Module oc_stat_measure
Measure represents a type of metric to be tracked and recorded.
Description
For example, latency, request Mb/s, and response Mb/s are measures to collect from a server.
Measure is a generic interface for recording values in aggregations via subscribed views. When recording a value, we have to obtain the list of all subscribed views and call respective aggregations. We use code generation to optimize this. When a view subscribed or unsubscribed we regenerate unrolled loop in a special module (one for each measure). Module names generated from measurement names (1-to-1). If we know a measure name at the compile time, we can eliminate the module name lookup and inject remote call directly, replacing oc_stat:record with <GENERATED_MEASURE_MODULE>:record. For that {parse_transform, oc_stat_measure} option must be used.
Data Types
description()
description() = binary() | string()
measure()
measure() = #measure{name = name(), module = module(), description = description(), unit = unit()}
name()
name() = atom() | binary() | string()
unit()
unit() = atom()
Function Index
| exists/1 |
Returns a measure with the Name or false.. |
| new/3 | Creates and registers a measure. |
| parse_transform/2 |
oc_stat_measure is also a parse transform. |
Function Details
exists/1
exists(Name::name()) -> measure() | false
Returns a measure with the Name or false..
new/3
new(Name::name(), Description::description(), Unit::unit()) -> oc_stat_view:measure()
Creates and registers a measure. If a measure with the same name already exists, old measure returned.
parse_transform/2
parse_transform(Forms, Options) -> any()
oc_stat_measure is also a parse transform. It can detect oc_stat:record calls with constant measure names and generate remote measure module call from that. At the run-time this means we don't have to do a lookup for the module name and if measure doesn't exist, {unknown_measure, Name} error will be thrown.