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chantools/cmd/chantools/compactdb.go

225 lines
5.2 KiB
Go

package main
import (
"fmt"
"github.com/coreos/bbolt"
"github.com/spf13/cobra"
)
const (
dbFilePermission = 0600
defaultTxMaxSize = 65536
)
type compactDBCommand struct {
TxMaxSize int64
SourceDB string
DestDB string
cmd *cobra.Command
}
func newCompactDBCommand() *cobra.Command {
cc := &compactDBCommand{}
cc.cmd = &cobra.Command{
Use: "compactdb",
Short: "Create a copy of a channel.db file in safe/read-only " +
"mode",
Long: `This command opens a database in read-only mode and tries
to create a copy of it to a destination file, compacting it in the process.`,
Example: `chantools compactdb \
--sourcedb ~/.lnd/data/graph/mainnet/channel.db \
--destdb ./results/compacted.db`,
RunE: cc.Execute,
}
cc.cmd.Flags().Int64Var(
&cc.TxMaxSize, "txmaxsize", defaultTxMaxSize, "maximum "+
"transaction size",
)
cc.cmd.Flags().StringVar(
&cc.SourceDB, "sourcedb", "", "lnd channel.db file to create "+
"the database backup from",
)
cc.cmd.Flags().StringVar(
&cc.DestDB, "destdb", "", "new lnd channel.db file to copy "+
"the compacted database to",
)
return cc.cmd
}
func (c *compactDBCommand) Execute(_ *cobra.Command, _ []string) error {
// Check that we have a source and destination channel DB.
if c.SourceDB == "" {
return fmt.Errorf("source channel DB is required")
}
if c.DestDB == "" {
return fmt.Errorf("destination channel DB is required")
}
if c.TxMaxSize <= 0 {
c.TxMaxSize = defaultTxMaxSize
}
src, err := c.openDB(c.SourceDB, true)
if err != nil {
return fmt.Errorf("error opening source DB: %w", err)
}
defer func() { _ = src.Close() }()
dst, err := c.openDB(c.DestDB, false)
if err != nil {
return fmt.Errorf("error opening destination DB: %w", err)
}
defer func() { _ = dst.Close() }()
err = c.compact(dst, src)
if err != nil {
return fmt.Errorf("error compacting DB: %w", err)
}
return nil
}
func (c *compactDBCommand) openDB(path string, ro bool) (*bbolt.DB, error) {
options := &bbolt.Options{
NoFreelistSync: false,
FreelistType: bbolt.FreelistMapType,
ReadOnly: ro,
}
bdb, err := bbolt.Open(path, dbFilePermission, options)
if err != nil {
return nil, err
}
return bdb, nil
}
func (c *compactDBCommand) compact(dst, src *bbolt.DB) error {
// commit regularly, or we'll run out of memory for large datasets if
// using one transaction.
var size int64
tx, err := dst.Begin(true)
if err != nil {
return err
}
defer func() {
_ = tx.Rollback()
}()
if err := c.walk(src, func(keys [][]byte, k, v []byte, seq uint64) error {
// On each key/value, check if we have exceeded tx size.
sz := int64(len(k) + len(v))
if size+sz > c.TxMaxSize && c.TxMaxSize != 0 {
// Commit previous transaction.
if err := tx.Commit(); err != nil {
return err
}
// Start new transaction.
tx, err = dst.Begin(true)
if err != nil {
return err
}
size = 0
}
size += sz
// Create bucket on the root transaction if this is the first
// level.
nk := len(keys)
if nk == 0 {
bkt, err := tx.CreateBucket(k)
if err != nil {
return err
}
if err := bkt.SetSequence(seq); err != nil {
return err
}
return nil
}
// Create buckets on subsequent levels, if necessary.
b := tx.Bucket(keys[0])
if nk > 1 {
for _, k := range keys[1:] {
b = b.Bucket(k)
}
}
// Fill the entire page for best compaction.
b.FillPercent = 1.0
// If there is no value then this is a bucket call.
if v == nil {
bkt, err := b.CreateBucket(k)
if err != nil {
return err
}
if err := bkt.SetSequence(seq); err != nil {
return err
}
return nil
}
// Otherwise treat it as a key/value pair.
return b.Put(k, v)
}); err != nil {
return err
}
return tx.Commit()
}
// walkFunc is the type of the function called for keys (buckets and "normal"
// values) discovered by Walk. keys is the list of keys to descend to the bucket
// owning the discovered key/value pair k/v.
type walkFunc func(keys [][]byte, k, v []byte, seq uint64) error
// walk walks recursively the bolt database db, calling walkFn for each key it
// finds.
func (c *compactDBCommand) walk(db *bbolt.DB, walkFn walkFunc) error {
return db.View(func(tx *bbolt.Tx) error {
return tx.ForEach(func(name []byte, b *bbolt.Bucket) error {
if b == nil {
log.Errorf("Bucket %x was nil! Probable data "+
"corruption suspected.", name)
return nil
}
return c.walkBucket(
b, nil, name, nil, b.Sequence(), walkFn,
)
})
})
}
func (c *compactDBCommand) walkBucket(b *bbolt.Bucket, keypath [][]byte,
k, v []byte, seq uint64, fn walkFunc) error {
// Execute callback.
if err := fn(keypath, k, v, seq); err != nil {
return err
}
// If this is not a bucket then stop.
if v != nil {
return nil
}
// Iterate over each child key/value.
keypath = append(keypath, k)
return b.ForEach(func(k, v []byte) error {
if v == nil {
bkt := b.Bucket(k)
if bkt == nil {
log.Warnf("Could not read bucket '%s' (full "+
"path '%s') database is likely "+
"corrupted. Continuing anyway but "+
"skipping corrupt bucket.", k, keypath)
return nil
}
return c.walkBucket(
bkt, keypath, k, nil, bkt.Sequence(), fn,
)
}
return c.walkBucket(b, keypath, k, v, b.Sequence(), fn)
})
}