func (n *node) expirationAndTTL(clock clockwork.Clock) (*time.Time, int64) {
	if !n.IsPermanent() {
		/* compute ttl as:
		   ceiling( (expireTime - timeNow) / nanosecondsPerSecond )
		   which ranges from 1..n
		   rather than as:
		   ( (expireTime - timeNow) / nanosecondsPerSecond ) + 1
		   which ranges 1..n+1
		*/
		ttlN := n.ExpireTime.Sub(clock.Now())
		ttl := ttlN / time.Second
		if (ttlN % time.Second) > 0 {
			ttl++
		}
		return &n.ExpireTime, int64(ttl)
	}
	return nil, 0
}

// parseKeyRequest converts a received http.Request on keysPrefix to
// a server Request, performing validation of supplied fields as appropriate.
// If any validation fails, an empty Request and non-nil error is returned.
func parseKeyRequest(r *http.Request, clock clockwork.Clock) (etcdserverpb.Request, error) {
	emptyReq := etcdserverpb.Request{}

	err := r.ParseForm()
	if err != nil {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodeInvalidForm,
			err.Error(),
		)
	}

	if !strings.HasPrefix(r.URL.Path, keysPrefix) {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodeInvalidForm,
			"incorrect key prefix",
		)
	}
	p := path.Join(etcdserver.StoreKeysPrefix, r.URL.Path[len(keysPrefix):])

	var pIdx, wIdx uint64
	if pIdx, err = getUint64(r.Form, "prevIndex"); err != nil {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodeIndexNaN,
			`invalid value for "prevIndex"`,
		)
	}
	if wIdx, err = getUint64(r.Form, "waitIndex"); err != nil {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodeIndexNaN,
			`invalid value for "waitIndex"`,
		)
	}

	var rec, sort, wait, dir, quorum, stream, blocking bool
	if rec, err = getBool(r.Form, "recursive"); err != nil {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodeInvalidField,
			`invalid value for "recursive"`,
		)
	}
	if sort, err = getBool(r.Form, "sorted"); err != nil {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodeInvalidField,
			`invalid value for "sorted"`,
		)
	}
	if wait, err = getBool(r.Form, "wait"); err != nil {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodeInvalidField,
			`invalid value for "wait"`,
		)
	}
	// TODO(jonboulle): define what parameters dir is/isn't compatible with?
	if dir, err = getBool(r.Form, "dir"); err != nil {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodeInvalidField,
			`invalid value for "dir"`,
		)
	}
	//if not specified, quorum should be true
	if quorum, err = getBool(r.Form, "quorum"); err != nil {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodeInvalidField,
			`invalid value for "quorum"`,
		)
	} else if _, exists := r.Form["quorum"]; !exists {
		quorum = true
	}
	if stream, err = getBool(r.Form, "stream"); err != nil {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodeInvalidField,
			`invalid value for "stream"`,
		)
	}

	if blocking, err = getBool(r.Form, "blocking"); err != nil {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodeInvalidField,
			`invalid value for "blocking"`,
		)
	}

	if wait && r.Method != "GET" {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodeInvalidField,
			`"wait" can only be used with GET requests`,
		)
	}

	pV := r.FormValue("prevValue")
	if _, ok := r.Form["prevValue"]; ok && pV == "" {
		return emptyReq, etcdErr.NewRequestError(
			etcdErr.EcodePrevValueRequired,
			`"prevValue" cannot be empty`,
		)
	}

//.........这里部分代码省略.........