/
hashcache.go
76 lines (66 loc) · 2.58 KB
/
hashcache.go
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package txscript
import (
"sync"
"github.com/cybriq/p9/pkg/chainhash"
"github.com/cybriq/p9/pkg/wire"
)
// TxSigHashes houses the partial set of sighashes introduced within BIP0143. This partial set of sighashes may be
// re-used within each input across a transaction when validating all inputs. As a result, validation complexity for
// SigHashAll can be reduced by a polynomial factor.
type TxSigHashes struct {
HashPrevOuts chainhash.Hash
HashSequence chainhash.Hash
HashOutputs chainhash.Hash
}
// NewTxSigHashes computes, and returns the cached sighashes of the given transaction.
func NewTxSigHashes(tx *wire.MsgTx) *TxSigHashes {
return &TxSigHashes{
HashPrevOuts: calcHashPrevOuts(tx),
HashSequence: calcHashSequence(tx),
HashOutputs: calcHashOutputs(tx),
}
}
// HashCache houses a set of partial sighashes keyed by txid. The set of partial sighashes are those introduced within
// BIP0143 by the new more efficient sighash digest calculation algorithm. Using this threadsafe shared cache, multiple
// goroutines can safely re-use the pre-computed partial sighashes speeding up validation time amongst all inputs found
// within a block.
type HashCache struct {
sigHashes map[chainhash.Hash]*TxSigHashes
sync.RWMutex
}
// NewHashCache returns a new instance of the HashCache given a maximum number of entries which may exist within it at
// anytime.
func NewHashCache(maxSize uint) *HashCache {
return &HashCache{
sigHashes: make(map[chainhash.Hash]*TxSigHashes, maxSize),
}
}
// AddSigHashes computes, then adds the partial sighashes for the passed transaction.
func (h *HashCache) AddSigHashes(tx *wire.MsgTx) {
h.Lock()
h.sigHashes[tx.TxHash()] = NewTxSigHashes(tx)
h.Unlock()
}
// ContainsHashes returns true if the partial sighashes for the passed transaction currently exist within the HashCache,
// and false otherwise.
func (h *HashCache) ContainsHashes(txid *chainhash.Hash) bool {
h.RLock()
_, found := h.sigHashes[*txid]
h.RUnlock()
return found
}
// GetSigHashes possibly returns the previously cached partial sighashes for the passed transaction. This function also
// returns an additional boolean value indicating if the sighashes for the passed transaction were found to be present
// within the HashCache.
func (h *HashCache) GetSigHashes(txid *chainhash.Hash) (*TxSigHashes, bool) {
h.RLock()
item, found := h.sigHashes[*txid]
h.RUnlock()
return item, found
}
// PurgeSigHashes removes all partial sighashes from the HashCache belonging to the passed transaction.
func (h *HashCache) PurgeSigHashes(txid *chainhash.Hash) {
h.Lock()
delete(h.sigHashes, *txid)
h.Unlock()
}