242 lines
7.0 KiB
Go
242 lines
7.0 KiB
Go
// Copyright 2016 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package storage
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import (
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"errors"
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"fmt"
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"io"
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"sync"
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"time"
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"github.com/ethereum/go-ethereum/log"
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)
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/*
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DPA provides the client API entrypoints Store and Retrieve to store and retrieve
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It can store anything that has a byte slice representation, so files or serialised objects etc.
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Storage: DPA calls the Chunker to segment the input datastream of any size to a merkle hashed tree of chunks. The key of the root block is returned to the client.
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Retrieval: given the key of the root block, the DPA retrieves the block chunks and reconstructs the original data and passes it back as a lazy reader. A lazy reader is a reader with on-demand delayed processing, i.e. the chunks needed to reconstruct a large file are only fetched and processed if that particular part of the document is actually read.
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As the chunker produces chunks, DPA dispatches them to its own chunk store
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implementation for storage or retrieval.
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*/
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const (
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storeChanCapacity = 100
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retrieveChanCapacity = 100
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singletonSwarmDbCapacity = 50000
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singletonSwarmCacheCapacity = 500
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maxStoreProcesses = 8
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maxRetrieveProcesses = 8
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)
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var (
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notFound = errors.New("not found")
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)
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type DPA struct {
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ChunkStore
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storeC chan *Chunk
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retrieveC chan *Chunk
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Chunker Chunker
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lock sync.Mutex
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running bool
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quitC chan bool
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}
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// for testing locally
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func NewLocalDPA(datadir string) (*DPA, error) {
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hash := MakeHashFunc("SHA256")
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dbStore, err := NewDbStore(datadir, hash, singletonSwarmDbCapacity, 0)
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if err != nil {
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return nil, err
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}
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return NewDPA(&LocalStore{
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NewMemStore(dbStore, singletonSwarmCacheCapacity),
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dbStore,
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}, NewChunkerParams()), nil
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}
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func NewDPA(store ChunkStore, params *ChunkerParams) *DPA {
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chunker := NewTreeChunker(params)
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return &DPA{
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Chunker: chunker,
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ChunkStore: store,
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}
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}
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// Public API. Main entry point for document retrieval directly. Used by the
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// FS-aware API and httpaccess
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// Chunk retrieval blocks on netStore requests with a timeout so reader will
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// report error if retrieval of chunks within requested range time out.
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func (self *DPA) Retrieve(key Key) LazySectionReader {
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return self.Chunker.Join(key, self.retrieveC)
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}
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// Public API. Main entry point for document storage directly. Used by the
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// FS-aware API and httpaccess
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func (self *DPA) Store(data io.Reader, size int64, swg *sync.WaitGroup, wwg *sync.WaitGroup) (key Key, err error) {
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return self.Chunker.Split(data, size, self.storeC, swg, wwg)
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}
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func (self *DPA) Start() {
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self.lock.Lock()
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defer self.lock.Unlock()
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if self.running {
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return
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}
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self.running = true
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self.retrieveC = make(chan *Chunk, retrieveChanCapacity)
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self.storeC = make(chan *Chunk, storeChanCapacity)
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self.quitC = make(chan bool)
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self.storeLoop()
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self.retrieveLoop()
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}
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func (self *DPA) Stop() {
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self.lock.Lock()
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defer self.lock.Unlock()
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if !self.running {
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return
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}
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self.running = false
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close(self.quitC)
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}
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// retrieveLoop dispatches the parallel chunk retrieval requests received on the
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// retrieve channel to its ChunkStore (NetStore or LocalStore)
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func (self *DPA) retrieveLoop() {
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for i := 0; i < maxRetrieveProcesses; i++ {
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go self.retrieveWorker()
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}
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log.Trace(fmt.Sprintf("dpa: retrieve loop spawning %v workers", maxRetrieveProcesses))
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}
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func (self *DPA) retrieveWorker() {
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for chunk := range self.retrieveC {
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log.Trace(fmt.Sprintf("dpa: retrieve loop : chunk %v", chunk.Key.Log()))
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storedChunk, err := self.Get(chunk.Key)
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if err == notFound {
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log.Trace(fmt.Sprintf("chunk %v not found", chunk.Key.Log()))
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} else if err != nil {
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log.Trace(fmt.Sprintf("error retrieving chunk %v: %v", chunk.Key.Log(), err))
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} else {
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chunk.SData = storedChunk.SData
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chunk.Size = storedChunk.Size
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}
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close(chunk.C)
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select {
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case <-self.quitC:
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return
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default:
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}
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}
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}
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// storeLoop dispatches the parallel chunk store request processors
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// received on the store channel to its ChunkStore (NetStore or LocalStore)
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func (self *DPA) storeLoop() {
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for i := 0; i < maxStoreProcesses; i++ {
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go self.storeWorker()
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}
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log.Trace(fmt.Sprintf("dpa: store spawning %v workers", maxStoreProcesses))
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}
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func (self *DPA) storeWorker() {
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for chunk := range self.storeC {
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self.Put(chunk)
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if chunk.wg != nil {
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log.Trace(fmt.Sprintf("dpa: store processor %v", chunk.Key.Log()))
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chunk.wg.Done()
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}
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select {
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case <-self.quitC:
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return
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default:
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}
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}
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}
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// DpaChunkStore implements the ChunkStore interface,
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// this chunk access layer assumed 2 chunk stores
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// local storage eg. LocalStore and network storage eg., NetStore
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// access by calling network is blocking with a timeout
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type dpaChunkStore struct {
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n int
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localStore ChunkStore
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netStore ChunkStore
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}
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func NewDpaChunkStore(localStore, netStore ChunkStore) *dpaChunkStore {
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return &dpaChunkStore{0, localStore, netStore}
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}
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// Get is the entrypoint for local retrieve requests
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// waits for response or times out
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func (self *dpaChunkStore) Get(key Key) (chunk *Chunk, err error) {
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chunk, err = self.netStore.Get(key)
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// timeout := time.Now().Add(searchTimeout)
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if chunk.SData != nil {
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log.Trace(fmt.Sprintf("DPA.Get: %v found locally, %d bytes", key.Log(), len(chunk.SData)))
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return
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}
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// TODO: use self.timer time.Timer and reset with defer disableTimer
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timer := time.After(searchTimeout)
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select {
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case <-timer:
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log.Trace(fmt.Sprintf("DPA.Get: %v request time out ", key.Log()))
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err = notFound
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case <-chunk.Req.C:
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log.Trace(fmt.Sprintf("DPA.Get: %v retrieved, %d bytes (%p)", key.Log(), len(chunk.SData), chunk))
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}
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return
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}
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// Put is the entrypoint for local store requests coming from storeLoop
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func (self *dpaChunkStore) Put(entry *Chunk) {
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chunk, err := self.localStore.Get(entry.Key)
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if err != nil {
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log.Trace(fmt.Sprintf("DPA.Put: %v new chunk. call netStore.Put", entry.Key.Log()))
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chunk = entry
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} else if chunk.SData == nil {
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log.Trace(fmt.Sprintf("DPA.Put: %v request entry found", entry.Key.Log()))
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chunk.SData = entry.SData
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chunk.Size = entry.Size
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} else {
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log.Trace(fmt.Sprintf("DPA.Put: %v chunk already known", entry.Key.Log()))
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return
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}
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// from this point on the storage logic is the same with network storage requests
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log.Trace(fmt.Sprintf("DPA.Put %v: %v", self.n, chunk.Key.Log()))
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self.n++
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self.netStore.Put(chunk)
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}
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// Close chunk store
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func (self *dpaChunkStore) Close() {}
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