError(
             'Region `{}` not in configured: {}.'.format(
                 region_name, region_meta.dogpile_cache_regions.keys()))
 
     region_uid_name = '{}:{}'.format(region_name, region_namespace)
     if isinstance(region_obj.actual_backend, FileNamespaceBackend):
         region_exist = region_meta.dogpile_cache_regions.get(region_namespace)
         if region_exist:
             log.debug('Using already configured region: %s', region_namespace)
             return region_exist
         cache_dir = region_meta.dogpile_config_defaults['cache_dir']
         expiration_time = region_obj.expiration_time
 
         if not os.path.isdir(cache_dir):
             os.makedirs(cache_dir)
         new_region = make_region(
             name=region_uid_name, function_key_generator=key_generator
         )
         namespace_filename = os.path.join(
             cache_dir, "{}.cache.dbm".format(region_namespace))
         # special type that allows 1db per namespace
         new_region.configure(
             backend='dogpile.cache.rc.file_namespace',
             expiration_time=expiration_time,
             arguments={"filename": namespace_filename}
         )
 
         # create and save in region caches
         log.debug('configuring new region: %s',region_uid_name)
         region_obj = region_meta.dogpile_cache_regions[region_namespace] = new_region
 
     return region_obj
 
 
 def clear_cache_namespace(cache_region, cache_namespace_uid):
     region = get_or_create_region(cache_region, cache_namespace_uid)
     cache_keys = region.backend.list_keys(prefix=cache_namespace_uid)
+    num_delete_keys = len(cache_keys)
+    if num_delete_keys:
     region.delete_multi(cache_keys)
-    return len(cache_keys)
+    return num_delete_keys
 
 
 class ActiveRegionCache(object):
     def __init__(self, context):
         self.context = context
 
     def should_invalidate(self):
         return False
 
 
 class FreshRegionCache(object):
     def __init__(self, context):
         self.context = context
 
     def should_invalidate(self):
         return True
 
 
 class InvalidationContext(object):
     """
     usage::
 
         from rhodecode.lib import rc_cache
 
         cache_namespace_uid = CacheKey.SOME_NAMESPACE.format(1)
         region = rc_cache.get_or_create_region('cache_perms', cache_namespace_uid)
 
         @region.conditional_cache_on_arguments(namespace=cache_namespace_uid, condition=True)
         def heavy_compute(cache_name, param1, param2):
             print('COMPUTE {}, {}, {}'.format(cache_name, param1, param2))
 
         # invalidation namespace is shared namespace key for all process caches
         # we use it to send a global signal
         invalidation_namespace = 'repo_cache:1'
 
         inv_context_manager = rc_cache.InvalidationContext(
             uid=cache_namespace_uid, invalidation_namespace=invalidation_namespace)
         with inv_context_manager as invalidation_context:
             args = ('one', 'two')
             # re-compute and store cache if we get invalidate signal
             if invalidation_context.should_invalidate():
                 result = heavy_compute.refresh(*args)
             else:
                 result = heavy_compute(*args)
 
             compute_time = inv_context_manager.compute_time
             log.debug('result computed in %.3fs' ,compute_time)
 
         # To send global invalidation signal, simply run
         CacheKey.set_invalidate(invalidation_namespace)
 
     """
 
     def __repr__(self):
         return '<InvalidationContext:{}[{}]>'.format(
             safe_str(self.cache_key), safe_str(self.uid))
 
     def __init__(self, uid, invalidation_namespace='',
                  raise_exception=False, thread_scoped=None):
         self.uid = uid
         self.invalidation_namespace = invalidation_namespace
         self.raise_exception = raise_exception
         self.proc_id = safe_unicode(rhodecode.CONFIG.get('instance_id') or 'DEFAULT')
         self.thread_id = 'global'
 
         if thread_scoped is None:
             # if we set "default" we can override this via .ini settings
             thread_scoped = str2bool(rhodecode.CONFIG.get('cache_thread_scoped'))
 
         # Append the thread id to the cache key if this invalidation context
         # should be scoped to the current thread.
         if thread_scoped is True:
             self.thread_id = threading.current_thread().ident
 
         self.cache_key = compute_key_from_params(uid)
         self.cache_key = 'proc:{}_thread:{}_{}'.format(
             self.proc_id, self.thread_id, self.cache_key)
         self.compute_time = 0
 
     def get_or_create_cache_obj(self, uid, invalidation_namespace=''):
         cache_obj = CacheKey.get_active_cache(self.cache_key)
         log.debug('Fetched cache obj %s using %s cache key.', cache_obj, self.cache_key)
         invalidation_namespace = invalidation_namespace or self.invalidation_namespace
         if not cache_obj:
             cache_obj = CacheKey(self.cache_key, cache_args=invalidation_namespace)
         return cache_obj
 
     def __enter__(self):
         """
         Test if current object is valid, and return CacheRegion function
         that does invalidation and calculation
         """
         # register or get a new key based on uid
         self.cache_obj = self.get_or_create_cache_obj(uid=self.uid)
         self._start_time = time.time()
         if self.cache_obj.cache_active:
             # means our cache obj is existing and marked as it's
             # cache is not outdated, we return ActiveRegionCache
             self.skip_cache_active_change = True
 
             return ActiveRegionCache(context=self)
 
             # the key is either not existing or set to False, we return
         # the real invalidator which re-computes value. We additionally set
         # the flag to actually update the Database objects
         self.skip_cache_active_change = False
         return FreshRegionCache(context=self)
 
     def __exit__(self, exc_type, exc_val, exc_tb):
         # save compute time
         self.compute_time = time.time() - self._start_time
 
         if self.skip_cache_active_change:
             return
 
         try:
             self.cache_obj.cache_active = True
             Session().add(self.cache_obj)
             Session().commit()
         except IntegrityError:
             # if we catch integrity error, it means we inserted this object
             # assumption is that's really an edge race-condition case and
             # it's safe is to skip it
             Session().rollback()
         except Exception:
             log.exception('Failed to commit on cache key update')
             Session().rollback()
             if self.raise_exception:
                 raise