[3] | 1 | from __future__ import absolute_import |
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| 2 | import cPickle |
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| 3 | import logging |
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| 4 | from datetime import datetime |
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| 5 | |
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| 6 | from beaker.container import OpenResourceNamespaceManager, Container |
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| 7 | from beaker.exceptions import InvalidCacheBackendError |
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| 8 | from beaker.synchronization import null_synchronizer |
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| 9 | |
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| 10 | log = logging.getLogger(__name__) |
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| 11 | |
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| 12 | try: |
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| 13 | from google.appengine.ext import db |
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| 14 | except ImportError: |
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| 15 | raise InvalidCacheBackendError("Datastore cache backend requires the " |
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| 16 | "'google.appengine.ext' library") |
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| 17 | |
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| 18 | |
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| 19 | class GoogleNamespaceManager(OpenResourceNamespaceManager): |
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| 20 | tables = {} |
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| 21 | |
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| 22 | def __init__(self, namespace, table_name='beaker_cache', **params): |
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| 23 | """Creates a datastore namespace manager""" |
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| 24 | OpenResourceNamespaceManager.__init__(self, namespace) |
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| 25 | |
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| 26 | def make_cache(): |
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| 27 | table_dict = dict(created=db.DateTimeProperty(), |
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| 28 | accessed=db.DateTimeProperty(), |
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| 29 | data=db.BlobProperty()) |
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| 30 | table = type(table_name, (db.Model,), table_dict) |
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| 31 | return table |
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| 32 | self.table_name = table_name |
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| 33 | self.cache = GoogleNamespaceManager.tables.setdefault(table_name, make_cache()) |
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| 34 | self.hash = {} |
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| 35 | self._is_new = False |
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| 36 | self.loaded = False |
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| 37 | self.log_debug = logging.DEBUG >= log.getEffectiveLevel() |
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| 38 | |
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| 39 | # Google wants namespaces to start with letters, change the namespace |
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| 40 | # to start with a letter |
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| 41 | self.namespace = 'p%s' % self.namespace |
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| 42 | |
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| 43 | def get_access_lock(self): |
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| 44 | return null_synchronizer() |
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| 45 | |
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| 46 | def get_creation_lock(self, key): |
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| 47 | # this is weird, should probably be present |
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| 48 | return null_synchronizer() |
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| 49 | |
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| 50 | def do_open(self, flags): |
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| 51 | # If we already loaded the data, don't bother loading it again |
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| 52 | if self.loaded: |
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| 53 | self.flags = flags |
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| 54 | return |
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| 55 | |
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| 56 | item = self.cache.get_by_key_name(self.namespace) |
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| 57 | |
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| 58 | if not item: |
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| 59 | self._is_new = True |
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| 60 | self.hash = {} |
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| 61 | else: |
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| 62 | self._is_new = False |
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| 63 | try: |
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| 64 | self.hash = cPickle.loads(str(item.data)) |
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| 65 | except (IOError, OSError, EOFError, cPickle.PickleError): |
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| 66 | if self.log_debug: |
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| 67 | log.debug("Couln't load pickle data, creating new storage") |
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| 68 | self.hash = {} |
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| 69 | self._is_new = True |
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| 70 | self.flags = flags |
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| 71 | self.loaded = True |
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| 72 | |
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| 73 | def do_close(self): |
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| 74 | if self.flags is not None and (self.flags == 'c' or self.flags == 'w'): |
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| 75 | if self._is_new: |
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| 76 | item = self.cache(key_name=self.namespace) |
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| 77 | item.data = cPickle.dumps(self.hash) |
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| 78 | item.created = datetime.now() |
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| 79 | item.accessed = datetime.now() |
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| 80 | item.put() |
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| 81 | self._is_new = False |
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| 82 | else: |
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| 83 | item = self.cache.get_by_key_name(self.namespace) |
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| 84 | item.data = cPickle.dumps(self.hash) |
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| 85 | item.accessed = datetime.now() |
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| 86 | item.put() |
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| 87 | self.flags = None |
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| 88 | |
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| 89 | def do_remove(self): |
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| 90 | item = self.cache.get_by_key_name(self.namespace) |
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| 91 | item.delete() |
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| 92 | self.hash = {} |
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| 93 | |
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| 94 | # We can retain the fact that we did a load attempt, but since the |
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| 95 | # file is gone this will be a new namespace should it be saved. |
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| 96 | self._is_new = True |
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| 97 | |
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| 98 | def __getitem__(self, key): |
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| 99 | return self.hash[key] |
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| 100 | |
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| 101 | def __contains__(self, key): |
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| 102 | return self.hash.has_key(key) |
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| 103 | |
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| 104 | def __setitem__(self, key, value): |
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| 105 | self.hash[key] = value |
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| 106 | |
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| 107 | def __delitem__(self, key): |
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| 108 | del self.hash[key] |
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| 109 | |
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| 110 | def keys(self): |
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| 111 | return self.hash.keys() |
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| 112 | |
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| 113 | |
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| 114 | class GoogleContainer(Container): |
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| 115 | namespace_class = GoogleNamespaceManager |
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