Example #1
0
File: http.go Project: faiq/consul
// parseWait is used to parse the ?wait and ?index query params
// Returns true on error
func parseWait(resp http.ResponseWriter, req *http.Request, b *structs.QueryOptions) bool {
	query := req.URL.Query()
	if wait := query.Get("wait"); wait != "" {
		dur, err := time.ParseDuration(wait)
		if err != nil {
			resp.WriteHeader(400)
			resp.Write([]byte("Invalid wait time"))
			return true
		}
		b.MaxQueryTime = dur
	}
	if idx := query.Get("index"); idx != "" {
		index, err := strconv.ParseUint(idx, 10, 64)
		if err != nil {
			resp.WriteHeader(400)
			resp.Write([]byte("Invalid index"))
			return true
		}
		b.MinQueryIndex = index
	}
	return false
}
Example #2
0
// EventList is used to retrieve the recent list of events
func (s *HTTPServer) EventList(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
	// Parse the query options, since we simulate a blocking query
	var b structs.QueryOptions
	if parseWait(resp, req, &b) {
		return nil, nil
	}

	// Look for a name filter
	var nameFilter string
	if filt := req.URL.Query().Get("name"); filt != "" {
		nameFilter = filt
	}

	// Lots of this logic is borrowed from consul/rpc.go:blockingRPC
	// However we cannot use that directly since this code has some
	// slight semantics differences...
	var timeout <-chan time.Time
	var notifyCh chan struct{}

	// Fast path non-blocking
	if b.MinQueryIndex == 0 {
		goto RUN_QUERY
	}

	// Restrict the max query time
	if b.MaxQueryTime > maxQueryTime {
		b.MaxQueryTime = maxQueryTime
	}

	// Ensure a time limit is set if we have an index
	if b.MinQueryIndex > 0 && b.MaxQueryTime == 0 {
		b.MaxQueryTime = maxQueryTime
	}

	// Setup a query timeout
	if b.MaxQueryTime > 0 {
		timeout = time.After(b.MaxQueryTime)
	}

	// Setup a notification channel for changes
SETUP_NOTIFY:
	if b.MinQueryIndex > 0 {
		notifyCh = make(chan struct{}, 1)
		s.agent.eventNotify.Wait(notifyCh)
	}

RUN_QUERY:
	// Get the recent events
	events := s.agent.UserEvents()

	// Filter the events if necessary
	if nameFilter != "" {
		for i := 0; i < len(events); i++ {
			if events[i].Name != nameFilter {
				events = append(events[:i], events[i+1:]...)
				i--
			}
		}
	}

	// Determine the index
	var index uint64
	if len(events) == 0 {
		// Return a non-zero index to prevent a hot query loop. This
		// can be caused by a watch for example when there is no matching
		// events.
		index = 1
	} else {
		last := events[len(events)-1]
		index = uuidToUint64(last.ID)
	}
	setIndex(resp, index)

	// Check for exact match on the query value. Because
	// the index value is not monotonic, we just ensure it is
	// not an exact match.
	if index > 0 && index == b.MinQueryIndex {
		select {
		case <-notifyCh:
			goto SETUP_NOTIFY
		case <-timeout:
		}
	}
	return events, nil
}