From 9cb4e14327bddaf0e8a01480c70ab58aec722a95 Mon Sep 17 00:00:00 2001
From: Alexander Neumann <alexander@bumpern.de>
Date: Sun, 22 Nov 2015 16:12:00 +0100
Subject: [PATCH] add MemBackend and MockBackend

---
 backend/backend_test.go     |   5 +
 backend/mem_backend.go      | 192 ++++++++++++++++++++++++++++++++++++
 backend/mem_backend_test.go |  12 +++
 3 files changed, 209 insertions(+)
 create mode 100644 backend/mem_backend.go
 create mode 100644 backend/mem_backend_test.go

diff --git a/backend/backend_test.go b/backend/backend_test.go
index 0ff5f01b4..ef928cf8e 100644
--- a/backend/backend_test.go
+++ b/backend/backend_test.go
@@ -96,6 +96,11 @@ func testBackend(b backend.Backend, t *testing.T) {
 		err = b.Remove(tpe, test.id)
 		OK(t, err)
 
+		// test that the blob is gone
+		ok, err := b.Test(tpe, test.id)
+		OK(t, err)
+		Assert(t, ok == false, "removed blob still present")
+
 		// create blob
 		blob, err = b.Create()
 		OK(t, err)
diff --git a/backend/mem_backend.go b/backend/mem_backend.go
new file mode 100644
index 000000000..213ddb68f
--- /dev/null
+++ b/backend/mem_backend.go
@@ -0,0 +1,192 @@
+package backend
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"sort"
+	"sync"
+)
+
+type entry struct {
+	Type Type
+	Name string
+}
+
+type memMap map[entry][]byte
+
+// MemoryBackend is a mock backend that uses a map for storing all data in
+// memory. This should only be used for tests.
+type MemoryBackend struct {
+	data memMap
+	m    sync.Mutex
+
+	MockBackend
+}
+
+// NewMemoryBackend returns a new backend that saves all data in a map in
+// memory.
+func NewMemoryBackend() *MemoryBackend {
+	be := &MemoryBackend{
+		data: make(memMap),
+	}
+
+	be.MockBackend.TestFn = func(t Type, name string) (bool, error) {
+		return memTest(be, t, name)
+	}
+
+	be.MockBackend.CreateFn = func() (Blob, error) {
+		return memCreate(be)
+	}
+
+	be.MockBackend.GetFn = func(t Type, name string) (io.ReadCloser, error) {
+		return memGet(be, t, name)
+	}
+
+	be.MockBackend.GetReaderFn = func(t Type, name string, offset, length uint) (io.ReadCloser, error) {
+		return memGetReader(be, t, name, offset, length)
+	}
+
+	be.MockBackend.RemoveFn = func(t Type, name string) error {
+		return memRemove(be, t, name)
+	}
+
+	be.MockBackend.ListFn = func(t Type, done <-chan struct{}) <-chan string {
+		return memList(be, t, done)
+	}
+
+	return be
+}
+
+func (be *MemoryBackend) insert(t Type, name string, data []byte) error {
+	be.m.Lock()
+	defer be.m.Unlock()
+
+	if _, ok := be.data[entry{t, name}]; ok {
+		return errors.New("already present")
+	}
+
+	be.data[entry{t, name}] = data
+	return nil
+}
+
+func memTest(be *MemoryBackend, t Type, name string) (bool, error) {
+	be.m.Lock()
+	defer be.m.Unlock()
+
+	if _, ok := be.data[entry{t, name}]; ok {
+		return true, nil
+	}
+
+	return false, nil
+}
+
+// tempMemEntry temporarily holds data written to the memory backend before it
+// is finalized.
+type tempMemEntry struct {
+	be   *MemoryBackend
+	data bytes.Buffer
+}
+
+func (e *tempMemEntry) Write(p []byte) (int, error) {
+	return e.data.Write(p)
+}
+
+func (e *tempMemEntry) Size() uint {
+	return uint(len(e.data.Bytes()))
+}
+
+func (e *tempMemEntry) Finalize(t Type, name string) error {
+	return e.be.insert(t, name, e.data.Bytes())
+}
+
+func memCreate(be *MemoryBackend) (Blob, error) {
+	return &tempMemEntry{be: be}, nil
+}
+
+// readCloser wraps a reader and adds a noop Close method.
+type readCloser struct {
+	io.Reader
+}
+
+func (rd readCloser) Close() error {
+	return nil
+}
+
+func memGet(be *MemoryBackend, t Type, name string) (io.ReadCloser, error) {
+	be.m.Lock()
+	defer be.m.Unlock()
+
+	if _, ok := be.data[entry{t, name}]; !ok {
+		return nil, errors.New("no such data")
+	}
+
+	return readCloser{bytes.NewReader(be.data[entry{t, name}])}, nil
+}
+
+func memGetReader(be *MemoryBackend, t Type, name string, offset, length uint) (io.ReadCloser, error) {
+	be.m.Lock()
+	defer be.m.Unlock()
+
+	if _, ok := be.data[entry{t, name}]; !ok {
+		return nil, errors.New("no such data")
+	}
+
+	buf := be.data[entry{t, name}]
+	if offset > uint(len(buf)) {
+		return nil, errors.New("offset beyond end of file")
+	}
+
+	buf = buf[offset:]
+
+	if length > uint(len(buf)) {
+		length = uint(len(buf))
+	}
+
+	buf = buf[:length]
+
+	return readCloser{bytes.NewReader(buf)}, nil
+}
+
+func memRemove(be *MemoryBackend, t Type, name string) error {
+	be.m.Lock()
+	defer be.m.Unlock()
+
+	if _, ok := be.data[entry{t, name}]; !ok {
+		return errors.New("no such data")
+	}
+
+	delete(be.data, entry{t, name})
+
+	return nil
+}
+
+func memList(be *MemoryBackend, t Type, done <-chan struct{}) <-chan string {
+	be.m.Lock()
+	defer be.m.Unlock()
+
+	ch := make(chan string)
+
+	var ids []string
+	for entry := range be.data {
+		if entry.Type != t {
+			continue
+		}
+		ids = append(ids, entry.Name)
+	}
+
+	sort.Strings(ids)
+
+	go func() {
+		defer close(ch)
+		for _, id := range ids {
+			select {
+			case ch <- id:
+			case <-done:
+				return
+			}
+		}
+	}()
+
+	return ch
+}
diff --git a/backend/mem_backend_test.go b/backend/mem_backend_test.go
new file mode 100644
index 000000000..c5b43415c
--- /dev/null
+++ b/backend/mem_backend_test.go
@@ -0,0 +1,12 @@
+package backend_test
+
+import (
+	"testing"
+
+	"github.com/restic/restic/backend"
+)
+
+func TestMemoryBackend(t *testing.T) {
+	be := backend.NewMemoryBackend()
+	testBackend(be, t)
+}