[Mono-devel-list] DbDataAdapter fix for out of memory errors when filling datasets

[Francisco Figueiredo Jr.]

Hi all,

Here is a patch for handling out of memory exceptions when trying to 
fill datasets with queries which doesn't return a resultset like insert, 
delete, update.

The out of memory exception happens in the following line of 
DbDataAdapter.cs:

around line 502.
int[] mapping = new int[reader.FieldCount]; // mapping the reader 
indexes to the datatable indexes

The problem is that when the query is an insert, update or delete, the 
FieldCount property is -1 which gives the problem.

The compiler can detect when you try to create an array with a negative 
index. But when this index is in a var, the runtime doesn't handle it 
and gives the error. The error is like that:


System.OutOfMemoryException: Out of memory.
in (unmanaged) (wrapper managed-to-native) 
System.Object:__icall_wrapper_mono_array_new_specific (intptr,int)
in <0x00004> (wrapper managed-to-native) 
System.Object:__icall_wrapper_mono_array_new_specific (intptr,int)
in <0x00091> System.Data.Common.DbDataAdapter:BuildSchema 
(System.Data.IDataReader,System.Data.DataTable,System.Data.SchemaType)
in <0x00079> (wrapper remoting-invoke-with-check) 
System.Data.Common.DbDataAdapter:BuildSchema 
(System.Data.IDataReader,System.Data.DataTable,System.Data.SchemaType)
in <0x00086> System.Data.Common.DbDataAdapter:FillTable 
(System.Data.DataTable,System.Data.IDataReader,int,int,int&)
in <0x000ad> (wrapper remoting-invoke-with-check) 
System.Data.Common.DbDataAdapter:FillTable 
(System.Data.DataTable,System.Data.IDataReader,int,int,int&)
in <0x0017d> System.Data.Common.DbDataAdapter:Fill 
(System.Data.DataSet,string,System.Data.IDataReader,int,int)
in <0x000da> System.Data.Common.DbDataAdapter:Fill 
(System.Data.DataSet,int,int,string,System.Data.IDbCommand,System.Data.CommandBehavior)
in <0x00049> System.Data.Common.DbDataAdapter:Fill 
(System.Data.DataSet,string)
in <0x0006b> (wrapper remoting-invoke-with-check) 
System.Data.Common.DbDataAdapter:Fill (System.Data.DataSet,string)



May I have to add a bugzilla entry?

The patch is attached.

Regards,

Francisco Figueiredo Jr.


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