lnd.xprv/chainntnfs/height_hint_cache.go

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package chainntnfs
import (
"bytes"
"errors"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/channeldb/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
}
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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
}
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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
})
}