// Top-level handler for _changes feed requests.
func (h *handler) handleChanges() error {
// http://wiki.apache.org/couchdb/HTTP_database_API#Changes
// http://docs.couchdb.org/en/latest/api/database/changes.html
var options db.ChangesOptions
options.Since = channels.TimedSetFromString(h.getQuery("since"))
options.Limit = int(h.getIntQuery("limit", 0))
options.Conflicts = (h.getQuery("style") == "all_docs")
options.IncludeDocs = (h.getBoolQuery("include_docs"))
options.Terminator = make(chan bool)
defer close(options.Terminator)
// Get the channels as parameters to an imaginary "bychannel" filter.
// The default is all channels the user can access.
userChannels := channels.SetOf("*")
filter := h.getQuery("filter")
if filter != "" {
if filter != "sync_gateway/bychannel" {
return base.HTTPErrorf(http.StatusBadRequest, "Unknown filter; try sync_gateway/bychannel")
}
channelsParam := h.getQuery("channels")
if channelsParam == "" {
return base.HTTPErrorf(http.StatusBadRequest, "Missing 'channels' filter parameter")
}
var err error
userChannels, err = channels.SetFromArray(strings.Split(channelsParam, ","),
channels.ExpandStar)
if err != nil {
return err
}
if len(userChannels) == 0 {
return base.HTTPErrorf(http.StatusBadRequest, "Empty channel list")
}
}
h.db.ChangesClientStats.Increment()
defer h.db.ChangesClientStats.Decrement()
switch h.getQuery("feed") {
case "normal", "":
return h.sendSimpleChanges(userChannels, options)
case "longpoll":
options.Wait = true
return h.sendSimpleChanges(userChannels, options)
case "continuous":
return h.sendContinuousChangesByHTTP(userChannels, options)
case "websocket":
return h.sendContinuousChangesByWebSocket(userChannels, options)
default:
return base.HTTPErrorf(http.StatusBadRequest, "Unknown feed type")
}
}
func (h *handler) handleChanges() error {
// http://wiki.apache.org/couchdb/HTTP_database_API#Changes
var options db.ChangesOptions
options.Since = channels.TimedSetFromString(h.getQuery("since"))
options.Limit = int(h.getIntQuery("limit", 0))
options.Conflicts = (h.getQuery("style") == "all_docs")
options.IncludeDocs = (h.getBoolQuery("include_docs"))
// Get the channels as parameters to an imaginary "bychannel" filter.
// The default is all channels the user can access.
userChannels := channels.SetOf("*")
filter := h.getQuery("filter")
if filter != "" {
if filter != "sync_gateway/bychannel" {
return &base.HTTPError{http.StatusBadRequest, "Unknown filter; try sync_gateway/bychannel"}
}
channelsParam := h.getQuery("channels")
if channelsParam == "" {
return &base.HTTPError{http.StatusBadRequest, "Missing 'channels' filter parameter"}
}
var err error
userChannels, err = channels.SetFromArray(strings.Split(channelsParam, ","),
channels.ExpandStar)
if err != nil {
return err
}
if len(userChannels) == 0 {
return &base.HTTPError{http.StatusBadRequest, "Empty channel list"}
}
}
switch h.getQuery("feed") {
case "continuous":
return h.handleContinuousChanges(userChannels, options)
case "longpoll":
options.Wait = true
}
return h.handleSimpleChanges(userChannels, options)
}
func readChangesOptionsFromJSON(jsonData []byte) (feed string, options db.ChangesOptions, filter string, channelsArray []string, err error) {
var input struct {
Feed string `json:"feed"`
Since string `json:"since"`
Limit int `json:"limit"`
Style string `json:"style"`
IncludeDocs bool `json:"include_docs"`
Filter string `json:"filter"`
Channels []string `json:"channels"`
}
if err = json.Unmarshal(jsonData, &input); err != nil {
return
}
feed = input.Feed
options.Since = channels.TimedSetFromString(input.Since)
options.Limit = input.Limit
options.Conflicts = (input.Style == "all_docs")
options.IncludeDocs = input.IncludeDocs
filter = input.Filter
channelsArray = input.Channels
return
}
// This is the core functionality of both the HTTP and WebSocket-based continuous change feed.
// It defers to a callback function 'send()' to actually send the changes to the client.
// It will call send(nil) to notify that it's caught up and waiting for new changes, or as
// a periodic heartbeat while waiting.
func (h *handler) generateContinuousChanges(inChannels base.Set, options db.ChangesOptions, send func([]*db.ChangeEntry) error) error {
// Set up heartbeat/timeout
var timeoutInterval time.Duration
var timer *time.Timer
var heartbeat <-chan time.Time
if ms := h.getRestrictedIntQuery("heartbeat", 0, kMinHeartbeatMS, 0); ms > 0 {
ticker := time.NewTicker(time.Duration(ms) * time.Millisecond)
defer ticker.Stop()
heartbeat = ticker.C
} else if ms := h.getRestrictedIntQuery("timeout", kDefaultTimeoutMS, 0, kMaxTimeoutMS); ms > 0 {
timeoutInterval = time.Duration(ms) * time.Millisecond
defer func() {
if timer != nil {
timer.Stop()
}
}()
}
options.Wait = true // we want the feed channel to wait for changes
var lastSeqID string
var feed <-chan *db.ChangeEntry
var timeout <-chan time.Time
var err error
loop:
for {
if feed == nil {
// Refresh the feed of all current changes:
if lastSeqID != "" { // start after end of last feed
options.Since = channels.TimedSetFromString(lastSeqID)
}
feed, err = h.db.MultiChangesFeed(inChannels, options)
if err != nil || feed == nil {
return err
}
}
if timeoutInterval > 0 && timer == nil {
// Timeout resets after every change is sent
timer = time.NewTimer(timeoutInterval)
timeout = timer.C
}
// Wait for either a new change, a heartbeat, or a timeout:
select {
case entry, ok := <-feed:
if !ok {
feed = nil
} else if entry == nil {
err = send(nil)
} else {
entries := []*db.ChangeEntry{entry}
waiting := false
// Batch up as many entries as we can without waiting:
collect:
for len(entries) < 20 {
select {
case entry, ok = <-feed:
if !ok {
feed = nil
break collect
} else if entry == nil {
waiting = true
break collect
}
entries = append(entries, entry)
default:
break collect
}
}
base.LogTo("Changes", "sending %d change(s)", len(entries))
err = send(entries)
if err == nil && waiting {
err = send(nil)
}
lastSeqID = entries[len(entries)-1].Seq
if options.Limit > 0 {
if len(entries) >= options.Limit {
break loop
}
options.Limit -= len(entries)
}
}
// Reset the timeout after sending an entry:
if timer != nil {
timer.Stop()
timer = nil
}
case <-heartbeat:
err = send(nil)
case <-timeout:
break loop
}
if err != nil {
h.logStatus(http.StatusOK, fmt.Sprintf("Write error: %v", err))
return nil // error is probably because the client closed the connection
}
}
h.logStatus(http.StatusOK, "OK (continuous feed closed)")
return nil
}
func (h *handler) handleContinuousChanges(inChannels base.Set, options db.ChangesOptions) error {
var timeoutInterval time.Duration
var timer *time.Timer
var heartbeat <-chan time.Time
if ms := h.getIntQuery("heartbeat", 0); ms > 0 {
ticker := time.NewTicker(time.Duration(ms) * time.Millisecond)
defer ticker.Stop()
heartbeat = ticker.C
} else if ms := h.getIntQuery("timeout", 60000); ms > 0 {
timeoutInterval = time.Duration(ms) * time.Millisecond
defer func() {
if timer != nil {
timer.Stop()
}
}()
}
options.Wait = true // we want the feed channel to wait for changes
var lastSeqID string
var feed <-chan *db.ChangeEntry
var timeout <-chan time.Time
var err error
loop:
for {
if feed == nil {
// Refresh the feed of all current changes:
if lastSeqID != "" { // start after end of last feed
options.Since = channels.TimedSetFromString(lastSeqID)
}
feed, err = h.db.MultiChangesFeed(inChannels, options)
if err != nil || feed == nil {
return err
}
}
if timeoutInterval > 0 && timer == nil {
timer = time.NewTimer(timeoutInterval)
timeout = timer.C
}
// Wait for either a new change, a heartbeat, or a timeout:
select {
case entry := <-feed:
if entry == nil {
feed = nil
} else {
str, _ := json.Marshal(entry)
base.LogTo("Changes", "send change: %s", str)
err = h.writeln(str)
lastSeqID = entry.Seq
if options.Limit > 0 {
options.Limit--
if options.Limit == 0 {
break loop
}
}
}
// Reset the timeout after sending an entry:
if timer != nil {
timer.Stop()
timer = nil
}
case <-heartbeat:
err = h.writeln([]byte{})
case <-timeout:
break loop
}
if err != nil {
return nil // error is probably because the client closed the connection
}
}
return nil
}
// Top-level handler for _changes feed requests. Accepts GET or POST requests.
func (h *handler) handleChanges() error {
// http://wiki.apache.org/couchdb/HTTP_database_API#Changes
// http://docs.couchdb.org/en/latest/api/database/changes.html
restExpvars.Add("changesFeeds_total", 1)
restExpvars.Add("changesFeeds_active", 1)
defer restExpvars.Add("changesFeeds_active", -1)
var feed string
var options db.ChangesOptions
var filter string
var channelsArray []string
if h.rq.Method == "GET" {
// GET request has parameters in URL:
feed = h.getQuery("feed")
options.Since = channels.TimedSetFromString(h.getQuery("since"))
options.Limit = int(h.getIntQuery("limit", 0))
options.Conflicts = (h.getQuery("style") == "all_docs")
options.IncludeDocs = (h.getBoolQuery("include_docs"))
filter = h.getQuery("filter")
channelsParam := h.getQuery("channels")
if channelsParam != "" {
channelsArray = strings.Split(channelsParam, ",")
}
} else {
// POST request has parameters in JSON body:
body, err := h.readBody()
if err != nil {
return err
}
feed, options, filter, channelsArray, err = readChangesOptionsFromJSON(body)
if err != nil {
return err
}
}
// Get the channels as parameters to an imaginary "bychannel" filter.
// The default is all channels the user can access.
userChannels := channels.SetOf("*")
if filter != "" {
if filter != "sync_gateway/bychannel" {
return base.HTTPErrorf(http.StatusBadRequest, "Unknown filter; try sync_gateway/bychannel")
}
if channelsArray == nil {
return base.HTTPErrorf(http.StatusBadRequest, "Missing 'channels' filter parameter")
}
var err error
userChannels, err = channels.SetFromArray(channelsArray, channels.ExpandStar)
if err != nil {
return err
}
if len(userChannels) == 0 {
return base.HTTPErrorf(http.StatusBadRequest, "Empty channel list")
}
}
h.db.ChangesClientStats.Increment()
defer h.db.ChangesClientStats.Decrement()
options.Terminator = make(chan bool)
defer close(options.Terminator)
switch feed {
case "normal", "":
return h.sendSimpleChanges(userChannels, options)
case "longpoll":
options.Wait = true
return h.sendSimpleChanges(userChannels, options)
case "continuous":
return h.sendContinuousChangesByHTTP(userChannels, options)
case "websocket":
return h.sendContinuousChangesByWebSocket(userChannels, options)
default:
return base.HTTPErrorf(http.StatusBadRequest, "Unknown feed type")
}
}