txscript: Add benchmark for sighash calculation.

txscript/bench_test.go

@@ -0,0 +1,51 @@
+// Copyright (c) 2018 The Decred developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package txscript
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"testing"
+
+	"github.com/decred/dcrd/wire"
+)
+
+var (
+	// manyInputsBenchTx is a transaction that contains a lot of inputs which is
+	// useful for benchmarking signature hash calculation.
+	manyInputsBenchTx wire.MsgTx
+
+	// A mock previous output script to use in the signing benchmark.
+	prevOutScript = hexToBytes("a914f5916158e3e2c4551c1796708db8367207ed13bb87")
+)
+
+// BenchmarkCalcSigHash benchmarks how long it takes to calculate the signature
+// hashes for all inputs of a transaction with many inputs.
+func BenchmarkCalcSigHash(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for j := 0; j < len(manyInputsBenchTx.TxIn); j++ {
+			_, err := CalcSignatureHash(prevOutScript, SigHashAll,
+				&manyInputsBenchTx, j, nil)
+			if err != nil {
+				b.Fatalf("failed to calc signature hash: %v", err)
+			}
+		}
+	}
+}
+
+func init() {
+	// tx 620f57c92cf05a7f7e7f7d28255d5f7089437bc48e34dcfebf7751d08b7fb8f5
+	txHex, err := ioutil.ReadFile("data/many_inputs_tx.hex")
+	if err != nil {
+		panic(fmt.Sprintf("unable to read benchmark tx file: %v", err))
+	}
+
+	txBytes := hexToBytes(string(txHex))
+	err = manyInputsBenchTx.Deserialize(bytes.NewReader(txBytes))
+	if err != nil {
+		panic(err)
+	}
+}