From 3425d33506a3a0db0a7182f20b3c6515eae0cd29 Mon Sep 17 00:00:00 2001
From: Jim Posen <jimpo@coinbase.com>
Date: Thu, 1 Feb 2018 00:00:45 -0800
Subject: [PATCH] blockchain/indexers: Add methods on CfIndex for batch
 retrieval.

Fetching all items in one db transaction will save time when
responding to getcfilters or getcfheaders requests.
---
 blockchain/indexers/cfindex.go | 47 +++++++++++++++++++++++++++++++++-
 1 file changed, 46 insertions(+), 1 deletion(-)

diff --git a/blockchain/indexers/cfindex.go b/blockchain/indexers/cfindex.go
index 51b3a7ce..93d00fff 100644
--- a/blockchain/indexers/cfindex.go
+++ b/blockchain/indexers/cfindex.go
@@ -271,6 +271,30 @@ func (idx *CfIndex) entryByBlockHash(filterTypeKeys [][]byte,
 	return entry, err
 }
 
+// entriesByBlockHashes batch fetches a filter index entry of a particular type
+// (eg. filter, filter header, etc) for a filter type and slice of block hashes.
+func (idx *CfIndex) entriesByBlockHashes(filterTypeKeys [][]byte,
+	filterType wire.FilterType, blockHashes []*chainhash.Hash) ([][]byte, error) {
+
+	if uint8(filterType) > maxFilterType {
+		return nil, errors.New("unsupported filter type")
+	}
+	key := filterTypeKeys[filterType]
+
+	entries := make([][]byte, 0, len(blockHashes))
+	err := idx.db.View(func(dbTx database.Tx) error {
+		for _, blockHash := range blockHashes {
+			entry, err := dbFetchFilterIdxEntry(dbTx, key, blockHash)
+			if err != nil {
+				return err
+			}
+			entries = append(entries, entry)
+		}
+		return nil
+	})
+	return entries, err
+}
+
 // FilterByBlockHash returns the serialized contents of a block's basic or
 // extended committed filter.
 func (idx *CfIndex) FilterByBlockHash(h *chainhash.Hash,
@@ -278,6 +302,13 @@ func (idx *CfIndex) FilterByBlockHash(h *chainhash.Hash,
 	return idx.entryByBlockHash(cfIndexKeys, filterType, h)
 }
 
+// FiltersByBlockHashes returns the serialized contents of a block's basic or
+// extended committed filter for a set of blocks by hash.
+func (idx *CfIndex) FiltersByBlockHashes(blockHashes []*chainhash.Hash,
+	filterType wire.FilterType) ([][]byte, error) {
+	return idx.entriesByBlockHashes(cfIndexKeys, filterType, blockHashes)
+}
+
 // FilterHeaderByBlockHash returns the serialized contents of a block's basic
 // or extended committed filter header.
 func (idx *CfIndex) FilterHeaderByBlockHash(h *chainhash.Hash,
@@ -285,13 +316,27 @@ func (idx *CfIndex) FilterHeaderByBlockHash(h *chainhash.Hash,
 	return idx.entryByBlockHash(cfHeaderKeys, filterType, h)
 }
 
-// FilterHeaderByBlockHash returns the serialized contents of a block's basic
+// FilterHeadersByBlockHashes returns the serialized contents of a block's basic
+// or extended committed filter header for a set of blocks by hash.
+func (idx *CfIndex) FilterHeadersByBlockHashes(blockHashes []*chainhash.Hash,
+	filterType wire.FilterType) ([][]byte, error) {
+	return idx.entriesByBlockHashes(cfHeaderKeys, filterType, blockHashes)
+}
+
+// FilterHashByBlockHash returns the serialized contents of a block's basic
 // or extended committed filter hash.
 func (idx *CfIndex) FilterHashByBlockHash(h *chainhash.Hash,
 	filterType wire.FilterType) ([]byte, error) {
 	return idx.entryByBlockHash(cfHashKeys, filterType, h)
 }
 
+// FilterHashesByBlockHashes returns the serialized contents of a block's basic
+// or extended committed filter hash for a set of blocks by hash.
+func (idx *CfIndex) FilterHashesByBlockHashes(blockHashes []*chainhash.Hash,
+	filterType wire.FilterType) ([][]byte, error) {
+	return idx.entriesByBlockHashes(cfHashKeys, filterType, blockHashes)
+}
+
 // NewCfIndex returns a new instance of an indexer that is used to create a
 // mapping of the hashes of all blocks in the blockchain to their respective
 // committed filters.