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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 (
"context"
"encoding/binary"
"errors"
"io"
"io/ioutil"
"sync"
"time"
"github.com/ethereum/go-ethereum/swarm/chunk"
"github.com/ethereum/go-ethereum/swarm/log"
)
/*
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 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
splitTimeout = time.Minute * 5
)
const (
DataChunk = 0
TreeChunk = 1
)
type PyramidSplitterParams struct {
SplitterParams
getter Getter
}
func NewPyramidSplitterParams(addr Address, reader io.Reader, putter Putter, getter Getter, chunkSize int64) *PyramidSplitterParams {
hashSize := putter.RefSize()
return &PyramidSplitterParams{
SplitterParams: SplitterParams{
ChunkerParams: ChunkerParams{
chunkSize: chunkSize,
hashSize: hashSize,
},
reader: reader,
putter: putter,
addr: addr,
},
getter: getter,
}
}
/*
When splitting, data is given as a SectionReader, and the key is a hashSize long byte slice (Key), the root hash of the entire content will fill this once processing finishes.
New chunks to store are store using the putter which the caller provides.
*/
func PyramidSplit(ctx context.Context, reader io.Reader, putter Putter, getter Getter) (Address, func(context.Context) error, error) {
return NewPyramidSplitter(NewPyramidSplitterParams(nil, reader, putter, getter, chunk.DefaultSize)).Split(ctx)
}
func PyramidAppend(ctx context.Context, addr Address, reader io.Reader, putter Putter, getter Getter) (Address, func(context.Context) error, error) {
return NewPyramidSplitter(NewPyramidSplitterParams(addr, reader, putter, getter, chunk.DefaultSize)).Append(ctx)
}
// 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 Address
chunk []byte
parentWg *sync.WaitGroup
}
type PyramidChunker struct {
chunkSize int64
hashSize int64
branches int64
reader io.Reader
putter Putter
getter Getter
key Address
workerCount int64
workerLock sync.RWMutex
jobC chan *chunkJob
wg *sync.WaitGroup
errC chan error
quitC chan bool
rootKey []byte
chunkLevel [][]*TreeEntry
}
func NewPyramidSplitter(params *PyramidSplitterParams) (pc *PyramidChunker) {
pc = &PyramidChunker{}
pc.reader = params.reader
pc.hashSize = params.hashSize
pc.branches = params.chunkSize / pc.hashSize
pc.chunkSize = pc.hashSize * pc.branches
pc.putter = params.putter
pc.getter = params.getter
pc.key = params.addr
pc.workerCount = 0
pc.jobC = make(chan *chunkJob, 2*ChunkProcessors)
pc.wg = &sync.WaitGroup{}
pc.errC = make(chan error)
pc.quitC = make(chan bool)
pc.rootKey = make([]byte, pc.hashSize)
pc.chunkLevel = make([][]*TreeEntry, pc.branches)
return
}
func (pc *PyramidChunker) Join(addr Address, getter Getter, depth int) LazySectionReader {
return &LazyChunkReader{
key: addr,
depth: depth,
chunkSize: pc.chunkSize,
branches: pc.branches,
hashSize: pc.hashSize,
getter: getter,
}
}
func (pc *PyramidChunker) incrementWorkerCount() {
pc.workerLock.Lock()
defer pc.workerLock.Unlock()
pc.workerCount += 1
}
func (pc *PyramidChunker) getWorkerCount() int64 {
pc.workerLock.Lock()
defer pc.workerLock.Unlock()
return pc.workerCount
}
func (pc *PyramidChunker) decrementWorkerCount() {
pc.workerLock.Lock()
defer pc.workerLock.Unlock()
pc.workerCount -= 1
}
func (pc *PyramidChunker) Split(ctx context.Context) (k Address, wait func(context.Context) error, err error) {
log.Debug("pyramid.chunker: Split()")
pc.wg.Add(1)
pc.prepareChunks(false)
// closes internal error channel if all subprocesses in the workgroup finished
go func() {
// waiting for all chunks to finish
pc.wg.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(pc.errC)
}()
defer close(pc.quitC)
defer pc.putter.Close()
select {
case err := <-pc.errC:
if err != nil {
return nil, nil, err
}
case <-time.NewTimer(splitTimeout).C:
}
return pc.rootKey, pc.putter.Wait, nil
}
func (pc *PyramidChunker) Append(ctx context.Context) (k Address, wait func(context.Context) error, err error) {
log.Debug("pyramid.chunker: Append()")
// Load the right most unfinished tree chunks in every level
pc.loadTree()
pc.wg.Add(1)
pc.prepareChunks(true)
// closes internal error channel if all subprocesses in the workgroup finished
go func() {
// waiting for all chunks to finish
pc.wg.Wait()
close(pc.errC)
}()
defer close(pc.quitC)
defer pc.putter.Close()
select {
case err := <-pc.errC:
if err != nil {
return nil, nil, err
}
case <-time.NewTimer(splitTimeout).C:
}
return pc.rootKey, pc.putter.Wait, nil
}
func (pc *PyramidChunker) processor(id int64) {
defer pc.decrementWorkerCount()
for {
select {
case job, ok := <-pc.jobC:
if !ok {
return
}
pc.processChunk(id, job)
case <-pc.quitC:
return
}
}
}
func (pc *PyramidChunker) processChunk(id int64, job *chunkJob) {
log.Debug("pyramid.chunker: processChunk()", "id", id)
ref, err := pc.putter.Put(context.TODO(), job.chunk)
if err != nil {
pc.errC <- err
}
// report hash of this chunk one level up (keys corresponds to the proper subslice of the parent chunk)
copy(job.key, ref)
// send off new chunk to storage
job.parentWg.Done()
}
func (pc *PyramidChunker) loadTree() error {
log.Debug("pyramid.chunker: loadTree()")
// Get the root chunk to get the total size
chunkData, err := pc.getter.Get(context.TODO(), Reference(pc.key))
if err != nil {
return errLoadingTreeRootChunk
}
chunkSize := chunkData.Size()
log.Trace("pyramid.chunker: root chunk", "chunk.Size", chunkSize, "pc.chunkSize", pc.chunkSize)
//if data size is less than a chunk... add a parent with update as pending
if chunkSize <= pc.chunkSize {
newEntry := &TreeEntry{
level: 0,
branchCount: 1,
subtreeSize: uint64(chunkSize),
chunk: make([]byte, pc.chunkSize+8),
key: make([]byte, pc.hashSize),
index: 0,
updatePending: true,
}
copy(newEntry.chunk[8:], pc.key)
pc.chunkLevel[0] = append(pc.chunkLevel[0], newEntry)
return nil
}
var treeSize int64
var depth int
treeSize = pc.chunkSize
for ; treeSize < chunkSize; treeSize *= pc.branches {
depth++
}
log.Trace("pyramid.chunker", "depth", depth)
// Add the root chunk entry
branchCount := int64(len(chunkData)-8) / pc.hashSize
newEntry := &TreeEntry{
level: depth - 1,
branchCount: branchCount,
subtreeSize: uint64(chunkSize),
chunk: chunkData,
key: pc.key,
index: 0,
updatePending: true,
}
pc.chunkLevel[depth-1] = append(pc.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 pc.chunkLevel[lvl] {
branchCount = int64(len(ent.chunk)-8) / pc.hashSize
for i := int64(0); i < branchCount; i++ {
key := ent.chunk[8+(i*pc.hashSize) : 8+((i+1)*pc.hashSize)]
newChunkData, err := pc.getter.Get(context.TODO(), Reference(key))
if err != nil {
return errLoadingTreeChunk
}
newChunkSize := newChunkData.Size()
bewBranchCount := int64(len(newChunkData)-8) / pc.hashSize
newEntry := &TreeEntry{
level: lvl - 1,
branchCount: bewBranchCount,
subtreeSize: uint64(newChunkSize),
chunk: newChunkData,
key: key,
index: 0,
updatePending: true,
}
pc.chunkLevel[lvl-1] = append(pc.chunkLevel[lvl-1], newEntry)
}
// We need to get only the right most unfinished branch.. so trim all finished branches
if int64(len(pc.chunkLevel[lvl-1])) >= pc.branches {
pc.chunkLevel[lvl-1] = nil
}
}
}
return nil
}
func (pc *PyramidChunker) prepareChunks(isAppend bool) {
log.Debug("pyramid.chunker: prepareChunks", "isAppend", isAppend)
defer pc.wg.Done()
chunkWG := &sync.WaitGroup{}
pc.incrementWorkerCount()
go pc.processor(pc.workerCount)
parent := NewTreeEntry(pc)
var unfinishedChunkData ChunkData
var unfinishedChunkSize int64
if isAppend && len(pc.chunkLevel[0]) != 0 {
lastIndex := len(pc.chunkLevel[0]) - 1
ent := pc.chunkLevel[0][lastIndex]
if ent.branchCount < pc.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*pc.hashSize : 8+(lastBranch+1)*pc.hashSize]
var err error
unfinishedChunkData, err = pc.getter.Get(context.TODO(), lastKey)
if err != nil {
pc.errC <- err
}
unfinishedChunkSize = unfinishedChunkData.Size()
if unfinishedChunkSize < pc.chunkSize {
parent.subtreeSize = parent.subtreeSize - uint64(unfinishedChunkSize)
parent.branchCount = parent.branchCount - 1
} else {
unfinishedChunkData = nil
}
}
}
for index := 0; ; index++ {
var err error
chunkData := make([]byte, pc.chunkSize+8)
var readBytes int
if unfinishedChunkData != nil {
copy(chunkData, unfinishedChunkData)
readBytes += int(unfinishedChunkSize)
unfinishedChunkData = nil
log.Trace("pyramid.chunker: found unfinished chunk", "readBytes", readBytes)
}
var res []byte
res, err = ioutil.ReadAll(io.LimitReader(pc.reader, int64(len(chunkData)-(8+readBytes))))
// hack for ioutil.ReadAll:
// a successful call to ioutil.ReadAll returns err == nil, not err == EOF, whereas we
// want to propagate the io.EOF error
if len(res) == 0 && err == nil {
err = io.EOF
}
copy(chunkData[8+readBytes:], res)
readBytes += len(res)
log.Trace("pyramid.chunker: copied all data", "readBytes", readBytes)
if err != nil {
if err == io.EOF || err == io.ErrUnexpectedEOF {
pc.cleanChunkLevels()
// Check if we are appending or the chunk is the only one.
if parent.branchCount == 1 && (pc.depth() == 0 || isAppend) {
// Data is exactly one chunk.. pick the last chunk key as root
chunkWG.Wait()
lastChunksKey := parent.chunk[8 : 8+pc.hashSize]
copy(pc.rootKey, lastChunksKey)
break
}
} else {
close(pc.quitC)
break
}
}
// Data ended in chunk boundary.. just signal to start bulding tree
if readBytes == 0 {
pc.buildTree(isAppend, parent, chunkWG, true, nil)
break
} else {
pkey := pc.enqueueDataChunk(chunkData, uint64(readBytes), parent, chunkWG)
// update tree related parent data structures
parent.subtreeSize += uint64(readBytes)
parent.branchCount++
// Data got exhausted... signal to send any parent tree related chunks
if int64(readBytes) < pc.chunkSize {
pc.cleanChunkLevels()
// only one data chunk .. so dont add any parent chunk
if parent.branchCount <= 1 {
chunkWG.Wait()
if isAppend || pc.depth() == 0 {
// No need to build the tree if the depth is 0
// or we are appending.
// Just use the last key.
copy(pc.rootKey, pkey)
} else {
// We need to build the tree and and provide the lonely
// chunk key to replace the last tree chunk key.
pc.buildTree(isAppend, parent, chunkWG, true, pkey)
}
break
}
pc.buildTree(isAppend, parent, chunkWG, true, nil)
break
}
if parent.branchCount == pc.branches {
pc.buildTree(isAppend, parent, chunkWG, false, nil)
parent = NewTreeEntry(pc)
}
}
workers := pc.getWorkerCount()
if int64(len(pc.jobC)) > workers && workers < ChunkProcessors {
pc.incrementWorkerCount()
go pc.processor(pc.workerCount)
}
}
}
func (pc *PyramidChunker) buildTree(isAppend bool, ent *TreeEntry, chunkWG *sync.WaitGroup, last bool, lonelyChunkKey []byte) {
chunkWG.Wait()
pc.enqueueTreeChunk(ent, chunkWG, last)
compress := false
endLvl := pc.branches
for lvl := int64(0); lvl < pc.branches; lvl++ {
lvlCount := int64(len(pc.chunkLevel[lvl]))
if lvlCount >= pc.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(pc.chunkLevel[lvl]))
if lvlCount == 1 && last {
copy(pc.rootKey, pc.chunkLevel[lvl][0].key)
return
}
for startCount := int64(0); startCount < lvlCount; startCount += pc.branches {
endCount := startCount + pc.branches
if endCount > lvlCount {
endCount = lvlCount
}
var nextLvlCount int64
var tempEntry *TreeEntry
if len(pc.chunkLevel[lvl+1]) > 0 {
nextLvlCount = int64(len(pc.chunkLevel[lvl+1]) - 1)
tempEntry = pc.chunkLevel[lvl+1][nextLvlCount]
}
if isAppend && tempEntry != nil && tempEntry.updatePending {
updateEntry := &TreeEntry{
level: int(lvl + 1),
branchCount: 0,
subtreeSize: 0,
chunk: make([]byte, pc.chunkSize+8),
key: make([]byte, pc.hashSize),
index: int(nextLvlCount),
updatePending: true,
}
for index := int64(0); index < lvlCount; index++ {
updateEntry.branchCount++
updateEntry.subtreeSize += pc.chunkLevel[lvl][index].subtreeSize
copy(updateEntry.chunk[8+(index*pc.hashSize):8+((index+1)*pc.hashSize)], pc.chunkLevel[lvl][index].key[:pc.hashSize])
}
pc.enqueueTreeChunk(updateEntry, chunkWG, last)
} else {
noOfBranches := endCount - startCount
newEntry := &TreeEntry{
level: int(lvl + 1),
branchCount: noOfBranches,
subtreeSize: 0,
chunk: make([]byte, (noOfBranches*pc.hashSize)+8),
key: make([]byte, pc.hashSize),
index: int(nextLvlCount),
updatePending: false,
}
index := int64(0)
for i := startCount; i < endCount; i++ {
entry := pc.chunkLevel[lvl][i]
newEntry.subtreeSize += entry.subtreeSize
copy(newEntry.chunk[8+(index*pc.hashSize):8+((index+1)*pc.hashSize)], entry.key[:pc.hashSize])
index++
}
// Lonely chunk key is the key of the last chunk that is only one on the last branch.
// In this case, ignore the its tree chunk key and replace it with the lonely chunk key.
if lonelyChunkKey != nil {
// Overwrite the last tree chunk key with the lonely data chunk key.
copy(newEntry.chunk[int64(len(newEntry.chunk))-pc.hashSize:], lonelyChunkKey[:pc.hashSize])
}
pc.enqueueTreeChunk(newEntry, chunkWG, last)
}
}
if !isAppend {
chunkWG.Wait()
if compress {
pc.chunkLevel[lvl] = nil
}
}
}
}
func (pc *PyramidChunker) enqueueTreeChunk(ent *TreeEntry, chunkWG *sync.WaitGroup, last bool) {
if ent != nil && ent.branchCount > 0 {
// 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, pc.hashSize)
chunkWG.Add(1)
select {
case pc.jobC <- &chunkJob{ent.key, ent.chunk[:ent.branchCount*pc.hashSize+8], chunkWG}:
case <-pc.quitC:
}
// Update or append based on weather it is a new entry or being reused
if ent.updatePending {
chunkWG.Wait()
pc.chunkLevel[ent.level][ent.index] = ent
} else {
pc.chunkLevel[ent.level] = append(pc.chunkLevel[ent.level], ent)
}
}
}
func (pc *PyramidChunker) enqueueDataChunk(chunkData []byte, size uint64, parent *TreeEntry, chunkWG *sync.WaitGroup) Address {
binary.LittleEndian.PutUint64(chunkData[:8], size)
pkey := parent.chunk[8+parent.branchCount*pc.hashSize : 8+(parent.branchCount+1)*pc.hashSize]
chunkWG.Add(1)
select {
case pc.jobC <- &chunkJob{pkey, chunkData[:size+8], chunkWG}:
case <-pc.quitC:
}
return pkey
}
// depth returns the number of chunk levels.
// It is used to detect if there is only one data chunk
// left for the last branch.
func (pc *PyramidChunker) depth() (d int) {
for _, l := range pc.chunkLevel {
if l == nil {
return
}
d++
}
return
}
// cleanChunkLevels removes gaps (nil levels) between chunk levels
// that are not nil.
func (pc *PyramidChunker) cleanChunkLevels() {
for i, l := range pc.chunkLevel {
if l == nil {
pc.chunkLevel = append(pc.chunkLevel[:i], append(pc.chunkLevel[i+1:], nil)...)
}
}
}
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