/
read_option.go
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/
read_option.go
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// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to You 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 natsio
import "errors"
var (
errInvalidFetchSize = errors.New("fetch size must be greater than 0")
errInvalidStartSeqNo = errors.New("start sequence number must be greater than 0")
errInvalidEndSeqNo = errors.New("end sequence number must be greater than 0")
)
type readOption struct {
CredsFile string
TimePolicy timePolicy
FetchSize int
StartSeqNo int64
EndSeqNo int64
}
// ReadOptionFn is a function that can be passed to Read to configure options for reading
// from NATS.
type ReadOptionFn func(option *readOption) error
// ReadUserCredentials sets the user credentials when connecting to NATS.
func ReadUserCredentials(credsFile string) ReadOptionFn {
return func(o *readOption) error {
o.CredsFile = credsFile
return nil
}
}
// ReadProcessingTimePolicy specifies that the pipeline processing time of the messages should be
// used to compute the watermark estimate.
func ReadProcessingTimePolicy() ReadOptionFn {
return func(o *readOption) error {
o.TimePolicy = processingTimePolicy
return nil
}
}
// ReadPublishingTimePolicy specifies that the publishing time of the messages should be used to
// compute the watermark estimate.
func ReadPublishingTimePolicy() ReadOptionFn {
return func(o *readOption) error {
o.TimePolicy = publishingTimePolicy
return nil
}
}
// ReadFetchSize sets the maximum number of messages to retrieve at a time.
func ReadFetchSize(size int) ReadOptionFn {
return func(o *readOption) error {
if size <= 0 {
return errInvalidFetchSize
}
o.FetchSize = size
return nil
}
}
// ReadStartSeqNo sets the start sequence number of messages to read.
func ReadStartSeqNo(seqNo int64) ReadOptionFn {
return func(o *readOption) error {
if seqNo <= 0 {
return errInvalidStartSeqNo
}
o.StartSeqNo = seqNo
return nil
}
}
// ReadEndSeqNo sets the end sequence number of messages to read (exclusive).
func ReadEndSeqNo(seqNo int64) ReadOptionFn {
return func(o *readOption) error {
if seqNo <= 0 {
return errInvalidEndSeqNo
}
o.EndSeqNo = seqNo
return nil
}
}