rdb

WARNING: This project is not production ready.

Package rdb is a Redis RDB File parser written in Go.

Feature

• Concurrent parsing.
• Built in memory report.
• Simple filter support.
• Layered skipping strategies.

Install

go get -u github.com/matthewjhe/rdb

Usage

Basic Example

The basic use case is very simple, just implements Filter interface and pass it to Parse:

package main

import (
    "github.com/matthewjhe/rdb"
)

func (f filter) Key(k rdb.Key) bool { return false }
func (f filter) Type(t rdb.Type) bool   { return false }
func (f filter) Database(db rdb.DB) bool { return false }
func (f filter) Set(v *rdb.Set) { }
func (f filter) List(v *rdb.List) { }
func (f filter) Hash(v *rdb.Hash) { }
func (f filter) String(v *rdb.String) { }
func (f filter) SortedSet(v *rdb.SortedSet) { }

func main() {
    const file = "/tmp/dump.rdb"
    reader, err := rdb.NewBufferReader(file, 0)
    if err != nil {
        panic(err)
    }

    if err := rdb.Parse(reader, rdb.WithFilter(filter{})); err != nil {
        panic(err)
    }
}

Skipping

NOTE: RDB file is read sequentially, when we say skips a database, we also need to parse this database's every single key, we just simply skips actions like decompress, unzip ziplist, etc. It is impossible to skips a key without reading its metadata.

• Global Skip Strategy

Global skip strategy applies to the whole parsing lifetime, it can be overwritten by Filter's Database method, it will be restored when parsing a database completely.

Global skip strategy is set by a ParseOption when rdb.Parse is called:

    // reads memory report only
    strategy := rdb.WithStrategy(rdb.SkipExpiry | rdb.SkipMeta | rdb.SkipValue)
    err := rdb.Parse(reader, strategy, rdb.WithFilter(filter{}))
    // ...

• Database Skip Strategy

Database skip strategy applies to a database lifetime, it is set by Filter's Database method, and it can be overwritten by Filter's Key or Type method. Database skip strategy is set to global skip strategy by default.

func (f filter) Database(db rdb.DB) bool {
    // skips this database
    db.Skip(rdb.SkipAll)

    // skips database's metadata and key's expiry
    // db.Skip(rdb.SkipMeta | rdb.SkipExpiry)
    return false
}

• Type and Key Skip Strategy

Type and key skip strategy overwrite database skip strategy. It only applies the key and value which will read next.

func (f filter) Type(t rdb.Type) bool {
    // skips this type
    t.Skip(rdb.SkipAll)
    return false
}

func (f filter) Key(key rdb.Key) bool {
    // skips this key
    // key.Skip(rdb.SkipAll)

    // skips value
    key.Skip(rdb.SkipValue)
    return false
}

Syncing

By default, rdb uses multiple goroutines to parse keys which would cause keys disorder. If the order of keys is important, use EnableSync ParseOption.

    rdb.Parse(reader, rdb.WithFilter(filter{}), rdb.EnableSync())

Aborting

Sometimes we want to abort the parsing process, this can be done by return true when one of the following methods is called: Note that the abort action is taking effect immediately when the function returns.

func (f filter) Key(k rdb.Key) bool {
    return true
}
func (f filter) Type(t rdb.Type) bool   {
    return true
}
func (f filter) Database(db rdb.DB) bool {
    return true
}

References

• redis-rdb-tools for Redis RDB format and memory profile.

License

MIT