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
}
}
}
