102 lines
2.6 KiB
Go
102 lines
2.6 KiB
Go
package wtdb
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import (
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"encoding/binary"
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"errors"
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"os"
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"path/filepath"
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"time"
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"github.com/lightningnetwork/lnd/kvdb"
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)
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const (
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// dbFilePermission requests read+write access to the db file.
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dbFilePermission = 0600
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)
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var (
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// metadataBkt stores all the meta information concerning the state of
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// the database.
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metadataBkt = []byte("metadata-bucket")
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// dbVersionKey is a static key used to retrieve the database version
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// number from the metadataBkt.
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dbVersionKey = []byte("version")
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// ErrUninitializedDB signals that top-level buckets for the database
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// have not been initialized.
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ErrUninitializedDB = errors.New("db not initialized")
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// ErrNoDBVersion signals that the database contains no version info.
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ErrNoDBVersion = errors.New("db has no version")
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// byteOrder is the default endianness used when serializing integers.
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byteOrder = binary.BigEndian
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)
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// fileExists returns true if the file exists, and false otherwise.
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func fileExists(path string) bool {
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if _, err := os.Stat(path); err != nil {
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if os.IsNotExist(err) {
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return false
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}
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}
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return true
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}
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// createDBIfNotExist opens the boltdb database at dbPath/name, creating one if
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// one doesn't exist. The boolean returned indicates if the database did not
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// exist before, or if it has been created but no version metadata exists within
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// it.
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func createDBIfNotExist(dbPath, name string,
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dbTimeout time.Duration) (kvdb.Backend, bool, error) {
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path := filepath.Join(dbPath, name)
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// If the database file doesn't exist, this indicates we much initialize
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// a fresh database with the latest version.
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firstInit := !fileExists(path)
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if firstInit {
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// Ensure all parent directories are initialized.
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err := os.MkdirAll(dbPath, 0700)
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if err != nil {
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return nil, false, err
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}
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}
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// Specify bbolt freelist options to reduce heap pressure in case the
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// freelist grows to be very large.
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bdb, err := kvdb.Create(
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kvdb.BoltBackendName, path, true, dbTimeout,
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)
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if err != nil {
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return nil, false, err
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}
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// If the file existed previously, we'll now check to see that the
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// metadata bucket is properly initialized. It could be the case that
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// the database was created, but we failed to actually populate any
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// metadata. If the metadata bucket does not actually exist, we'll
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// set firstInit to true so that we can treat is initialize the bucket.
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if !firstInit {
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var metadataExists bool
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err = kvdb.View(bdb, func(tx kvdb.RTx) error {
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metadataExists = tx.ReadBucket(metadataBkt) != nil
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return nil
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}, func() {
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metadataExists = false
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})
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if err != nil {
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return nil, false, err
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}
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if !metadataExists {
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firstInit = true
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}
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}
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return bdb, firstInit, nil
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}
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