bug 793: fix detection of database not completely inited

[osm/RO.git] / osm_ro / db_base.py

diff --git a/osm_ro/db_base.py b/osm_ro/db_base.py
index 2a6cd8c..e6e1134 100644 (file)
--- a/osm_ro/db_base.py
+++ b/osm_ro/db_base.py
@@ -35,16 +35,85 @@ import json
 import time
 import logging
 import datetime
 import time
 import logging
 import datetime

+from contextlib import contextmanager
+from functools import wraps, partial
+from threading import Lock

 from jsonschema import validate as js_v, exceptions as js_e
 
 from jsonschema import validate as js_v, exceptions as js_e
 

-HTTP_Bad_Request = 400
-HTTP_Unauthorized = 401 
-HTTP_Not_Found = 404 
-HTTP_Method_Not_Allowed = 405 
-HTTP_Request_Timeout = 408
-HTTP_Conflict = 409
-HTTP_Service_Unavailable = 503 
-HTTP_Internal_Server_Error = 500 
+from .http_tools import errors as httperrors
+from .utils import Attempt, get_arg, inject_args
+
+
+RECOVERY_TIME = 3
+
+_ATTEMPT = Attempt()
+
+
+def with_transaction(fn=None, cursor=None):
+    """Decorator that can be used together with instances of the ``db_base``
+    class, to perform database actions wrapped in a commit/rollback fashion
+
+    This decorator basically executes the function inside the context object
+    given by the ``transaction`` method in ``db_base``
+
+    Arguments:
+        cursor: [Optional] cursor class
+    """
+    if fn is None:  # Allows calling the decorator directly or with parameters
+        return partial(with_transaction, cursor=cursor)
+
+    @wraps(fn)
+    def _wrapper(self, *args, **kwargs):
+        cursor_type = None
+        if cursor == 'dict':
+            # MySQLdB define the "cursors" module attribute lazily,
+            # so we have to defer references to mdb.cursors.DictCursor
+            cursor_type = mdb.cursors.DictCursor
+
+        with self.transaction(cursor_type):
+            return fn(self, *args, **kwargs)
+
+    return _wrapper
+
+
+def retry(fn=None, max_attempts=Attempt.MAX, **info):
+    """Decorator that can be used together with instances of the ``db_base``
+    class, to replay a method again after a unexpected error.
+
+    The function being decorated needs to either be a method of ``db_base``
+    subclasses or accept an ``db_base`` instance as the first parameter.
+
+    All the extra keyword arguments will be passed to the ``_format_error``
+    method
+    """
+    if fn is None:  # Allows calling the decorator directly or with parameters
+        return partial(retry, max_attempts=max_attempts, **info)
+
+    @wraps(fn)
+    def _wrapper(*args, **kwargs):
+        self = args[0]
+        info.setdefault('table', get_arg('table', fn, args, kwargs))
+        attempt = Attempt(max_attempts=max_attempts, info=info)
+        while attempt.countdown >= 0:
+            try:
+                return inject_args(fn, attempt=attempt)(*args, **kwargs)
+            except (mdb.Error, AttributeError) as ex:
+                self.logger.debug("Attempt #%d", attempt.number)
+                try:
+                    # The format error will throw exceptions, however it can
+                    # tolerate a certain amount of retries if it judges that
+                    # the error can be solved with retrying
+                    self._format_error(ex, attempt.countdown, **attempt.info)
+                    # Anyway, unexpected/unknown errors can still be retried
+                except db_base_Exception as db_ex:
+                    if (attempt.countdown < 0 or db_ex.http_code !=
+                            httperrors.Internal_Server_Error):
+                        raise
+
+            attempt.count += 1
+
+    return _wrapper
+

 
 def _check_valid_uuid(uuid):
     id_schema = {"type" : "string", "pattern": "^[a-fA-F0-9]{8}(-[a-fA-F0-9]{4}){3}-[a-fA-F0-9]{12}$"}
 
 def _check_valid_uuid(uuid):
     id_schema = {"type" : "string", "pattern": "^[a-fA-F0-9]{8}(-[a-fA-F0-9]{4}){3}-[a-fA-F0-9]{12}$"}


@@ -68,7 +137,7 @@ def _convert_datetime2str(var):
         for k,v in var.items():
             if type(v) is datetime.datetime:
                 var[k]= v.strftime('%Y-%m-%dT%H:%M:%S')
         for k,v in var.items():
             if type(v) is datetime.datetime:
                 var[k]= v.strftime('%Y-%m-%dT%H:%M:%S')

-            elif type(v) is dict or type(v) is list or type(v) is tuple: 
+            elif type(v) is dict or type(v) is list or type(v) is tuple:

                 _convert_datetime2str(v)
         if len(var) == 0: return True
     elif type(var) is list or type(var) is tuple:
                 _convert_datetime2str(v)
         if len(var) == 0: return True
     elif type(var) is list or type(var) is tuple:


@@ -76,7 +145,7 @@ def _convert_datetime2str(var):
             _convert_datetime2str(v)
 
 def _convert_bandwidth(data, reverse=False, logger=None):
             _convert_datetime2str(v)
 
 def _convert_bandwidth(data, reverse=False, logger=None):

-    '''Check the field bandwidth recursivelly and when found, it removes units and convert to number 
+    '''Check the field bandwidth recursivelly and when found, it removes units and convert to number

     It assumes that bandwidth is well formed
     Attributes:
         'data': dictionary bottle.FormsDict variable to be checked. None or empty is consideted valid
     It assumes that bandwidth is well formed
     Attributes:
         'data': dictionary bottle.FormsDict variable to be checked. None or empty is consideted valid


@@ -111,7 +180,7 @@ def _convert_bandwidth(data, reverse=False, logger=None):
                 _convert_bandwidth(k, reverse, logger)
 
 def _convert_str2boolean(data, items):
                 _convert_bandwidth(k, reverse, logger)
 
 def _convert_str2boolean(data, items):

-    '''Check recursively the content of data, and if there is an key contained in items, convert value from string to boolean 
+    '''Check recursively the content of data, and if there is an key contained in items, convert value from string to boolean

     Done recursively
     Attributes:
         'data': dictionary variable to be checked. None or empty is considered valid
     Done recursively
     Attributes:
         'data': dictionary variable to be checked. None or empty is considered valid


@@ -135,17 +204,17 @@ def _convert_str2boolean(data, items):
             if type(k) is dict or type(k) is tuple or type(k) is list:
                 _convert_str2boolean(k, items)
 
             if type(k) is dict or type(k) is tuple or type(k) is list:
                 _convert_str2boolean(k, items)
 

-class db_base_Exception(Exception):
+class db_base_Exception(httperrors.HttpMappedError):

     '''Common Exception for all database exceptions'''
     '''Common Exception for all database exceptions'''

-    
-    def __init__(self, message, http_code=HTTP_Bad_Request):
-        Exception.__init__(self, message)
-        self.http_code = http_code
+
+    def __init__(self, message, http_code=httperrors.Bad_Request):
+        super(db_base_Exception, self).__init__(message, http_code)

 
 class db_base():
     tables_with_created_field=()
 
 class db_base():
     tables_with_created_field=()

-    
-    def __init__(self, host=None, user=None, passwd=None, database=None, log_name='db', log_level=None):
+
+    def __init__(self, host=None, user=None, passwd=None, database=None,
+                 log_name='db', log_level=None, lock=None):

         self.host = host
         self.user = user
         self.passwd = passwd
         self.host = host
         self.user = user
         self.passwd = passwd


@@ -155,9 +224,10 @@ class db_base():
         self.logger = logging.getLogger(log_name)
         if self.log_level:
             self.logger.setLevel( getattr(logging, log_level) )
         self.logger = logging.getLogger(log_name)
         if self.log_level:
             self.logger.setLevel( getattr(logging, log_level) )

-        
+        self.lock = lock or Lock()
+

     def connect(self, host=None, user=None, passwd=None, database=None):
     def connect(self, host=None, user=None, passwd=None, database=None):

-        '''Connect to specific data base. 
+        '''Connect to specific data base.

         The first time a valid host, user, passwd and database must be provided,
         Following calls can skip this parameters
         '''
         The first time a valid host, user, passwd and database must be provided,
         Following calls can skip this parameters
         '''


@@ -172,33 +242,33 @@ class db_base():
         except mdb.Error as e:
             raise db_base_Exception("Cannot connect to DataBase '{}' at '{}@{}' Error {}: {}".format(
                                     self.database, self.user, self.host, e.args[0], e.args[1]),
         except mdb.Error as e:
             raise db_base_Exception("Cannot connect to DataBase '{}' at '{}@{}' Error {}: {}".format(
                                     self.database, self.user, self.host, e.args[0], e.args[1]),

-                                    http_code = HTTP_Unauthorized )
-        
+                                    http_code = httperrors.Unauthorized )
+
+    def escape(self, value):
+        return self.con.escape(value)
+
+    def escape_string(self, value):
+        if isinstance(value, unicode):
+            value = value.encode("utf8")
+        return self.con.escape_string(value)
+
+    @retry
+    @with_transaction

     def get_db_version(self):
         ''' Obtain the database schema version.
         Return: (negative, text) if error or version 0.0 where schema_version table is missing
                 (version_int, version_text) if ok
         '''
         cmd = "SELECT version_int,version FROM schema_version"
     def get_db_version(self):
         ''' Obtain the database schema version.
         Return: (negative, text) if error or version 0.0 where schema_version table is missing
                 (version_int, version_text) if ok
         '''
         cmd = "SELECT version_int,version FROM schema_version"

-        tries = 2
-        while tries:
-            try:
-                with self.con:
-                    self.cur = self.con.cursor()
-                    self.logger.debug(cmd)
-                    self.cur.execute(cmd)
-                    rows = self.cur.fetchall()
-                    highest_version_int=0
-                    highest_version=""
-                    for row in rows: #look for the latest version
-                        if row[0]>highest_version_int:
-                            highest_version_int, highest_version = row[0:2]
-                    return highest_version_int, highest_version
-            except (mdb.Error, AttributeError) as e:
-                self.logger.error("Exception '{}' with command '{}'".format(e, cmd))
-                #self.logger.error("get_db_version DB Exception %d: %s. Command %s",e.args[0], e.args[1], cmd)
-                self._format_error(e, tries)
-            tries -= 1
+        self.logger.debug(cmd)
+        self.cur.execute(cmd)
+        rows = self.cur.fetchall()
+        highest_version_int=0
+        highest_version=""
+        for row in rows: #look for the latest version
+            if row[0]>highest_version_int:
+                highest_version_int, highest_version = row[0:2]
+        return highest_version_int, highest_version

 
     def disconnect(self):
         '''disconnect from specific data base'''
 
     def disconnect(self):
         '''disconnect from specific data base'''


@@ -212,10 +282,76 @@ class db_base():
             if e[0][-5:] == "'con'":
                 self.logger.warn("while disconnecting from DB: Error %d: %s",e.args[0], e.args[1])
                 return
             if e[0][-5:] == "'con'":
                 self.logger.warn("while disconnecting from DB: Error %d: %s",e.args[0], e.args[1])
                 return

-            else: 
+            else:
+                raise
+
+    def reconnect(self):
+        """Try to gracefully to the database in case of error"""
+        try:
+            self.con.ping(True)  # auto-reconnect if the server is available
+        except:
+            # The server is probably not available...
+            # Let's wait a bit
+            time.sleep(RECOVERY_TIME)
+            self.con = None
+            self.connect()
+
+    def fork_connection(self):
+        """Return a new database object, with a separated connection to the
+        database (and lock), so it can act independently
+        """
+        obj =  self.__class__(
+            host=self.host,
+            user=self.user,
+            passwd=self.passwd,
+            database=self.database,
+            log_name=self.logger.name,
+            log_level=self.log_level,
+            lock=Lock()
+        )
+
+        obj.connect()
+
+        return obj
+
+    @contextmanager
+    def transaction(self, cursor_type=None):
+        """DB changes that are executed inside this context will be
+        automatically rolled back in case of error.
+
+        This implementation also adds a lock, so threads sharing the same
+        connection object are synchronized.
+
+        Arguments:
+            cursor_type: default: MySQLdb.cursors.DictCursor
+
+        Yields:
+            Cursor object
+
+        References:
+            https://www.oreilly.com/library/view/mysql-cookbook-2nd/059652708X/ch15s08.html
+            https://github.com/PyMySQL/mysqlclient-python/commit/c64915b1e5c705f4fb10e86db5dcfed0b58552cc
+        """
+        # Previously MySQLdb had built-in support for that using the context
+        # API for the connection object.
+        # This support was removed in version 1.40
+        # https://github.com/PyMySQL/mysqlclient-python/blob/master/HISTORY.rst#whats-new-in-140
+        with self.lock:
+            try:
+                if self.con.get_autocommit():
+                    self.con.query("BEGIN")
+
+                self.cur = self.con.cursor(cursor_type)
+                yield self.cur
+            except:  # noqa
+                self.con.rollback()

                 raise
                 raise

+            else:
+                self.con.commit()
+

 
 

-    def _format_error(self, e, tries=1, command=None, extra=None): 
+    def _format_error(self, e, tries=1, command=None,
+                      extra=None, table=None, cmd=None, **_):

         '''Creates a text error base on the produced exception
             Params:
                 e: mdb exception
         '''Creates a text error base on the produced exception
             Params:
                 e: mdb exception


@@ -225,24 +361,32 @@ class db_base():
                 extra: extra information to add to some commands
             Return
                 HTTP error in negative, formatted error text
                 extra: extra information to add to some commands
             Return
                 HTTP error in negative, formatted error text

-        '''
+        '''  # the **_ ignores extra kwargs
+        table_info = ' (table `{}`)'.format(table) if table else ''
+        if cmd:
+            self.logger.debug("Exception '%s' with command '%s'%s",
+                              e, cmd, table_info)
+

         if isinstance(e,AttributeError ):
         if isinstance(e,AttributeError ):

-            raise db_base_Exception("DB Exception " + str(e), HTTP_Internal_Server_Error)
+            self.logger.debug(str(e), exc_info=True)
+            raise db_base_Exception("DB Exception " + str(e), httperrors.Internal_Server_Error)

         if e.args[0]==2006 or e.args[0]==2013 : #MySQL server has gone away (((or)))    Exception 2013: Lost connection to MySQL server during query
         if e.args[0]==2006 or e.args[0]==2013 : #MySQL server has gone away (((or)))    Exception 2013: Lost connection to MySQL server during query

-            if tries>1:
+            # Let's aways reconnect if the connection is lost
+            # so future calls are not affected.
+            self.reconnect()
+
+            if tries > 1:

                 self.logger.warn("DB Exception '%s'. Retry", str(e))
                 self.logger.warn("DB Exception '%s'. Retry", str(e))

-                #reconnect
-                self.connect()

                 return
             else:
                 return
             else:

-                raise db_base_Exception("Database connection timeout Try Again", HTTP_Request_Timeout)
-        
+                raise db_base_Exception("Database connection timeout Try Again", httperrors.Request_Timeout)
+

         fk=e.args[1].find("foreign key constraint fails")
         if fk>=0:
             if command=="update":
         fk=e.args[1].find("foreign key constraint fails")
         if fk>=0:
             if command=="update":

-                raise db_base_Exception("tenant_id '{}' not found.".format(extra), HTTP_Not_Found)
+                raise db_base_Exception("tenant_id '{}' not found.".format(extra), httperrors.Not_Found)

             elif command=="delete":
             elif command=="delete":

-                raise db_base_Exception("Resource is not free. There are {} that prevent deleting it.".format(extra), HTTP_Conflict)
+                raise db_base_Exception("Resource is not free. There are {} that prevent deleting it.".format(extra), httperrors.Conflict)

         de = e.args[1].find("Duplicate entry")
         fk = e.args[1].find("for key")
         uk = e.args[1].find("Unknown column")
         de = e.args[1].find("Duplicate entry")
         fk = e.args[1].find("for key")
         uk = e.args[1].find("Unknown column")


@@ -251,46 +395,58 @@ class db_base():
         #print de, fk, uk, wc,fl
         if de>=0:
             if fk>=0: #error 1062
         #print de, fk, uk, wc,fl
         if de>=0:
             if fk>=0: #error 1062

-                raise db_base_Exception("Value {} already in use for {}".format(e.args[1][de+15:fk], e.args[1][fk+7:]), HTTP_Conflict)
+                raise db_base_Exception(
+                    "Value {} already in use for {}{}".format(
+                        e.args[1][de+15:fk], e.args[1][fk+7:], table_info),
+                    httperrors.Conflict)

         if uk>=0:
             if wc>=0:
         if uk>=0:
             if wc>=0:

-                raise db_base_Exception("Field {} can not be used for filtering".format(e.args[1][uk+14:wc]), HTTP_Bad_Request)
+                raise db_base_Exception(
+                    "Field {} can not be used for filtering{}".format(
+                        e.args[1][uk+14:wc], table_info),
+                    httperrors.Bad_Request)

             if fl>=0:
             if fl>=0:

-                raise db_base_Exception("Field {} does not exist".format(e.args[1][uk+14:wc]), HTTP_Bad_Request)
-        raise db_base_Exception("Database internal Error {}: {}".format(e.args[0], e.args[1]), HTTP_Internal_Server_Error)
-    
+                raise db_base_Exception(
+                    "Field {} does not exist{}".format(
+                        e.args[1][uk+14:wc], table_info),
+                    httperrors.Bad_Request)
+        raise db_base_Exception(
+                "Database internal Error{} {}: {}".format(
+                    table_info, e.args[0], e.args[1]),
+                httperrors.Internal_Server_Error)
+

     def __str2db_format(self, data):
     def __str2db_format(self, data):

-        '''Convert string data to database format. 
+        """Convert string data to database format.

         If data is None it returns the 'Null' text,
         otherwise it returns the text surrounded by quotes ensuring internal quotes are escaped.
         If data is None it returns the 'Null' text,
         otherwise it returns the text surrounded by quotes ensuring internal quotes are escaped.

-        '''
-        if data==None:
+        """
+        if data is None:

             return 'Null'
             return 'Null'

-        elif isinstance(data[1], str):
+        elif isinstance(data[1], (str, unicode)):

             return json.dumps(data)
         else:
             return json.dumps(str(data))
             return json.dumps(data)
         else:
             return json.dumps(str(data))

-    
+

     def __tuple2db_format_set(self, data):
         """Compose the needed text for a SQL SET, parameter 'data' is a pair tuple (A,B),
     def __tuple2db_format_set(self, data):
         """Compose the needed text for a SQL SET, parameter 'data' is a pair tuple (A,B),

-        and it returns the text 'A="B"', where A is a field of a table and B is the value 
+        and it returns the text 'A="B"', where A is a field of a table and B is the value

         If B is None it returns the 'A=Null' text, without surrounding Null by quotes
         If B is not None it returns the text "A='B'" or 'A="B"' where B is surrounded by quotes,
         and it ensures internal quotes of B are escaped.
         B can be also a dict with special keys:
             {"INCREMENT": NUMBER}, then it produce "A=A+NUMBER"
         """
         If B is None it returns the 'A=Null' text, without surrounding Null by quotes
         If B is not None it returns the text "A='B'" or 'A="B"' where B is surrounded by quotes,
         and it ensures internal quotes of B are escaped.
         B can be also a dict with special keys:
             {"INCREMENT": NUMBER}, then it produce "A=A+NUMBER"
         """

-        if data[1] == None:
+        if data[1] is None:

             return str(data[0]) + "=Null"
             return str(data[0]) + "=Null"

-        elif isinstance(data[1], str):
+        elif isinstance(data[1], (str, unicode)):

             return str(data[0]) + '=' + json.dumps(data[1])
         elif isinstance(data[1], dict):
             if "INCREMENT" in data[1]:
                 return "{A}={A}{N:+d}".format(A=data[0], N=data[1]["INCREMENT"])
             return str(data[0]) + '=' + json.dumps(data[1])
         elif isinstance(data[1], dict):
             if "INCREMENT" in data[1]:
                 return "{A}={A}{N:+d}".format(A=data[0], N=data[1]["INCREMENT"])

-            raise db_base_Exception("Format error for UPDATE field")
+            raise db_base_Exception("Format error for UPDATE field: {!r}".format(data[0]))

         else:
             return str(data[0]) + '=' + json.dumps(str(data[1]))
         else:
             return str(data[0]) + '=' + json.dumps(str(data[1]))

-    
+

     def __create_where(self, data, use_or=None):
         """
         Compose the needed text for a SQL WHERE, parameter 'data' can be a dict or a list of dict. By default lists are
     def __create_where(self, data, use_or=None):
         """
         Compose the needed text for a SQL WHERE, parameter 'data' can be a dict or a list of dict. By default lists are


@@ -327,9 +483,13 @@ class db_base():
                     for v2 in v:
                         if v2 is None:
                             cmd2.append(k.replace("=", " is").replace("<>", " is not") + " Null")
                     for v2 in v:
                         if v2 is None:
                             cmd2.append(k.replace("=", " is").replace("<>", " is not") + " Null")

+                        elif isinstance(v2, (str, unicode)):
+                            cmd2.append(k + json.dumps(v2))

                         else:
                             cmd2.append(k + json.dumps(str(v2)))
                     cmd.append("(" + " OR ".join(cmd2) + ")")
                         else:
                             cmd2.append(k + json.dumps(str(v2)))
                     cmd.append("(" + " OR ".join(cmd2) + ")")

+                elif isinstance(v, (str, unicode)):
+                    cmd.append(k + json.dumps(v))

                 else:
                     cmd.append(k + json.dumps(str(v)))
         elif isinstance(data, (tuple, list)):
                 else:
                     cmd.append(k + json.dumps(str(v)))
         elif isinstance(data, (tuple, list)):


@@ -347,9 +507,9 @@ class db_base():
         '''remove single quotes ' of any string content of data dictionary'''
         for k,v in data.items():
             if type(v) == str:
         '''remove single quotes ' of any string content of data dictionary'''
         for k,v in data.items():
             if type(v) == str:

-                if "'" in v: 
+                if "'" in v:

                     data[k] = data[k].replace("'","_")
                     data[k] = data[k].replace("'","_")

-    
+

     def _update_rows(self, table, UPDATE, WHERE, modified_time=0):
         """ Update one or several rows of a table.
         :param UPDATE: dictionary with the changes. dict keys are database columns that will be set with the dict values
     def _update_rows(self, table, UPDATE, WHERE, modified_time=0):
         """ Update one or several rows of a table.
         :param UPDATE: dictionary with the changes. dict keys are database columns that will be set with the dict values


@@ -369,7 +529,7 @@ class db_base():
             values += ",modified_at={:f}".format(modified_time)
         cmd= "UPDATE " + table + " SET " + values + " WHERE " + self.__create_where(WHERE)
         self.logger.debug(cmd)
             values += ",modified_at={:f}".format(modified_time)
         cmd= "UPDATE " + table + " SET " + values + " WHERE " + self.__create_where(WHERE)
         self.logger.debug(cmd)

-        self.cur.execute(cmd) 
+        self.cur.execute(cmd)

         return self.cur.rowcount
 
     def _new_uuid(self, root_uuid=None, used_table=None, created_time=0):
         return self.cur.rowcount
 
     def _new_uuid(self, root_uuid=None, used_table=None, created_time=0):


@@ -398,11 +558,11 @@ class db_base():
 
     def _new_row_internal(self, table, INSERT, add_uuid=False, root_uuid=None, created_time=0, confidential_data=False):
         ''' Add one row into a table. It DOES NOT begin or end the transaction, so self.con.cursor must be created
 
     def _new_row_internal(self, table, INSERT, add_uuid=False, root_uuid=None, created_time=0, confidential_data=False):
         ''' Add one row into a table. It DOES NOT begin or end the transaction, so self.con.cursor must be created

-        Attribute 
+        Attribute

             INSERT: dictionary with the key:value to insert
             table: table where to insert
             add_uuid: if True, it will create an uuid key entry at INSERT if not provided
             INSERT: dictionary with the key:value to insert
             table: table where to insert
             add_uuid: if True, it will create an uuid key entry at INSERT if not provided

-            created_time: time to add to the created_time column
+            created_time: time to add to the created_at column

         It checks presence of uuid and add one automatically otherwise
         Return: uuid
         '''
         It checks presence of uuid and add one automatically otherwise
         Return: uuid
         '''


@@ -411,7 +571,7 @@ class db_base():
             #create uuid if not provided
             if 'uuid' not in INSERT:
                 uuid = INSERT['uuid'] = str(myUuid.uuid1()) # create_uuid
             #create uuid if not provided
             if 'uuid' not in INSERT:
                 uuid = INSERT['uuid'] = str(myUuid.uuid1()) # create_uuid

-            else: 
+            else:

                 uuid = str(INSERT['uuid'])
         else:
             uuid=None
                 uuid = str(INSERT['uuid'])
         else:
             uuid=None


@@ -429,9 +589,9 @@ class db_base():
             self.cur.execute(cmd)
         #insertion
         cmd= "INSERT INTO " + table +" SET " + \
             self.cur.execute(cmd)
         #insertion
         cmd= "INSERT INTO " + table +" SET " + \

-            ",".join(map(self.__tuple2db_format_set, INSERT.iteritems() )) 
+            ",".join(map(self.__tuple2db_format_set, INSERT.iteritems() ))

         if created_time:
         if created_time:

-            cmd += ",created_at=%f" % created_time
+            cmd += ",created_at={time:.9f},modified_at={time:.9f}".format(time=created_time)

         if confidential_data:
             index = cmd.find("SET")
             subcmd = cmd[:index] + 'SET...'
         if confidential_data:
             index = cmd.find("SET")
             subcmd = cmd[:index] + 'SET...'


@@ -448,31 +608,26 @@ class db_base():
         self.cur.execute(cmd)
         rows = self.cur.fetchall()
         return rows
         self.cur.execute(cmd)
         rows = self.cur.fetchall()
         return rows

-    
+
+    @retry
+    @with_transaction

     def new_row(self, table, INSERT, add_uuid=False, created_time=0, confidential_data=False):
         ''' Add one row into a table.
     def new_row(self, table, INSERT, add_uuid=False, created_time=0, confidential_data=False):
         ''' Add one row into a table.

-        Attribute 
+        Attribute

             INSERT: dictionary with the key: value to insert
             table: table where to insert
             tenant_id: only useful for logs. If provided, logs will use this tenant_id
             add_uuid: if True, it will create an uuid key entry at INSERT if not provided
         It checks presence of uuid and add one automatically otherwise
             INSERT: dictionary with the key: value to insert
             table: table where to insert
             tenant_id: only useful for logs. If provided, logs will use this tenant_id
             add_uuid: if True, it will create an uuid key entry at INSERT if not provided
         It checks presence of uuid and add one automatically otherwise

-        Return: (result, uuid) where result can be 0 if error, or 1 if ok
+        Return: uuid

         '''
         if table in self.tables_with_created_field and created_time==0:
             created_time=time.time()
         '''
         if table in self.tables_with_created_field and created_time==0:
             created_time=time.time()

-        tries = 2
-        while tries:
-            try:
-                with self.con:
-                    self.cur = self.con.cursor()
-                    return self._new_row_internal(table, INSERT, add_uuid, None, created_time, confidential_data)
-                    
-            except (mdb.Error, AttributeError) as e:
-                self._format_error(e, tries)
-            tries -= 1
-
-    def update_rows(self, table, UPDATE, WHERE, modified_time=0):
+        return self._new_row_internal(table, INSERT, add_uuid, None, created_time, confidential_data)
+
+    @retry
+    @with_transaction
+    def update_rows(self, table, UPDATE, WHERE, modified_time=None, attempt=_ATTEMPT):

         """ Update one or several rows of a table.
         :param UPDATE: dictionary with the changes. dict keys are database columns that will be set with the dict values
         :param table: database table to update
         """ Update one or several rows of a table.
         :param UPDATE: dictionary with the changes. dict keys are database columns that will be set with the dict values
         :param table: database table to update


@@ -483,21 +638,14 @@ class db_base():
                 keys can be suffixed by >,<,<>,>=,<= so that this is used to compare key and value instead of "="
                 The special keys "OR", "AND" with a dict value is used to create a nested WHERE
             If a list, each item will be a dictionary that will be concatenated with OR
                 keys can be suffixed by >,<,<>,>=,<= so that this is used to compare key and value instead of "="
                 The special keys "OR", "AND" with a dict value is used to create a nested WHERE
             If a list, each item will be a dictionary that will be concatenated with OR

-        :param modified_time: Can contain the time to be set to the table row
+        :param modified_time: Can contain the time to be set to the table row.
+            None to set automatically, 0 to do not modify it

         :return: the number of updated rows, raises exception upon error
         """
         :return: the number of updated rows, raises exception upon error
         """

-        if table in self.tables_with_created_field and modified_time==0:
-            modified_time=time.time()
-        tries = 2
-        while tries:
-            try:
-                with self.con:
-                    self.cur = self.con.cursor()
-                    return self._update_rows(table, UPDATE, WHERE)
-                    
-            except (mdb.Error, AttributeError) as e:
-                self._format_error(e, tries)
-            tries -= 1
+        if table in self.tables_with_created_field and modified_time is None:
+            modified_time = time.time()
+
+        return self._update_rows(table, UPDATE, WHERE, modified_time)

 
     def _delete_row_by_id_internal(self, table, uuid):
         cmd = "DELETE FROM {} WHERE uuid = '{}'".format(table, uuid)
 
     def _delete_row_by_id_internal(self, table, uuid):
         cmd = "DELETE FROM {} WHERE uuid = '{}'".format(table, uuid)


@@ -511,18 +659,13 @@ class db_base():
         self.cur.execute(cmd)
         return deleted
 
         self.cur.execute(cmd)
         return deleted
 

+    @retry(command='delete', extra='dependencies')
+    @with_transaction

     def delete_row_by_id(self, table, uuid):
     def delete_row_by_id(self, table, uuid):

-        tries = 2
-        while tries:
-            try:
-                with self.con:
-                    self.cur = self.con.cursor()
-                    return self._delete_row_by_id_internal(table, uuid)
-            except (mdb.Error, AttributeError) as e:
-                self._format_error(e, tries, "delete", "dependencies")
-            tries -= 1
-
-    def delete_row(self, **sql_dict):
+        return self._delete_row_by_id_internal(table, uuid)
+
+    @retry
+    def delete_row(self, attempt=_ATTEMPT, **sql_dict):

         """ Deletes rows from a table.
         :param UPDATE: dictionary with the changes. dict keys are database columns that will be set with the dict values
         :param FROM: string with table name (Mandatory)
         """ Deletes rows from a table.
         :param UPDATE: dictionary with the changes. dict keys are database columns that will be set with the dict values
         :param FROM: string with table name (Mandatory)


@@ -541,36 +684,28 @@ class db_base():
             cmd += " WHERE " + self.__create_where(sql_dict['WHERE'])
         if sql_dict.get('LIMIT'):
             cmd += " LIMIT " + str(sql_dict['LIMIT'])
             cmd += " WHERE " + self.__create_where(sql_dict['WHERE'])
         if sql_dict.get('LIMIT'):
             cmd += " LIMIT " + str(sql_dict['LIMIT'])

-        tries = 2
-        while tries:
-            try:
-                with self.con:
-                    self.cur = self.con.cursor()
-                    self.logger.debug(cmd)
-                    self.cur.execute(cmd)
-                    deleted = self.cur.rowcount
-                return deleted
-            except (mdb.Error, AttributeError) as e:
-                self._format_error(e, tries)
-            tries -= 1
-
-    def get_rows_by_id(self, table, uuid):
+
+        attempt.info['cmd'] = cmd
+
+        with self.transaction():
+            self.logger.debug(cmd)
+            self.cur.execute(cmd)
+            deleted = self.cur.rowcount
+        return deleted
+
+    @retry
+    @with_transaction(cursor='dict')
+    def get_rows_by_id(self, table, uuid, attempt=_ATTEMPT):

         '''get row from a table based on uuid'''
         '''get row from a table based on uuid'''

-        tries = 2
-        while tries:
-            try:
-                with self.con:
-                    self.cur = self.con.cursor(mdb.cursors.DictCursor)
-                    cmd="SELECT * FROM {} where uuid='{}'".format(str(table), str(uuid))
-                    self.logger.debug(cmd)
-                    self.cur.execute(cmd)
-                    rows = self.cur.fetchall()
-                    return rows
-            except (mdb.Error, AttributeError) as e:
-                self._format_error(e, tries)
-            tries -= 1
-    
-    def get_rows(self, **sql_dict):
+        cmd="SELECT * FROM {} where uuid='{}'".format(str(table), str(uuid))
+        attempt.info['cmd'] = cmd
+        self.logger.debug(cmd)
+        self.cur.execute(cmd)
+        rows = self.cur.fetchall()
+        return rows
+
+    @retry
+    def get_rows(self, attempt=_ATTEMPT, **sql_dict):

         """ Obtain rows from a table.
         :param SELECT: list or tuple of fields to retrieve) (by default all)
         :param FROM: string with table name (Mandatory)
         """ Obtain rows from a table.
         :param SELECT: list or tuple of fields to retrieve) (by default all)
         :param FROM: string with table name (Mandatory)


@@ -581,7 +716,7 @@ class db_base():
                 keys can be suffixed by >,<,<>,>=,<= so that this is used to compare key and value instead of "="
                 The special keys "OR", "AND" with a dict value is used to create a nested WHERE
             If a list, each item will be a dictionary that will be concatenated with OR
                 keys can be suffixed by >,<,<>,>=,<= so that this is used to compare key and value instead of "="
                 The special keys "OR", "AND" with a dict value is used to create a nested WHERE
             If a list, each item will be a dictionary that will be concatenated with OR

-        :param LIMIT: limit the number of obtianied entries (Optional)
+        :param LIMIT: limit the number of obtained entries (Optional)

         :param ORDER_BY:  list or tuple of fields to order, add ' DESC' to each item if inverse order is required
         :return: a list with dictionaries at each row, raises exception upon error
         """
         :param ORDER_BY:  list or tuple of fields to order, add ' DESC' to each item if inverse order is required
         :return: a list with dictionaries at each row, raises exception upon error
         """


@@ -609,29 +744,24 @@ class db_base():
         if 'LIMIT' in sql_dict:
             cmd += " LIMIT " + str(sql_dict['LIMIT'])
 
         if 'LIMIT' in sql_dict:
             cmd += " LIMIT " + str(sql_dict['LIMIT'])
 

-        tries = 2
-        while tries:
-            try:
-                with self.con:
-                    self.cur = self.con.cursor(mdb.cursors.DictCursor)
-                    self.logger.debug(cmd)
-                    self.cur.execute(cmd)
-                    rows = self.cur.fetchall()
-                    return rows
-            except (mdb.Error, AttributeError) as e:
-                self.logger.error("Exception '{}' with command '{}'".format(e, cmd))
-                self._format_error(e, tries)
-            tries -= 1
-
-    def get_table_by_uuid_name(self, table, uuid_name, error_item_text=None, allow_serveral=False, WHERE_OR={}, WHERE_AND_OR="OR"):
+        attempt.info['cmd'] = cmd
+
+        with self.transaction(mdb.cursors.DictCursor):
+            self.logger.debug(cmd)
+            self.cur.execute(cmd)
+            rows = self.cur.fetchall()
+            return rows
+
+    @retry
+    def get_table_by_uuid_name(self, table, uuid_name, error_item_text=None, allow_several=False, WHERE_OR={}, WHERE_AND_OR="OR", attempt=_ATTEMPT):

         ''' Obtain One row from a table based on name or uuid.
         Attribute:
             table: string of table name
             uuid_name: name or uuid. If not uuid format is found, it is considered a name
         ''' Obtain One row from a table based on name or uuid.
         Attribute:
             table: string of table name
             uuid_name: name or uuid. If not uuid format is found, it is considered a name

-            allow_severeral: if False return ERROR if more than one row are founded 
-            error_item_text: in case of error it identifies the 'item' name for a proper output text 
+            allow_several: if False return ERROR if more than one row are found
+            error_item_text: in case of error it identifies the 'item' name for a proper output text

             'WHERE_OR': dict of key:values, translated to key=value OR ... (Optional)
             'WHERE_OR': dict of key:values, translated to key=value OR ... (Optional)

-            'WHERE_AND_OR: str 'AND' or 'OR'(by default) mark the priority to 'WHERE AND (WHERE_OR)' or (WHERE) OR WHERE_OR' (Optional  
+            'WHERE_AND_OR: str 'AND' or 'OR'(by default) mark the priority to 'WHERE AND (WHERE_OR)' or (WHERE) OR WHERE_OR' (Optional

         Return: if allow_several==False, a dictionary with this row, or error if no item is found or more than one is found
                 if allow_several==True, a list of dictionaries with the row or rows, error if no item is found
         '''
         Return: if allow_several==False, a dictionary with this row, or error if no item is found or more than one is found
                 if allow_several==True, a list of dictionaries with the row or rows, error if no item is found
         '''


@@ -647,58 +777,40 @@ class db_base():
             else:
                 cmd += " OR " + where_or
 
             else:
                 cmd += " OR " + where_or
 

-        tries = 2
-        while tries:
-            try:
-                with self.con:
-                    self.cur = self.con.cursor(mdb.cursors.DictCursor)
-                    self.logger.debug(cmd)
-                    self.cur.execute(cmd)
-                    number = self.cur.rowcount
-                    if number == 0:
-                        raise db_base_Exception("No {} found with {} '{}'".format(error_item_text, what, uuid_name), http_code=HTTP_Not_Found)
-                    elif number > 1 and not allow_serveral:
-                        raise db_base_Exception("More than one {} found with {} '{}'".format(error_item_text, what, uuid_name), http_code=HTTP_Conflict)
-                    if allow_serveral:
-                        rows = self.cur.fetchall()
-                    else:
-                        rows = self.cur.fetchone()
-                    return rows
-            except (mdb.Error, AttributeError) as e:
-                self._format_error(e, tries)
-            tries -= 1
+        attempt.info['cmd'] = cmd
+
+        with self.transaction(mdb.cursors.DictCursor):
+            self.logger.debug(cmd)
+            self.cur.execute(cmd)
+            number = self.cur.rowcount
+            if number == 0:
+                raise db_base_Exception("No {} found with {} '{}'".format(error_item_text, what, uuid_name), http_code=httperrors.Not_Found)
+            elif number > 1 and not allow_several:
+                raise db_base_Exception("More than one {} found with {} '{}'".format(error_item_text, what, uuid_name), http_code=httperrors.Conflict)
+            if allow_several:
+                rows = self.cur.fetchall()
+            else:
+                rows = self.cur.fetchone()
+            return rows

 
 

+    @retry(table='uuids')
+    @with_transaction(cursor='dict')

     def get_uuid(self, uuid):
         '''check in the database if this uuid is already present'''
     def get_uuid(self, uuid):
         '''check in the database if this uuid is already present'''

-        tries = 2
-        while tries:
-            try:
-                with self.con:
-                    self.cur = self.con.cursor(mdb.cursors.DictCursor)
-                    self.cur.execute("SELECT * FROM uuids where uuid='" + str(uuid) + "'")
-                    rows = self.cur.fetchall()
-                    return self.cur.rowcount, rows
-            except (mdb.Error, AttributeError) as e:
-                self._format_error(e, tries)
-            tries -= 1
+        self.cur.execute("SELECT * FROM uuids where uuid='" + str(uuid) + "'")
+        rows = self.cur.fetchall()
+        return self.cur.rowcount, rows

 
 

+    @retry
+    @with_transaction(cursor='dict')

     def get_uuid_from_name(self, table, name):
         '''Searchs in table the name and returns the uuid
     def get_uuid_from_name(self, table, name):
         '''Searchs in table the name and returns the uuid

-        ''' 
-        tries = 2
-        while tries:
-            try:
-                with self.con:
-                    self.cur = self.con.cursor(mdb.cursors.DictCursor)
-                    where_text = "name='" + name +"'"
-                    self.cur.execute("SELECT * FROM " + table + " WHERE "+ where_text)
-                    rows = self.cur.fetchall()
-                    if self.cur.rowcount==0:
-                        return 0, "Name %s not found in table %s" %(name, table)
-                    elif self.cur.rowcount>1:
-                        return self.cur.rowcount, "More than one VNF with name %s found in table %s" %(name, table)
-                    return self.cur.rowcount, rows[0]["uuid"]
-            except (mdb.Error, AttributeError) as e:
-                self._format_error(e, tries)
-            tries -= 1
-
+        '''
+        where_text = "name='" + name +"'"
+        self.cur.execute("SELECT * FROM " + table + " WHERE "+ where_text)
+        rows = self.cur.fetchall()
+        if self.cur.rowcount==0:
+            return 0, "Name %s not found in table %s" %(name, table)
+        elif self.cur.rowcount>1:
+            return self.cur.rowcount, "More than one VNF with name %s found in table %s" %(name, table)
+        return self.cur.rowcount, rows[0]["uuid"]