func (r *Replyer) ServeHTTP(w http.ResponseWriter, req *http.Request) {
base := filepath.Base(req.URL.Path)
mylog.Debug("request for response ", base)
session := r.SessionSeed.New()
defer session.Close()
session.SetMode(mgo.Eventual, true)
db := session.DB(r.Cfg.Database)
respColl := db.C(r.Cfg.ResponsesColl)
rpl := &Reply{}
mylog.Debug("searching response", base)
e := respColl.Find(bson.M{"id": base}).One(&rpl)
if e != nil {
mylog.Debug("reply not found ", base)
http.Error(w, e.Error(), http.StatusNotFound)
return
}
mylog.Debug("json marshaling response", base)
text, e := json.MarshalIndent(rpl, "", " ")
if e != nil {
mylog.Debug("error marshaling JSON ", base, e)
http.Error(w, e.Error(), http.StatusInternalServerError)
return
}
mylog.Debugf("returning JSON %q for %v", text, base)
w.Header().Set("Content-Type", "application/json")
w.Write(text)
}
func onEnd(f func()) {
sigCh := make(chan os.Signal)
signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
go func() {
s := <-sigCh
mylog.Debugf("Signal %+v received", s)
f()
}()
}
//ServeHTTP implements HTTP handler interface
func (l *Listener) ServeHTTP(w http.ResponseWriter, r *http.Request) {
mylog.Debugf("received request %+v", r)
w.Header().Set("Content-Type", "application/json")
if l.Stopped() {
mylog.Debug("warning client server is stopping")
http.Error(w, `{"error":"Server is shutting down"}`, 503)
return
}
relayedRequest, e := newPetition(r)
if e != nil {
mylog.Debug("petition with error", e)
http.Error(w, fmt.Sprintf(`{"error": %q }`, e), 400)
return
}
db := l.SessionSeed.DB(l.Cfg.Database)
petColl := db.C(l.Cfg.Instance + l.Cfg.PetitionsColl)
mylog.Debugf("petition created %+v", relayedRequest)
e = petColl.Insert(relayedRequest)
if e != nil {
http.Error(w, fmt.Sprintf(`{"error": %q, "ref":%q }`, e, relayedRequest.ID), 500)
mylog.Alert("ERROR inserting", relayedRequest.ID, e)
l.SessionSeed.Refresh()
return
}
select {
case l.SendTo <- relayedRequest:
mylog.Debug("enqueued petition", relayedRequest)
fmt.Fprintf(w, "{\"id\":%q}\n", relayedRequest.ID)
default:
mylog.Alert("server is busy")
http.Error(w, `{"error":"Server is busy"}`, 500)
mylog.Debugf("before remove petition", relayedRequest.ID)
err := petColl.Remove(bson.M{"id": relayedRequest.ID})
mylog.Debugf("after remove petition", relayedRequest.ID)
if err != nil {
mylog.Alert("ERROR removing petition", relayedRequest.ID, e)
l.SessionSeed.Refresh()
return
}
return
}
}
//process recreates the request that should be sent to the target host
//it stores the response in the store of replies.
func (c *Consumer) process(petition *Petition) {
var (
req *http.Request
resp *http.Response
reply *Reply
start = bson.Now()
)
db := c.SessionSeed.DB(c.Cfg.Database)
petColl := db.C(c.Cfg.Instance + c.Cfg.PetitionsColl)
replyColl := db.C(c.Cfg.ResponsesColl)
errColl := db.C(c.Cfg.ErrorsColl)
mylog.Debugf("processing petition %+v", petition)
req, err := petition.Request()
if err != nil {
mylog.Alert(petition.ID, err)
return
}
mylog.Debugf("restored request %+v", req)
mylog.Debug("before making request", petition.ID)
resp, err = c.doRequest(req, petition.ID)
if err == nil {
mylog.Debug("after making request", petition.ID)
defer func() {
mylog.Debug("closing response body", petition.ID)
resp.Body.Close()
}()
}
reply = newReply(resp, petition, err)
reply.Created = start
mylog.Debugf("created reply %+v", reply)
if err != nil || resp.StatusCode < 200 || resp.StatusCode >= 300 {
e := errColl.Insert(reply)
if e != nil {
mylog.Alert("ERROR inserting erroneous reply", petition.ID, err)
c.SessionSeed.Refresh()
}
}
mylog.Debugf("before insert reply %+v", reply)
err = replyColl.Insert(reply)
mylog.Debugf("after insert reply %+v", reply)
if err != nil {
mylog.Alert("ERROR inserting reply", petition.ID, err)
c.SessionSeed.Refresh()
}
mylog.Debugf("before remove petition %+v", petition)
err = petColl.Remove(bson.M{"id": petition.ID})
mylog.Debugf("after remove petition %+v", petition)
if err != nil {
mylog.Alert("ERROR removing petition", petition.ID, err)
c.SessionSeed.Refresh()
}
}
//newReply returns the Reply for the Petition made, the http.Response gotten and the possible error
func newReply(resp *http.Response, p *Petition, e error) *Reply {
var reply = &Reply{ID: p.ID, Petition: p, TraceID: p.TraceID}
if e != nil {
reply.Error = e.Error()
return reply
}
reply.StatusCode = resp.StatusCode
reply.Proto = resp.Proto
reply.Header = resp.Header
reply.Trailer = resp.Trailer
mylog.Debug("before reading response body", p.ID)
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
mylog.Debugf("error reading response body %v %+v", err, p)
reply.Error = e.Error()
} else {
mylog.Debug("after reading response body", p.ID)
reply.Body = body
}
reply.Done = bson.Now()
mylog.Debugf("reply done %+v", reply)
return reply
}
//Request returns the original http.Request with the body restored as a CloserReader
//so it can be used to do a request to the original target host
func (p *Petition) Request() (*http.Request, error) {
p.URL.Host = p.TargetHost
p.URL.Scheme = p.TargetScheme
p.URLString = p.URL.String()
req, err := http.NewRequest(
p.Method,
p.URLString,
ioutil.NopCloser(bytes.NewReader(p.Body))) //Restore body as ReadCloser
if err != nil {
mylog.Debugf("error restoring request %v %+v", err, p)
return nil, err
}
req.Header = p.Header
req.Trailer = p.Trailer
return req, nil
}
//Loop of taking a petition and making the request it represents.
func (c *Consumer) relay() {
defer c.wg.Done()
SERVE:
for {
select {
case <-c.endChan:
break SERVE
default:
select {
case req := <-c.GetFrom:
mylog.Debugf("extracted petition %+v", req)
c.process(req)
case <-c.endChan:
break SERVE
}
}
}
}
//Start starts n goroutines for taking Petitions from the GetFrom channel.
//It returns a channel for notifying when the consumer has ended (hopefully after a Stop() method invocation).
func (c *Consumer) Start(n int) <-chan bool {
mylog.Debugf("starting consumer %+v", c)
c.n = n
finalDone := make(chan bool)
c.endChan = make(chan struct{})
c.wg.Add(c.n)
for i := 0; i < c.n; i++ {
go c.relay()
}
go func() {
c.wg.Wait()
mylog.Debug("consumer waiting for children")
finalDone <- true
mylog.Debug("all consumer's children finished")
}()
return finalDone
}
//Recover gets all the petitions stored and sends them to a channel for processing by a consumer.
//It returns when all of them are re-enqueued or when an error happens. It should be run before starting
//a listener (with the same PetitionStore) or new petitions could be enqueued twice. Listeners with a different PetitionStore
//should not be a problem. A Consumer can be started before with the same PetitionStore to avoid overflowing the queue.
func (r *Recoverer) Recover() error {
mylog.Debug("begin recoverer")
db := r.SessionSeed.DB(r.Cfg.Database)
petColl := db.C(r.Cfg.Instance + r.Cfg.PetitionsColl)
p := Petition{}
iter := petColl.Find(nil).Iter()
for iter.Next(&p) {
paux := p
mylog.Debugf("re-enqueue petition %+v", paux)
r.SendTo <- &paux
}
//iter.Err()
if err := iter.Close(); err != nil {
mylog.Alertf("error closing cursor %+v", err)
return err
}
mylog.Debug("end recoverer")
return nil
}
//doRequest makes and retries the request as many times as is set, increasing the time between retries, doubling the initial time
func (c *Consumer) doRequest(req *http.Request, petid string) (resp *http.Response, err error) {
resp, err = c.Client.Do(req)
if err == nil && resp.StatusCode != 503 { //Good, not error and non challenging response
return resp, nil
}
mylog.Debug("error making request", petid, err)
var retryTime = time.Duration(c.Cfg.RetryTime) * time.Millisecond
var retries = c.Cfg.Retries
for i := 0; i < retries; i++ {
time.Sleep(retryTime)
mylog.Debugf("retrying request %v retry #%v after %v error %v", petid, i+1, retryTime, err)
resp, err = c.Client.Do(req)
if err == nil && resp.StatusCode != 503 {
break
}
retryTime *= 2
}
return resp, err
}
//newPetition creates a petition from an http.Request. It checks header fields and make necessary transformations.
//The body is read and saved as a slice of byte.
func newPetition(original *http.Request) (*Petition, error) {
targetHost := original.Header.Get(RelayerHost)
if targetHost == "" {
return nil, fmt.Errorf("gridas: Missing mandatory header %s", RelayerHost)
}
original.Header.Del(RelayerHost)
scheme := strings.ToLower(original.Header.Get(RelayerProtocol))
switch scheme {
case "http", "https":
case "":
scheme = "http"
default:
mylog.Debug("unsupported protocol", scheme)
return nil, fmt.Errorf("gridas: unsupported protocol %s", scheme)
}
original.Header.Del(RelayerProtocol)
traceID := original.Header.Get(RelayerTraceID)
if traceID == "" {
//Just in case an older version client using "Topic"
traceID = original.Header.Get(RelayerTopic)
}
original.Header.Del(RelayerTraceID)
original.Header.Del(RelayerTopic)
//Delete older header fields, ignore them, do nothing yet
original.Header.Del(RelayerProxy)
original.Header.Del(RelayerRetry)
{
//Hack for clients of older version
const HTTPS = "https://"
const HTTPSLen = len(HTTPS)
const HTTP = "http://"
const HTTPLen = len(HTTP)
if strings.HasPrefix(targetHost, HTTPS) {
targetHost = targetHost[HTTPSLen:]
scheme = "https"
} else if strings.HasPrefix(targetHost, HTTP) {
targetHost = targetHost[HTTPLen:]
scheme = "http"
}
}
//save body content
body, err := ioutil.ReadAll(original.Body)
if err != nil {
mylog.Debugf("error reading body request %v %+v", err, original)
return nil, err
}
id := uuid.New()
relayedRequest := &Petition{
ID: id,
Body: body,
Method: original.Method,
URL: original.URL,
Proto: original.Proto, // "HTTP/1.0"
Header: original.Header,
Trailer: original.Trailer,
RemoteAddr: original.RemoteAddr,
RequestURI: original.RequestURI,
TargetHost: targetHost,
TargetScheme: scheme,
Created: bson.Now(),
TraceID: traceID}
return relayedRequest, nil
}
func main() {
var cfgFile = flag.String("config", "./gridas.yaml", "configuration file")
flag.Parse()
cfg, err := config.ReadConfig(*cfgFile)
if err != nil {
mylog.Alert(err)
os.Exit(-1)
}
fmt.Printf("configuration %q %+v\n", *cfgFile, cfg)
mylog.SetLevel(cfg.LogLevel)
mylog.Alert("hello World!")
reqChan := make(chan *gridas.Petition, cfg.QueueSize)
session, err := mgo.Dial(cfg.Mongo)
if err != nil {
mylog.Alert(err)
panic(err)
}
defer func() {
session.Close()
mylog.Debugf("mongo session closed %+v", session)
}()
mylog.Debugf("mongo session %+v", session)
db := session.DB(cfg.Database)
mylog.Debug("mongo database", db)
listener := &gridas.Listener{SendTo: reqChan, Cfg: cfg, SessionSeed: session}
mylog.Debugf("listener %+v", listener)
consumer := &gridas.Consumer{GetFrom: reqChan, Cfg: cfg, SessionSeed: session}
mylog.Debugf("consumer %+v", consumer)
rplyr := &gridas.Replyer{Cfg: cfg, SessionSeed: session}
mylog.Debugf("replyer %+v", rplyr)
rcvr := &gridas.Recoverer{SendTo: reqChan, Cfg: cfg, SessionSeed: session}
mylog.Debugf("recoverer %+v", rcvr)
endConsumers := consumer.Start(cfg.Consumers)
if err := rcvr.Recover(); err != nil {
mylog.Alert(err)
os.Exit(-1)
}
http.Handle("/", listener)
http.Handle("/responses/", http.StripPrefix("/responses/", rplyr))
go func() {
mylog.Debug("starting HTTP server (listener)")
err := http.ListenAndServe(":"+cfg.Port, nil)
if err != nil {
mylog.Alert(err)
os.Exit(-1)
}
}()
onEnd(func() {
mylog.Info("shutting down gridas ...")
listener.Stop()
mylog.Debug("listener stopped")
consumer.Stop()
mylog.Debug("consumer stopped")
})
<-endConsumers
mylog.Alert("bye World!")
}