status-go/mailserver/cleaner.go

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package mailserver
import (
"github.com/ethereum/go-ethereum/common"
"github.com/syndtr/goleveldb/leveldb"
"github.com/syndtr/goleveldb/leveldb/iterator"
"github.com/syndtr/goleveldb/leveldb/util"
)
const batchSize = 1000
// Cleaner removes old messages from a db
type Cleaner struct {
db dbImpl
batchSize int
}
// NewCleanerWithDB returns a new Cleaner for db
func NewCleanerWithDB(db dbImpl) *Cleaner {
return &Cleaner{
db: db,
batchSize: batchSize,
}
}
// Prune removes messages sent between lower and upper timestamps and returns how many has been removed
func (c *Cleaner) Prune(lower, upper uint32) (int, error) {
var zero common.Hash
kl := NewDbKey(lower, zero)
ku := NewDbKey(upper, zero)
i := c.db.NewIterator(&util.Range{Start: kl.raw, Limit: ku.raw}, nil)
defer i.Release()
return c.prune(i)
}
func (c *Cleaner) prune(i iterator.Iterator) (int, error) {
batch := leveldb.Batch{}
removed := 0
for i.Next() {
batch.Delete(i.Key())
if batch.Len() == c.batchSize {
if err := c.db.Write(&batch, nil); err != nil {
return removed, err
}
removed = removed + batch.Len()
batch.Reset()
}
}
if batch.Len() > 0 {
if err := c.db.Write(&batch, nil); err != nil {
return removed, err
}
removed = removed + batch.Len()
}
return removed, nil
}