Service exposes the following methods to discover registered meters using an meter iterator:

meter_iterator_create : create meter iterator (on success points to 1st meter)
meter_iterator_destroy : destroy meter iterator
meter_iterator_advance : advance meter iterator to point to next meter (if exists)
meter_get_name : get name of the meter, given an iterator pointing to it
meter_get_frequency : get export frequency of the meter (in seconds), given an iterator
meter_get_enabled : get enabled status of the meter, given an iterator
meter_get_description : get meter description, given an iterator

Another set of methods is used to discover (or get measurements of) metrics within a given meter using a metric iterator:

metric_iterator_create : create metric iterator (on success points to 1st metric of a given meter)
metric_iterator_destroy : destroy metric iterator
metric_iterator_advance : advance metric iterator to point to next meter (if exists)
metric_get_group : get meter name this metric belongs to, given an iterator
metric_get_name : get metric name, given an iterator
metric_get_description : get metric description, given an iterator
metric_get_unit : get metric unit, given an iterator
metric_get_numeric_type : get metric measurement numeric type (integer or float), given an iterator
metric_get_metric_type : get metric Open Telemetry type, given an iterator
metric_get_value : get metric measurement values (with optional key/value attributes attached to each value)
metrics_get_callback : get metric measurement callback function pointer
metrics_get_callback_context : get metric measurement context pointer

The last set of methods is used on telemetry metrics measurement export to optimize internal locking: