package chainntnfs import ( "bytes" "errors" "github.com/lightningnetwork/lnd/channeldb" "github.com/lightningnetwork/lnd/kvdb" ) var ( // spendHintBucket is the name of the bucket which houses the height // hint for outpoints. Each height hint represents the earliest height // at which its corresponding outpoint could have been spent within. spendHintBucket = []byte("spend-hints") // confirmHintBucket is the name of the bucket which houses the height // hints for transactions. Each height hint represents the earliest // height at which its corresponding transaction could have been // confirmed within. confirmHintBucket = []byte("confirm-hints") // ErrCorruptedHeightHintCache indicates that the on-disk bucketing // structure has altered since the height hint cache instance was // initialized. ErrCorruptedHeightHintCache = errors.New("height hint cache has been " + "corrupted") // ErrSpendHintNotFound is an error returned when a spend hint for an // outpoint was not found. ErrSpendHintNotFound = errors.New("spend hint not found") // ErrConfirmHintNotFound is an error returned when a confirm hint for a // transaction was not found. ErrConfirmHintNotFound = errors.New("confirm hint not found") ) // CacheConfig contains the HeightHintCache configuration type CacheConfig struct { // QueryDisable prevents reliance on the Height Hint Cache. This is // necessary to recover from an edge case when the height recorded in // the cache is higher than the actual height of a spend, causing a // channel to become "stuck" in a pending close state. QueryDisable bool } // SpendHintCache is an interface whose duty is to cache spend hints for // outpoints. A spend hint is defined as the earliest height in the chain at // which an outpoint could have been spent within. type SpendHintCache interface { // CommitSpendHint commits a spend hint for the outpoints to the cache. CommitSpendHint(height uint32, spendRequests ...SpendRequest) error // QuerySpendHint returns the latest spend hint for an outpoint. // ErrSpendHintNotFound is returned if a spend hint does not exist // within the cache for the outpoint. QuerySpendHint(spendRequest SpendRequest) (uint32, error) // PurgeSpendHint removes the spend hint for the outpoints from the // cache. PurgeSpendHint(spendRequests ...SpendRequest) error } // ConfirmHintCache is an interface whose duty is to cache confirm hints for // transactions. A confirm hint is defined as the earliest height in the chain // at which a transaction could have been included in a block. type ConfirmHintCache interface { // CommitConfirmHint commits a confirm hint for the transactions to the // cache. CommitConfirmHint(height uint32, confRequests ...ConfRequest) error // QueryConfirmHint returns the latest confirm hint for a transaction // hash. ErrConfirmHintNotFound is returned if a confirm hint does not // exist within the cache for the transaction hash. QueryConfirmHint(confRequest ConfRequest) (uint32, error) // PurgeConfirmHint removes the confirm hint for the transactions from // the cache. PurgeConfirmHint(confRequests ...ConfRequest) error } // HeightHintCache is an implementation of the SpendHintCache and // ConfirmHintCache interfaces backed by a channeldb DB instance where the hints // will be stored. type HeightHintCache struct { cfg CacheConfig db *channeldb.DB } // Compile-time checks to ensure HeightHintCache satisfies the SpendHintCache // and ConfirmHintCache interfaces. var _ SpendHintCache = (*HeightHintCache)(nil) var _ ConfirmHintCache = (*HeightHintCache)(nil) // NewHeightHintCache returns a new height hint cache backed by a database. func NewHeightHintCache(cfg CacheConfig, db *channeldb.DB) (*HeightHintCache, error) { cache := &HeightHintCache{cfg, db} if err := cache.initBuckets(); err != nil { return nil, err } return cache, nil } // initBuckets ensures that the primary buckets used by the circuit are // initialized so that we can assume their existence after startup. func (c *HeightHintCache) initBuckets() error { return kvdb.Batch(c.db.Backend, func(tx kvdb.RwTx) error { _, err := tx.CreateTopLevelBucket(spendHintBucket) if err != nil { return err } _, err = tx.CreateTopLevelBucket(confirmHintBucket) return err }) } // CommitSpendHint commits a spend hint for the outpoints to the cache. func (c *HeightHintCache) CommitSpendHint(height uint32, spendRequests ...SpendRequest) error { if len(spendRequests) == 0 { return nil } Log.Tracef("Updating spend hint to height %d for %v", height, spendRequests) return kvdb.Batch(c.db.Backend, func(tx kvdb.RwTx) error { spendHints := tx.ReadWriteBucket(spendHintBucket) if spendHints == nil { return ErrCorruptedHeightHintCache } var hint bytes.Buffer if err := channeldb.WriteElement(&hint, height); err != nil { return err } for _, spendRequest := range spendRequests { spendHintKey, err := spendRequest.SpendHintKey() if err != nil { return err } err = spendHints.Put(spendHintKey, hint.Bytes()) if err != nil { return err } } return nil }) } // QuerySpendHint returns the latest spend hint for an outpoint. // ErrSpendHintNotFound is returned if a spend hint does not exist within the // cache for the outpoint. func (c *HeightHintCache) QuerySpendHint(spendRequest SpendRequest) (uint32, error) { var hint uint32 if c.cfg.QueryDisable { Log.Debugf("Ignoring spend height hint for %v (height hint cache "+ "query disabled)", spendRequest) return 0, nil } err := kvdb.View(c.db, func(tx kvdb.RTx) error { spendHints := tx.ReadBucket(spendHintBucket) if spendHints == nil { return ErrCorruptedHeightHintCache } spendHintKey, err := spendRequest.SpendHintKey() if err != nil { return err } spendHint := spendHints.Get(spendHintKey) if spendHint == nil { return ErrSpendHintNotFound } return channeldb.ReadElement(bytes.NewReader(spendHint), &hint) }, func() { hint = 0 }) if err != nil { return 0, err } return hint, nil } // PurgeSpendHint removes the spend hint for the outpoints from the cache. func (c *HeightHintCache) PurgeSpendHint(spendRequests ...SpendRequest) error { if len(spendRequests) == 0 { return nil } Log.Tracef("Removing spend hints for %v", spendRequests) return kvdb.Batch(c.db.Backend, func(tx kvdb.RwTx) error { spendHints := tx.ReadWriteBucket(spendHintBucket) if spendHints == nil { return ErrCorruptedHeightHintCache } for _, spendRequest := range spendRequests { spendHintKey, err := spendRequest.SpendHintKey() if err != nil { return err } if err := spendHints.Delete(spendHintKey); err != nil { return err } } return nil }) } // CommitConfirmHint commits a confirm hint for the transactions to the cache. func (c *HeightHintCache) CommitConfirmHint(height uint32, confRequests ...ConfRequest) error { if len(confRequests) == 0 { return nil } Log.Tracef("Updating confirm hints to height %d for %v", height, confRequests) return kvdb.Batch(c.db.Backend, func(tx kvdb.RwTx) error { confirmHints := tx.ReadWriteBucket(confirmHintBucket) if confirmHints == nil { return ErrCorruptedHeightHintCache } var hint bytes.Buffer if err := channeldb.WriteElement(&hint, height); err != nil { return err } for _, confRequest := range confRequests { confHintKey, err := confRequest.ConfHintKey() if err != nil { return err } err = confirmHints.Put(confHintKey, hint.Bytes()) if err != nil { return err } } return nil }) } // QueryConfirmHint returns the latest confirm hint for a transaction hash. // ErrConfirmHintNotFound is returned if a confirm hint does not exist within // the cache for the transaction hash. func (c *HeightHintCache) QueryConfirmHint(confRequest ConfRequest) (uint32, error) { var hint uint32 if c.cfg.QueryDisable { Log.Debugf("Ignoring confirmation height hint for %v (height hint "+ "cache query disabled)", confRequest) return 0, nil } err := kvdb.View(c.db, func(tx kvdb.RTx) error { confirmHints := tx.ReadBucket(confirmHintBucket) if confirmHints == nil { return ErrCorruptedHeightHintCache } confHintKey, err := confRequest.ConfHintKey() if err != nil { return err } confirmHint := confirmHints.Get(confHintKey) if confirmHint == nil { return ErrConfirmHintNotFound } return channeldb.ReadElement(bytes.NewReader(confirmHint), &hint) }, func() { hint = 0 }) if err != nil { return 0, err } return hint, nil } // PurgeConfirmHint removes the confirm hint for the transactions from the // cache. func (c *HeightHintCache) PurgeConfirmHint(confRequests ...ConfRequest) error { if len(confRequests) == 0 { return nil } Log.Tracef("Removing confirm hints for %v", confRequests) return kvdb.Batch(c.db.Backend, func(tx kvdb.RwTx) error { confirmHints := tx.ReadWriteBucket(confirmHintBucket) if confirmHints == nil { return ErrCorruptedHeightHintCache } for _, confRequest := range confRequests { confHintKey, err := confRequest.ConfHintKey() if err != nil { return err } if err := confirmHints.Delete(confHintKey); err != nil { return err } } return nil }) }