[V4CC] VTable.Field() Vcursor.Field() and no leaks.

[Ruslan Zasukhin]

Hi Erne,
Hi Thorsten,

Today I have made attempt reproduce any leaks in V4CC with help of
    [tbl FieldAtIndex:i]
    [curs FieldAtIndex:i]

And I have not found any leaks guys.
I still think you have some mirage :-)

So I have take V4CC/Example/Sql_Way/Records_AddDeleteUpdate

==============================================
Then I have change method pbSelect to be as

- (IBAction)pbSelect:(id)sender
{
    @try
    { 
        for( int i = 1; i <= 100 ; ++i )
        {
            VTable* pTable = [mDatabase tableForName:@"T1"];
        
            int Count = [pTable    fieldCount];
            for( int i = 1; i <= Count ; ++i )
            {
                VField* pFld = [pTable fieldAtIndex:i];
            } 
        } 
    }
    @catch(NSException* pe)
    {
        [mwPropertyPanel showError:[pe name] reason:[pe reason]];
    }
}

==============================================
- (IBAction)pbSelect:(id)sender
{
    @try
    { 
        NSString* query = @"SELECT * FROM T1 WHERE false";

        for( int i = 1; i <= 100 ; ++i )
        {
            NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];

                VCursor* pCursor = [mDatabase sqlSelect:query
cursorLocation:EVCursorLocation_kServerSide
                            lockType:EVLockType_kReadWrite
direction:EVCursorDirection_kRandom];
        
                int Count = [pCursor fieldCount];
                for( int i = 1; i <= Count ; ++i )
                {
                    VField* pFld = [pCursor fieldAtIndex:i];
                } 
            
            [pool release];
        } 
    }
    @catch(NSException* pe)
    {
        [mwPropertyPanel showError:[pe name] reason:[pe reason]];
    }
}



AS you can see in first case I test VTable and in the second Vcursor.

1) Note that Vtable* and Vfield* never are   retained, released or
autoreleases.
No need for this because of internal structure and tricks

There is nothing bad here guys, because RULES of course are rules,
But they also mention that in some cases,  IF YOU KNOW something special,
you can avoid do extra  retain/release calls.

Here we have exactly such special case.
VDatabase is a root of tree of schema objects.
   VDatabase keeps tables and links. Tables keep fields, ...
   V4CC designed in such way that we do not have overheads here.


And only when Vdatabase object ‹ ROOT will be release
And start destroy self it will destroy the whole tree, including both
KERNEL objects and wow!  V4CC cocoa objects.



2) VCursor test above is shown with NSAutoReleasePool usage.

VCursor is one more ROOT of tree, like VDatabase.
VCursor keeps  set of fields and is their owner.
NOT you. NOT your classes. VCursor is owner.

So you can take fields by simple line:
             VField* pFld = [pCursor fieldAtIndex:i];

And no need for any special steps here.
No need retain, no need release.


===========================================
Once again, I have run this modified example project to search
Zombies, and later Leaks.

No Zombies.
No Leaks...   There was only few minor by singlentons in vkernel.

If you still think that something is wrong, please
Take above example, copy above my code.
Modify code to expose problem, and describe steps to see that problem.


-- 
Best regards,

Ruslan Zasukhin
VP Engineering and New Technology
Paradigma Software, Inc

Valentina - Joining Worlds of Information
http://www.paradigmasoft.com

[I feel the need: the need for speed]

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