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server.go
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server.go
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package embed
import (
"fmt"
"io/ioutil"
"net/http"
"os"
"time"
badger "github.com/dgraph-io/badger/v3"
"github.com/genshinsim/gcsim/services/pkg/store"
"github.com/go-chi/chi"
"github.com/go-chi/chi/middleware"
"go.uber.org/zap"
)
//Server contains an authentication server
type Server struct {
Router *chi.Mux
db *badger.DB
Log *zap.SugaredLogger
Store store.SimStore
Generator ImageGenerator
cfg Config
work chan string //key to generate embed for
}
type Config struct {
DataFolder string
}
type ImageGenerator interface {
Generate(sim store.Simulation, outpath string) error
}
func New(cfg Config, cust ...func(*Server) error) (*Server, error) {
s := &Server{
cfg: cfg,
}
//read config
for _, f := range cust {
err := f(s)
if err != nil {
return nil, err
}
}
if s.Log == nil {
logger, err := zap.NewDevelopment()
if err != nil {
return nil, err
}
sugar := logger.Sugar()
sugar.Debugw("logger initiated")
s.Log = sugar
}
db, err := badger.Open(badger.DefaultOptions(cfg.DataFolder))
if err != nil {
return nil, err
}
s.db = db
s.Router = chi.NewRouter()
s.routes()
s.work = make(chan string)
go s.pool()
return s, nil
}
func (s *Server) pool() {
var queue []string
done := make(chan bool)
count := 0
for {
select {
case w := <-s.work:
queue = append(queue, w)
case <-done:
count--
}
s.Log.Infow("worker status", "depth", len(queue), "count", count, "queue", queue)
if count == 0 && len(queue) > 0 {
//send out worker
go s.worker(queue[0], done)
count++
queue = queue[1:]
}
}
}
func (s *Server) worker(key string, done chan bool) {
res, err := s.Store.Fetch(key)
if err != nil {
s.Log.Warnw("error getting simulation", "err", err)
done <- true
return
}
filepath := fmt.Sprintf("./%v.png", key)
os.Remove(filepath)
err = s.Generator.Generate(res, filepath)
if err != nil {
s.Log.Warnw("error generating image", "key", key, "path", filepath, "err", err)
done <- true
return
}
//try reading file and storing in db
b, err := ioutil.ReadFile(filepath)
if err != nil {
s.Log.Warnw("error loading image", "key", key, "path", filepath, "err", err)
done <- true
return
}
err = s.db.Update(func(txn *badger.Txn) error {
e := badger.NewEntry([]byte(key), b).WithTTL(time.Hour * 24 * 60)
err := txn.SetEntry(e)
return err
})
if err != nil {
s.Log.Warnw("error saving image to db", "key", key, "path", filepath, "err", err)
}
s.Log.Infow("generating embed ok", "key", key)
//clean up after ourselves
os.Remove(filepath)
done <- true
}
func (s *Server) routes() {
r := s.Router
r.Use(middleware.Logger)
r.Post("/embed/{key}", s.handleGenerateEmbed())
r.Get("/embed/{key}", s.handleRetrieveEmbed())
}
func (s *Server) handleGenerateEmbed() http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
key := chi.URLParam(r, "key")
s.Log.Infof("we got work: %v", key)
s.work <- key
w.WriteHeader(http.StatusOK)
}
}
func (s *Server) handleRetrieveEmbed() http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
key := chi.URLParam(r, "key")
var data []byte
err := s.db.View(func(txn *badger.Txn) error {
item, err := txn.Get([]byte(key))
if err != nil {
return err
}
err = item.Value(func(val []byte) error {
data = append([]byte{}, val...)
return nil
})
return err
})
if err != nil {
if err == badger.ErrKeyNotFound {
s.Log.Warnw("error getting image - not found", "key", key)
//we should try to regenerate it
s.work <- key
//in which case we return 404 anyways
w.WriteHeader(http.StatusNotFound)
return
}
s.Log.Warnw("unexpected error reading image", "err", err)
w.WriteHeader(http.StatusInternalServerError)
return
}
w.Header().Set("Content-Type", "image/png")
w.WriteHeader(http.StatusOK)
w.Write(data)
}
}