lnd.xprv/channeldb/kvdb/etcd/readwrite_bucket.go

357 lines
8.8 KiB
Go

// +build kvdb_etcd
package etcd
import (
"strconv"
"github.com/btcsuite/btcwallet/walletdb"
)
// readWriteBucket stores the bucket id and the buckets transaction.
type readWriteBucket struct {
// id is used to identify the bucket and is created by
// hashing the parent id with the bucket key. For each key/value,
// sub-bucket or the bucket sequence the bucket id is used with the
// appropriate prefix to prefix the key.
id []byte
// tx holds the parent transaction.
tx *readWriteTx
}
// newReadWriteBucket creates a new rw bucket with the passed transaction
// and bucket id.
func newReadWriteBucket(tx *readWriteTx, key, id []byte) *readWriteBucket {
return &readWriteBucket{
id: id,
tx: tx,
}
}
// NestedReadBucket retrieves a nested read bucket with the given key.
// Returns nil if the bucket does not exist.
func (b *readWriteBucket) NestedReadBucket(key []byte) walletdb.ReadBucket {
return b.NestedReadWriteBucket(key)
}
// ForEach invokes the passed function with every key/value pair in
// the bucket. This includes nested buckets, in which case the value
// is nil, but it does not include the key/value pairs within those
// nested buckets.
func (b *readWriteBucket) ForEach(cb func(k, v []byte) error) error {
prefix := string(b.id)
// Get the first matching key that is in the bucket.
kv, err := b.tx.stm.First(prefix)
if err != nil {
return err
}
for kv != nil {
key, val := getKeyVal(kv)
if err := cb(key, val); err != nil {
return err
}
// Step to the next key.
kv, err = b.tx.stm.Next(prefix, kv.key)
if err != nil {
return err
}
}
return nil
}
// Get returns the value for the given key. Returns nil if the key does
// not exist in this bucket.
func (b *readWriteBucket) Get(key []byte) []byte {
// Return nil if the key is empty.
if len(key) == 0 {
return nil
}
// Fetch the associated value.
val, err := b.tx.stm.Get(string(makeValueKey(b.id, key)))
if err != nil {
// TODO: we should return the error once the
// kvdb inteface is extended.
return nil
}
if val == nil {
return nil
}
return val
}
func (b *readWriteBucket) ReadCursor() walletdb.ReadCursor {
return newReadWriteCursor(b)
}
// NestedReadWriteBucket retrieves a nested bucket with the given key.
// Returns nil if the bucket does not exist.
func (b *readWriteBucket) NestedReadWriteBucket(key []byte) walletdb.ReadWriteBucket {
if len(key) == 0 {
return nil
}
// Get the bucket id (and return nil if bucket doesn't exist).
bucketKey := makeBucketKey(b.id, key)
bucketVal, err := b.tx.stm.Get(string(bucketKey))
if err != nil {
// TODO: we should return the error once the
// kvdb inteface is extended.
return nil
}
if !isValidBucketID(bucketVal) {
return nil
}
// Return the bucket with the fetched bucket id.
return newReadWriteBucket(b.tx, bucketKey, bucketVal)
}
// assertNoValue checks if the value for the passed key exists.
func (b *readWriteBucket) assertNoValue(key []byte) error {
val, err := b.tx.stm.Get(string(makeValueKey(b.id, key)))
if err != nil {
return err
}
if val != nil {
return walletdb.ErrIncompatibleValue
}
return nil
}
// CreateBucket creates and returns a new nested bucket with the given
// key. Returns ErrBucketExists if the bucket already exists,
// ErrBucketNameRequired if the key is empty, or ErrIncompatibleValue
// if the key value is otherwise invalid for the particular database
// implementation. Other errors are possible depending on the
// implementation.
func (b *readWriteBucket) CreateBucket(key []byte) (
walletdb.ReadWriteBucket, error) {
if len(key) == 0 {
return nil, walletdb.ErrBucketNameRequired
}
// Check if the bucket already exists.
bucketKey := makeBucketKey(b.id, key)
bucketVal, err := b.tx.stm.Get(string(bucketKey))
if err != nil {
return nil, err
}
if isValidBucketID(bucketVal) {
return nil, walletdb.ErrBucketExists
}
if err := b.assertNoValue(key); err != nil {
return nil, err
}
// Create a deterministic bucket id from the bucket key.
newID := makeBucketID(bucketKey)
// Create the bucket.
b.tx.stm.Put(string(bucketKey), string(newID[:]))
return newReadWriteBucket(b.tx, bucketKey, newID[:]), nil
}
// CreateBucketIfNotExists creates and returns a new nested bucket with
// the given key if it does not already exist. Returns
// ErrBucketNameRequired if the key is empty or ErrIncompatibleValue
// if the key value is otherwise invalid for the particular database
// backend. Other errors are possible depending on the implementation.
func (b *readWriteBucket) CreateBucketIfNotExists(key []byte) (
walletdb.ReadWriteBucket, error) {
if len(key) == 0 {
return nil, walletdb.ErrBucketNameRequired
}
// Check for the bucket and create if it doesn't exist.
bucketKey := makeBucketKey(b.id, key)
bucketVal, err := b.tx.stm.Get(string(bucketKey))
if err != nil {
return nil, err
}
if !isValidBucketID(bucketVal) {
if err := b.assertNoValue(key); err != nil {
return nil, err
}
newID := makeBucketID(bucketKey)
b.tx.stm.Put(string(bucketKey), string(newID[:]))
return newReadWriteBucket(b.tx, bucketKey, newID[:]), nil
}
// Otherwise return the bucket with the fetched bucket id.
return newReadWriteBucket(b.tx, bucketKey, bucketVal), nil
}
// DeleteNestedBucket deletes the nested bucket and its sub-buckets
// pointed to by the passed key. All values in the bucket and sub-buckets
// will be deleted as well.
func (b *readWriteBucket) DeleteNestedBucket(key []byte) error {
// TODO shouldn't empty key return ErrBucketNameRequired ?
if len(key) == 0 {
return walletdb.ErrIncompatibleValue
}
// Get the bucket first.
bucketKey := string(makeBucketKey(b.id, key))
bucketVal, err := b.tx.stm.Get(bucketKey)
if err != nil {
return err
}
if !isValidBucketID(bucketVal) {
return walletdb.ErrBucketNotFound
}
// Enqueue the top level bucket id.
queue := [][]byte{bucketVal}
// Traverse the buckets breadth first.
for len(queue) != 0 {
if !isValidBucketID(queue[0]) {
return walletdb.ErrBucketNotFound
}
id := queue[0]
queue = queue[1:]
kv, err := b.tx.stm.First(string(id))
if err != nil {
return err
}
for kv != nil {
b.tx.stm.Del(kv.key)
if isBucketKey(kv.key) {
queue = append(queue, []byte(kv.val))
}
kv, err = b.tx.stm.Next(string(id), kv.key)
if err != nil {
return err
}
}
// Finally delete the sequence key for the bucket.
b.tx.stm.Del(string(makeSequenceKey(id)))
}
// Delete the top level bucket and sequence key.
b.tx.stm.Del(bucketKey)
b.tx.stm.Del(string(makeSequenceKey(bucketVal)))
return nil
}
// Put updates the value for the passed key.
// Returns ErrKeyRequred if te passed key is empty.
func (b *readWriteBucket) Put(key, value []byte) error {
if len(key) == 0 {
return walletdb.ErrKeyRequired
}
val, err := b.tx.stm.Get(string(makeBucketKey(b.id, key)))
if err != nil {
return err
}
if val != nil {
return walletdb.ErrIncompatibleValue
}
// Update the transaction with the new value.
b.tx.stm.Put(string(makeValueKey(b.id, key)), string(value))
return nil
}
// Delete deletes the key/value pointed to by the passed key.
// Returns ErrKeyRequred if the passed key is empty.
func (b *readWriteBucket) Delete(key []byte) error {
if key == nil {
return nil
}
if len(key) == 0 {
return walletdb.ErrKeyRequired
}
// Update the transaction to delete the key/value.
b.tx.stm.Del(string(makeValueKey(b.id, key)))
return nil
}
// ReadWriteCursor returns a new read-write cursor for this bucket.
func (b *readWriteBucket) ReadWriteCursor() walletdb.ReadWriteCursor {
return newReadWriteCursor(b)
}
// Tx returns the buckets transaction.
func (b *readWriteBucket) Tx() walletdb.ReadWriteTx {
return b.tx
}
// NextSequence returns an autoincrementing sequence number for this bucket.
// Note that this is not a thread safe function and as such it must not be used
// for synchronization.
func (b *readWriteBucket) NextSequence() (uint64, error) {
seq := b.Sequence() + 1
return seq, b.SetSequence(seq)
}
// SetSequence updates the sequence number for the bucket.
func (b *readWriteBucket) SetSequence(v uint64) error {
// Convert the number to string.
val := strconv.FormatUint(v, 10)
// Update the transaction with the new value for the sequence key.
b.tx.stm.Put(string(makeSequenceKey(b.id)), val)
return nil
}
// Sequence returns the current sequence number for this bucket without
// incrementing it.
func (b *readWriteBucket) Sequence() uint64 {
val, err := b.tx.stm.Get(string(makeSequenceKey(b.id)))
if err != nil {
// TODO: This update kvdb interface such that error
// may be returned here.
return 0
}
if val == nil {
// If the sequence number is not yet
// stored, then take the default value.
return 0
}
// Otherwise try to parse a 64 bit unsigned integer from the value.
num, _ := strconv.ParseUint(string(val), 10, 64)
return num
}