2a358327f4
This commit adds a reset() closure to the kvdb.View function which will be called before each retry (including the first) of the view transaction. The reset() closure can be used to reset external state (eg slices or maps) where the view closure puts intermediate results.
97 lines
2.6 KiB
Go
97 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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"github.com/lightningnetwork/lnd/channeldb/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) (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(kvdb.BoltBackendName, path, true)
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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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