From f893ec57cb858dd2730ec5dbd09cf3951d986d84 Mon Sep 17 00:00:00 2001
From: Alexander Neumann <alexander@bumpern.de>
Date: Sat, 5 Mar 2016 15:58:39 +0100
Subject: [PATCH] Add test and benchmark for PackerManager

---
 src/restic/repository/packer_manager.go      |   7 +-
 src/restic/repository/packer_manager_test.go | 122 +++++++++++++++++++
 2 files changed, 128 insertions(+), 1 deletion(-)
 create mode 100644 src/restic/repository/packer_manager_test.go

diff --git a/src/restic/repository/packer_manager.go b/src/restic/repository/packer_manager.go
index a7716418e..2791af51c 100644
--- a/src/restic/repository/packer_manager.go
+++ b/src/restic/repository/packer_manager.go
@@ -9,9 +9,14 @@ import (
 	"restic/pack"
 )
 
+// Saver implements saving data in a backend.
+type Saver interface {
+	Save(h backend.Handle, p []byte) error
+}
+
 // packerManager keeps a list of open packs and creates new on demand.
 type packerManager struct {
-	be    backend.Backend
+	be    Saver
 	key   *crypto.Key
 	pm    sync.Mutex
 	packs []*pack.Packer
diff --git a/src/restic/repository/packer_manager_test.go b/src/restic/repository/packer_manager_test.go
new file mode 100644
index 000000000..4af073e4d
--- /dev/null
+++ b/src/restic/repository/packer_manager_test.go
@@ -0,0 +1,122 @@
+package repository
+
+import (
+	"io"
+	"math/rand"
+	"restic/backend"
+	"restic/backend/mem"
+	"restic/crypto"
+	"restic/pack"
+	"testing"
+)
+
+func randomID(rd io.Reader) backend.ID {
+	id := backend.ID{}
+	_, err := io.ReadFull(rd, id[:])
+	if err != nil {
+		panic(err)
+	}
+	return id
+}
+
+func fillPacks(t testing.TB, rnd *rand.Rand, be Saver, pm *packerManager) (bytes int) {
+	for i := 0; i < 100; i++ {
+		l := rnd.Intn(1 << 20)
+		seed := rnd.Int63()
+
+		packer, err := pm.findPacker(uint(l))
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		rd := rand.New(rand.NewSource(seed))
+		id := randomID(rd)
+		n, err := packer.Add(pack.Data, id, io.LimitReader(rd, int64(l)))
+
+		if n != int64(l) {
+			t.Errorf("Add() returned invalid number of bytes: want %v, got %v", n, l)
+		}
+		bytes += l
+
+		if packer.Size() < minPackSize && pm.countPacker() < maxPackers {
+			pm.insertPacker(packer)
+			continue
+		}
+
+		data, err := packer.Finalize()
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		h := backend.Handle{Type: backend.Data, Name: randomID(rd).String()}
+
+		err = be.Save(h, data)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	return bytes
+}
+
+func flushRemainingPacks(t testing.TB, rnd *rand.Rand, be Saver, pm *packerManager) (bytes int) {
+	if pm.countPacker() > 0 {
+		for _, packer := range pm.packs {
+			data, err := packer.Finalize()
+			if err != nil {
+				t.Fatal(err)
+			}
+			bytes += len(data)
+
+			h := backend.Handle{Type: backend.Data, Name: randomID(rnd).String()}
+
+			err = be.Save(h, data)
+			if err != nil {
+				t.Fatal(err)
+			}
+		}
+	}
+
+	return bytes
+}
+
+type fakeBackend struct{}
+
+func (f *fakeBackend) Save(h backend.Handle, data []byte) error {
+	return nil
+}
+
+func TestPackerManager(t *testing.T) {
+	rnd := rand.New(rand.NewSource(23))
+
+	be := mem.New()
+	pm := &packerManager{
+		be:  be,
+		key: crypto.NewRandomKey(),
+	}
+
+	bytes := fillPacks(t, rnd, be, pm)
+	bytes += flushRemainingPacks(t, rnd, be, pm)
+
+	t.Logf("saved %d bytes", bytes)
+}
+
+func BenchmarkPackerManager(t *testing.B) {
+	rnd := rand.New(rand.NewSource(23))
+
+	be := &fakeBackend{}
+	pm := &packerManager{
+		be:  be,
+		key: crypto.NewRandomKey(),
+	}
+
+	t.ResetTimer()
+
+	bytes := 0
+	for i := 0; i < t.N; i++ {
+		bytes += fillPacks(t, rnd, be, pm)
+	}
+
+	bytes += flushRemainingPacks(t, rnd, be, pm)
+	t.Logf("saved %d bytes", bytes)
+}