code.grnet.gr Git - pithos/blob - snf-pithos-backend/pithos/backends/lib/sqlalchemy/xfeatures.py

   1 # Copyright 2011-2012 GRNET S.A. All rights reserved.
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  32 # or implied, of GRNET S.A.
  33
  34 from collections import defaultdict
  35 from sqlalchemy import Table, Column, String, Integer, MetaData, ForeignKey
  36 from sqlalchemy.sql import select, and_
  37 from sqlalchemy.schema import Index
  38 from sqlalchemy.sql.expression import desc
  39 from sqlalchemy.exc import NoSuchTableError
  40
  41 from dbworker import DBWorker
  42
  43 def create_tables(engine):
  44     metadata = MetaData()
  45     columns=[]
  46     columns.append(Column('feature_id', Integer, primary_key=True))
  47     columns.append(Column('path', String(2048)))
  48     xfeatures = Table('xfeatures', metadata, *columns, mysql_engine='InnoDB')
  49     # place an index on path
  50     Index('idx_features_path', xfeatures.c.path, unique=True)
  51
  52     columns=[]
  53     columns.append(Column('feature_id', Integer,
  54                           ForeignKey('xfeatures.feature_id',
  55                                      ondelete='CASCADE'),
  56                           primary_key=True))
  57     columns.append(Column('key', Integer, primary_key=True,
  58                           autoincrement=False))
  59     columns.append(Column('value', String(256), primary_key=True))
  60     xfeaturevals = Table('xfeaturevals', metadata, *columns, mysql_engine='InnoDB')
  61
  62     metadata.create_all(engine)
  63     return metadata.sorted_tables
  64
  65 class XFeatures(DBWorker):
  66     """XFeatures are path properties that allow non-nested
  67        inheritance patterns. Currently used for storing permissions.
  68     """
  69
  70     def __init__(self, **params):
  71         DBWorker.__init__(self, **params)
  72         try:
  73             metadata = MetaData(self.engine)
  74             self.xfeatures = Table('xfeatures', metadata, autoload=True)
  75             self.xfeaturevals = Table('xfeaturevals', metadata, autoload=True)
  76         except NoSuchTableError:
  77             tables = create_tables(self.engine)
  78             map(lambda t: self.__setattr__(t.name, t), tables)
  79
  80 #     def xfeature_inherit(self, path):
  81 #         """Return the (path, feature) inherited by the path, or None."""
  82 #
  83 #         s = select([self.xfeatures.c.path, self.xfeatures.c.feature_id])
  84 #         s = s.where(self.xfeatures.c.path <= path)
  85 #         #s = s.where(self.xfeatures.c.path.like(self.escape_like(path) + '%', escape='\\')) # XXX: Implement reverse and escape like...
  86 #         s = s.order_by(desc(self.xfeatures.c.path))
  87 #         r = self.conn.execute(s)
  88 #         l = r.fetchall()
  89 #         r.close()
  90 #         return l
  91
  92     def xfeature_get(self, path):
  93         """Return feature for path."""
  94
  95         s = select([self.xfeatures.c.feature_id])
  96         s = s.where(self.xfeatures.c.path == path)
  97         s = s.order_by(self.xfeatures.c.path)
  98         r = self.conn.execute(s)
  99         row = r.fetchone()
 100         r.close()
 101         if row:
 102             return row[0]
 103         return None
 104
 105     def xfeature_create(self, path):
 106         """Create and return a feature for path.
 107            If the path has a feature, return it.
 108         """
 109
 110         feature = self.xfeature_get(path)
 111         if feature is not None:
 112             return feature
 113         s = self.xfeatures.insert()
 114         r = self.conn.execute(s, path=path)
 115         inserted_primary_key = r.inserted_primary_key[0]
 116         r.close()
 117         return inserted_primary_key
 118
 119     def xfeature_destroy(self, path):
 120         """Destroy a feature and all its key, value pairs."""
 121
 122         s = self.xfeatures.delete().where(self.xfeatures.c.path == path)
 123         r = self.conn.execute(s)
 124         r.close()
 125
 126     def xfeature_destroy_bulk(self, paths):
 127         """Destroy features and all their key, value pairs."""
 128
 129         s = self.xfeatures.delete().where(self.xfeatures.c.path.in_(paths))
 130         r = self.conn.execute(s)
 131         r.close()
 132
 133     def feature_dict(self, feature):
 134         """Return a dict mapping keys to list of values for feature."""
 135
 136         s = select([self.xfeaturevals.c.key, self.xfeaturevals.c.value])
 137         s = s.where(self.xfeaturevals.c.feature_id == feature)
 138         r = self.conn.execute(s)
 139         d = defaultdict(list)
 140         for key, value in r.fetchall():
 141             d[key].append(value)
 142         r.close()
 143         return d
 144
 145     def feature_set(self, feature, key, value):
 146         """Associate a key, value pair with a feature."""
 147
 148         s = self.xfeaturevals.select()
 149         s = s.where(self.xfeaturevals.c.feature_id == feature)
 150         s = s.where(self.xfeaturevals.c.key == key)
 151         s = s.where(self.xfeaturevals.c.value == value)
 152         r = self.conn.execute(s)
 153         xfeaturevals = r.fetchall()
 154         r.close()
 155         if len(xfeaturevals) == 0:
 156             s = self.xfeaturevals.insert()
 157             r = self.conn.execute(s, feature_id=feature, key=key, value=value)
 158             r.close()
 159
 160     def feature_setmany(self, feature, key, values):
 161         """Associate the given key, and values with a feature."""
 162
 163         #TODO: more efficient way to do it
 164         for v in values:
 165             self.feature_set(feature, key, v)
 166
 167     def feature_unset(self, feature, key, value):
 168         """Disassociate a key, value pair from a feature."""
 169
 170         s = self.xfeaturevals.delete()
 171         s = s.where(and_(self.xfeaturevals.c.feature_id == feature,
 172                      self.xfeaturevals.c.key == key,
 173                      self.xfeaturevals.c.value == value))
 174         r = self.conn.execute(s)
 175         r.close()
 176
 177     def feature_unsetmany(self, feature, key, values):
 178         """Disassociate the key for the values given, from a feature."""
 179
 180         for v in values:
 181             conditional = and_(self.xfeaturevals.c.feature_id == feature,
 182                                self.xfeaturevals.c.key == key,
 183                                self.xfeaturevals.c.value == v)
 184             s = self.xfeaturevals.delete().where(conditional)
 185             r = self.conn.execute(s)
 186             r.close()
 187
 188     def feature_get(self, feature, key):
 189         """Return the list of values for a key of a feature."""
 190
 191         s = select([self.xfeaturevals.c.value])
 192         s = s.where(and_(self.xfeaturevals.c.feature_id == feature,
 193                      self.xfeaturevals.c.key == key))
 194         r = self.conn.execute(s)
 195         l = [row[0] for row in r.fetchall()]
 196         r.close()
 197         return l
 198
 199     def feature_clear(self, feature, key):
 200         """Delete all key, value pairs for a key of a feature."""
 201
 202         s = self.xfeaturevals.delete()
 203         s = s.where(and_(self.xfeaturevals.c.feature_id == feature,
 204                      self.xfeaturevals.c.key == key))
 205         r = self.conn.execute(s)
 206         r.close()