#include <db.h> int DB_ENV->memp_trickle(DB_ENV *env, int percent, int *nwrotep);
         The DB_ENV->memp_trickle() method ensures that a specified percent of
         the pages in the cache are clean, by writing dirty pages
         to their backing files.
    
         The purpose of the DB_ENV->memp_trickle() function is to enable a
         memory pool manager to ensure that a page is always available for
         reading in new information without having to wait for a write.
    
         The DB_ENV->memp_trickle() 
            
                  method returns a non-zero error value on failure and 0 on success.
            
            
        
    
                         The DB_ENV->memp_trickle() 
            
                 method may fail and return one of the following non-zero errors:
            
            
        
                         following non-zero errors: