cachemanager: new active creation

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

cachemanager/cachemanager.go

@@ -2,12 +2,15 @@ package cachemanager
 
 import (
 	"context"
+	"crypto/rand"
+	"encoding/hex"
 	"os"
 	"path/filepath"
 	"sync"
 	"time"
 
 	"github.com/boltdb/bolt"
+	"github.com/containerd/containerd/mount"
 	"github.com/pkg/errors"
 	"github.com/tonistiigi/buildkit_poc/snapshot"
 )
@@ -45,23 +48,18 @@ type SnapshotRef interface {
 
 type ActiveRef interface {
 	Mountable
-	Release() (SnapshotRef, error)
+	ReleaseActive() (SnapshotRef, error)
 	ReleaseAndCommit(ctx context.Context) (SnapshotRef, error)
 	Size() (int64, error)
 }
 
 type Mountable interface {
-	Mount() (Mount, error)
-}
-
-type Mount interface { // replace with containerd.Mount
-	Mount() (string, error)
-	Unmount() error
+	Mount() ([]mount.Mount, error)
 }
 
 type CacheAccessor interface {
 	Get(id string) (SnapshotRef, error)
-	New(id string, s SnapshotRef) (ActiveRef, error)
+	New(s SnapshotRef) (ActiveRef, error)
 	GetActive(id string) (ActiveRef, error) // Rebase?
 }
 
@@ -133,8 +131,25 @@ func (cm *cacheManager) Get(id string) (SnapshotRef, error) {
 	}
 	return rec.ref(), nil
 }
-func (cm *cacheManager) New(id string, s SnapshotRef) (ActiveRef, error) {
-	return nil, errors.New("New not implemented")
+func (cm *cacheManager) New(s SnapshotRef) (ActiveRef, error) {
+	if s != nil {
+		return nil, errors.New("snapshot parents not implemented") // TODO
+	}
+
+	id := generateID()
+
+	if _, err := cm.Snapshotter.Prepare(context.TODO(), id, ""); err != nil {
+		return nil, errors.Wrapf(err, "failed to prepare %s", id)
+	}
+
+	rec := &cacheRecord{
+		active: true,
+		id:     id,
+		cm:     cm,
+		refs:   make(map[*snapshotRef]struct{}),
+	}
+
+	return rec.ref(), nil
 }
 func (cm *cacheManager) GetActive(id string) (ActiveRef, error) { // Rebase?
 	return nil, errors.New("GetActive not implemented")
@@ -153,9 +168,12 @@ func (cm *cacheManager) GC(ctx context.Context) error {
 }
 
 type cacheRecord struct {
+	mu     sync.Mutex
 	active bool
 	// meta   SnapMeta
 	refs map[*snapshotRef]struct{}
+	id   string
+	cm   *cacheManager
 }
 
 // hold manager lock before calling
@@ -169,14 +187,41 @@ type snapshotRef struct {
 	*cacheRecord
 }
 
-func (sr *snapshotRef) Mount() (Mount, error) {
-	return nil, errors.New("Mount not implemented")
+func (sr *snapshotRef) Mount() ([]mount.Mount, error) {
+	sr.mu.Lock()
+	defer sr.mu.Unlock()
+
+	if sr.active {
+		m, err := sr.cm.Snapshotter.Mounts(context.TODO(), sr.id)
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to mount %s", sr.id)
+		}
+		return m, nil
+	}
+
+	return nil, errors.New("snapshot mount not implemented")
 }
 
 func (sr *snapshotRef) Release() error {
 	return errors.New("Release not implemented")
 }
 
+func (sr *snapshotRef) ReleaseActive() (SnapshotRef, error) {
+	return nil, errors.New("ReleaseActive not implemented")
+}
+
+func (sr *snapshotRef) ReleaseAndCommit(ctx context.Context) (SnapshotRef, error) {
+	return nil, errors.New("ReleaseActive not implemented")
+}
+
 func (sr *snapshotRef) Size() (int64, error) {
 	return -1, errors.New("Size not implemented")
 }
+
+func generateID() string {
+	b := make([]byte, 32)
+	if _, err := rand.Read(b); err != nil {
+		panic(err)
+	}
+	return hex.EncodeToString(b)
+}

cachemanager/cachemanager_test.go

@@ -3,9 +3,12 @@ package cachemanager
 import (
 	"io/ioutil"
 	"os"
+	"path/filepath"
 	"testing"
 
+	"github.com/containerd/containerd/snapshot/naive"
 	"github.com/stretchr/testify/assert"
+	"github.com/tonistiigi/buildkit_poc/snapshot"
 )
 
 func TestCacheManager(t *testing.T) {
@@ -13,12 +16,35 @@ func TestCacheManager(t *testing.T) {
 	assert.NoError(t, err)
 	defer os.RemoveAll(tmpdir)
 
-	cm, err := NewCacheManager(CacheManagerOpt{Root: tmpdir})
+	snapshotter, err := naive.NewSnapshotter(filepath.Join(tmpdir, "snapshots"))
+	assert.NoError(t, err)
+
+	cm, err := NewCacheManager(CacheManagerOpt{
+		Root:        tmpdir,
+		Snapshotter: snapshotter,
+	})
 	assert.NoError(t, err)
 
 	_, err = cm.Get("foobar")
 	assert.Error(t, err)
 
+	active, err := cm.New(nil)
+	assert.NoError(t, err)
+
+	m, err := active.Mount()
+	assert.NoError(t, err)
+
+	lm := snapshot.LocalMounter(m)
+	target, err := lm.Mount()
+	assert.NoError(t, err)
+
+	fi, err := os.Stat(target)
+	assert.NoError(t, err)
+	assert.Equal(t, fi.IsDir(), true)
+
+	err = lm.Unmount()
+	assert.NoError(t, err)
+
 	err = cm.Close()
 	assert.NoError(t, err)
 }

hack/dockerfiles/test.Dockerfile

@@ -1,4 +1,5 @@
 FROM golang:1.8-alpine AS vndr
+RUN  apk add --no-cache g++
 WORKDIR /go/src/github.com/tonistiigi/buildkit_poc
 COPY . .
 RUN go test ./...

snapshot/localmounter.go

@@ -0,0 +1,59 @@
+package snapshot
+
+import (
+	"io/ioutil"
+	"os"
+	"sync"
+
+	"github.com/containerd/containerd/mount"
+	"github.com/pkg/errors"
+)
+
+type Mounter interface {
+	Mount() (string, error)
+	Unmount() error
+}
+
+func LocalMounter(m []mount.Mount) Mounter {
+	return &localMounter{m: m}
+}
+
+type localMounter struct {
+	mu     sync.Mutex
+	m      []mount.Mount
+	target string
+}
+
+func (lm *localMounter) Mount() (string, error) {
+	lm.mu.Lock()
+	defer lm.mu.Unlock()
+
+	if len(lm.m) == 1 && lm.m[0].Type == "bind" {
+		return lm.m[0].Source, nil
+	}
+
+	dir, err := ioutil.TempDir("", "buildkit-mount")
+	if err != nil {
+		return "", errors.Wrap(err, "failed to create temp dir")
+	}
+
+	if err := mount.MountAll(lm.m, dir); err != nil {
+		os.RemoveAll(dir)
+		return "", err
+	}
+	lm.target = dir
+	return "", nil
+}
+
+func (lm *localMounter) Unmount() error {
+	lm.mu.Lock()
+	defer lm.mu.Unlock()
+
+	if lm.target != "" {
+		if err := mount.Unmount(lm.target, 0); err != nil {
+			return err
+		}
+		lm.target = ""
+	}
+	return nil
+}

snapshot/snapshotter.go

@@ -1,5 +1,13 @@
 package snapshot
 
+import (
+	"context"
+
+	"github.com/containerd/containerd/mount"
+)
+
 // Snapshotter defines interface that any snapshot implementation should satisfy
 type Snapshotter interface {
+	Prepare(ctx context.Context, key, parent string) ([]mount.Mount, error)
+	Mounts(ctx context.Context, key string) ([]mount.Mount, error)
 }