Custom Metrics
Motivation:
The go-metrics package offers a comprehensive set of standard metrics, but sometimes custom metrics are needed to address specific project requirements. This outline details how to define and register such custom metrics.
Defining Custom Metrics
Custom metrics are typically implemented as structs that embed the go-metrics.Metric interface. This interface defines methods for updating and retrieving the metric’s value.
Example:
// Example custom metric: a simple counter
type MyCounter struct {
go-metrics.Metric
count int64
}
// Implement the Metric interface
func (c *MyCounter) Get() interface{} {
return c.count
}
func (c *MyCounter) Update(val interface{}) {
if v, ok := val.(int64); ok {
c.count += v
}
}
This example demonstrates a custom counter. You can adapt this pattern to implement various custom metrics, such as gauges, timers, histograms, etc.
Registering Custom Metrics
Custom metrics need to be registered with a go-metrics.Registry to become accessible for reporting and consumption.
Example:
// Register the custom counter
registry := go-metrics.NewRegistry()
registry.Register("my.custom.counter", &MyCounter{})
This example shows how to register the MyCounter with a registry. You can use a global registry or create registries for specific components of your application.
Usage
After registering, custom metrics can be updated and retrieved using the registry.
Example:
// Update the custom counter
registry.Get("my.custom.counter").Update(1) // Increment by 1
// Get the value of the counter
value := registry.Get("my.custom.counter").Get() // Get the current count
This example illustrates updating the counter and retrieving its current value.
Further Exploration
For more in-depth information on creating custom metrics, refer to the official documentation of the go-metrics package:
These resources offer a comprehensive guide to using the go-metrics package, including extensive examples and best practices.
