Merge pull request ipfs/go-ipfs-ds-help#18 from ipfs/feat/mh-backed-datastore

feat: switch to raw multihashes for blocks

This commit was moved from ipfs/go-ipfs-ds-help@4782beb

Author: hsanjuan

datastore/dshelp/key.go

@@ -3,9 +3,10 @@
 package dshelp
 
 import (
-	cid "github.com/ipfs/go-cid"
+	"github.com/ipfs/go-cid"
 	"github.com/ipfs/go-datastore"
 	"github.com/multiformats/go-base32"
+	mh "github.com/multiformats/go-multihash"
 )
 
 // NewKeyFromBinary creates a new key from a byte slice.
@@ -21,16 +22,30 @@ func BinaryFromDsKey(k datastore.Key) ([]byte, error) {
 	return base32.RawStdEncoding.DecodeString(k.String()[1:])
 }
 
-// CidToDsKey creates a Key from the given Cid.
-func CidToDsKey(k cid.Cid) datastore.Key {
-	return NewKeyFromBinary(k.Bytes())
+// MultihashToDsKey creates a Key from the given Multihash.
+// If working with Cids, you can call cid.Hash() to obtain
+// the multihash. Note that different CIDs might represent
+// the same multihash.
+func MultihashToDsKey(k mh.Multihash) datastore.Key {
+	return NewKeyFromBinary(k)
 }
 
-// DsKeyToCid converts the given Key to its corresponding Cid.
-func DsKeyToCid(dsKey datastore.Key) (cid.Cid, error) {
+// DsKeyToMultihash converts a dsKey to the corresponding Multihash.
+func DsKeyToMultihash(dsKey datastore.Key) (mh.Multihash, error) {
 	kb, err := BinaryFromDsKey(dsKey)
+	if err != nil {
+		return nil, err
+	}
+	return mh.Cast(kb)
+}
+
+// DsKeyToCidV1Raw converts the given Key (which should be a raw multihash
+// key) to a Cid V1 of the given type (see
+// https://godoc.org/github.com/ipfs/go-cid#pkg-constants).
+func DsKeyToCidV1(dsKey datastore.Key, codecType uint64) (cid.Cid, error) {
+	hash, err := DsKeyToMultihash(dsKey)
 	if err != nil {
 		return cid.Cid{}, err
 	}
-	return cid.Cast(kb)
+	return cid.NewCidV1(codecType, hash), nil
 }

datastore/dshelp/key_test.go

@@ -8,12 +8,17 @@ import (
 
 func TestKey(t *testing.T) {
 	c, _ := cid.Decode("QmP63DkAFEnDYNjDYBpyNDfttu1fvUw99x1brscPzpqmmq")
-	dsKey := CidToDsKey(c)
-	c2, err := DsKeyToCid(dsKey)
+	dsKey := MultihashToDsKey(c.Hash())
+	mh, err := DsKeyToMultihash(dsKey)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if c.String() != c2.String() {
-		t.Fatal("should have parsed the same key")
+	if string(c.Hash()) != string(mh) {
+		t.Fatal("should have parsed the same multihash")
+	}
+
+	c2, err := DsKeyToCidV1(dsKey, cid.Raw)
+	if err != nil || c.Equals(c2) || c2.Type() != cid.Raw || c2.Version() != 1 {
+		t.Fatal("should have been converted to CIDv1-raw")
 	}
 }