[Mapserver-dev] FastCGI and MapServer 4.4

[Frank Warmerdam]

Smith, Michael ERDC-CRREL-NH wrote:
> Frank,
> 
> What extra would it take to extend the connection pooling to Oracle.  We 
> may be able to provide that.
> If not for 4.4, then for 4.5.

Mike,

My intention is to define fairly clear instructions on how to take advantage
of a "new" connection pooling API and those instructions should make it pretty
clear how it could be used.  Basically, I am looking at an API like this:

void MS_DLL_EXPORT *msConnPoolRequest( layerObj *layer );
void MS_DLL_EXPORT *msConnPoolRelease( layerObj *layer, void * );
void MS_DLL_EXPORT  msConnPoolRegister( layerObj *layer,
                                         void *connect_handle,
                                         void (*close)( void * ) );
void MS_DLL_EXPORT  msConnPoolMapDrawComplete();
void MS_DLL_EXPORT  msConnPoolFinalCleanup();

Particular format providers that want to support connection pooling will
call msConnPoolRequest() with their layer.  The connection pooling code
will look at the CONNECTION and CONNECTIONTYPE string, and see if there is
an existing handle associated with that pair.  If so, it will be returned
(as a void *).

If not, the provider establishes a connection and then registers it with
msConnPoolRegister(), along with a function to be called when it should be
closed.

When the LayerClose function is called for the provider, it would call
msConnPoolRelease() and the connection pooling code would decide whether
to invoke the low level close() or not.

The connection pooling API would inspect some keyword(s) on the layer to
determine whether to keep a connection alive, or let it close immediately
after the last release against it.  I expect to use PROCESSING options for
this for now, though we might introduce a first class keyword for this
at a later date.

So, I believe that updating particular providers such as the Oracle, SDE,
PostGIS, or OGR ones would be pretty straight forward.  The main issue would
be that it be done by some who can test if the code changes work.  Ideally the
Oracle connecton maintainers would implement (or at least test) changes for
this.

The actual work is likely not enough to justify cutting a contract of some
kind if that is what you are thinking.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent