func distributedOperation(masterNode string, store *storage.Store, volumeId storage.VolumeId, op func(location operation.Location) bool) bool {
if lookupResult, lookupErr := operation.Lookup(masterNode, volumeId.String()); lookupErr == nil {
length := 0
selfUrl := (store.Ip + ":" + strconv.Itoa(store.Port))
results := make(chan bool)
for _, location := range lookupResult.Locations {
//排除自己
if location.Url != selfUrl {
length++
//异步复制
go func(location operation.Location, results chan bool) {
results <- op(location)
}(location, results)
}
}
ret := true
//等待操作结束 无论成功与否
for i := 0; i < length; i++ {
ret = ret && <-results
}
return ret
} else {
glog.V(0).Infoln("Failed to lookup for", volumeId, lookupErr.Error())
}
return false
}
func (fs *FilerServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request, isGetMethod bool) {
//只返回目录
if strings.HasSuffix(r.URL.Path, "/") {
fs.listDirectoryHandler(w, r)
return
}
fileId, err := fs.filer.FindFile(r.URL.Path)
if err == leveldb.ErrNotFound {
glog.V(3).Infoln("Not found in db", r.URL.Path)
w.WriteHeader(http.StatusNotFound)
return
}
parts := strings.Split(fileId, ",") //3,12345
if len(parts) != 2 {
glog.V(1).Infoln("Invalid fileId", fileId)
w.WriteHeader(http.StatusNotFound)
return
}
lookup, lookupError := operation.Lookup(fs.master, parts[0])
if lookupError != nil {
glog.V(1).Infoln("Invalid lookup", lookupError.Error())
w.WriteHeader(http.StatusNotFound)
return
}
if len(lookup.Locations) == 0 {
glog.V(1).Infoln("Can not find location for volume", parts[0])
w.WriteHeader(http.StatusNotFound)
return
}
//从合适的DataNode中随机选择一个 从中读取fileId指定的文件
urlLocation := lookup.Locations[rand.Intn(len(lookup.Locations))].PublicUrl
u, _ := url.Parse("http://" + urlLocation + "/" + fileId)
request := &http.Request{
Method: r.Method,
URL: u,
Proto: r.Proto,
ProtoMajor: r.ProtoMajor,
ProtoMinor: r.ProtoMinor,
Header: r.Header,
Body: r.Body,
Host: r.Host,
ContentLength: r.ContentLength,
}
glog.V(3).Infoln("retrieving from", u)
resp, do_err := util.Do(request)
if do_err != nil {
glog.V(0).Infoln("failing to connect to volume server", do_err.Error())
writeJsonError(w, r, do_err)
return
}
defer resp.Body.Close()
for k, v := range resp.Header {
w.Header()[k] = v
}
w.WriteHeader(resp.StatusCode)
io.Copy(w, resp.Body)
}
/*
此api完成数据的返回,处理了multi-part等
*/
func (vs *VolumeServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request) {
n := new(storage.Needle)
vid, fid, filename, ext, _ := parseURLPath(r.URL.Path)
volumeId, err := storage.NewVolumeId(vid)
if err != nil {
glog.V(2).Infoln("parsing error:", err, r.URL.Path)
w.WriteHeader(http.StatusBadRequest)
return
}
err = n.ParsePath(fid)
if err != nil {
glog.V(2).Infoln("parsing fid error:", err, r.URL.Path)
w.WriteHeader(http.StatusBadRequest)
return
}
glog.V(4).Infoln("volume", volumeId, "reading", n)
if !vs.store.HasVolume(volumeId) { //自己没有
//向master查找
lookupResult, err := operation.Lookup(vs.masterNode, volumeId.String())
glog.V(2).Infoln("volume", volumeId, "found on", lookupResult, "error", err)
//重定向
if err == nil && len(lookupResult.Locations) > 0 {
http.Redirect(w, r, "http://"+lookupResult.Locations[0].PublicUrl+r.URL.Path, http.StatusMovedPermanently)
} else {
glog.V(2).Infoln("lookup error:", err, r.URL.Path)
w.WriteHeader(http.StatusNotFound)
}
return
}
cookie := n.Cookie
count, e := vs.store.Read(volumeId, n)
glog.V(4).Infoln("read bytes", count, "error", e)
//读取失败
if e != nil || count <= 0 {
glog.V(0).Infoln("read error:", e, r.URL.Path)
w.WriteHeader(http.StatusNotFound)
return
}
//文件cookie不匹配
if n.Cookie != cookie {
glog.V(0).Infoln("request", r.URL.Path, "with unmaching cookie seen:", cookie, "expected:", n.Cookie, "from", r.RemoteAddr, "agent", r.UserAgent())
w.WriteHeader(http.StatusNotFound)
return
}
if n.LastModified != 0 {
w.Header().Set("Last-Modified", time.Unix(int64(n.LastModified), 0).UTC().Format(http.TimeFormat))
if r.Header.Get("If-Modified-Since") != "" {
if t, parseError := time.Parse(http.TimeFormat, r.Header.Get("If-Modified-Since")); parseError == nil {
if t.Unix() >= int64(n.LastModified) {
w.WriteHeader(http.StatusNotModified)
return
}
}
}
}
etag := n.Etag()
if inm := r.Header.Get("If-None-Match"); inm == etag {
w.WriteHeader(http.StatusNotModified)
return
}
w.Header().Set("Etag", etag)
if n.NameSize > 0 && filename == "" {
filename = string(n.Name)
dotIndex := strings.LastIndex(filename, ".")
if dotIndex > 0 {
ext = filename[dotIndex:]
}
}
mtype := ""
if ext != "" {
mtype = mime.TypeByExtension(ext)
}
if n.MimeSize > 0 {
mt := string(n.Mime)
if mt != "application/octet-stream" {
mtype = mt
}
}
if mtype != "" {
w.Header().Set("Content-Type", mtype)
}
if filename != "" {
w.Header().Set("Content-Disposition", "filename=\""+fileNameEscaper.Replace(filename)+"\"")
}
if ext != ".gz" {
if n.IsGzipped() {
if strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
w.Header().Set("Content-Encoding", "gzip")
} else {
if n.Data, err = storage.UnGzipData(n.Data); err != nil {
glog.V(0).Infoln("lookup error:", err, r.URL.Path)
}
}
}
}
if ext == ".png" || ext == ".jpg" || ext == ".gif" {
width, height := 0, 0
if r.FormValue("width") != "" {
width, _ = strconv.Atoi(r.FormValue("width"))
}
if r.FormValue("height") != "" {
height, _ = strconv.Atoi(r.FormValue("height"))
}
//获得缩略图
n.Data, _, _ = images.Resized(ext, n.Data, width, height)
}
//如果是head协议 简单返回
w.Header().Set("Accept-Ranges", "bytes")
if r.Method == "HEAD" {
w.Header().Set("Content-Length", strconv.Itoa(len(n.Data)))
return
}
rangeReq := r.Header.Get("Range")
if rangeReq == "" {
w.Header().Set("Content-Length", strconv.Itoa(len(n.Data)))
//写入实际数据
if _, e = w.Write(n.Data); e != nil {
glog.V(0).Infoln("response write error:", e)
}
return
}
//the rest is dealing with partial content request
//mostly copy from src/pkg/net/http/fs.go
size := int64(len(n.Data))
ranges, err := parseRange(rangeReq, size)
if err != nil {
http.Error(w, err.Error(), http.StatusRequestedRangeNotSatisfiable)
return
}
if sumRangesSize(ranges) > size {
// The total number of bytes in all the ranges
// is larger than the size of the file by
// itself, so this is probably an attack, or a
// dumb client. Ignore the range request.
ranges = nil
return
}
if len(ranges) == 0 {
return
}
if len(ranges) == 1 {
// RFC 2616, Section 14.16:
// "When an HTTP message includes the content of a single
// range (for example, a response to a request for a
// single range, or to a request for a set of ranges
// that overlap without any holes), this content is
// transmitted with a Content-Range header, and a
// Content-Length header showing the number of bytes
// actually transferred.
// ...
// A response to a request for a single range MUST NOT
// be sent using the multipart/byteranges media type."
ra := ranges[0]
w.Header().Set("Content-Length", strconv.FormatInt(ra.length, 10))
w.Header().Set("Content-Range", ra.contentRange(size))
w.WriteHeader(http.StatusPartialContent)
if _, e = w.Write(n.Data[ra.start : ra.start+ra.length]); e != nil {
glog.V(0).Infoln("response write error:", e)
}
return
}
// process mulitple ranges
for _, ra := range ranges {
if ra.start > size {
http.Error(w, "Out of Range", http.StatusRequestedRangeNotSatisfiable)
return
}
}
sendSize := rangesMIMESize(ranges, mtype, size)
pr, pw := io.Pipe()
mw := multipart.NewWriter(pw)
w.Header().Set("Content-Type", "multipart/byteranges; boundary="+mw.Boundary())
sendContent := pr
defer pr.Close() // cause writing goroutine to fail and exit if CopyN doesn't finish.
go func() {
for _, ra := range ranges {
part, err := mw.CreatePart(ra.mimeHeader(mtype, size))
if err != nil {
pw.CloseWithError(err)
return
}
if _, err = part.Write(n.Data[ra.start : ra.start+ra.length]); err != nil {
pw.CloseWithError(err)
return
}
}
mw.Close()
pw.Close()
}()
if w.Header().Get("Content-Encoding") == "" {
w.Header().Set("Content-Length", strconv.FormatInt(sendSize, 10))
}
w.WriteHeader(http.StatusPartialContent)
io.CopyN(w, sendContent, sendSize)
}