THC - Timed HTTP Client for Go

THC is a thin wrapper around Go's http.Client package which provides the following extra features.

Metrics

THC exports metrics of your requests using expvar. You can observe average times for DNS lookups, TLS handshakes, TCP sessions and more. Look at the documentation for a list of exported metrics.

Circuit breaker

After a defined number of consecutive failures, THC will switch to an out of service state. In this state, the client will stop sending HTTP requests and instead will return the error ErrOutOfService. It is up to the application to decide what to do in that case. After a predefined amount of time, the service will be restores and THC will resume to work normally.

Example

package main

import (
    "net/http"
    "time"

    "github.com/oliwer/thc"
)

var client = &thc.THC{
    Client:      &http.Client{Timeout: 100 * time.Millisecond},
    Name:        "example",
    MaxErrors:   10,
    HealingTime: 20 * time.Second,
}

func init() {
    client.PublishExpvar()
}

func main() {
    for {
        resp, err := client.Get("https://example.com/thing.json")

        if err == thc.ErrOutOfService {
            // The service is down for 20s. (HealingTime)
        }

        if err != nil {
            // There was an error but we are still OK because
            // still under MaxErrors consecutive errors.
        }

        // Process resp normally...
    }
}

Notes

THC requires Go v1.8 or above. It is thread-safe and lock-less.