聊聊canalgo的position

序

本文主要研究一下 canal-go 的 position

Position

canal-go-v1.0.7/protocol/Position/Position.go

package position

type Position interface {}

• Position.go 定义了一个 Position 接口

MetaqPosition

canal-go-v1.0.7/protocol/Position/metaq_position.go

package position

type MetaqPosition struct {
    Topic    string
    MsgNewId string
    Offset   int64
}

• MetaqPosition 定义了 Topic、MsgNewId、Offset 属性

TimePosition

canal-go-v1.0.7/protocol/Position/time_position.go

package position

type TimePosition struct {Timestamp int64}

func NewTimePosition(timestamp int64) *TimePosition {tstamp := &TimePosition{Timestamp: timestamp}
    return tstamp
}

• TimePosition 定义了 Timestamp 属性，NewTimePosition 方法实例化 TimePosition

EntryPosition

canal-go-v1.0.7/protocol/Position/entry_position.go

package position

const (
    EVENTIDENTITY_SEGMENT = 3
    EVENTIDENTITY_SPLIT   = 5
)

type EntryPosition struct {
    TimePosition
    Included    bool
    JournalName string
    Position    int64
    ServerId    int64
}

func NewEntryPosition(journalName string, position int64, timestamp int64, serverId int64, Included bool) *EntryPosition {entryPosition := &EntryPosition{TimePosition{timestamp}, false, journalName, position, serverId}
    return entryPosition
}

• EntryPosition 定义了 TimePosition、Included、JournalName、Position、ServerId 属性；NewEntryPosition 方法实例一个 EntryPosition

LogPosition

go-projects/canal-go-v1.0.7/protocol/Position/log_position.go

package position

type LogPosition struct {
    Identity LogIdentity
    Postion  EntryPosition
}

• LogPosition 定义了 LogIdentity、EntryPosition 属性

小结

canal-go 定义了 Position、MetaqPosition、TimePosition、EntryPosition、LogPosition

doc

• Position