plugeth/swarm/storage/pyramid.go

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// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package storage
import (
"encoding/binary"
"errors"
"io"
"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.
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This opens up new aveneus such as easy append and other sort of modifications to the tree thereby 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")
)
const (
ChunkProcessors = 8
DefaultBranches int64 = 128
splitTimeout = time.Minute * 5
)
const (
DataChunk = 0
TreeChunk = 1
)
type ChunkerParams struct {
Branches int64
Hash string
}
func NewChunkerParams() *ChunkerParams {
return &ChunkerParams{
Branches: DefaultBranches,
Hash: SHA3Hash,
}
}
// 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 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,
}
}
// 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 SwarmHasher
chunkSize int64
hashSize int64
branches int64
workerCount int64
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workerLock sync.RWMutex
}
func NewPyramidChunker(params *ChunkerParams) (self *PyramidChunker) {
self = &PyramidChunker{}
self.hashFunc = MakeHashFunc(params.Hash)
self.branches = params.Branches
self.hashSize = int64(self.hashFunc().Size())
self.chunkSize = self.hashSize * self.branches
self.workerCount = 0
return
}
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,
}
}
func (self *PyramidChunker) incrementWorkerCount() {
self.workerLock.Lock()
defer self.workerLock.Unlock()
self.workerCount += 1
}
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:
}
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:
}
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()
}
for {
select {
case job, ok := <-jobC:
if !ok {
return
}
self.processChunk(id, hasher, job, chunkC, swg)
case <-quitC:
return
}
}
}
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)
}
}
job.parentWg.Done()
if chunkC != nil {
chunkC <- newChunk
}
}
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
}
//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: 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
}
bewBranchCount := int64(len(newChunk.SData)-8) / self.hashSize
newEntry := &TreeEntry{
level: lvl - 1,
branchCount: bewBranchCount,
subtreeSize: uint64(newChunk.Size),
chunk: newChunk.SData,
key: key,
index: 0,
updatePending: true,
}
chunkLevel[lvl-1] = append(chunkLevel[lvl-1], newEntry)
}
// 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
}
}
}
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
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// 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 && 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,
}
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
}
}
}
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
}
}
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// Data ended in chunk boundary.. 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 && !last {
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 {
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 && tempEntry != nil && tempEntry.updatePending {
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 {
chunkWG.Wait()
if compress {
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 {
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 {
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
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}