ToC path:

mco_statrt_update
RT

Update the value of a registered runtime statistics counter using a specified operation.

Prototype

    MCO_RET mco_statrt_update(
        /*IN*/ mco_stat_hdl h,
        /*IN*/ mco_statrt_op_t op,
        /*IN*/ mco_stat_counter_value arg
    );

Arguments

h

Handle of the statistics counter to update (obtained from mco_statrt_register_counter() or a built-in constant like MCO_STATRT_COMMIT_COUNT).

op

Operation to perform on the counter. One of:

mco_statrt_op_set — set counter to arg,
mco_statrt_op_inc — increment by 1 (ignores arg),
mco_statrt_op_add — add arg,
mco_statrt_op_sub — subtract arg,
mco_statrt_op_min — set to minimum of current value and arg,
mco_statrt_op_max — set to maximum of current value and arg.

arg

Operand value used by the operation (ignored for mco_statrt_op_inc).

Description

This function atomically updates the value of a runtime statistics counter according to the specified operation. It is the primary mechanism for instrumenting application code or internal database components with custom metrics.

If the counter was registered with histogram collection enabled (collect_histogram = MCO_YES), the new counter value is automatically appended to the associated histogram after the update.

The counter must be valid and the statistics subsystem must be initialized (i.e., a database with statistics support must be open).

Note: This function does not return the updated value. Use mco_statrt_get() or mco_stat_counter_get() to read the current value.

Return Codes

MCO_S_OK

Counter successfully updated.

MCO_E_INVALID_HANDLE

The counter handle is invalid or the statistics subsystem is not initialized.

MCO_E_ILLEGAL_PARAM

The specified operation is not supported.

Example

    // Increment a built-in counter
    mco_statrt_update(MCO_STATRT_COMMIT_COUNT, mco_statrt_op_inc, 0);

    // Update a custom counter with max operation
    mco_stat_hdl latency_counter = /* previously registered */;
    mco_statrt_update(latency_counter, mco_statrt_op_max, measured_latency);

    // Add to an error counter
    mco_statrt_update(my_error_counter, mco_statrt_op_add, 1);

Files

Header file:

mco.h

Source file:

mcostat.c

Library:

libmcolib.a

mco_statrt_update RT