From 7a06d0ee3ed12643d2c12aafeafffeda2bd91fcf Mon Sep 17 00:00:00 2001
From: Ye Yin <eyniy@qq.com>
Date: Wed, 23 Nov 2016 16:46:04 +0800
Subject: [PATCH] Use hardlink to copy layer between oci and bt engine

---
 cmd/daemon/main.go |  5 ++++
 daemon/config.go   |  1 +
 daemon/daemon.go   | 72 +++++++++++++++++++++++++++++-----------------
 oci/dir.go         |  8 ++++++
 oci/layout.go      |  3 ++
 5 files changed, 63 insertions(+), 26 deletions(-)

diff --git a/cmd/daemon/main.go b/cmd/daemon/main.go
index 3077f85..b4a9e21 100644
--- a/cmd/daemon/main.go
+++ b/cmd/daemon/main.go
@@ -71,6 +71,10 @@ var daemonFlags = []cli.Flag{
 		Value: 1 * time.Second,
 		Usage: "GRPC connection timeout",
 	},
+	cli.BoolFlag{
+		Name:  "hardlink",
+		Usage: "use hard link to copy layer between oci engine and bt engine",
+	},
 }
 
 // DumpStacks dumps the runtime stack.
@@ -138,6 +142,7 @@ func runDaemon(context *cli.Context) error {
 		BtSeederServer:    context.StringSlice("seeder-addr"),
 		UploadRateLimit:   context.Int("upload-rate"),
 		DownloadRateLimit: context.Int("download-rate"),
+		UseHardlink:       context.Bool("hardlink"),
 	}
 	s := make(chan os.Signal, 2048)
 	signal.Notify(s, syscall.SIGTERM, syscall.SIGINT)
diff --git a/daemon/config.go b/daemon/config.go
index 3979845..5255725 100644
--- a/daemon/config.go
+++ b/daemon/config.go
@@ -8,6 +8,7 @@ type Config struct {
 	Pidfile     string
 	Root        string
 	ConnTimeout time.Duration
+	UseHardlink bool
 
 	BtEnable          bool
 	BtSeeder          bool
diff --git a/daemon/daemon.go b/daemon/daemon.go
index 1f19c7e..5948766 100644
--- a/daemon/daemon.go
+++ b/daemon/daemon.go
@@ -196,27 +196,37 @@ func (daemon *Daemon) startSeedingLayer(ctx context.Context, ociImg *OciImage, d
 	id := distdigests.Digest(digest).Hex()
 	// Write layer to file
 	fn := daemon.btEngine.GetFilePath(id)
-	layerFile, err := os.Create(fn)
-	if err != nil {
-		return fmt.Errorf("Create layer file %s failed: %v", fn, err)
-	}
-	defer layerFile.Close()
+	if daemon.config.UseHardlink {
+		src, err := ociImg.layout.GetBlobPath(ctx, digest)
+		if err != nil {
+			return fmt.Errorf("Get oci blob path error: %v", err)
+		}
+		if err = os.Link(src, fn); err != nil {
+			return fmt.Errorf("Create hardlink error: %v", err)
+		}
+	} else {
+		layerFile, err := os.Create(fn)
+		if err != nil {
+			return fmt.Errorf("Create layer file %s failed: %v", fn, err)
+		}
+		defer layerFile.Close()
 
-	// Copy from OCI directory
-	srcFile, err := ociImg.layout.GetBlob(ctx, digest)
-	if err != nil {
-		return fmt.Errorf("Open oci layer %s error: %v", digest, err)
-	}
-	defer srcFile.Close()
+		// Copy from OCI directory
+		srcFile, err := ociImg.layout.GetBlob(ctx, digest)
+		if err != nil {
+			return fmt.Errorf("Open oci layer %s error: %v", digest, err)
+		}
+		defer srcFile.Close()
 
-	_, err = io.Copy(layerFile, srcFile)
-	if err != nil {
-		return fmt.Errorf("Copy oci layer %s error: %v", digest, err)
+		_, err = io.Copy(layerFile, srcFile)
+		if err != nil {
+			return fmt.Errorf("Copy oci layer %s error: %v", digest, err)
+		}
 	}
 
 	writeReport("Start seeding %s\n", id)
 	// Seed layer file
-	if err = daemon.btEngine.StartSeed(id); err != nil {
+	if err := daemon.btEngine.StartSeed(id); err != nil {
 		log.Errorf("Seed layer %s failed: %v", id, err)
 	} else {
 		log.Infof("Seed layer %s success", id)
@@ -336,19 +346,29 @@ func (daemon *Daemon) startLeechingLayer(ctx context.Context, ociImg *OciImage,
 	writeReport("%s: Copy to OCI directory\n", id)
 
 	fn := daemon.btEngine.GetFilePath(id)
-	layerFile, err := os.Open(fn)
-	if err != nil {
-		return fmt.Errorf("Open layer file %s failed: %v", fn, err)
-	}
-	defer layerFile.Close()
+	if daemon.config.UseHardlink {
+		dst, err := ociImg.layout.GetBlobPath(ctx, layer.Digest)
+		if err != nil {
+			return fmt.Errorf("Get oci blob path error: %v", err)
+		}
+		if err = os.Link(fn, dst); err != nil {
+			return fmt.Errorf("Create hardlink error: %v", err)
+		}
+	} else {
+		layerFile, err := os.Open(fn)
+		if err != nil {
+			return fmt.Errorf("Open layer file %s failed: %v", fn, err)
+		}
+		defer layerFile.Close()
 
-	digest, _, err := ociImg.layout.PutBlob(ctx, layerFile)
-	if err != nil {
-		return fmt.Errorf("Error to put blob %s: %v", layer.Digest, err)
-	}
+		digest, _, err := ociImg.layout.PutBlob(ctx, layerFile)
+		if err != nil {
+			return fmt.Errorf("Error to put blob %s: %v", layer.Digest, err)
+		}
 
-	if digest != layer.Digest {
-		return fmt.Errorf("Digest not match, src: %s, dest: %s", layer.Digest, digest)
+		if digest != layer.Digest {
+			return fmt.Errorf("Digest not match, src: %s, dest: %s", layer.Digest, digest)
+		}
 	}
 	return nil
 }
diff --git a/oci/dir.go b/oci/dir.go
index 9f9dc83..9b4f979 100644
--- a/oci/dir.go
+++ b/oci/dir.go
@@ -297,6 +297,14 @@ func (e dirLayout) Close() error {
 	return os.RemoveAll(e.temp)
 }
 
+func (e dirLayout) GetBlobPath(ctx context.Context, digest string) (path string, err error) {
+	path, err = blobPath(digest)
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(e.path, path), nil
+}
+
 func newDirLayout(path string) (*dirLayout, error) {
 	layout := &dirLayout{
 		path: path,
diff --git a/oci/layout.go b/oci/layout.go
index b50a0cf..381b9b5 100644
--- a/oci/layout.go
+++ b/oci/layout.go
@@ -87,6 +87,9 @@ type Layout interface {
 	// Close releases all references held by the engine. Subsequent operations
 	// may fail.
 	Close() (err error)
+
+	// GetBlobPath returns a path of a blob from the image
+	GetBlobPath(ctx context.Context, digest string) (path string, err error)
 }
 
 // Open will create an Layout reference to the OCI image at the provided