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sequence.go
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sequence.go
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// Copyright 2015-2017 trivago GmbH
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package format
import (
"github.com/trivago/gollum/core"
"github.com/trivago/gollum/shared"
"strconv"
)
// Sequence formatter plugin
// Sequence is a formatter that allows prefixing a message with the message's
// sequence number
// Configuration example
//
// - "stream.Broadcast":
// Formatter: "format.Sequence"
// SequenceFormatter: "format.Envelope"
// SequenceSeparator: ":"
//
// SequenceSeparator sets the separator character placed after the sequence
// number. This is set to ":" by default.
//
// SequenceDataFormatter defines the formatter for the data transferred as
// message. By default this is set to "format.Forward"
type Sequence struct {
base core.Formatter
length int
sequence string
separator string
}
func init() {
shared.TypeRegistry.Register(Sequence{})
}
// Configure initializes this formatter with values from a plugin config.
func (format *Sequence) Configure(conf core.PluginConfig) error {
plugin, err := core.NewPluginWithType(conf.GetString("SequenceFormatter", "format.Forward"), conf)
if err != nil {
return err
}
format.separator = conf.GetString("SequenceSeparator", ":")
format.base = plugin.(core.Formatter)
return nil
}
// Format prepends the sequence number of the message (followed by ":") to the
// message.
func (format *Sequence) Format(msg core.Message) ([]byte, core.MessageStreamID) {
basePayload, stream := format.base.Format(msg)
baseLength := len(basePayload)
sequenceStr := strconv.FormatUint(msg.Sequence, 10) + format.separator
payload := make([]byte, len(sequenceStr)+baseLength)
len := copy(payload, []byte(sequenceStr))
copy(payload[len:], basePayload)
return payload, stream
}