From b16b5b9d03da7e009e00c6d781868b9195a93905 Mon Sep 17 00:00:00 2001
From: Juan Batiz-Benet <juan@benet.ai>
Date: Thu, 30 Oct 2014 01:04:10 -0700
Subject: [PATCH] dagwriter-parallel

---
 unixfs/io/dagwriter.go | 73 ++++++++++++++++++++++++++++++------------
 1 file changed, 52 insertions(+), 21 deletions(-)

diff --git a/unixfs/io/dagwriter.go b/unixfs/io/dagwriter.go
index 6575b1edff6..cb9d3a2a885 100644
--- a/unixfs/io/dagwriter.go
+++ b/unixfs/io/dagwriter.go
@@ -1,6 +1,8 @@
 package io
 
 import (
+	"sync"
+
 	"github.com/jbenet/go-ipfs/importer/chunk"
 	dag "github.com/jbenet/go-ipfs/merkledag"
 	"github.com/jbenet/go-ipfs/pin"
@@ -46,51 +48,66 @@ func (dw *DagWriter) startSplitter() {
 	mbf := new(ft.MultiBlock)
 	root := new(dag.Node)
 
+	// concurrent writing to disk
+	indirectNodes := make(chan *dag.Node)
+	var wg sync.WaitGroup
+
+	// function to consume the nodesToWrite channel
+	writeNodes := func() {
+		defer wg.Done()
+		for {
+			node, more := <-indirectNodes
+			if !more {
+				return
+			}
+			log.Info("dagwriter worker writing")
+			dw.writeNode(node, pin.Indirect)
+			log.Info("dagwriter worker writing done")
+		}
+	}
+
+	// spin off 10 worker goroutines.
+	for i := 0; i < 100; i++ {
+		wg.Add(1)
+		go writeNodes()
+	}
+
 	for blkData := range blkchan {
+		if dw.seterr != nil {
+			return
+		}
+
 		// Store the block size in the root node
 		mbf.AddBlockSize(uint64(len(blkData)))
 		node := &dag.Node{Data: ft.WrapData(blkData)}
-		nk, err := dw.dagserv.Add(node)
-		if dw.Pinner != nil {
-			dw.Pinner.PinWithMode(nk, pin.Indirect)
-		}
-		if err != nil {
-			dw.seterr = err
-			log.Critical("Got error adding created node to dagservice: %s", err)
-			return
-		}
+		indirectNodes <- node
 
 		// Add a link to this node without storing a reference to the memory
-		err = root.AddNodeLinkClean("", node)
+		err := root.AddNodeLinkClean("", node)
 		if err != nil {
 			dw.seterr = err
-			log.Critical("Got error adding created node to root node: %s", err)
+			log.Criticalf("Got error adding created node to root node: %s", err)
 			return
 		}
 	}
+	close(indirectNodes)
 
 	// Generate the root node data
 	mbf.Data = first
 	data, err := mbf.GetBytes()
 	if err != nil {
 		dw.seterr = err
-		log.Critical("Failed generating bytes for multiblock file: %s", err)
+		log.Criticalf("Failed generating bytes for multiblock file: %s", err)
 		return
 	}
 	root.Data = data
 
 	// Add root node to the dagservice
-	rootk, err := dw.dagserv.Add(root)
-	if err != nil {
-		dw.seterr = err
-		log.Critical("Got error adding created node to dagservice: %s", err)
-		return
-	}
-	if dw.Pinner != nil {
-		dw.Pinner.PinWithMode(rootk, pin.Recursive)
-	}
+	dw.writeNode(root, pin.Recursive)
 	dw.node = root
+	wg.Wait()
 	dw.done <- struct{}{}
+	log.Info("dagwriter done")
 }
 
 func (dw *DagWriter) Write(b []byte) (int, error) {
@@ -101,6 +118,20 @@ func (dw *DagWriter) Write(b []byte) (int, error) {
 	return len(b), nil
 }
 
+func (dw *DagWriter) writeNode(nd *dag.Node, pinMode pin.PinMode) {
+	nk, err := dw.dagserv.Add(nd)
+	if err != nil {
+		dw.seterr = err
+		log.Criticalf("Got error adding created node to dagservice: %s", err)
+		return
+	}
+
+	if dw.Pinner != nil {
+		dw.Pinner.PinWithMode(nk, pinMode)
+	}
+	return
+}
+
 // Close the splitters input channel and wait for it to finish
 // Must be called to finish up splitting, otherwise split method
 // will never halt