harness-drone/server/ws.go

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package server
import (
"time"
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"github.com/drone/drone/common"
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"github.com/drone/drone/eventbus"
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log "github.com/Sirupsen/logrus"
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"github.com/gin-gonic/gin"
"github.com/gorilla/websocket"
)
const (
// Time allowed to write the message to the client.
writeWait = 10 * time.Second
// Time allowed to read the next pong message from the client.
pongWait = 60 * time.Second
// Send pings to client with this period. Must be less than pongWait.
pingPeriod = (pongWait * 9) / 10
)
var upgrader = websocket.Upgrader{
ReadBufferSize: 1024,
WriteBufferSize: 1024,
}
// GetEvents will upgrade the connection to a Websocket and will stream
// event updates to the browser.
func GetEvents(c *gin.Context) {
bus := ToBus(c)
user := ToUser(c)
remote := ToRemote(c)
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// TODO (bradrydzewski) revisit this approach at some point.
//
// instead of constantly checking for remote permissions, we will
// cache them for the lifecycle of this websocket. The pro here is
// that we are making way less external calls (good). The con is that
// if a ton of developers conntect to websockets for long periods of
// time with heavy build traffic (not super likely, but possible) this
// caching strategy could take up a lot of memory.
perms_ := map[string]*common.Perm{}
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// upgrade the websocket
ws, err := upgrader.Upgrade(c.Writer, c.Request, nil)
if err != nil {
c.Fail(400, err)
return
}
ticker := time.NewTicker(pingPeriod)
eventc := make(chan *eventbus.Event, 1)
bus.Subscribe(eventc)
defer func() {
bus.Unsubscribe(eventc)
ticker.Stop()
ws.Close()
close(eventc)
}()
go func() {
for {
select {
case event := <-eventc:
if event == nil {
return // why would this ever happen?
}
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perm, ok := perms_[event.Repo.FullName]
if !ok {
perm = perms(remote, user, event.Repo)
perms_[event.Repo.FullName] = perm
}
if perm != nil && perm.Pull {
err := ws.WriteJSON(event)
if err != nil {
log.Errorln(err, event)
}
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}
case <-ticker.C:
ws.SetWriteDeadline(time.Now().Add(writeWait))
err := ws.WriteMessage(websocket.PingMessage, []byte{})
if err != nil {
ws.Close()
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log.Debugf("closed websocket")
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return
}
}
}
}()
readWebsocket(ws)
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log.Debugf("closed websocket")
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}
// readWebsocket will block while reading the websocket data
func readWebsocket(ws *websocket.Conn) {
defer ws.Close()
ws.SetReadLimit(512)
ws.SetReadDeadline(time.Now().Add(pongWait))
ws.SetPongHandler(func(string) error {
ws.SetReadDeadline(time.Now().Add(pongWait))
return nil
})
for {
_, _, err := ws.ReadMessage()
if err != nil {
break
}
}
}