From 582e5dee3a97f994e7d204ed23960f5752f86553 Mon Sep 17 00:00:00 2001
From: Jeromy <why@ipfs.io>
Date: Fri, 19 Aug 2016 18:33:44 -0700
Subject: [PATCH] blockservice: don't store blocks we already have

License: MIT
Signed-off-by: Jeromy <why@ipfs.io>
---
 blockservice/blockservice.go | 28 +++++++++++++++++++++++++---
 exchange/bitswap/workers.go  |  1 +
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/blockservice/blockservice.go b/blockservice/blockservice.go
index 71058061444..12aa022c000 100644
--- a/blockservice/blockservice.go
+++ b/blockservice/blockservice.go
@@ -43,7 +43,15 @@ func New(bs blockstore.Blockstore, rem exchange.Interface) *BlockService {
 // TODO pass a context into this if the remote.HasBlock is going to remain here.
 func (s *BlockService) AddBlock(b blocks.Block) (key.Key, error) {
 	k := b.Key()
-	err := s.Blockstore.Put(b)
+	has, err := s.Blockstore.Has(k)
+	if err != nil {
+		return k, err
+	}
+	if has {
+		return k, nil
+	}
+
+	err = s.Blockstore.Put(b)
 	if err != nil {
 		return k, err
 	}
@@ -54,13 +62,27 @@ func (s *BlockService) AddBlock(b blocks.Block) (key.Key, error) {
 }
 
 func (s *BlockService) AddBlocks(bs []blocks.Block) ([]key.Key, error) {
-	err := s.Blockstore.PutMany(bs)
+	var toput []blocks.Block
+	for _, b := range bs {
+		has, err := s.Blockstore.Has(b.Key())
+		if err != nil {
+			return nil, err
+		}
+
+		if has {
+			continue
+		}
+
+		toput = append(toput, b)
+	}
+
+	err := s.Blockstore.PutMany(toput)
 	if err != nil {
 		return nil, err
 	}
 
 	var ks []key.Key
-	for _, b := range bs {
+	for _, b := range toput {
 		if err := s.Exchange.HasBlock(b); err != nil {
 			return nil, errors.New("blockservice is closed")
 		}
diff --git a/exchange/bitswap/workers.go b/exchange/bitswap/workers.go
index 4aa45791733..b7e4a4a7cf5 100644
--- a/exchange/bitswap/workers.go
+++ b/exchange/bitswap/workers.go
@@ -133,6 +133,7 @@ func (bs *Bitswap) provideCollector(ctx context.Context) {
 				log.Debug("newBlocks channel closed")
 				return
 			}
+
 			if keysOut == nil {
 				nextKey = blk.Key()
 				keysOut = bs.provideKeys