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handler.go
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/
handler.go
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package messaging
import (
"io/ioutil"
"net/http"
"net/url"
"strconv"
"strings"
"github.com/influxdb/influxdb/raft"
)
// Handler represents an HTTP handler by the broker.
type Handler struct {
raftHandler *raft.Handler
broker *Broker
}
// NewHandler returns a new instance of Handler.
func NewHandler(b *Broker) *Handler {
h := &Handler{}
h.SetBroker(b)
return h
}
// Broker returns the broker on the handler.
func (h *Handler) Broker() *Broker { return h.broker }
// SetBroker sets the broker on the handler.
func (h *Handler) SetBroker(b *Broker) {
h.broker = b
if b != nil {
h.raftHandler = &raft.Handler{Log: b.log}
} else {
h.raftHandler = nil
}
}
// ServeHTTP serves an HTTP request.
func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// h.broker.Logger.Printf("%s %s", r.Method, r.URL.String())
// Delegate raft requests to its own handler.
if strings.HasPrefix(r.URL.Path, "/raft") {
h.raftHandler.ServeHTTP(w, r)
return
}
// Route all InfluxDB broker requests.
switch r.URL.Path {
case "/messaging/messages":
if r.Method == "GET" {
h.stream(w, r)
} else if r.Method == "POST" {
h.publish(w, r)
} else {
http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
}
case "/messaging/replicas":
if r.Method == "POST" {
h.createReplica(w, r)
} else if r.Method == "DELETE" {
h.deleteReplica(w, r)
} else {
http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
}
case "/messaging/subscriptions":
if r.Method == "POST" {
h.subscribe(w, r)
} else if r.Method == "DELETE" {
h.unsubscribe(w, r)
} else {
http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
}
default:
http.NotFound(w, r)
}
}
// connects the requestor as the replica's writer.
func (h *Handler) stream(w http.ResponseWriter, r *http.Request) {
// Read the replica ID.
var replicaID uint64
if n, err := strconv.ParseUint(r.URL.Query().Get("replicaID"), 10, 64); err != nil {
h.error(w, ErrReplicaIDRequired, http.StatusBadRequest)
return
} else {
replicaID = uint64(n)
}
// Find the replica on the broker.
replica := h.broker.Replica(replicaID)
if replica == nil {
h.error(w, ErrReplicaNotFound, http.StatusNotFound)
return
}
// Connect the response writer to the replica.
// This will block until the replica is closed or a new writer connects.
_, _ = replica.WriteTo(w)
}
// publishes a message to the broker.
func (h *Handler) publish(w http.ResponseWriter, r *http.Request) {
m := &Message{}
// Read the message type.
if n, err := strconv.ParseUint(r.URL.Query().Get("type"), 10, 16); err != nil {
h.error(w, ErrMessageTypeRequired, http.StatusBadRequest)
return
} else {
m.Type = MessageType(n)
}
// Read the topic ID.
if n, err := strconv.ParseUint(r.URL.Query().Get("topicID"), 10, 64); err != nil {
h.error(w, ErrTopicRequired, http.StatusBadRequest)
return
} else {
m.TopicID = uint64(n)
}
// Read the request body.
data, err := ioutil.ReadAll(r.Body)
if err != nil {
h.error(w, err, http.StatusInternalServerError)
return
}
m.Data = data
// Publish message to the broker.
index, err := h.broker.Publish(m)
if err == raft.ErrNotLeader {
h.redirectToLeader(w, r)
return
} else if err != nil {
h.error(w, err, http.StatusInternalServerError)
return
}
// Return index.
w.Header().Set("X-Broker-Index", strconv.FormatUint(index, 10))
}
// createReplica creates a new replica with a given ID.
func (h *Handler) createReplica(w http.ResponseWriter, r *http.Request) {
// Read the replica ID.
var replicaID uint64
if n, err := strconv.ParseUint(r.URL.Query().Get("id"), 10, 64); err != nil {
h.error(w, ErrReplicaIDRequired, http.StatusBadRequest)
return
} else {
replicaID = uint64(n)
}
u, err := url.Parse(r.URL.Query().Get("url"))
if err != nil {
h.error(w, err, http.StatusBadRequest)
return
}
// Create a new replica on the broker.
if err := h.broker.CreateReplica(replicaID, u); err == raft.ErrNotLeader {
h.redirectToLeader(w, r)
return
} else if err == ErrReplicaExists {
h.error(w, err, http.StatusConflict)
return
} else if err != nil {
h.error(w, err, http.StatusInternalServerError)
return
}
w.WriteHeader(http.StatusCreated)
}
// deleteReplica deletes an existing replica by ID.
func (h *Handler) deleteReplica(w http.ResponseWriter, r *http.Request) {
// Read the replica ID.
var replicaID uint64
if n, err := strconv.ParseUint(r.URL.Query().Get("id"), 10, 64); err != nil {
h.error(w, ErrReplicaIDRequired, http.StatusBadRequest)
return
} else {
replicaID = uint64(n)
}
// Delete the replica on the broker.
if err := h.broker.DeleteReplica(replicaID); err == raft.ErrNotLeader {
h.redirectToLeader(w, r)
return
} else if err != nil {
h.error(w, err, http.StatusInternalServerError)
return
}
w.WriteHeader(http.StatusNoContent)
}
// subscribe creates a new subscription for a replica on a topic.
func (h *Handler) subscribe(w http.ResponseWriter, r *http.Request) {
// Read the replica ID.
var replicaID uint64
if n, err := strconv.ParseUint(r.URL.Query().Get("replicaID"), 10, 64); err != nil {
h.error(w, ErrReplicaIDRequired, http.StatusBadRequest)
return
} else {
replicaID = uint64(n)
}
// Read the topic ID.
var topicID uint64
if n, err := strconv.ParseUint(r.URL.Query().Get("topicID"), 10, 64); err != nil {
h.error(w, ErrTopicRequired, http.StatusBadRequest)
return
} else {
topicID = uint64(n)
}
// Subscribe a replica to a topic.
if err := h.broker.Subscribe(replicaID, topicID); err == raft.ErrNotLeader {
h.redirectToLeader(w, r)
return
} else if err == ErrReplicaNotFound {
h.error(w, err, http.StatusNotFound)
return
} else if err != nil {
h.error(w, err, http.StatusInternalServerError)
return
}
w.WriteHeader(http.StatusCreated)
}
// unsubscribe removes a subscription from a replica for a topic.
func (h *Handler) unsubscribe(w http.ResponseWriter, r *http.Request) {
// Read the replica ID.
var replicaID uint64
if n, err := strconv.ParseUint(r.URL.Query().Get("replicaID"), 10, 64); err != nil {
h.error(w, ErrReplicaIDRequired, http.StatusBadRequest)
return
} else {
replicaID = uint64(n)
}
// Read the topic ID.
var topicID uint64
if n, err := strconv.ParseUint(r.URL.Query().Get("topicID"), 10, 64); err != nil {
h.error(w, ErrTopicRequired, http.StatusBadRequest)
return
} else {
topicID = uint64(n)
}
// Unsubscribe the replica from the topic.
if err := h.broker.Unsubscribe(replicaID, topicID); err == raft.ErrNotLeader {
h.redirectToLeader(w, r)
return
} else if err == ErrReplicaNotFound {
h.error(w, err, http.StatusNotFound)
return
} else if err != nil {
h.error(w, err, http.StatusInternalServerError)
return
}
w.WriteHeader(http.StatusNoContent)
}
// error writes an error to the client and sets the status code.
func (h *Handler) error(w http.ResponseWriter, err error, code int) {
s := err.Error()
w.Header().Set("X-Broker-Error", s)
http.Error(w, s, code)
}
// redirects to the current known leader.
// If no leader is found then returns a 500.
func (h *Handler) redirectToLeader(w http.ResponseWriter, r *http.Request) {
if u := h.broker.LeaderURL(); u != nil {
redirectURL := *r.URL
redirectURL.Scheme = u.Scheme
redirectURL.Host = u.Host
http.Redirect(w, r, redirectURL.String(), http.StatusTemporaryRedirect)
return
}
h.error(w, raft.ErrNotLeader, http.StatusInternalServerError)
}