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db.py

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'''$Id: db.py,v 1.21 2005/03/06 02:35:06 adustman Exp $'''
__version__='$Revision: 1.21 $'[11:-2]

import _mysql
from _mysql_exceptions import OperationalError, NotSupportedError
MySQLdb_version_required = (1,0,0)

_v = getattr(_mysql, 'version_info', (0,0,0))
if _v < MySQLdb_version_required:
    raise NotSupportedError, \
      "ZMySQLDA requires at least MySQLdb %s, %s found" % \
      (MySQLdb_version_required, _v)

from MySQLdb.converters import conversions
from MySQLdb.constants import FIELD_TYPE, CR, CLIENT
from Shared.DC.ZRDB.TM import TM
from DateTime import DateTime
from zLOG import LOG, ERROR, INFO

import string, sys
from string import strip, split, find, upper, rfind
from time import time

key_types = {
    "PRI": "PRIMARY KEY",
    "MUL": "INDEX",
    "UNI": "UNIQUE",
    }

field_icons = "bin", "date", "datetime", "float", "int", "text", "time"

icon_xlate = {
    "varchar": "text", "char": "text",
    "enum": "what", "set": "what",
    "double": "float", "numeric": "float",
    "blob": "bin", "mediumblob": "bin", "longblob": "bin",
    "tinytext": "text", "mediumtext": "text",
    "longtext": "text", "timestamp": "datetime",
    "decimal": "float", "smallint": "int",
    "mediumint": "int", "bigint": "int",
    }

type_xlate = {
    "double": "float", "numeric": "float",
    "decimal": "float", "smallint": "int",
    "mediumint": "int", "bigint": "int",
    "int": "int", "float": "float",
    "timestamp": "datetime", "datetime": "datetime",
    "time": "datetime",
    }
    
def _mysql_timestamp_converter(s):
      if len(s) < 14:
            s = s + "0"*(14-len(s))
        parts = map(int, (s[:4],s[4:6],s[6:8],
                          s[8:10],s[10:12],s[12:14]))
      return DateTime("%04d-%02d-%02d %02d:%02d:%02d" % tuple(parts))

def DateTime_or_None(s):
    try: return DateTime(s)
    except: return None

def int_or_long(s):
    try: return int(s)
    except: return long(s)

"""Locking strategy:

The minimum that must be done is a mutex around a query, store_result
sequence. When using transactions, the mutex must go around the
entire transaction."""

class DB(TM):

    Database_Connection=_mysql.connect
    Database_Error=_mysql.Error

    defs={
        FIELD_TYPE.CHAR: "i", FIELD_TYPE.DATE: "d",
        FIELD_TYPE.DATETIME: "d", FIELD_TYPE.DECIMAL: "n",
        FIELD_TYPE.DOUBLE: "n", FIELD_TYPE.FLOAT: "n", FIELD_TYPE.INT24: "i",
        FIELD_TYPE.LONG: "i", FIELD_TYPE.LONGLONG: "l",
        FIELD_TYPE.SHORT: "i", FIELD_TYPE.TIMESTAMP: "d",
        FIELD_TYPE.TINY: "i", FIELD_TYPE.YEAR: "i",
        }

    conv=conversions.copy()
    conv[FIELD_TYPE.LONG] = int_or_long
    conv[FIELD_TYPE.DATETIME] = DateTime_or_None
    conv[FIELD_TYPE.DATE] = DateTime_or_None
    conv[FIELD_TYPE.DECIMAL] = float
    del conv[FIELD_TYPE.TIME]
    del conv[FIELD_TYPE.BLOB]

    _p_oid=_p_changed=_registered=None

    def __init__(self,connection):
        from thread import allocate_lock
        self.connection=connection
        self.kwargs = kwargs = self._parse_connection_string(connection)
        self.db=apply(self.Database_Connection, (), kwargs)
        LOG("ZMySQLDA", INFO, "Opened new connection %s: %s" \
            % (self.db, connection)) 
        transactional = self.db.server_capabilities & CLIENT.TRANSACTIONS
        if self._try_transactions == '-':
            transactional = 0
        elif not transactional and self._try_transactions == '+':
            raise NotSupportedError, "transactions not supported by this server"
        self._use_TM = self._transactions = transactional
        if self._mysql_lock:
            self._use_TM = 1
        if self._use_TM:
            self._tlock = allocate_lock()
        self._lock = allocate_lock()

    def _parse_connection_string(self, connection):
        kwargs = {'conv': self.conv}
        items = split(connection)
        self._use_TM = None
        if not items: return kwargs
        lockreq, items = items[0], items[1:]
        if lockreq[0] == "*":
            self._mysql_lock = lockreq[1:]
            db_host, items = items[0], items[1:]
            self._use_TM = 1
        else:
            self._mysql_lock = None
            db_host = lockreq
        if '@' in db_host:
            db, host = split(db_host,'@',1)
            kwargs['db'] = db
            if ':' in host:
                host, port = split(host,':',1)
                kwargs['port'] = int(port)
            kwargs['host'] = host
        else:
            kwargs['db'] = db_host
        if kwargs['db'] and kwargs['db'][0] in ('+', '-'):
            self._try_transactions = kwargs['db'][0]
            kwargs['db'] = kwargs['db'][1:]
        else:
            self._try_transactions = None
        if not kwargs['db']:
            del kwargs['db']
        if not items: return kwargs
        kwargs['user'], items = items[0], items[1:]
        if not items: return kwargs
        kwargs['passwd'], items = items[0], items[1:]
        if not items: return kwargs
        kwargs['unix_socket'], items = items[0], items[1:]
        return kwargs
        
    def tables(self, rdb=0,
               _care=('TABLE', 'VIEW')):
        r=[]
        a=r.append
        self._lock.acquire()
        try:
            self.db.query("SHOW TABLES")
            result = self.db.store_result()
        finally:
            self._lock.release()
        row = result.fetch_row(1)
      while row:
            a({'TABLE_NAME': row[0][0], 'TABLE_TYPE': 'TABLE'})
            row = result.fetch_row(1)
        return r

    def columns(self, table_name):
        from string import join
        try:
            try:
                self._lock.acquire()
                # Field, Type, Null, Key, Default, Extra
                self.db.query('SHOW COLUMNS FROM %s' % table_name)
                c=self.db.store_result()
            finally:
                self._lock.release()
        except:
            return ()
        r=[]
        for Field, Type, Null, Key, Default, Extra in c.fetch_row(0):
            info = {}
            field_default = Default and "DEFAULT %s"%Default or ''
            if Default: info['Default'] = Default
            if '(' in Type:
                end = rfind(Type,')')
                short_type, size = split(Type[:end],'(',1)
                if short_type not in ('set','enum'):
                    if ',' in size:
                        info['Scale'], info['Precision'] = \
                                       map(int, split(size,',',1))
                    else:
                        info['Scale'] = int(size)
            else:
                short_type = Type
            if short_type in field_icons:
                info['Icon'] = short_type
            else:
                info['Icon'] = icon_xlate.get(short_type, "what")
            info['Name'] = Field
            info['Type'] = type_xlate.get(short_type,'string')
            info['Extra'] = Extra,
            info['Description'] = join([Type, field_default, Extra or '',
                                        key_types.get(Key, Key or ''),
                                        Null != 'YES' and 'NOT NULL' or '']),
            info['Nullable'] = (Null == 'YES') and 1 or 0
            if Key:
                info['Index'] = 1
            if Key == 'PRI':
                info['PrimaryKey'] = 1
                info['Unique'] = 1
            elif Key == 'UNI':
                info['Unique'] = 1
            r.append(info)
        return r

    def query(self,query_string, max_rows=1000):
        self._use_TM and self._register()
        desc=None
        result=()
        db=self.db
        try:
            self._lock.acquire()
            for qs in filter(None, map(strip,split(query_string, '\0'))):
                qtype = upper(split(qs, None, 1)[0])
                if qtype == "SELECT" and max_rows:
                    qs = "%s LIMIT %d" % (qs,max_rows)
                    r=0
                db.query(qs)
                c=db.store_result()
                if desc is not None:
                    if c and (c.describe() != desc):
                        raise 'Query Error', (
                            'Multiple select schema are not allowed'
                            )
                if c:
                    desc=c.describe()
                    result=c.fetch_row(max_rows)
                else:
                    desc=None
        finally:
            self._lock.release()

        if desc is None: return (),()

        items=[]
        func=items.append
        defs=self.defs
        for d in desc:
            item={'name': d[0],
                  'type': defs.get(d[1],"t"),
                  'width': d[2],
                  'null': d[6]
                 }
            func(item)
        return items, result

    def string_literal(self, s): return self.db.string_literal(s)

    def _begin(self, *ignored):
        self._tlock.acquire()
        try:
            self.db.ping()
            if self._transactions:
                self.db.query("BEGIN")
                self.db.store_result()
            if self._mysql_lock:
                self.db.query("SELECT GET_LOCK('%s',0)" % self._mysql_lock)
                self.db.store_result()
        except:
            LOG('ZMySQLDA', ERROR, "exception during _begin",
                error=sys.exc_info())
            self._tlock.release()
            raise
        
    def _finish(self, *ignored):
        try:
            try:
                if self._mysql_lock:
                    self.db.query("SELECT RELEASE_LOCK('%s')" % self._mysql_lock)
                    self.db.store_result()
                if self._transactions:
                    self.db.query("COMMIT")
                self.db.store_result()
            except:
                LOG('ZMySQLDA', ERROR, "exception during _finish",
                    error=sys.exc_info())
                raise
        finally:
            self._tlock.release()

    def _abort(self, *ignored):
        try:
            if self._mysql_lock:
                self.db.query("SELECT RELEASE_LOCK('%s')" % self._mysql_lock)
                self.db.store_result()
            if self._transactions:
                self.db.query("ROLLBACK")
                self.db.store_result()
            else:
                LOG('ZMySQLDA', ERROR, "aborting when non-transactional")
        finally:
            self._tlock.release()

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