# Allocation Callback Threshold Kinds

When `mco_register_alloc_callback()` or `mco_register_disk_alloc_callback()` is called it must pass an argument of type `mco_alloc_callback_threshold_kind_t`.

The following threshold kinds are defined in `mco.h`:

        typedef enum mco_alloc_callback_threshold_kind_t
        { /* Report when ... */
            MCO_ALLOC_PERCENT_USED, /* Specified percent value of the database size will be reached */
            MCO_ALLOC_FREE_LEFT,    /* Specified percent value of the database free space will be reached */
            MCO_ALLOC_DELTA_USED,   /* Specified amount of memory will be allocated at once */
            MCO_ALLOC_USED          /* Database memory usage will reach treshold */
        } mco_alloc_callback_threshold_kind_t;

MCO_ALLOC_PERCENT_USED | Specified percent value of the database size will be reached
MCO_ALLOC_FREE_LEFT | Specified percent value of the database free space will be reached
MCO_ALLOC_DELTA_USED | Specified amount of memory will be allocated at once
MCO_ALLOC_USED | Database memory usage will reach treshold