blockchain/indexers: Reduce duplication in cfindex.

The index will hold three types of entries for each filter type, block
pair: filter, header, and hash. Since they all have similar methods
and implementations, refactor to reduce duplication.

blockchain/indexers/cfindex.go

@@ -14,7 +14,6 @@ import (
 	"github.com/btcsuite/btcutil"
 	"github.com/btcsuite/btcutil/gcs"
 	"github.com/btcsuite/btcutil/gcs/builder"
-	"github.com/btcsuite/fastsha256"
 	"github.com/roasbeef/btcd/wire"
 )
 
@@ -48,49 +47,21 @@ var (
 	maxFilterType = uint8(len(cfHeaderKeys) - 1)
 )
 
-// dbFetchFilter retrieves a block's basic or extended filter. A filter's
+// dbFetchFilterIdxEntry retrieves a data blob from the filter index database.
-// absence is not considered an error.
+// An entry's absence is not considered an error.
-func dbFetchFilter(dbTx database.Tx, key []byte, h *chainhash.Hash) ([]byte, error) {
+func dbFetchFilterIdxEntry(dbTx database.Tx, key []byte, h *chainhash.Hash) ([]byte, error) {
 	idx := dbTx.Metadata().Bucket(cfIndexParentBucketKey).Bucket(key)
 	return idx.Get(h[:]), nil
 }
 
-// dbFetchFilterHeader retrieves a block's basic or extended filter header.
+// dbStoreFilterIdxEntry stores a data blob in the filter index database.
-// A filter's absence is not considered an error.
+func dbStoreFilterIdxEntry(dbTx database.Tx, key []byte, h *chainhash.Hash, f []byte) error {
-func dbFetchFilterHeader(dbTx database.Tx, key []byte, h *chainhash.Hash) ([]byte, error) {
-	idx := dbTx.Metadata().Bucket(cfIndexParentBucketKey).Bucket(key)
-
-	fh := idx.Get(h[:])
-	if len(fh) != fastsha256.Size {
-		return nil, errors.New("invalid filter header length")
-	}
-
-	return fh, nil
-}
-
-// dbStoreFilter stores a block's basic or extended filter.
-func dbStoreFilter(dbTx database.Tx, key []byte, h *chainhash.Hash, f []byte) error {
 	idx := dbTx.Metadata().Bucket(cfIndexParentBucketKey).Bucket(key)
 	return idx.Put(h[:], f)
 }
 
-// dbStoreFilterHeader stores a block's basic or extended filter header.
+// dbDeleteFilterIdxEntry deletes a data blob from the filter index database.
-func dbStoreFilterHeader(dbTx database.Tx, key []byte, h *chainhash.Hash, fh []byte) error {
+func dbDeleteFilterIdxEntry(dbTx database.Tx, key []byte, h *chainhash.Hash) error {
-	if len(fh) != fastsha256.Size {
-		return errors.New("invalid filter header length")
-	}
-	idx := dbTx.Metadata().Bucket(cfIndexParentBucketKey).Bucket(key)
-	return idx.Put(h[:], fh)
-}
-
-// dbDeleteFilter deletes a filter's basic or extended filter.
-func dbDeleteFilter(dbTx database.Tx, key []byte, h *chainhash.Hash) error {
-	idx := dbTx.Metadata().Bucket(cfIndexParentBucketKey).Bucket(key)
-	return idx.Delete(h[:])
-}
-
-// dbDeleteFilterHeader deletes a filter's basic or extended filter header.
-func dbDeleteFilterHeader(dbTx database.Tx, key []byte, h *chainhash.Hash) error {
 	idx := dbTx.Metadata().Bucket(cfIndexParentBucketKey).Bucket(key)
 	return idx.Delete(h[:])
 }
@@ -148,7 +119,7 @@ func (idx *CfIndex) Create(dbTx database.Tx) error {
 	}
 
 	firstHeader := make([]byte, chainhash.HashSize)
-	err = dbStoreFilterHeader(
+	err = dbStoreFilterIdxEntry(
 		dbTx,
 		cfHeaderKeys[wire.GCSFilterRegular],
 		&idx.chainParams.GenesisBlock.Header.PrevBlock,
@@ -158,7 +129,7 @@ func (idx *CfIndex) Create(dbTx database.Tx) error {
 		return err
 	}
 
-	return dbStoreFilterHeader(
+	return dbStoreFilterIdxEntry(
 		dbTx,
 		cfHeaderKeys[wire.GCSFilterExtended],
 		&idx.chainParams.GenesisBlock.Header.PrevBlock,
@@ -184,14 +155,14 @@ func storeFilter(dbTx database.Tx, block *btcutil.Block, f *gcs.Filter,
 	if f != nil {
 		basicFilterBytes = f.NBytes()
 	}
-	err := dbStoreFilter(dbTx, fkey, h, basicFilterBytes)
+	err = dbStoreFilterIdxEntry(dbTx, fkey, h, filterBytes)
 	if err != nil {
 		return err
 	}
 
 	// Then fetch the previous block's filter header.
 	ph := &block.MsgBlock().Header.PrevBlock
-	pfh, err := dbFetchFilterHeader(dbTx, hkey, ph)
+	pfh, err := dbFetchFilterIdxEntry(dbTx, hkey, ph)
 	if err != nil {
 		return err
 	}
@@ -201,8 +172,11 @@ func storeFilter(dbTx database.Tx, block *btcutil.Block, f *gcs.Filter,
 	if err != nil {
 		return err
 	}
-	fh := builder.MakeHeaderForFilter(f, *prevHeader)
+	fh, err := builder.MakeHeaderForFilter(f, *prevHeader)
-	return dbStoreFilterHeader(dbTx, hkey, h, fh[:])
+	if err != nil {
+		return err
+	}
+	return dbStoreFilterIdxEntry(dbTx, hkey, h, fh[:])
 }
 
 // ConnectBlock is invoked by the index manager when a new block has been
@@ -236,14 +210,14 @@ func (idx *CfIndex) DisconnectBlock(dbTx database.Tx, block *btcutil.Block,
 	view *blockchain.UtxoViewpoint) error {
 
 	for _, key := range cfIndexKeys {
-		err := dbDeleteFilter(dbTx, key, block.Hash())
+		err := dbDeleteFilterIdxEntry(dbTx, key, block.Hash())
 		if err != nil {
 			return err
 		}
 	}
 
 	for _, key := range cfHeaderKeys {
-		err := dbDeleteFilterHeader(dbTx, key, block.Hash())
+		err := dbDeleteFilterIdxEntry(dbTx, key, block.Hash())
 		if err != nil {
 			return err
 		}
@@ -252,39 +226,37 @@ func (idx *CfIndex) DisconnectBlock(dbTx database.Tx, block *btcutil.Block,
 	return nil
 }
 
+// entryByBlockHash fetches a filter index entry of a particular type
+// (eg. filter, filter header, etc) for a filter type and block hash.
+func (idx *CfIndex) entryByBlockHash(filterTypeKeys [][]byte,
+	filterType wire.FilterType, h *chainhash.Hash) ([]byte, error) {
+
+	if uint8(filterType) > maxFilterType {
+		return nil, errors.New("unsupported filter type")
+	}
+	key := filterTypeKeys[filterType]
+
+	var entry []byte
+	err := idx.db.View(func(dbTx database.Tx) error {
+		var err error
+		entry, err = dbFetchFilterIdxEntry(dbTx, key, h)
+		return err
+	})
+	return entry, err
+}
+
 // FilterByBlockHash returns the serialized contents of a block's basic or
 // extended committed filter.
 func (idx *CfIndex) FilterByBlockHash(h *chainhash.Hash,
 	filterType wire.FilterType) ([]byte, error) {
-	var f []byte
+	return idx.entryByBlockHash(cfIndexKeys, filterType, h)
-	err := idx.db.View(func(dbTx database.Tx) error {
-		if uint8(filterType) > maxFilterType {
-			return errors.New("unsupported filter type")
-		}
-
-		var err error
-		f, err = dbFetchFilter(dbTx, cfIndexKeys[filterType], h)
-		return err
-	})
-	return f, err
 }
 
 // FilterHeaderByBlockHash returns the serialized contents of a block's basic
 // or extended committed filter header.
 func (idx *CfIndex) FilterHeaderByBlockHash(h *chainhash.Hash,
 	filterType wire.FilterType) ([]byte, error) {
-	var fh []byte
+	return idx.entryByBlockHash(cfHeaderKeys, filterType, h)
-	err := idx.db.View(func(dbTx database.Tx) error {
-		if uint8(filterType) > maxFilterType {
-			return errors.New("unsupported filter type")
-		}
-
-		var err error
-		fh, err = dbFetchFilterHeader(dbTx,
-			cfHeaderKeys[filterType], h)
-		return err
-	})
-	return fh, err
 }
 
 // NewCfIndex returns a new instance of an indexer that is used to create a