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http.go
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http.go
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package mycache
import (
"fmt"
"io/ioutil"
"log"
"net/http"
"net/url"
"strings"
"sync"
"github.com/golang/protobuf/proto"
"github.com/hfpublic/mycache/consistenthash"
"github.com/hfpublic/mycache/pd"
)
const (
defaultBasePath = "/_mycache/"
defaultReplicas = 50
)
type HTTPPool struct {
self string
basePath string
mu sync.Mutex
peers *consistenthash.Map
httpGetters map[string]*httpGetter
}
func NewHTTPPool(self string) *HTTPPool {
return &HTTPPool{
self: self,
basePath: defaultBasePath,
}
}
func (p *HTTPPool) Log(format string, v ...any) {
log.Printf("[Server %s] %s", p.self, fmt.Sprintf(format, v...))
}
func (p *HTTPPool) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if !strings.HasPrefix(r.URL.Path, p.basePath) {
panic("HTTPPool serving unexpected path: " + r.URL.Path)
}
p.Log("%s %s", r.Method, r.URL.Path)
params := strings.SplitN(r.URL.Path[len(p.basePath):], "/", 2)
if len(params) != 2 {
http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
return
}
groupName := params[0]
key := params[1]
group := GetGroup(groupName)
if group == nil {
http.Error(w, "no search group: "+groupName, http.StatusNotFound)
return
}
v, err := group.Get(key)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
body, err := proto.Marshal(&pd.Response{Value: v.ByteSlice()})
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
w.Header().Set("Content-Type", "application/octet-stream")
w.Write(body)
}
func (p *HTTPPool) Set(peers ...string) {
p.mu.Lock()
defer p.mu.Unlock()
p.peers = consistenthash.New(defaultReplicas, nil)
p.peers.Add(peers...)
p.httpGetters = make(map[string]*httpGetter, len(peers))
for _, peer := range peers {
p.httpGetters[peer] = &httpGetter{baseURL: peer + p.basePath}
}
}
func (p *HTTPPool) PickPeer(key string) (PeerGetter, bool) {
p.mu.Lock()
defer p.mu.Unlock()
if peer := p.peers.Get(key); peer != "" && peer != p.self {
p.Log("Pick peer %s", peer)
return p.httpGetters[peer], true
}
return nil, false
}
type httpGetter struct {
baseURL string
}
func (h *httpGetter) Get(in *pd.Request, out *pd.Response) error {
url := fmt.Sprintf("%v%v/%v", h.baseURL, url.QueryEscape(in.Group), url.QueryEscape(in.Key))
resp, err := http.Get(url)
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("server returned: %v", resp.Status)
}
bytes, err := ioutil.ReadAll(resp.Body)
if err != nil {
return fmt.Errorf("reading response body: %v", err)
}
if err = proto.Unmarshal(bytes, out); err != nil {
return fmt.Errorf("decoding response body: %v", err)
}
return nil
}
var _ PeerGetter = (*httpGetter)(nil)