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// Copyright 2015 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package marbl
import (
"crypto/rand"
"encoding/hex"
"net/http"
"sync"
"github.com/google/martian/log"
"golang.org/x/net/websocket"
)
// Handler exposes marbl logs over websockets.
type Handler struct {
mu sync.RWMutex
subs map[string]chan<- []byte
}
// NewHandler instantiates a Handler with an empty set of subscriptions.
func NewHandler() *Handler {
return &Handler{
subs: make(map[string]chan<- []byte),
}
}
// Write writes frames to all websocket subscribers and returns the number
// of bytes written and an error.
func (h *Handler) Write(b []byte) (int, error) {
h.mu.RLock()
defer h.mu.RUnlock()
for id, framec := range h.subs {
select {
case framec <- b:
default:
log.Errorf("logstream: buffer full for connection, dropping")
close(framec)
delete(h.subs, id)
}
}
return len(b), nil
}
func (h *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
websocket.Server{Handler: h.streamLogs}.ServeHTTP(rw, req)
}
func (h *Handler) streamLogs(conn *websocket.Conn) {
defer conn.Close()
id, err := newID()
if err != nil {
log.Errorf("logstream: failed to create ID: %v", err)
return
}
framec := make(chan []byte, 16384)
h.subscribe(id, framec)
defer h.unsubscribe(id)
for b := range framec {
if err := websocket.Message.Send(conn, b); err != nil {
log.Errorf("logstream: failed to send message: %v", err)
return
}
}
}
func newID() (string, error) {
src := make([]byte, 8)
if _, err := rand.Read(src); err != nil {
return "", err
}
return hex.EncodeToString(src), nil
}
func (h *Handler) unsubscribe(id string) {
h.mu.Lock()
defer h.mu.Unlock()
delete(h.subs, id)
}
func (h *Handler) subscribe(id string, framec chan<- []byte) {
h.mu.Lock()
defer h.mu.Unlock()
h.subs[id] = framec
}
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