[3] | 1 | import cPickle |
---|
| 2 | import logging |
---|
| 3 | import pickle |
---|
| 4 | from datetime import datetime |
---|
| 5 | |
---|
| 6 | from beaker.container import OpenResourceNamespaceManager, Container |
---|
| 7 | from beaker.exceptions import InvalidCacheBackendError, MissingCacheParameter |
---|
| 8 | from beaker.synchronization import file_synchronizer, null_synchronizer |
---|
| 9 | from beaker.util import verify_directory, SyncDict |
---|
| 10 | |
---|
| 11 | sa_version = None |
---|
| 12 | |
---|
| 13 | log = logging.getLogger(__name__) |
---|
| 14 | |
---|
| 15 | try: |
---|
| 16 | import sqlalchemy as sa |
---|
| 17 | import sqlalchemy.pool as pool |
---|
| 18 | from sqlalchemy import types |
---|
| 19 | sa_version = '0.3' |
---|
| 20 | except ImportError: |
---|
| 21 | raise InvalidCacheBackendError("Database cache backend requires the 'sqlalchemy' library") |
---|
| 22 | |
---|
| 23 | if not hasattr(sa, 'BoundMetaData'): |
---|
| 24 | sa_version = '0.4' |
---|
| 25 | |
---|
| 26 | class DatabaseNamespaceManager(OpenResourceNamespaceManager): |
---|
| 27 | metadatas = SyncDict() |
---|
| 28 | tables = SyncDict() |
---|
| 29 | |
---|
| 30 | def __init__(self, namespace, url=None, sa_opts=None, optimistic=False, |
---|
| 31 | table_name='beaker_cache', data_dir=None, lock_dir=None, |
---|
| 32 | **params): |
---|
| 33 | """Creates a database namespace manager |
---|
| 34 | |
---|
| 35 | ``url`` |
---|
| 36 | SQLAlchemy compliant db url |
---|
| 37 | ``sa_opts`` |
---|
| 38 | A dictionary of SQLAlchemy keyword options to initialize the engine |
---|
| 39 | with. |
---|
| 40 | ``optimistic`` |
---|
| 41 | Use optimistic session locking, note that this will result in an |
---|
| 42 | additional select when updating a cache value to compare version |
---|
| 43 | numbers. |
---|
| 44 | ``table_name`` |
---|
| 45 | The table name to use in the database for the cache. |
---|
| 46 | """ |
---|
| 47 | OpenResourceNamespaceManager.__init__(self, namespace) |
---|
| 48 | |
---|
| 49 | if sa_opts is None: |
---|
| 50 | sa_opts = params |
---|
| 51 | |
---|
| 52 | if lock_dir: |
---|
| 53 | self.lock_dir = lock_dir |
---|
| 54 | elif data_dir: |
---|
| 55 | self.lock_dir = data_dir + "/container_db_lock" |
---|
| 56 | if self.lock_dir: |
---|
| 57 | verify_directory(self.lock_dir) |
---|
| 58 | |
---|
| 59 | # Check to see if the table's been created before |
---|
| 60 | url = url or sa_opts['sa.url'] |
---|
| 61 | table_key = url + table_name |
---|
| 62 | def make_cache(): |
---|
| 63 | # Check to see if we have a connection pool open already |
---|
| 64 | meta_key = url + table_name |
---|
| 65 | def make_meta(): |
---|
| 66 | if sa_version == '0.3': |
---|
| 67 | if url.startswith('mysql') and not sa_opts: |
---|
| 68 | sa_opts['poolclass'] = pool.QueuePool |
---|
| 69 | engine = sa.create_engine(url, **sa_opts) |
---|
| 70 | meta = sa.BoundMetaData(engine) |
---|
| 71 | else: |
---|
| 72 | # SQLAlchemy pops the url, this ensures it sticks around |
---|
| 73 | # later |
---|
| 74 | sa_opts['sa.url'] = url |
---|
| 75 | engine = sa.engine_from_config(sa_opts, 'sa.') |
---|
| 76 | meta = sa.MetaData() |
---|
| 77 | meta.bind = engine |
---|
| 78 | return meta |
---|
| 79 | meta = DatabaseNamespaceManager.metadatas.get(meta_key, make_meta) |
---|
| 80 | # Create the table object and cache it now |
---|
| 81 | cache = sa.Table(table_name, meta, |
---|
| 82 | sa.Column('id', types.Integer, primary_key=True), |
---|
| 83 | sa.Column('namespace', types.String(255), nullable=False), |
---|
| 84 | sa.Column('accessed', types.DateTime, nullable=False), |
---|
| 85 | sa.Column('created', types.DateTime, nullable=False), |
---|
| 86 | sa.Column('data', types.PickleType, nullable=False), |
---|
| 87 | sa.UniqueConstraint('namespace') |
---|
| 88 | ) |
---|
| 89 | cache.create(checkfirst=True) |
---|
| 90 | return cache |
---|
| 91 | self.hash = {} |
---|
| 92 | self._is_new = False |
---|
| 93 | self.loaded = False |
---|
| 94 | self.cache = DatabaseNamespaceManager.tables.get(table_key, make_cache) |
---|
| 95 | |
---|
| 96 | def get_access_lock(self): |
---|
| 97 | return null_synchronizer() |
---|
| 98 | |
---|
| 99 | def get_creation_lock(self, key): |
---|
| 100 | return file_synchronizer( |
---|
| 101 | identifier ="databasecontainer/funclock/%s" % self.namespace, |
---|
| 102 | lock_dir = self.lock_dir) |
---|
| 103 | |
---|
| 104 | def do_open(self, flags): |
---|
| 105 | # If we already loaded the data, don't bother loading it again |
---|
| 106 | if self.loaded: |
---|
| 107 | self.flags = flags |
---|
| 108 | return |
---|
| 109 | |
---|
| 110 | cache = self.cache |
---|
| 111 | result = sa.select([cache.c.data], |
---|
| 112 | cache.c.namespace==self.namespace |
---|
| 113 | ).execute().fetchone() |
---|
| 114 | if not result: |
---|
| 115 | self._is_new = True |
---|
| 116 | self.hash = {} |
---|
| 117 | else: |
---|
| 118 | self._is_new = False |
---|
| 119 | try: |
---|
| 120 | self.hash = result['data'] |
---|
| 121 | except (IOError, OSError, EOFError, cPickle.PickleError, |
---|
| 122 | pickle.PickleError): |
---|
| 123 | log.debug("Couln't load pickle data, creating new storage") |
---|
| 124 | self.hash = {} |
---|
| 125 | self._is_new = True |
---|
| 126 | self.flags = flags |
---|
| 127 | self.loaded = True |
---|
| 128 | |
---|
| 129 | def do_close(self): |
---|
| 130 | if self.flags is not None and (self.flags == 'c' or self.flags == 'w'): |
---|
| 131 | cache = self.cache |
---|
| 132 | if self._is_new: |
---|
| 133 | cache.insert().execute(namespace=self.namespace, data=self.hash, |
---|
| 134 | accessed=datetime.now(), |
---|
| 135 | created=datetime.now()) |
---|
| 136 | self._is_new = False |
---|
| 137 | else: |
---|
| 138 | cache.update(cache.c.namespace==self.namespace).execute( |
---|
| 139 | data=self.hash, accessed=datetime.now()) |
---|
| 140 | self.flags = None |
---|
| 141 | |
---|
| 142 | def do_remove(self): |
---|
| 143 | cache = self.cache |
---|
| 144 | cache.delete(cache.c.namespace==self.namespace).execute() |
---|
| 145 | self.hash = {} |
---|
| 146 | |
---|
| 147 | # We can retain the fact that we did a load attempt, but since the |
---|
| 148 | # file is gone this will be a new namespace should it be saved. |
---|
| 149 | self._is_new = True |
---|
| 150 | |
---|
| 151 | def __getitem__(self, key): |
---|
| 152 | return self.hash[key] |
---|
| 153 | |
---|
| 154 | def __contains__(self, key): |
---|
| 155 | return self.hash.has_key(key) |
---|
| 156 | |
---|
| 157 | def __setitem__(self, key, value): |
---|
| 158 | self.hash[key] = value |
---|
| 159 | |
---|
| 160 | def __delitem__(self, key): |
---|
| 161 | del self.hash[key] |
---|
| 162 | |
---|
| 163 | def keys(self): |
---|
| 164 | return self.hash.keys() |
---|
| 165 | |
---|
| 166 | class DatabaseContainer(Container): |
---|
| 167 | namespace_manager = DatabaseNamespaceManager |
---|