root/trunk/storage/storemysql.py

"""
References the MySQLdb package at:
http://sourceforge.net/projects/mysql-python

From the MySQL manual:

"If the server SQL mode has ANSI_QUOTES enabled, string literals can be
quoted only with single quotes. A string quoted with double quotes will be
interpreted as an identifier."

So use single quotes throughout.
"""

# Use _mysql directly to avoid all of the DB-API overhead.
import _mysql
import datetime
from dejavu import storage, logic
from dejavu.storage import db


class AdapterToMySQL(db.AdapterToSQL):
    
    escapes = [("'", "''"), ("\\", r"\\")]
    like_escapes = [("%", r"\%"), ("_", r"\_")]
    
    def coerce_str(self, value):
        return "'" + _mysql.escape_string(value) + "'"


class AdapterFromMySQL(db.AdapterFromDB):
    
    def coerce_bool(self, value, coltype):
        if isinstance(value, basestring):
            # either '0' or '1'
            value = (value == '1')
        return bool(value)
    
    def coerce_unicode(self, value, coltype):
        return unicode(value, "utf-8")


class MySQLDecompiler(db.SQLDecompiler):
    
    def column_name(self, name):
        # MySQL forces lowercase column names.
        return '%s.`%s`' % (self.tablename, name.lower())
    
    # --------------------------- Dispatchees --------------------------- #
    
    def dejavu_today(self):
        return "CURDATE()"


class MySQLDecompiler411(MySQLDecompiler):
    # Before MySQL 4.1.1, BINARY comparisons could use UPPER()
    # or LOWER() to perform case-insensitive comparisons. Newer
    # versions must use CONVERT() to obtain a case-sensitive
    # encoding, like utf8.
    
    def dejavu_icontainedby(self, op1, op2):
        if isinstance(op1, db.ConstWrapper):
            # Looking for text in a field. Use Like (reverse terms).
            return ("CONVERT("+ op2 + " USING utf8) LIKE '%" +
                    self.adapter.escape_like(op1) + "%'")
        else:
            # Looking for field in (a, b, c).
            atoms = [self.adapter.coerce(x) for x in op2.basevalue]
            return "CONVERT(%s USING utf8) IN (%s)" % (op1, ", ".join(atoms))
    
    def dejavu_istartswith(self, x, y):
        return ("CONVERT(" + x + " USING utf8) LIKE '" +
                self.adapter.escape_like(y) + "%'")
    
    def dejavu_iendswith(self, x, y):
        return ("CONVERT(" + x + " USING utf8) LIKE '%" +
                self.adapter.escape_like(y) + "'")
    
    def dejavu_ieq(self, x, y):
        return "CONVERT(" + x + " USING utf8) = " + y


class FieldTypeAdapterMySQL(db.FieldTypeAdapter):
    """Return the SQL typename of a DB column."""
    
    # This was determined through experimentation. Don't change it.
    numeric_max_precision = 253
    
    def coerce_str(self, cls, key):
        prop = getattr(cls, key)
        bytes = int(prop.hints.get(u'bytes', '0'))
        if bytes:
            # MySQL VARBINARY/BLOBs will do case-sensitive comparisons.
            # They also won't truncate trailing spaces like VARCHAR does.
            if bytes <= 255:
                return u"VARBINARY(%s) CHARACTER SET utf8" % bytes
            elif bytes < 2 ** 16:
                return "BLOB"
            elif bytes < 2 ** 24:
                return "MEDIUMBLOB"
        return u"LONGBLOB"
    
    def coerce_bool(self, cls, key):
        # We could use BOOLEAN, but it wasn't introduced until 4.1.0.
        return u"BOOL"
    
    def coerce_datetime_datetime(self, cls, key):
        return u"DATETIME"


class StorageManagerMySQL(db.StorageManagerDB):
    """StoreManager to save and retrieve Units via _mysql."""
    
    identifier_length = 64
    identifier_caseless = True
    typeAdapter = FieldTypeAdapterMySQL()
    toAdapter = AdapterToMySQL()
    fromAdapter = AdapterFromMySQL()
    
    def __init__(self, name, arena, allOptions={}):
        db.StorageManagerDB.__init__(self, name, arena, allOptions)
        
        connargs = ["host", "user", "passwd", "db", "port", "unix_socket",
                    "conv", "connect_time", "compress", "named_pipe",
                    "init_command", "read_default_file", "read_default_group",
                    "cursorclass", "client_flag",
                    ]
        self.connargs = dict([(k, v) for k, v in allOptions.iteritems()
                              if k in connargs])
        self.dbname = self.connargs['db']
        
        self.decompiler = MySQLDecompiler
        # Try to get the version string from MySQL, to see if we need
        # a different decompiler.
        data, columns = self.fetch("SELECT VERSION();")
        if data:
            version = storage.Version(data[0][0])
            if version > storage.Version("4.1.1"):
                self.decompiler = MySQLDecompiler411
    
    def identifier(self, *atoms):
        # MySQL uses case-sensitive database and table names on Unix, but
        # not on Windows. Use all-lowercase identifiers to work around the
        # problem. "Column names, index names, and column aliases are not
        # case sensitive on any platform."
        # If deployers set lower_case_table_names to 1, it would help.
        ident = ''.join(map(str, atoms)).replace('`', '``').lower()
        idlen = self.identifier_length
        if idlen and len(ident) > idlen:
            warnings.warn("Identifier is longer than %s characters." % idlen)
            ident = ident[:idlen]
        return '`' + ident + '`'
    
    def _get_conn(self):
        try:
            conn = _mysql.connect(**self.connargs)
        except _mysql.OperationalError, x:
            if x.args[0] == 1040:   # Too many connections
                raise db.OutOfConnectionsError
            elif x.args[0] == 1049 and self.CreateIfMissing:
                self.create_database()
                conn = _mysql.connect(**self.connargs)
            else:
                raise
        return conn
    
    def _template_conn(self):
        tmplconn = self.connargs.copy()
        tmplconn['db'] = 'mysql'
        return _mysql.connect(**tmplconn)
    
    def create_database(self):
        # _mysql has create_db and drop_db commands, but they're deprecated.
        sql = 'CREATE DATABASE %s;' % self.identifier(self.dbname)
        conn = self._template_conn()
        self.execute(sql, conn)
        conn.close()
    
    def drop_database(self):
        sql = 'DROP DATABASE %s;' % self.identifier(self.dbname)
        conn = self._template_conn()
        self.execute(sql, conn)
        conn.close()
    
    def create_storage(self, unitClass):
        # MySQL won't allow indexes on a BLOB field without a specific length.
        tablename = self.tablename(unitClass)
        
        coerce = self.typeAdapter.coerce
        fields = []
        for key in unitClass.properties():
            fields.append(u'%s %s' % (self.identifier(key),
                                      coerce(unitClass, key)))
        self.execute(u'CREATE TABLE %s (%s);' % (tablename, ", ".join(fields)))
        
        for index in unitClass.indices():
            i = self.identifier(self.prefix, "i", unitClass.__name__, index)
            
            dbtype = coerce(unitClass, index)
            if dbtype.endswith('BLOB') or dbtype == 'TEXT':
                self.execute(u'CREATE INDEX %s ON %s (%s(%s));' %
                             (i, tablename, self.identifier(index), 255))
            else:
                self.execute(u'CREATE INDEX %s ON %s (%s);' %
                             (i, tablename, self.identifier(index)))
    
    def fetch(self, query, conn=None):
        """fetch(query, conn=None) -> rowdata, columns.
        
        rowdata: a nested list (or tuples), column values within rows.
        columns: a series of 2-tuples (or more). The first tuple value
            will be the column name, the second value will be the column
            type.
        """
        if conn is None:
            conn = self.connection()
        self.execute(query, conn)
        # store_result uses a client-side cursor
        res = conn.store_result()
        return res.fetch_row(0, 0), res.describe()
    
    def destroy(self, unit):
        """destroy(unit). Delete the unit."""
        self.execute(u'DELETE FROM %s WHERE %s = %s;' %
                     (self.tablename(unit), self.identifier("ID"),
                      self.toAdapter.coerce(unit.ID)))