Golang errors.New函数代码示例

// This returns a field descriptor for FieldType_BLOB (i.e., Field_blob)
func NewBlobFieldDescriptor(nullable NullableColumn, metadata []byte) (
	fd FieldDescriptor,
	remaining []byte,
	err error) {

	if len(metadata) < 1 {
		return nil, nil, errors.New("Metadata has too few bytes")
	}

	packedLen := LittleEndian.Uint8(metadata)

	if packedLen > 4 {
		return nil, nil, errors.New("Invalid packed length")
	}

	return &blobFieldDescriptor{
		packedLengthFieldDescriptor: packedLengthFieldDescriptor{
			baseFieldDescriptor: baseFieldDescriptor{
				fieldType:  mysql_proto.FieldType_BLOB,
				isNullable: nullable,
			},
			packedLength: int(packedLen),
		},
	}, metadata[1:], nil
}

// Lock for writing, waiting up to 'timeout' for successful exclusive
// acquisition of the lock.
func (rw *BoundedRWLock) WLock(timeout time.Duration) (err error) {
	deadline := time.After(timeout)
	rw.control.Lock()
	if rw.readers != 0 || rw.nextWriter != nil {
		me := newWait(true)
		if rw.nextWriter == nil {
			rw.nextWriter = me
		} else {
			select {
			case rw.waiters <- me:
			default:
				err = errors.New("Waiter capacity reached in WLock")
			}
		}
		rw.control.Unlock()
		if err != nil {
			return
		}

		woken := me.WaitAtomic(deadline)
		if !woken {
			return errors.New("Waiter timeout")
		}
		rw.control.Lock()
		if rw.readers != 0 {
			panic("readers??")
		}
	} else {
		rw.nextWriter = newWait(true)
	}
	rw.control.Unlock()
	return
}

func (d *usecTemporalFieldDescriptor) init(
	fieldType mysql_proto.FieldType_Type,
	nullable NullableColumn,
	fixedSize int,
	metadata []byte) (
	remaining []byte,
	err error) {

	d.fieldType = fieldType
	d.isNullable = nullable

	if len(metadata) < 1 {
		return nil, errors.New("Metadata has too few bytes")
	}

	d.fixedSize = fixedSize
	d.neededBytes = fixedSize
	d.microSecondPrecision = uint8(metadata[0])
	switch d.microSecondPrecision {
	case 0:
		// do nothing
	case 1, 2:
		d.neededBytes++
	case 3, 4:
		d.neededBytes += 2
	case 5, 6:
		d.neededBytes += 3
	default:
		return nil, errors.New("Invalid usec precision")
	}

	return metadata[1:], nil
}

// Wait for a read lock for up to 'timeout'.
//
// Error will be non-nil on timeout or when the wait list is at capacity.
func (rw *BoundedRWLock) RLock(timeout time.Duration) (err error) {
	deadline := time.After(timeout)
	rw.control.Lock()
	if rw.nextWriter != nil {
		me := newWait(false)
		select {
		case rw.waiters <- me:
		default:
			err = errors.New("Waiter capacity reached in RLock")
		}
		rw.control.Unlock()
		if err != nil {
			return
		}

		woken := me.WaitAtomic(deadline)
		if !woken {
			return errors.New("Waiter timeout")
		}
		rw.control.Lock()
	}
	rw.readers++
	rw.control.Unlock()
	return
}

func Page(q PageQuery) (*PageResponse, error) {

	if q.ID == 0 {
		return nil, errors.New("a page id is required")
	}

	resp, err := http.Get(q.urlString())
	if err != nil {
		return nil, errors.Wrap(err, "could not get http response")
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		return nil, errors.Wrapf(errors.New(resp.Status), "StatusCode: %d; URL: %s", resp.StatusCode, q.urlString())
	}

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return nil, errors.Wrap(err, "could not read http response body")
	}

	var response PageResponse
	if err := json.Unmarshal(body, &response); err != nil {
		return nil, errors.Wrap(err, "could not unmarshal http response")
	}

	return &response, nil

}

func (s *lockStatementImpl) String(database string) (sql string, err error) {
	if !validIdentifierName(database) {
		return "", errors.New("Invalid database name specified")
	}

	if len(s.locks) == 0 {
		return "", errors.New("No locks added")
	}

	buf := new(bytes.Buffer)
	buf.WriteString("LOCK TABLES ")

	for idx, lock := range s.locks {
		if lock.t == nil {
			return "", errors.Newf("nil table.  Generated sql: %s", buf.String())
		}

		if err = lock.t.SerializeSql(database, buf); err != nil {
			return
		}

		if lock.w {
			buf.WriteString(" WRITE")
		} else {
			buf.WriteString(" READ")
		}

		if idx != len(s.locks)-1 {
			buf.WriteString(", ")
		}
	}

	return buf.String(), nil
}

// Compile launches the search and compiles a list of weather list.
func Request(q *Query) ([]*Record, error) {

	if q.Start.IsZero() || q.End.IsZero() {
		return nil, errors.New("StartDate and EndDate (time.Time) values are required to compile weather data.")
	}

	if len(q.Stations) == 0 {
		return nil, errors.New("at least one weather station is required to provide weather response")
	}

	var list []*Record

	for _, station := range q.Stations {

		values, err := q.getAPIList(station)
		if err != nil {
			return nil, err
		}

		for _, v := range values {

			list = q.addToList(list, v, station)

		}

	}

	sort.Sort(weatherSorter{list})

	return list, nil

}

func (c *RawClient) sendCountRequest(
	code opCode,
	key string,
	delta uint64,
	initValue uint64,
	expiration uint32) CountResponse {

	if !c.validState {
		// An error has occurred in one of the previous requests.  It's not
		// safe to continue sending.
		return NewCountErrorResponse(
			key,
			errors.New("Skipping due to previous error"))
	}

	if !isValidKeyString(key) {
		return NewCountErrorResponse(
			key,
			errors.New("Invalid key"))
	}

	err := c.sendRequest(
		code,
		0,
		[]byte(key),
		nil,
		delta,
		initValue,
		expiration)
	if err != nil {
		c.validState = false
		return NewCountErrorResponse(key, err)
	}
	return nil
}

func (p *QueryEventParser) parseUpdatedDbNames(data []byte, q *QueryEvent) (
	[]byte,
	error) {

	if len(data) == 0 {
		return data, errors.New("Not enough data")
	}

	q.numUpdatedDbs = new(uint8)
	data, err := readLittleEndian(data, q.numUpdatedDbs)
	if err != nil {
		return data, err
	}

	if *q.numUpdatedDbs < MaxDbsInEventMts {
		q.updatedDbNames = make([][]byte, *q.numUpdatedDbs, *q.numUpdatedDbs)
		for i := uint8(0); i < *q.numUpdatedDbs; i++ {
			idx := bytes.IndexByte(data, byte(0))
			if idx > -1 {
				q.updatedDbNames[i] = data[:idx]
				data = data[idx+1:]
			} else {
				return data, errors.New("Not enough data")
			}
		}
	}
	return data, nil
}

func (r *rawV4EventReader) NextEvent() (Event, error) {
	if r.isClosed {
		return nil, errors.New("Event reader is closed")
	}

	if r.nextEvent == nil { // new event
		r.nextEvent = &RawV4Event{
			sourceName:     r.srcName,
			sourcePosition: r.logPosition,
		}
	}

	if r.nextEvent.data == nil { // still parsing the header
		headerBytes, err := r.getHeaderBuffer().PeekAll()
		if err != nil {
			return nil, err
		}

		_, err = readLittleEndian(headerBytes, &r.nextEvent.header)
		if err != nil {
			return nil, err
		}

		bodySize := int(r.nextEvent.EventLength()) - sizeOfBasicV4EventHeader
		if bodySize < 0 { // should never happen
			return nil, errors.New("Invalid event size")
		}

		r.nextEvent.data = make(
			[]byte,
			r.nextEvent.EventLength(),
			r.nextEvent.EventLength())

		copied := copy(r.nextEvent.data, headerBytes)
		if copied != sizeOfBasicV4EventHeader { // should never happen
			panic("Failed to copy header")
		}

		r.bodyBuffer = bufio2.NewLookAheadBufferUsing(
			r.src,
			r.nextEvent.data[sizeOfBasicV4EventHeader:])
	}

	_, err := r.bodyBuffer.PeekAll()
	if err != nil {
		return nil, err
	}

	// consume the constructed event and clean the look ahead buffers
	event := r.nextEvent
	r.nextEvent = nil
	r.headerBuffer = nil
	r.bodyBuffer = nil

	r.logPosition += int64(event.EventLength())

	return event, nil
}

func (c *RawAsciiClient) DeleteMulti(keys []string) []MutateResponse {
	responses := make([]MutateResponse, len(keys), len(keys))

	c.mutex.Lock()
	defer c.mutex.Unlock()

	// NOTE: delete requests are pipelined.
	for i, key := range keys {
		if !isValidKeyString(key) {
			responses[i] = NewMutateErrorResponse(
				key,
				errors.New("Invalid key"))
			continue
		}

		err := c.writeStrings("delete ", key, "\r\n")
		if err != nil {
			responses[i] = NewMutateErrorResponse(key, err)
		}
	}

	err := c.flushWriter()
	if err != nil {
		// The delete requests may or may not have successfully reached the
		// memcached, just error out.
		for i, key := range keys {
			if responses[i] == nil {
				responses[i] = NewMutateErrorResponse(key, err)
			}
		}
	}

	for i, key := range keys {
		if responses[i] != nil {
			continue
		}

		line, err := c.readLine()
		if err != nil {
			responses[i] = NewMutateErrorResponse(key, err)
			continue
		}

		if line == "DELETED" {
			responses[i] = NewMutateResponse(key, StatusNoError, 0, true)
		} else if line == "NOT_FOUND" {
			responses[i] = NewMutateResponse(key, StatusKeyNotFound, 0, true)
		} else { // Unexpected error msg
			responses[i] = NewMutateErrorResponse(key, errors.New(line))
		}
	}

	_ = c.checkEmptyBuffers()

	return responses
}

func (c *RawAsciiClient) countRequest(
	cmd string,
	key string,
	delta uint64,
	initValue uint64,
	expiration uint32) CountResponse {

	if expiration != 0xffffffff {
		return NewCountErrorResponse(
			key,
			errors.New(
				"Ascii protocol does not support initial value / "+
					"expiration.  expiration must be set to 0xffffffff."))
	}

	if !isValidKeyString(key) {
		return NewCountErrorResponse(
			key,
			errors.New("Invalid key"))
	}

	c.mutex.Lock()
	defer c.mutex.Unlock()

	err := c.writeStrings(
		cmd, " ",
		key, " ",
		strconv.FormatUint(delta, 10), "\r\n")
	if err != nil {
		return NewCountErrorResponse(key, err)
	}

	err = c.flushWriter()
	if err != nil {
		return NewCountErrorResponse(key, err)
	}

	line, err := c.readLine()
	if err != nil {
		return NewCountErrorResponse(key, err)
	}

	_ = c.checkEmptyBuffers()

	if line == "NOT_FOUND" {
		return NewCountResponse(key, StatusKeyNotFound, 0)
	}

	val, err := strconv.ParseUint(line, 10, 64)
	if err != nil {
		return NewCountErrorResponse(key, err)
	}

	return NewCountResponse(key, StatusNoError, val)
}

// checkExtensionTypes checks that the given extension is valid for pb.
func checkExtensionTypes(pb extendableProto, extension *ExtensionDesc) error {
	// Check the extended type.
	if a, b := reflect.TypeOf(pb), reflect.TypeOf(extension.ExtendedType); a != b {
		return errors.New("proto: bad extended type; " + b.String() + " does not extend " + a.String())
	}
	// Check the range.
	if !isExtensionField(pb, extension.Field) {
		return errors.New("proto: bad extension number; not in declared ranges")
	}
	return nil
}

func (c *RawAsciiClient) Stat(statsKey string) StatResponse {
	shardEntries := make(map[int](map[string]string))
	entries := make(map[string]string)
	shardEntries[c.ShardId()] = entries

	if statsKey != "" {
		return NewStatErrorResponse(
			errors.New("Ascii protocol does not support specific stats lookup"),
			shardEntries)
	}

	var err error

	c.mutex.Lock()
	defer c.mutex.Unlock()

	err = c.writeStrings("stats\r\n")
	if err != nil {
		return NewStatErrorResponse(err, shardEntries)
	}

	err = c.flushWriter()
	if err != nil {
		return NewStatErrorResponse(err, shardEntries)
	}

	for {
		line, err := c.readLine()
		if err != nil {
			NewStatErrorResponse(err, shardEntries)
		}

		if line == "END" {
			break
		}

		// line is of the form: STAT <key> <value>
		slice := strings.SplitN(line, " ", 3)

		if len(slice) != 3 || slice[0] != "STAT" {
			// The channel is no longer in valid state since we're exiting
			// stats mid stream.
			c.validState = false
			return NewStatErrorResponse(errors.New(line), shardEntries)
		}

		entries[slice[1]] = slice[2]
	}

	_ = c.checkEmptyBuffers()

	return NewStatResponse(StatusNoError, shardEntries)
}

func (c *RawAsciiClient) checkEmptyBuffers() error {
	if c.writer.Buffered() != 0 {
		c.validState = false
		return errors.New("writer buffer not fully flushed")
	}
	if c.reader.Buffered() != 0 {
		c.validState = false
		return errors.New("reader buffer not fully drained")
	}

	return nil
}