mco_aio_start

Adjust Asynchronous IO parameters for persistent databases.

Prototype

 
    MCO_RET	mco_aio_start(	mco_size_t max_queue_length, mco_size_t n_workers);
 

Arguments

Description

This function allows the application to adjust the AIO buffer size and number of threads used for AIO. It must be called before mco_db_open_dev() and, if called, the companion function mco_aio_stop() should be called when database write activity is finished. By default one AIO thread is started for each database and the default queue size is set to 10007. Sometimes it could be beneficial to change the number of AIO threads (for example is the database is comprised of multiple physical IO devices, or is resided on a RAID) and/or the queue size. However note that the number of I/O threads won't exceed the number of databases created in a process,

Return Codes

Example

 
    Application snippet:
        
     
    const char * dbname = "SimpleDb";
     
    int main(int argc, char* argv[])
    {
        mco_db_h db;
        MCO_RET rc;
        mco_device_t       dev;
        mco_db_params_t    db_params;
         
         
        if( (rc = mco_runtime_start()) != MCO_S_OK)
            exit(-1);
             
        ...
        rc = mco_aio_start( 20000, 2 );
        
        rc = mco_db_open_dev( dbname, simpledb_get_dictionary(), &dev, 1, &db_params);
        ...
        rc = mco_db_connect(dbname, &db);
        ...
        mco_aio_stop();
    }
     
 

Files