swarm/storage: pyramid chunker re-write (#14382)

1 files changed, 559 insertions, 122 deletions

diff --git a/swarm/storage/pyramid.go b/swarm/storage/pyramid.go
index 74e00a497..e3be2a987 100644
--- a/swarm/storage/pyramid.go
+++ b/swarm/storage/pyramid.go
@@ -18,53 +18,112 @@ package storage
 
 import (
 	"encoding/binary"
-	"fmt"
+	"errors"
 	"io"
-	"math"
-	"strings"
 	"sync"
+	"time"
+)
+
+/*
+   The main idea of a pyramid chunker is to process the input data without knowing the entire size apriori.
+   For this to be achieved, the chunker tree is built from the ground up until the data is exhausted.
+   This opens up new aveneus such as easy append and other sort of modifications to the tree therby avoiding
+   duplication of data chunks.
+
+
+   Below is an example of a two level chunks tree. The leaf chunks are called data chunks and all the above
+   chunks are called tree chunks. The tree chunk above data chunks is level 0 and so on until it reaches
+   the root tree chunk.
+
+
+
+                                            T10                                        <- Tree chunk lvl1
+                                            |
+                  __________________________|_____________________________
+                 /                  |                   |                \
+                /                   |                   \                 \
+            __T00__             ___T01__           ___T02__           ___T03__         <- Tree chunks lvl 0
+           / /     \           / /      \         / /      \         / /      \
+          / /       \         / /        \       / /       \        / /        \
+         D1 D2 ... D128	     D1 D2 ... D128     D1 D2 ... D128     D1 D2 ... D128      <-  Data Chunks
+
+
+    The split function continuously read the data and creates data chunks and send them to storage.
+    When certain no of data chunks are created (defaultBranches), a signal is sent to create a tree
+    entry. When the level 0 tree entries reaches certain threshold (defaultBranches), another signal
+    is sent to a tree entry one level up.. and so on... until only the data is exhausted AND only one
+    tree entry is present in certain level. The key of tree entry is given out as the rootKey of the file.
+
+*/
+
+var (
+	errLoadingTreeRootChunk = errors.New("LoadTree Error: Could not load root chunk")
+	errLoadingTreeChunk     = errors.New("LoadTree Error: Could not load chunk")
+)
 
-	"github.com/ethereum/go-ethereum/common"
+const (
+	ChunkProcessors       = 8
+	DefaultBranches int64 = 128
+	splitTimeout          = time.Minute * 5
 )
 
 const (
-	processors = 8
+	DataChunk = 0
+	TreeChunk = 1
 )
 
-type Tree struct {
-	Chunks int64
-	Levels []map[int64]*Node
-	Lock   sync.RWMutex
+type ChunkerParams struct {
+	Branches int64
+	Hash     string
+}
+
+func NewChunkerParams() *ChunkerParams {
+	return &ChunkerParams{
+		Branches: DefaultBranches,
+		Hash:     SHA3Hash,
+	}
 }
 
-type Node struct {
-	Pending  int64
-	Size     uint64
-	Children []common.Hash
-	Last     bool
+// Entry to create a tree node
+type TreeEntry struct {
+	level         int
+	branchCount   int64
+	subtreeSize   uint64
+	chunk         []byte
+	key           []byte
+	index         int  // used in append to indicate the index of existing tree entry
+	updatePending bool // indicates if the entry is loaded from existing tree
 }
 
-func (self *Node) String() string {
-	var children []string
-	for _, node := range self.Children {
-		children = append(children, node.Hex())
+func NewTreeEntry(pyramid *PyramidChunker) *TreeEntry {
+	return &TreeEntry{
+		level:         0,
+		branchCount:   0,
+		subtreeSize:   0,
+		chunk:         make([]byte, pyramid.chunkSize+8),
+		key:           make([]byte, pyramid.hashSize),
+		index:         0,
+		updatePending: false,
 	}
-	return fmt.Sprintf("pending: %v, size: %v, last :%v, children: %v", self.Pending, self.Size, self.Last, strings.Join(children, ", "))
 }
 
-type Task struct {
-	Index int64 // Index of the chunk being processed
-	Size  uint64
-	Data  []byte // Binary blob of the chunk
-	Last  bool
+// Used by the hash processor to create a data/tree chunk and send to storage
+type chunkJob struct {
+	key       Key
+	chunk     []byte
+	size      int64
+	parentWg  *sync.WaitGroup
+	chunkType int // used to identify the tree related chunks for debugging
+	chunkLvl  int // leaf-1 is level 0 and goes upwards until it reaches root
 }
 
 type PyramidChunker struct {
-	hashFunc    Hasher
+	hashFunc    SwarmHasher
 	chunkSize   int64
 	hashSize    int64
 	branches    int64
-	workerCount int
+	workerCount int64
+	workerLock	sync.RWMutex
 }
 
 func NewPyramidChunker(params *ChunkerParams) (self *PyramidChunker) {
@@ -73,128 +132,506 @@ func NewPyramidChunker(params *ChunkerParams) (self *PyramidChunker) {
 	self.branches = params.Branches
 	self.hashSize = int64(self.hashFunc().Size())
 	self.chunkSize = self.hashSize * self.branches
-	self.workerCount = 1
+	self.workerCount = 0
 	return
 }
 
-func (self *PyramidChunker) Split(data io.Reader, size int64, chunkC chan *Chunk, swg, wwg *sync.WaitGroup) (Key, error) {
+func (self *PyramidChunker) Join(key Key, chunkC chan *Chunk) LazySectionReader {
+	return &LazyChunkReader{
+		key:       key,
+		chunkC:    chunkC,
+		chunkSize: self.chunkSize,
+		branches:  self.branches,
+		hashSize:  self.hashSize,
+	}
+}
 
-	chunks := (size + self.chunkSize - 1) / self.chunkSize
-	depth := int(math.Ceil(math.Log(float64(chunks))/math.Log(float64(self.branches)))) + 1
+func (self *PyramidChunker) incrementWorkerCount() {
+	self.workerLock.Lock()
+	defer self.workerLock.Unlock()
+	self.workerCount += 1
+}
 
-	results := Tree{
-		Chunks: chunks,
-		Levels: make([]map[int64]*Node, depth),
+func (self *PyramidChunker) getWorkerCount() int64 {
+	self.workerLock.Lock()
+	defer self.workerLock.Unlock()
+	return self.workerCount
+}
+
+func (self *PyramidChunker) decrementWorkerCount() {
+	self.workerLock.Lock()
+	defer self.workerLock.Unlock()
+	self.workerCount -= 1
+}
+
+func (self *PyramidChunker) Split(data io.Reader, size int64, chunkC chan *Chunk, storageWG, processorWG *sync.WaitGroup) (Key, error) {
+	jobC := make(chan *chunkJob, 2*ChunkProcessors)
+	wg := &sync.WaitGroup{}
+	errC := make(chan error)
+	quitC := make(chan bool)
+	rootKey := make([]byte, self.hashSize)
+	chunkLevel := make([][]*TreeEntry, self.branches)
+
+	wg.Add(1)
+	go self.prepareChunks(false, chunkLevel, data, rootKey, quitC, wg, jobC, processorWG, chunkC, errC, storageWG)
+
+	// closes internal error channel if all subprocesses in the workgroup finished
+	go func() {
+
+		// waiting for all chunks to finish
+		wg.Wait()
+
+		// if storage waitgroup is non-nil, we wait for storage to finish too
+		if storageWG != nil {
+			storageWG.Wait()
+		}
+		//We close errC here because this is passed down to 8 parallel routines underneath.
+		// if a error happens in one of them.. that particular routine raises error...
+		// once they all complete successfully, the control comes back and we can safely close this here.
+		close(errC)
+	}()
+
+	defer close(quitC)
+
+	select {
+	case err := <-errC:
+		if err != nil {
+			return nil, err
+		}
+	case <-time.NewTimer(splitTimeout).C:
 	}
-	for i := 0; i < depth; i++ {
-		results.Levels[i] = make(map[int64]*Node)
+	return rootKey, nil
+
+}
+
+func (self *PyramidChunker) Append(key Key, data io.Reader, chunkC chan *Chunk, storageWG, processorWG *sync.WaitGroup) (Key, error) {
+	quitC := make(chan bool)
+	rootKey := make([]byte, self.hashSize)
+	chunkLevel := make([][]*TreeEntry, self.branches)
+
+	// Load the right most unfinished tree chunks in every level
+	self.loadTree(chunkLevel, key, chunkC, quitC)
+
+	jobC := make(chan *chunkJob, 2*ChunkProcessors)
+	wg := &sync.WaitGroup{}
+	errC := make(chan error)
+
+	wg.Add(1)
+	go self.prepareChunks(true, chunkLevel, data, rootKey, quitC, wg, jobC, processorWG, chunkC, errC, storageWG)
+
+	// closes internal error channel if all subprocesses in the workgroup finished
+	go func() {
+
+		// waiting for all chunks to finish
+		wg.Wait()
+
+		// if storage waitgroup is non-nil, we wait for storage to finish too
+		if storageWG != nil {
+			storageWG.Wait()
+		}
+		close(errC)
+	}()
+
+	defer close(quitC)
+
+	select {
+	case err := <-errC:
+		if err != nil {
+			return nil, err
+		}
+	case <-time.NewTimer(splitTimeout).C:
 	}
-	// Create a pool of workers to crunch through the file
-	tasks := make(chan *Task, 2*processors)
-	pend := new(sync.WaitGroup)
-	abortC := make(chan bool)
-	for i := 0; i < processors; i++ {
-		pend.Add(1)
-		go self.processor(pend, swg, tasks, chunkC, &results)
+	return rootKey, nil
+
+}
+
+func (self *PyramidChunker) processor(id int64, jobC chan *chunkJob, chunkC chan *Chunk, errC chan error, quitC chan bool, swg, wwg *sync.WaitGroup) {
+	defer self.decrementWorkerCount()
+
+	hasher := self.hashFunc()
+	if wwg != nil {
+		defer wwg.Done()
 	}
-	// Feed the chunks into the task pool
-	read := 0
-	for index := 0; ; index++ {
-		buffer := make([]byte, self.chunkSize+8)
-		n, err := data.Read(buffer[8:])
-		read += n
-		last := int64(read) == size || err == io.ErrUnexpectedEOF || err == io.EOF
-		if err != nil && !last {
-			close(abortC)
-			break
-		}
-		binary.LittleEndian.PutUint64(buffer[:8], uint64(n))
-		pend.Add(1)
+	for {
 		select {
-		case tasks <- &Task{Index: int64(index), Size: uint64(n), Data: buffer[:n+8], Last: last}:
-		case <-abortC:
-			return nil, err
+
+		case job, ok := <-jobC:
+			if !ok {
+				return
+			}
+			self.processChunk(id, hasher, job, chunkC, swg)
+		case <-quitC:
+			return
 		}
-		if last {
-			break
+	}
+}
+
+func (self *PyramidChunker) processChunk(id int64, hasher SwarmHash, job *chunkJob, chunkC chan *Chunk, swg *sync.WaitGroup) {
+	hasher.ResetWithLength(job.chunk[:8]) // 8 bytes of length
+	hasher.Write(job.chunk[8:])           // minus 8 []byte length
+	h := hasher.Sum(nil)
+
+	newChunk := &Chunk{
+		Key:   h,
+		SData: job.chunk,
+		Size:  job.size,
+		wg:    swg,
+	}
+
+	// report hash of this chunk one level up (keys corresponds to the proper subslice of the parent chunk)
+	copy(job.key, h)
+
+	// send off new chunk to storage
+	if chunkC != nil {
+		if swg != nil {
+			swg.Add(1)
 		}
 	}
-	// Wait for the workers and return
-	close(tasks)
-	pend.Wait()
+	job.parentWg.Done()
 
-	key := results.Levels[0][0].Children[0][:]
-	return key, nil
+	if chunkC != nil {
+		chunkC <- newChunk
+	}
 }
 
-func (self *PyramidChunker) processor(pend, swg *sync.WaitGroup, tasks chan *Task, chunkC chan *Chunk, results *Tree) {
-	defer pend.Done()
+func (self *PyramidChunker) loadTree(chunkLevel [][]*TreeEntry, key Key, chunkC chan *Chunk, quitC chan bool) error {
+	// Get the root chunk to get the total size
+	chunk := retrieve(key, chunkC, quitC)
+	if chunk == nil {
+		return errLoadingTreeRootChunk
+	}
 
-	// Start processing leaf chunks ad infinitum
-	hasher := self.hashFunc()
-	for task := range tasks {
-		depth, pow := len(results.Levels)-1, self.branches
-		size := task.Size
-		data := task.Data
-		var node *Node
-		for depth >= 0 {
-			// New chunk received, reset the hasher and start processing
-			hasher.Reset()
-			if node == nil { // Leaf node, hash the data chunk
-				hasher.Write(task.Data)
-			} else { // Internal node, hash the children
-				size = node.Size
-				data = make([]byte, hasher.Size()*len(node.Children)+8)
-				binary.LittleEndian.PutUint64(data[:8], size)
-
-				hasher.Write(data[:8])
-				for i, hash := range node.Children {
-					copy(data[i*hasher.Size()+8:], hash[:])
-					hasher.Write(hash[:])
+	//if data size is less than a chunk... add a parent with update as pending
+	if chunk.Size <= self.chunkSize {
+		newEntry := &TreeEntry{
+			level:         0,
+			branchCount:   1,
+			subtreeSize:   uint64(chunk.Size),
+			chunk:         make([]byte, self.chunkSize+8),
+			key:           make([]byte, self.hashSize),
+			index:         0,
+			updatePending: true,
+		}
+		copy(newEntry.chunk[8:], chunk.Key)
+		chunkLevel[0] = append(chunkLevel[0], newEntry)
+		return nil
+	}
+
+	var treeSize int64
+	var depth int
+	treeSize = self.chunkSize
+	for ; treeSize < chunk.Size; treeSize *= self.branches {
+		depth++
+	}
+
+	// Add the root chunk entry
+	branchCount := int64(len(chunk.SData)-8) / self.hashSize
+	newEntry := &TreeEntry{
+		level:         int(depth - 1),
+		branchCount:   branchCount,
+		subtreeSize:   uint64(chunk.Size),
+		chunk:         chunk.SData,
+		key:           key,
+		index:         0,
+		updatePending: true,
+	}
+	chunkLevel[depth-1] = append(chunkLevel[depth-1], newEntry)
+
+	// Add the rest of the tree
+	for lvl := (depth - 1); lvl >= 1; lvl-- {
+
+		//TODO(jmozah): instead of loading finished branches and then trim in the end,
+		//avoid loading them in the first place
+		for _, ent := range chunkLevel[lvl] {
+			branchCount = int64(len(ent.chunk)-8) / self.hashSize
+			for i := int64(0); i < branchCount; i++ {
+				key := ent.chunk[8+(i*self.hashSize) : 8+((i+1)*self.hashSize)]
+				newChunk := retrieve(key, chunkC, quitC)
+				if newChunk == nil {
+					return errLoadingTreeChunk
 				}
-			}
-			hash := hasher.Sum(nil)
-			last := task.Last || (node != nil) && node.Last
-			// Insert the subresult into the memoization tree
-			results.Lock.Lock()
-			if node = results.Levels[depth][task.Index/pow]; node == nil {
-				// Figure out the pending tasks
-				pending := self.branches
-				if task.Index/pow == results.Chunks/pow {
-					pending = (results.Chunks + pow/self.branches - 1) / (pow / self.branches) % self.branches
+				bewBranchCount := int64(len(newChunk.SData)-8) / self.hashSize
+				newEntry := &TreeEntry{
+					level:         int(lvl - 1),
+					branchCount:   bewBranchCount,
+					subtreeSize:   uint64(newChunk.Size),
+					chunk:         newChunk.SData,
+					key:           key,
+					index:         0,
+					updatePending: true,
 				}
-				node = &Node{pending, 0, make([]common.Hash, pending), last}
-				results.Levels[depth][task.Index/pow] = node
+				chunkLevel[lvl-1] = append(chunkLevel[lvl-1], newEntry)
+
 			}
-			node.Pending--
-			i := task.Index / (pow / self.branches) % self.branches
-			if last {
-				node.Last = true
+
+			// We need to get only the right most unfinished branch.. so trim all finished branches
+			if int64(len(chunkLevel[lvl-1])) >= self.branches {
+				chunkLevel[lvl-1] = nil
 			}
-			copy(node.Children[i][:], hash)
-			node.Size += size
-			left := node.Pending
-			if chunkC != nil {
-				if swg != nil {
-					swg.Add(1)
-				}
+		}
+	}
+
+	return nil
+}
+
+func (self *PyramidChunker) prepareChunks(isAppend bool, chunkLevel [][]*TreeEntry, data io.Reader, rootKey []byte, quitC chan bool, wg *sync.WaitGroup, jobC chan *chunkJob, processorWG *sync.WaitGroup, chunkC chan *Chunk, errC chan error, storageWG *sync.WaitGroup) {
+	defer wg.Done()
+
+	chunkWG := &sync.WaitGroup{}
+	totalDataSize := 0
 
-				chunkC <- &Chunk{Key: hash, SData: data, wg: swg}
-				// TODO: consider selecting on self.quitC to avoid blocking forever on shutdown
+	// processorWG keeps track of workers spawned for hashing chunks
+	if processorWG != nil {
+		processorWG.Add(1)
+	}
+
+	self.incrementWorkerCount()
+	go self.processor(self.workerCount, jobC, chunkC, errC, quitC, storageWG, processorWG)
+
+	parent := NewTreeEntry(self)
+	var unFinishedChunk *Chunk
+
+	if isAppend == true && len(chunkLevel[0]) != 0 {
+
+		lastIndex := len(chunkLevel[0]) - 1
+		ent := chunkLevel[0][lastIndex]
+
+		if ent.branchCount < self.branches {
+			parent = &TreeEntry{
+				level:         0,
+				branchCount:   ent.branchCount,
+				subtreeSize:   ent.subtreeSize,
+				chunk:         ent.chunk,
+				key:           ent.key,
+				index:         lastIndex,
+				updatePending: true,
 			}
-			if depth+1 < len(results.Levels) {
-				delete(results.Levels[depth+1], task.Index/(pow/self.branches))
+
+			lastBranch := parent.branchCount - 1
+			lastKey := parent.chunk[8+lastBranch*self.hashSize : 8+(lastBranch+1)*self.hashSize]
+
+			unFinishedChunk = retrieve(lastKey, chunkC, quitC)
+			if unFinishedChunk.Size < self.chunkSize {
+
+				parent.subtreeSize = parent.subtreeSize - uint64(unFinishedChunk.Size)
+				parent.branchCount = parent.branchCount - 1
+			} else {
+				unFinishedChunk = nil
 			}
+		}
+	}
 
-			results.Lock.Unlock()
-			// If there's more work to be done, leave for others
-			if left > 0 {
+	for index := 0; ; index++ {
+
+		var n int
+		var err error
+		chunkData := make([]byte, self.chunkSize+8)
+		if unFinishedChunk != nil {
+			copy(chunkData, unFinishedChunk.SData)
+			n, err = data.Read(chunkData[8+unFinishedChunk.Size:])
+			n += int(unFinishedChunk.Size)
+			unFinishedChunk = nil
+		} else {
+			n, err = data.Read(chunkData[8:])
+		}
+
+		totalDataSize += n
+		if err != nil {
+			if err == io.EOF || err == io.ErrUnexpectedEOF {
+				if parent.branchCount == 1 {
+					// Data is exactly one chunk.. pick the last chunk key as root
+					chunkWG.Wait()
+					lastChunksKey := parent.chunk[8 : 8+self.hashSize]
+					copy(rootKey, lastChunksKey)
+					break
+				}
+			} else {
+				close(quitC)
 				break
 			}
-			// We're the last ones in this batch, merge the children together
-			depth--
-			pow *= self.branches
 		}
-		pend.Done()
+
+		// Data ended in chunk boundry.. just signal to start bulding tree
+		if n == 0 {
+			self.buildTree(isAppend, chunkLevel, parent, chunkWG, jobC, quitC, true, rootKey)
+			break
+		} else {
+
+			pkey := self.enqueueDataChunk(chunkData, uint64(n), parent, chunkWG, jobC, quitC)
+
+			// update tree related parent data structures
+			parent.subtreeSize += uint64(n)
+			parent.branchCount++
+
+			// Data got exhausted... signal to send any parent tree related chunks
+			if int64(n) < self.chunkSize {
+
+				// only one data chunk .. so dont add any parent chunk
+				if parent.branchCount <= 1 {
+					chunkWG.Wait()
+					copy(rootKey, pkey)
+					break
+				}
+
+				self.buildTree(isAppend, chunkLevel, parent, chunkWG, jobC, quitC, true, rootKey)
+				break
+			}
+
+			if parent.branchCount == self.branches {
+				self.buildTree(isAppend, chunkLevel, parent, chunkWG, jobC, quitC, false, rootKey)
+				parent = NewTreeEntry(self)
+			}
+
+		}
+
+		workers := self.getWorkerCount()
+		if int64(len(jobC)) > workers && workers < ChunkProcessors {
+			if processorWG != nil {
+				processorWG.Add(1)
+			}
+			self.incrementWorkerCount()
+			go self.processor(self.workerCount, jobC, chunkC, errC, quitC, storageWG, processorWG)
+		}
+
+	}
+
+}
+
+func (self *PyramidChunker) buildTree(isAppend bool, chunkLevel [][]*TreeEntry, ent *TreeEntry, chunkWG *sync.WaitGroup, jobC chan *chunkJob, quitC chan bool, last bool, rootKey []byte) {
+	chunkWG.Wait()
+	self.enqueueTreeChunk(chunkLevel, ent, chunkWG, jobC, quitC, last)
+
+	compress := false
+	endLvl := self.branches
+	for lvl := int64(0); lvl < self.branches; lvl++ {
+		lvlCount := int64(len(chunkLevel[lvl]))
+		if lvlCount >= self.branches {
+			endLvl = lvl + 1
+			compress = true
+			break
+		}
+	}
+
+	if compress == false && last == false {
+		return
+	}
+
+	// Wait for all the keys to be processed before compressing the tree
+	chunkWG.Wait()
+
+	for lvl := int64(ent.level); lvl < endLvl; lvl++ {
+
+		lvlCount := int64(len(chunkLevel[lvl]))
+		if lvlCount == 1 && last == true {
+			copy(rootKey, chunkLevel[lvl][0].key)
+			return
+		}
+
+		for startCount := int64(0); startCount < lvlCount; startCount += self.branches {
+
+			endCount := startCount + self.branches
+			if endCount > lvlCount {
+				endCount = lvlCount
+			}
+
+			var nextLvlCount int64
+			var tempEntry *TreeEntry
+			if len(chunkLevel[lvl+1]) > 0 {
+				nextLvlCount = int64(len(chunkLevel[lvl+1]) - 1)
+				tempEntry = chunkLevel[lvl+1][nextLvlCount]
+			}
+			if isAppend == true && tempEntry != nil && tempEntry.updatePending == true {
+				updateEntry := &TreeEntry{
+					level:         int(lvl + 1),
+					branchCount:   0,
+					subtreeSize:   0,
+					chunk:         make([]byte, self.chunkSize+8),
+					key:           make([]byte, self.hashSize),
+					index:         int(nextLvlCount),
+					updatePending: true,
+				}
+				for index := int64(0); index < lvlCount; index++ {
+					updateEntry.branchCount++
+					updateEntry.subtreeSize += chunkLevel[lvl][index].subtreeSize
+					copy(updateEntry.chunk[8+(index*self.hashSize):8+((index+1)*self.hashSize)], chunkLevel[lvl][index].key[:self.hashSize])
+				}
+
+				self.enqueueTreeChunk(chunkLevel, updateEntry, chunkWG, jobC, quitC, last)
+
+			} else {
+
+				noOfBranches := endCount - startCount
+				newEntry := &TreeEntry{
+					level:         int(lvl + 1),
+					branchCount:   noOfBranches,
+					subtreeSize:   0,
+					chunk:         make([]byte, (noOfBranches*self.hashSize)+8),
+					key:           make([]byte, self.hashSize),
+					index:         int(nextLvlCount),
+					updatePending: false,
+				}
+
+				index := int64(0)
+				for i := startCount; i < endCount; i++ {
+					entry := chunkLevel[lvl][i]
+					newEntry.subtreeSize += entry.subtreeSize
+					copy(newEntry.chunk[8+(index*self.hashSize):8+((index+1)*self.hashSize)], entry.key[:self.hashSize])
+					index++
+				}
+
+				self.enqueueTreeChunk(chunkLevel, newEntry, chunkWG, jobC, quitC, last)
+
+			}
+
+		}
+
+		if isAppend == false {
+			chunkWG.Wait()
+			if compress == true {
+				chunkLevel[lvl] = nil
+			}
+		}
 	}
+
 }
+
+func (self *PyramidChunker) enqueueTreeChunk(chunkLevel [][]*TreeEntry, ent *TreeEntry, chunkWG *sync.WaitGroup, jobC chan *chunkJob, quitC chan bool, last bool) {
+	if ent != nil {
+
+		// wait for data chunks to get over before processing the tree chunk
+		if last == true {
+			chunkWG.Wait()
+		}
+
+		binary.LittleEndian.PutUint64(ent.chunk[:8], ent.subtreeSize)
+		ent.key = make([]byte, self.hashSize)
+		chunkWG.Add(1)
+		select {
+		case jobC <- &chunkJob{ent.key, ent.chunk[:ent.branchCount*self.hashSize+8], int64(ent.subtreeSize), chunkWG, TreeChunk, 0}:
+		case <-quitC:
+		}
+
+		// Update or append based on weather it is a new entry or being reused
+		if ent.updatePending == true {
+			chunkWG.Wait()
+			chunkLevel[ent.level][ent.index] = ent
+		} else {
+			chunkLevel[ent.level] = append(chunkLevel[ent.level], ent)
+		}
+
+	}
+}
+
+func (self *PyramidChunker) enqueueDataChunk(chunkData []byte, size uint64, parent *TreeEntry, chunkWG *sync.WaitGroup, jobC chan *chunkJob, quitC chan bool) Key {
+	binary.LittleEndian.PutUint64(chunkData[:8], size)
+	pkey := parent.chunk[8+parent.branchCount*self.hashSize : 8+(parent.branchCount+1)*self.hashSize]
+
+	chunkWG.Add(1)
+	select {
+	case jobC <- &chunkJob{pkey, chunkData[:size+8], int64(size), chunkWG, DataChunk, -1}:
+	case <-quitC:
+	}
+
+	return pkey
+
+}
\ No newline at end of file