lnd.xprv/channeldb/waitingproof.go

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package channeldb
import (
"encoding/binary"
"sync"
"io"
"bytes"
"github.com/coreos/bbolt"
"github.com/go-errors/errors"
"github.com/lightningnetwork/lnd/lnwire"
)
var (
// waitingProofsBucketKey byte string name of the waiting proofs store.
waitingProofsBucketKey = []byte("waitingproofs")
// ErrWaitingProofNotFound is returned if waiting proofs haven't been
// found by db.
ErrWaitingProofNotFound = errors.New("waiting proofs haven't been " +
"found")
// ErrWaitingProofAlreadyExist is returned if waiting proofs haven't been
// found by db.
ErrWaitingProofAlreadyExist = errors.New("waiting proof with such " +
"key already exist")
)
// WaitingProofStore is the bold db map-like storage for half announcement
// signatures. The one responsibility of this storage is to be able to
// retrieve waiting proofs after client restart.
type WaitingProofStore struct {
// cache is used in order to reduce the number of redundant get
// calls, when object isn't stored in it.
cache map[WaitingProofKey]struct{}
db *DB
mu sync.RWMutex
}
// NewWaitingProofStore creates new instance of proofs storage.
func NewWaitingProofStore(db *DB) (*WaitingProofStore, error) {
s := &WaitingProofStore{
db: db,
cache: make(map[WaitingProofKey]struct{}),
}
if err := s.ForAll(func(proof *WaitingProof) error {
s.cache[proof.Key()] = struct{}{}
return nil
}); err != nil && err != ErrWaitingProofNotFound {
return nil, err
}
return s, nil
}
// Add adds new waiting proof in the storage.
func (s *WaitingProofStore) Add(proof *WaitingProof) error {
s.mu.Lock()
defer s.mu.Unlock()
err := s.db.Update(func(tx *bolt.Tx) error {
var err error
var b bytes.Buffer
// Get or create the bucket.
bucket, err := tx.CreateBucketIfNotExists(waitingProofsBucketKey)
if err != nil {
return err
}
// Encode the objects and place it in the bucket.
if err := proof.Encode(&b); err != nil {
return err
}
key := proof.Key()
return bucket.Put(key[:], b.Bytes())
})
if err != nil {
return err
}
// Knowing that the write succeeded, we can now update the in-memory
// cache with the proof's key.
s.cache[proof.Key()] = struct{}{}
return nil
}
// Remove removes the proof from storage by its key.
func (s *WaitingProofStore) Remove(key WaitingProofKey) error {
s.mu.Lock()
defer s.mu.Unlock()
if _, ok := s.cache[key]; !ok {
return ErrWaitingProofNotFound
}
err := s.db.Update(func(tx *bolt.Tx) error {
// Get or create the top bucket.
bucket := tx.Bucket(waitingProofsBucketKey)
if bucket == nil {
return ErrWaitingProofNotFound
}
return bucket.Delete(key[:])
})
if err != nil {
return err
}
// Since the proof was successfully deleted from the store, we can now
// remove it from the in-memory cache.
delete(s.cache, key)
return nil
}
// ForAll iterates thought all waiting proofs and passing the waiting proof
// in the given callback.
func (s *WaitingProofStore) ForAll(cb func(*WaitingProof) error) error {
return s.db.View(func(tx *bolt.Tx) error {
bucket := tx.Bucket(waitingProofsBucketKey)
if bucket == nil {
return ErrWaitingProofNotFound
}
// Iterate over objects buckets.
return bucket.ForEach(func(k, v []byte) error {
// Skip buckets fields.
if v == nil {
return nil
}
r := bytes.NewReader(v)
proof := &WaitingProof{}
if err := proof.Decode(r); err != nil {
return err
}
return cb(proof)
})
})
}
// Get returns the object which corresponds to the given index.
func (s *WaitingProofStore) Get(key WaitingProofKey) (*WaitingProof, error) {
proof := &WaitingProof{}
s.mu.RLock()
defer s.mu.RUnlock()
if _, ok := s.cache[key]; !ok {
return nil, ErrWaitingProofNotFound
}
err := s.db.View(func(tx *bolt.Tx) error {
bucket := tx.Bucket(waitingProofsBucketKey)
if bucket == nil {
return ErrWaitingProofNotFound
}
// Iterate over objects buckets.
v := bucket.Get(key[:])
if v == nil {
return ErrWaitingProofNotFound
}
r := bytes.NewReader(v)
return proof.Decode(r)
})
return proof, err
}
// WaitingProofKey is the proof key which uniquely identifies the waiting
// proof object. The goal of this key is distinguish the local and remote
// proof for the same channel id.
type WaitingProofKey [9]byte
// WaitingProof is the storable object, which encapsulate the half proof and
// the information about from which side this proof came. This structure is
// needed to make channel proof exchange persistent, so that after client
// restart we may receive remote/local half proof and process it.
type WaitingProof struct {
*lnwire.AnnounceSignatures
isRemote bool
}
// NewWaitingProof constructs a new waiting prof instance.
func NewWaitingProof(isRemote bool, proof *lnwire.AnnounceSignatures) *WaitingProof {
return &WaitingProof{
AnnounceSignatures: proof,
isRemote: isRemote,
}
}
// OppositeKey returns the key which uniquely identifies opposite waiting proof.
func (p *WaitingProof) OppositeKey() WaitingProofKey {
var key [9]byte
binary.BigEndian.PutUint64(key[:8], p.ShortChannelID.ToUint64())
if !p.isRemote {
key[8] = 1
}
return key
}
// Key returns the key which uniquely identifies waiting proof.
func (p *WaitingProof) Key() WaitingProofKey {
var key [9]byte
binary.BigEndian.PutUint64(key[:8], p.ShortChannelID.ToUint64())
if p.isRemote {
key[8] = 1
}
return key
}
// Encode writes the internal representation of waiting proof in byte stream.
func (p *WaitingProof) Encode(w io.Writer) error {
if err := binary.Write(w, byteOrder, p.isRemote); err != nil {
return err
}
if err := p.AnnounceSignatures.Encode(w, 0); err != nil {
return err
}
return nil
}
// Decode reads the data from the byte stream and initializes the
// waiting proof object with it.
func (p *WaitingProof) Decode(r io.Reader) error {
if err := binary.Read(r, byteOrder, &p.isRemote); err != nil {
return err
}
msg := &lnwire.AnnounceSignatures{}
if err := msg.Decode(r, 0); err != nil {
return err
}
(*p).AnnounceSignatures = msg
return nil
}