chore: extract DeferredCarWriter to go-car

Ref: ipld/go-car#493

Author: rvagg

cmd/lassie/fetch.go

@@ -13,6 +13,8 @@ import (
 	"github.com/filecoin-project/lassie/pkg/storage"
 	"github.com/filecoin-project/lassie/pkg/types"
 	"github.com/ipfs/go-cid"
+	"github.com/ipld/go-car/v2"
+	"github.com/ipld/go-car/v2/storage/deferred"
 	"github.com/ipld/go-ipld-prime/datamodel"
 	cidlink "github.com/ipld/go-ipld-prime/linking/cid"
 	trustlessutils "github.com/ipld/go-trustless-utils"
@@ -253,14 +255,14 @@ func defaultFetchRun(
 		lassie.RegisterSubscriber(pp.subscriber)
 	}
 
-	var carWriter *storage.DeferredCarWriter
+	var carWriter *deferred.DeferredCarWriter
 	if outfile == stdoutFileString {
 		// we need the onlyWriter because stdout is presented as an os.File, and
 		// therefore pretend to support seeks, so feature-checking in go-car
 		// will make bad assumptions about capabilities unless we hide it
-		carWriter = storage.NewDeferredCarWriterForStream(rootCid, &onlyWriter{dataWriter})
+		carWriter = deferred.NewDeferredCarWriterForStream(&onlyWriter{dataWriter}, []cid.Cid{rootCid})
 	} else {
-		carWriter = storage.NewDeferredCarWriterForPath(rootCid, outfile)
+		carWriter = deferred.NewDeferredCarWriterForPath(outfile, []cid.Cid{rootCid}, car.WriteAsCarV1(true))
 	}
 
 	tempStore := storage.NewDeferredStorageCar(tempDir, rootCid)

pkg/server/http/ipfs.go

@@ -13,6 +13,7 @@ import (
 	"github.com/filecoin-project/lassie/pkg/types"
 	"github.com/ipfs/go-cid"
 	"github.com/ipfs/go-unixfsnode"
+	"github.com/ipld/go-car/v2/storage/deferred"
 	cidlink "github.com/ipld/go-ipld-prime/linking/cid"
 	trustlessutils "github.com/ipld/go-trustless-utils"
 	trustlesshttp "github.com/ipld/go-trustless-utils/http"
@@ -50,9 +51,9 @@ func IpfsHandler(fetcher types.Fetcher, cfg HttpServerConfig) func(http.Response
 		tempStore := storage.NewDeferredStorageCar(cfg.TempDir, request.Root)
 		var carWriter storage.DeferredWriter
 		if request.Duplicates {
-			carWriter = storage.NewDuplicateAdderCarForStream(req.Context(), request.Root, request.Path, request.Scope, request.Bytes, tempStore, res)
+			carWriter = storage.NewDuplicateAdderCarForStream(req.Context(), res, request.Root, request.Path, request.Scope, request.Bytes, tempStore)
 		} else {
-			carWriter = storage.NewDeferredCarWriterForStream(request.Root, res)
+			carWriter = deferred.NewDeferredCarWriterForStream(res, []cid.Cid{request.Root})
 		}
 		carStore := storage.NewCachingTempStore(carWriter.BlockWriteOpener(), tempStore)
 		defer func() {

pkg/storage/cachingtempstore_test.go

@@ -4,14 +4,21 @@ import (
 	"bytes"
 	"context"
 	"io"
+	"math/rand"
+	"sync"
 	"testing"
 	"time"
 
 	"github.com/ipfs/go-cid"
 	carv2 "github.com/ipld/go-car/v2"
+	"github.com/ipld/go-car/v2/storage/deferred"
+	mh "github.com/multiformats/go-multihash"
 	"github.com/stretchr/testify/require"
 )
 
+var rng = rand.New(rand.NewSource(3333))
+var rngLk sync.Mutex
+
 func TestDeferredCarWriterWritesCARv1(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
 	defer cancel()
@@ -48,7 +55,7 @@ func TestDeferredCarWriterWritesCARv1(t *testing.T) {
 			testCid2, testData2 := randBlock()
 
 			var buf bytes.Buffer
-			cw := NewDeferredCarWriterForStream(testCid1, &buf)
+			cw := deferred.NewDeferredCarWriterForStream(&buf, []cid.Cid{testCid1})
 			ss := NewCachingTempStore(cw.BlockWriteOpener(), NewDeferredStorageCar("", testCid1))
 			t.Cleanup(func() { ss.Close() })
 
@@ -155,3 +162,20 @@ func TestDeferredCarWriterWritesCARv1(t *testing.T) {
 		})
 	}
 }
+
+func randBlock() (cid.Cid, []byte) {
+	data := make([]byte, 1024)
+	rngLk.Lock()
+	rng.Read(data)
+	rngLk.Unlock()
+	h, err := mh.Sum(data, mh.SHA2_512, -1)
+	if err != nil {
+		panic(err)
+	}
+	return cid.NewCidV1(cid.Raw, h), data
+}
+
+func randCid() cid.Cid {
+	c, _ := randBlock()
+	return c
+}