func searchPut(w http.ResponseWriter, r *http.Request) { id := "PA6-5001" user := &User{ Customer: "Carl Corral", Comment: "I am <em>riled up</em> text", Visits: 1, LastVisit: time.Now(), Birthday: time.Date(1968, time.May, 19, 0, 0, 0, 0, time.UTC), } c := appengine.NewContext(r) index, err := search.Open("users") util_err.Err_log(err) ret_id, err := index.Put(c, id, user) util_err.Err_log(err) fmt.Fprint(w, "OK, saved "+ret_id+"\n\n") var u2 User err = index.Get(c, ret_id, &u2) util_err.Err_log(err) fmt.Fprint(w, "Retrieved document: ", u2) }
func readBothNamespaces(w http.ResponseWriter, r *http.Request) { var c1, c2 int64 var s1, s2 string var err error var reset bool = false p := r.FormValue("reset") if p != "" { reset = true } c := appengine.NewContext(r) c1, err = agnosticReadReset(c, reset) util_err.Err_log(err) { c, err = appengine.Namespace(c, altNamespace) util_err.Err_log(err) c2, err = agnosticReadReset(c, reset) util_err.Err_log(err) } s1 = fmt.Sprintf("%v", c1) s2 = fmt.Sprintf("%v", c2) io.WriteString(w, "|"+s1+"| |"+s2+"|") if reset { io.WriteString(w, " and reset") } }
// unused // probably efficient enough just to call // var bEnc []byte = []byte(sEnc) func StringToVByte(s string) (*bytes.Buffer, *bytes.Buffer) { bMsg := new(bytes.Buffer) bDst := new(bytes.Buffer) const chunksize = 20 lb := make([]byte, chunksize) // loop buffer rdr := strings.NewReader(s) for { n1, err := rdr.Read(lb) if err == io.EOF { break } util_err.Err_log(err) if n1 < 1 { break } independentCopy := make([]byte, n1) copy(independentCopy, lb) n2, err := bDst.Write(independentCopy) util_err.Err_log(err) bMsg.WriteString(fmt.Sprintln("reading", n1, "bytes - writing", n2, "bytes: \n")) bMsg.WriteString(fmt.Sprint(" --", string(independentCopy), "--<br>\n")) } return bDst, bMsg }
func incrementBothNamespaces(w http.ResponseWriter, r *http.Request) { c := appengine.NewContext(r) err := agnosticIncrement(c) util_err.Err_log(err) { c, err := appengine.Namespace(c, altNamespace) util_err.Err_log(err) err = agnosticIncrement(c) util_err.Err_log(err) } s := `counters updates für ns='' and ns='ns01'.` + "\n" io.WriteString(w, s) readBothNamespaces(w, r) }
func Base64_str_to_img(base64_img string) (img image.Image, format string) { pos := base64HeaderPosition(base64_img) reader := base64.NewDecoder(base64.StdEncoding, strings.NewReader(base64_img[pos:])) img, format, err := image.Decode(reader) util_err.Err_log(err) return }
// based on bytes.Buffer and Writing into it func VVByte_to_string(m [][]byte) (*bytes.Buffer, *bytes.Buffer) { bRet := new(bytes.Buffer) bMsg := new(bytes.Buffer) //for i,v := range m { for i := 0; i < len(m); i++ { n, err := bRet.Write(m[i]) util_err.Err_log(err) bMsg.WriteString(" lp" + util.Itos(i) + ": writing " + util.Itos(n) + " bytes: \n") } return bRet, bMsg }
// BufGet - buffered get - fetches value from memory, or from memcache or from the datastore // todo: Paramter to reach "through" to datastore - without the buffer layers func BufGet(w http.ResponseWriter, r *http.Request, mkk string) (WrapBlob, error) { c := appengine.NewContext(r) wb1 := new(WrapBlob) // first check instance memory wb1, ok := memoryInstanceStore[mkk] if ok { c.Infof("received %q from static instance memory", mkk) //util_err.StackTrace(6) return *wb1, nil } // secondly check memcache ok = McacheGet(c, mkk, wb1) if ok && wb1 != nil && wb1.Name != "" { // we could replenish memcache TTL here - instead we do that below c.Infof("retrieved from memcache - combi_key %v", mkk) memoryInstanceStore[mkk] = wb1 return *wb1, nil } // third: retrieve from datastore var wb2 = WrapBlob{} vk := strings.Split(mkk, "__") if len(vk) != 2 { return WrapBlob{}, fmt.Errorf("key must have one '__' delimiter; %q, size %v", mkk, len(vk)) } t := vk[0] skey := vk[1] key := datastore.NewKey(c, t, skey, 0, nil) err := datastore.Get(c, key, &wb2) util_err.Err_log(err) // missing entity and a present entity will both work. if err != nil && err != datastore.ErrNoSuchEntity { return wb2, err } McacheSet(c, mkk, wb2) memoryInstanceStore[mkk] = &wb2 c.Infof("retrieved from ds - re-inserted into memcache + instance RAM - combi_key %v", mkk) return wb2, nil }
// convert image to string, prepend mime header // inspiration_1 http://stackoverflow.com/questions/22945486/golang-converting-image-image-to-byte // inspiration_2 https://github.com/polds/imgbase64/blob/master/images.go // // mime type is always image/png // because we only accept *image.RGBA and use image/png Encoder func Rgba_img_to_base64_str(img *image.RGBA) string { // img to bytes buf := new(bytes.Buffer) err := png.Encode(buf, img) util_err.Err_log(err) imgBytes := buf.Bytes() // binary bytes to base64 bytes e64 := base64.StdEncoding maxEncLen := e64.EncodedLen(len(imgBytes)) imgEnc := make([]byte, maxEncLen) e64.Encode(imgEnc, imgBytes) // base64 bytes to string mimeType := "image/png" return fmt.Sprintf("data:%s;base64,%s", mimeType, imgEnc) }
func searchRetrieve(w http.ResponseWriter, r *http.Request) { c := appengine.NewContext(r) index, err := search.Open("users") util_err.Err_log(err) for t := index.Search(c, "Comment:riled", nil); ; { var res User id, err := t.Next(&res) fmt.Fprintf(w, "\n-- ") if err == search.Done { break } if err != nil { fmt.Fprintf(w, "Search error: %v\n", err) break } fmt.Fprintf(w, "%s -> %#v\n", id, res) } }
func String_to_VVByte(base64_img string) ([][]byte, *bytes.Buffer) { bMsg := new(bytes.Buffer) const chunksize = 400 // var size_o int if len(base64_img)%chunksize == 0 { size_o = len(base64_img) / chunksize } else { size_o = len(base64_img)/chunksize + 1 } VVByte := make([][]byte, size_o) cntr := -1 b := make([]byte, chunksize) rdr := strings.NewReader(base64_img) for { cntr++ n, err := rdr.Read(b) if err == io.EOF { break } util_err.Err_log(err) if n < 1 { break } indep_copy := make([]byte, n) copy(indep_copy, b) VVByte[cntr] = indep_copy bMsg.WriteString("reading " + util.Itos(n) + " bytes:\n") //bMsg.Write( VVByte[util.Itos(cntr)] ) } return VVByte, bMsg }
func queuePush(w http.ResponseWriter, r *http.Request) { c := appengine.NewContext(r) m := map[string][]string{"counter_name": []string{nscStringKey}} t := taskqueue.NewPOSTTask("/_ah/namespaced-counters/queue-pop", m) taskqueue.Add(c, t, "") c, err := appengine.Namespace(c, altNamespace) util_err.Err_log(err) taskqueue.Add(c, t, "") io.WriteString(w, "tasks enqueued\n") io.WriteString(w, "\ncounter values now: \n") readBothNamespaces(w, r) io.WriteString(w, "\n\n...sleeping... \n") time.Sleep(time.Duration(400) * time.Millisecond) readBothNamespaces(w, r) }
// saving some data by kind and key // without ancestor key func saveURLNoAnc(w http.ResponseWriter, r *http.Request) { c := appengine.NewContext(r) k := ds.NewKey(c, kindUrl, keyUrl, 0, nil) e := new(LastURL) err := ds.Get(c, k, e) if err == ds.ErrNoSuchEntity { util_err.Err_log(err) } else { util_err.Err_http(w, r, err, false) } old := e.Value e.Value = r.URL.Path + r.URL.RawQuery _, err = ds.Put(c, k, e) util_err.Err_http(w, r, err, false) w.Header().Set("Content-Type", "text/plain; charset=utf-8") w.Write([]byte("old=" + old + "\n")) w.Write([]byte("new=" + e.Value + "\n")) }
func renameOrDelete(c appengine.Context, w http.ResponseWriter, r *http.Request) { b1 := new(bytes.Buffer) s1 := "" defer func() { w.Header().Set("Content-type", "text/html; charset=utf-8") w.Write(b1.Bytes()) }() // c := appengine.NewContext(r) bk := r.FormValue("blobkey") if bk == "" { b1.WriteString("No blob key given<br>") return } else { s1 = fmt.Sprintf("Blob key given %q<br>", bk) b1.WriteString(s1) } dsKey := datastore.NewKey(c, "__BlobInfo__", bk, 0, nil) q := datastore.NewQuery("__BlobInfo__").Filter("__key__=", dsKey) var bi BlobInfo var found bool for t := q.Run(c); ; { _, err := t.Next(&bi) if err == datastore.Done { c.Infof(" No Results (any more), blob-rename-delete %v", err) break } // other err if err != nil { util_err.Err_log(err) return } found = true break } if found { ac := r.FormValue("action") if ac == "delete" { b1.WriteString("deletion ") // first the binary data keyBlob, err := blobstore.BlobKeyForFile(c, bi.Filename) util_err.Err_log(err) if err != nil { b1.WriteString(fmt.Sprintf(" ... failed (1) %v", err)) } else { err = blobstore.Delete(c, keyBlob) util_err.Err_log(err) if err != nil { b1.WriteString(fmt.Sprintf(" ... failed (2) %v<br>", err)) } else { // now the datastore record err = datastore.Delete(c, dsKey) util_err.Err_log(err) if err != nil { b1.WriteString(fmt.Sprintf(" ... failed (3) %v<br>%#v<br>", err, dsKey)) } else { b1.WriteString(" ... succeeded<br>") } } } } if ac == "rename" { b1.WriteString("renaming ") nfn := r.FormValue("filename") if nfn == "" || len(nfn) < 4 { b1.WriteString(" ... failed - at LEAST 4 chars required<br>") return } nfn = strings.ToLower(nfn) bi.Filename = nfn _, err := datastore.Put(c, dsKey, &bi) util_err.Err_log(err) if err != nil { b1.WriteString(fmt.Sprintf(" ... failed. %v", err)) } else { b1.WriteString(" ... succeeded<br>") } } } else { b1.WriteString("no blob found for given blobkey<br>") } b1.WriteString("<a href='/blob2'>Back to list</a><br>") }
func queuePop(w http.ResponseWriter, r *http.Request) { c := appengine.NewContext(r) err := agnosticIncrement(c) c.Infof("qp") util_err.Err_log(err) }
// McacheSet is a generic memcache saving function. // It takes scalars as well as structs. // // Integers and strings are put into the memcache Value []byte // structs are put into the memcache *Object* - using memcache.JSON // Todo: types WrapString and WrapInt should be handled like string/int // // Scalars are tentatively saved using the CAS (compare and save) methods func McacheSet(c appengine.Context, skey string, str_int_struct interface{}) { var err error var val string tMold := reflect.TypeOf(str_int_struct) stMold := tMold.Name() // strangely this is empty stMold = fmt.Sprintf("%T", str_int_struct) // unlike this if stMold != "int" && stMold != "string" && stMold != "dsu.WrapInt" && stMold != "dsu.WrapString" { // struct - save it with JSON encoder n := tMold.NumField() _ = n miPut := &memcache.Item{ Key: skey, Value: []byte(tMold.Name()), // sadly - value is ignored Object: &str_int_struct, Expiration: 3600 * time.Second, } memcache.JSON.Set(c, miPut) c.Infof("mcache set obj key %v[%s] - err %v", skey, stMold, err) } else { // scalar value - save it switch chamaeleon := str_int_struct.(type) { default: panic(fmt.Sprintf("only string or int - instead: -%T", str_int_struct)) case nil: val = "" case WrapString: val = chamaeleon.S case string: val = chamaeleon case int: val = util.Itos(chamaeleon) case WrapInt: val = util.Itos(chamaeleon.I) } /* This is a Compare and Set (CAS) implementation of "set". It implements optimistic locking. We fetch the item first, then modify it, then put it back. We rely on the hidden "casID" of the memcache item, to detect intermittent changes by competitors. Biggest downside is the additional roundtrip for the fetch. Second downside: We should implement a retry after failure. Instead I resorted to a simple "SET" Upside: Prevention of race conditions. But race conditions only matter if newval = f(oldval) Otherwise last one wins should apply anyway. */ maxTries := 3 miCas, eget := memcache.Get(c, skey) // compare and swap for i := 0; i <= maxTries; i++ { if i == maxTries { panic(fmt.Sprintf("memcache set CAS failed after %v attempts", maxTries)) } var eput error var putMode = "" if eget != memcache.ErrCacheMiss { putMode = "CAS" miCas.Value = []byte(val) eput = memcache.CompareAndSwap(c, miCas) } else { putMode = "ADD" miCas := &memcache.Item{ Key: skey, Value: []byte(val), } eput = memcache.Add(c, miCas) } if eput == memcache.ErrCASConflict { c.Errorf("\t memcache CAS FAILED - concurrent update?") // we brutally fallback to set(): miCas := &memcache.Item{ Key: skey, Value: []byte(val), } eset := memcache.Set(c, miCas) util_err.Err_log(eset) time.Sleep(10 * time.Millisecond) continue } if eput == memcache.ErrNotStored { c.Errorf("\t memcache save FAILED - no idea why it would") time.Sleep(10 * time.Millisecond) continue } c.Infof("mcache set scalar %v[%T]=%v - mode %v - eget/eput: %v/%v", skey, str_int_struct, val, putMode, eget, eput) break } } }