cchat-gtk/internal/gts/httputil/httputil.go

package httputil

import (
	"context"
	"net/http"
	"os"
	"path/filepath"
	"time"

	"github.com/gregjones/httpcache"
	"github.com/gregjones/httpcache/diskcache"
	"github.com/peterbourgon/diskv"
	"github.com/pkg/errors"
)

var basePath = filepath.Join(os.TempDir(), "cchat-gtk-caching-is-hard")

var dskcached = http.Client{
	Timeout: 15 * time.Second,
	Transport: &httpcache.Transport{
		Transport: &http.Transport{
			// Be generous: use a 128KB buffer instead of 4KB to hopefully
			// reduce cgo calls.
			WriteBufferSize: 128 * 1024,
			ReadBufferSize:  128 * 1024,
		},
		Cache: diskcache.NewWithDiskv(diskv.New(diskv.Options{
			BasePath:     basePath,
			TempDir:      filepath.Join(basePath, "tmp"),
			PathPerm:     0750,
			FilePerm:     0750,
			Compression:  diskv.NewZlibCompressionLevel(4),
			CacheSizeMax: 25 * 1024 * 1024, // 25 MiB in memory
		})),
		MarkCachedResponses: true,
	},
}

// TODO: log cache misses with httpcache.XFromCache

func get(ctx context.Context, url string, cached bool) (r *http.Response, err error) {
	q, err := http.NewRequestWithContext(ctx, "GET", url, nil)
	if err != nil {
		return nil, errors.Wrap(err, "Failed to make a request")
	}

	r, err = dskcached.Do(q)
	if err != nil {
		return nil, err
	}

	if r.StatusCode < 200 || r.StatusCode > 299 {
		r.Body.Close()
		return nil, errors.Errorf("Unexpected status %d", r.StatusCode)
	}

	return r, nil
}