90 lines
2.8 KiB
Go
90 lines
2.8 KiB
Go
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// Copyright (c) 2016 The btcsuite developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package txscript
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import (
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"sync"
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"github.com/btcsuite/btcd/chaincfg/chainhash"
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"github.com/btcsuite/btcd/wire"
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)
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// TxSigHashes houses the partial set of sighashes introduced within BIP0143.
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// This partial set of sighashes may be re-used within each input across a
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// transaction when validating all inputs. As a result, validation complexity
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// for SigHashAll can be reduced by a polynomial factor.
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type TxSigHashes struct {
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HashPrevOuts chainhash.Hash
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HashSequence chainhash.Hash
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HashOutputs chainhash.Hash
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}
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// NewTxSigHashes computes, and returns the cached sighashes of the given
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// transaction.
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func NewTxSigHashes(tx *wire.MsgTx) *TxSigHashes {
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return &TxSigHashes{
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HashPrevOuts: calcHashPrevOuts(tx),
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HashSequence: calcHashSequence(tx),
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HashOutputs: calcHashOutputs(tx),
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}
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}
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// HashCache houses a set of partial sighashes keyed by txid. The set of partial
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// sighashes are those introduced within BIP0143 by the new more efficient
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// sighash digest calculation algorithm. Using this threadsafe shared cache,
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// multiple goroutines can safely re-use the pre-computed partial sighashes
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// speeding up validation time amongst all inputs found within a block.
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type HashCache struct {
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sigHashes map[chainhash.Hash]*TxSigHashes
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sync.RWMutex
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}
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// NewHashCache returns a new instance of the HashCache given a maximum number
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// of entries which may exist within it at anytime.
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func NewHashCache(maxSize uint) *HashCache {
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return &HashCache{
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sigHashes: make(map[chainhash.Hash]*TxSigHashes, maxSize),
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}
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}
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// AddSigHashes computes, then adds the partial sighashes for the passed
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// transaction.
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func (h *HashCache) AddSigHashes(tx *wire.MsgTx) {
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h.Lock()
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h.sigHashes[tx.TxHash()] = NewTxSigHashes(tx)
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h.Unlock()
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}
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// ContainsHashes returns true if the partial sighashes for the passed
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// transaction currently exist within the HashCache, and false otherwise.
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func (h *HashCache) ContainsHashes(txid *chainhash.Hash) bool {
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h.RLock()
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_, found := h.sigHashes[*txid]
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h.RUnlock()
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return found
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}
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// GetSigHashes possibly returns the previously cached partial sighashes for
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// the passed transaction. This function also returns an additional boolean
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// value indicating if the sighashes for the passed transaction were found to
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// be present within the HashCache.
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func (h *HashCache) GetSigHashes(txid *chainhash.Hash) (*TxSigHashes, bool) {
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h.RLock()
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item, found := h.sigHashes[*txid]
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h.RUnlock()
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return item, found
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}
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// PurgeSigHashes removes all partial sighashes from the HashCache belonging to
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// the passed transaction.
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func (h *HashCache) PurgeSigHashes(txid *chainhash.Hash) {
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h.Lock()
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delete(h.sigHashes, *txid)
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h.Unlock()
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}
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