btcutil: add benchmarks for Hash + WitnessHash

btcutil/bench_test.go

@@ -0,0 +1,80 @@
+package btcutil_test
+
+import (
+	"testing"
+
+	"github.com/btcsuite/btcd/btcutil"
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
+)
+
+var (
+	bencHash *chainhash.Hash
+)
+
+// BenchmarkTxHash benchmarks the performance of calculating the hash of a
+// transaction.
+func BenchmarkTxHash(b *testing.B) {
+	// Make a new block from the test block, we'll then call the Bytes
+	// function to cache the serialized block. Afterwards we all
+	// Transactions to populate the serialization cache.
+	testBlock := btcutil.NewBlock(&Block100000)
+	_, _ = testBlock.Bytes()
+
+	// The second transaction in the block has no witness data. The first
+	// does however.
+	testTx := testBlock.Transactions()[1]
+	testTx2 := testBlock.Transactions()[0]
+
+	// Run a benchmark for the portion that needs to strip the non-witness
+	// data from the transaction.
+	b.Run("tx_hash_has_witness", func(b *testing.B) {
+		b.ResetTimer()
+		b.ReportAllocs()
+
+		var txHash *chainhash.Hash
+		for i := 0; i < b.N; i++ {
+			txHash = testTx2.Hash()
+		}
+
+		bencHash = txHash
+	})
+
+	// Next, run it for the portion that can just hash the bytes directly.
+	b.Run("tx_hash_no_witness", func(b *testing.B) {
+		b.ResetTimer()
+		b.ReportAllocs()
+
+		var txHash *chainhash.Hash
+		for i := 0; i < b.N; i++ {
+			txHash = testTx.Hash()
+		}
+
+		bencHash = txHash
+	})
+
+}
+
+// BenchmarkTxWitnessHash benchmarks the performance of calculating the hash of
+// a transaction.
+func BenchmarkTxWitnessHash(b *testing.B) {
+	// Make a new block from the test block, we'll then call the Bytes
+	// function to cache the serialized block. Afterwards we all
+	// Transactions to populate the serialization cache.
+	testBlock := btcutil.NewBlock(&Block100000)
+	_, _ = testBlock.Bytes()
+
+	// The first transaction in the block has been modified to have witness
+	// data.
+	testTx := testBlock.Transactions()[0]
+
+	b.ResetTimer()
+	b.ReportAllocs()
+
+	var txHash *chainhash.Hash
+	for i := 0; i < b.N; i++ {
+		txHash = testTx.WitnessHash()
+	}
+
+	bencHash = txHash
+
+}