1
0
out-of-tree/distro/debian/snapshot/metasnap/metasnap.go

154 lines
2.7 KiB
Go

package metasnap
import (
"context"
"errors"
"fmt"
"io"
"net/http"
"strings"
"time"
"github.com/rs/zerolog/log"
"golang.org/x/time/rate"
)
// Note: Metasnap does not have all the packages, and its API is
// rather buggy.
const apiURL = "http://metasnap.debian.net/cgi-bin/api?"
var (
limiterTimeout time.Duration = time.Second / 20
limiterBurst int = 3
limiterUpdateDelay time.Duration = time.Second * 10
Limiter = rate.NewLimiter(rate.Every(limiterTimeout), limiterBurst)
)
func lowerLimit() {
limiterTimeout = limiterTimeout * 2
log.Info().Msgf("limiter timeout set to %v", limiterTimeout)
Limiter.SetLimitAt(
time.Now().Add(limiterUpdateDelay),
rate.Every(limiterTimeout),
)
time.Sleep(limiterUpdateDelay)
}
// Retries in case of 5xx errors
var Retries = 10
var ErrNotFound = errors.New("404 not found")
func query(q string) (result string, err error) {
flog := log.With().Str("url", q).Logger()
var resp *http.Response
for i := Retries; i > 0; i-- {
flog.Trace().Msg("wait")
Limiter.Wait(context.Background())
flog.Trace().Msg("start")
resp, err = http.Get(q)
if err != nil {
if strings.Contains(err.Error(), "reset by peer") {
flog.Debug().Err(err).Msg("")
lowerLimit()
continue
}
flog.Error().Err(err).Msg("")
return
}
defer resp.Body.Close()
flog.Debug().Msgf("%s", resp.Status)
if resp.StatusCode == 404 {
err = ErrNotFound
return
}
if resp.StatusCode < 500 {
break
}
flog.Debug().Msgf("retry (%d left)", i)
}
if resp.StatusCode >= 400 {
err = fmt.Errorf("%d (%s)", resp.StatusCode, q)
}
buf, err := io.ReadAll(resp.Body)
if err != nil {
return
}
result = string(buf)
return
}
func queryAPIf(f string, s ...interface{}) (result string, err error) {
return query(apiURL + fmt.Sprintf(f, s...))
}
type Snapshot struct {
First string
Last string
}
type Repo struct {
Archive string
Suite string
Component string
Snapshot Snapshot
}
func GetRepos(archive, pkg, arch, ver string) (repos []Repo, err error) {
result, err := queryAPIf("archive=%s&pkg=%s&arch=%s",
archive, pkg, arch)
if err != nil {
return
}
if result == "" {
err = ErrNotFound
return
}
for _, line := range strings.Split(result, "\n") {
if line == "" {
break
}
fields := strings.Split(line, " ")
if len(fields) != 5 {
err = fmt.Errorf("metasnap api returned %s", result)
return
}
repo := Repo{
Archive: archive,
Suite: fields[1],
Component: fields[2],
Snapshot: Snapshot{
First: fields[3],
Last: fields[4],
},
}
if fields[0] == ver {
repos = append(repos, repo)
}
}
if len(repos) == 0 {
err = ErrNotFound
return
}
return
}