lib/model, lib/scanner: Efficient inserts/deletes in the middle of the file

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3527

lib/weakhash/benchmark_test.go

@@ -0,0 +1,30 @@
+// Copyright (C) 2016 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package weakhash
+
+import (
+	"os"
+	"testing"
+)
+
+const testFile = "../model/testdata/~syncthing~file.tmp"
+
+func BenchmarkFind1MFile(b *testing.B) {
+	b.ReportAllocs()
+	b.SetBytes(1 << 20)
+	for i := 0; i < b.N; i++ {
+		fd, err := os.Open(testFile)
+		if err != nil {
+			b.Fatal(err)
+		}
+		_, err = Find(fd, []uint32{0, 1, 2}, 128<<10)
+		if err != nil {
+			b.Fatal(err)
+		}
+		fd.Close()
+	}
+}