Mutable Resources Scratch Pad

readme.md

Instructions

1. In a new project directory you create, copypasta the main.go file.
2. Checkout the network rewrite branch of ethersphere/go-ethereum.
3. Then, add the Append function to the bottom of swarm/storage/filestore.go
4. run main.go

Append.go

// Add this function to the bottom of swarm/storage/filestore.go

func (f *FileStore) Append(addr Address, data io.Reader, toEncrypt bool) (newAddr Address, wait func(), err error) {
	putter := NewHasherStore(f.ChunkStore, f.hashFunc, toEncrypt)
	return PyramidAppend(addr, data, putter, putter)
}

main.go

package main

import (
    "bytes"
    "fmt"
    "github.com/ethereum/go-ethereum/swarm/storage"
    "github.com/ethereum/go-ethereum/log"
    "os"
    "github.com/ethereum/go-ethereum/swarm/storage/mru"
    "github.com/ethereum/go-ethereum/crypto"
    "context"
    "math/big"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/common"
    "time"
    "io/ioutil"
    "io"
)

type fakeBackend struct {
    blocknumber int64
}

func(f *fakeBackend) HeaderByNumber(context context.Context, name string, bigblock *big.Int) (*types.Header, error){
    f.blocknumber++
    return &types.Header{
        Number: big.NewInt(f.blocknumber),
    }, nil
}

type owner bool

func (o *owner) ValidateOwner(name string, address common.Address) (bool, error) {
    return true, nil
}


func main() {
    setupLogging()

    // Create Dummy Handler Parameters
    mruParams := defaultHandlerParams()
    mruHandler, err := mru.NewHandler(mruParams)
    if err != nil {
        panic("mruHandler Error!")
    }

    // Setup a LocalStore & NetStore for Handler
    dir, err := ioutil.TempDir("", "mru")
    if err != nil {
        panic("dir Error!")
    }
    defer os.RemoveAll(dir)

    localStoreParams := storage.NewDefaultLocalStoreParams()
    localStoreParams.Init(dir)
    localStore, err := storage.NewLocalStore(localStoreParams, nil)
    if err != nil {
        panic("localStore Error!")
    }
    netStore := storage.NewNetStore(localStore, nil)

    mruHandler.SetStore(netStore)

    // 💪 Create a new root entry for a Mutable Resource
    ctx, cancel := context.WithTimeout(context.Background(), time.Second)
    defer cancel()
    mruAddr, _, err := mruHandler.New(ctx, "awesomemru.eth", uint64(2))
    if err != nil {
        panic("mruHandler Errors!")
    }

    // 👀 print the address of the mutable resource root
    fmt.Printf("mru Root Addr = %s\n", mruAddr)


    // Create fileStore
    mapStore := storage.NewMapChunkStore()
    fileStoreParams := storage.NewFileStoreParams()
    fileStore := storage.NewFileStore(mapStore, fileStoreParams)

    // Create demoData to store
    demoData := bytes.NewBufferString("Testing 1234")

    // Persist demoData
    addr, wait, err := fileStore.Store(demoData, int64(demoData.Len()), false)
    if err != nil {
        panic("Store Error")
    }
    wait()

    // print the address of our persisted data
    fmt.Printf("persisted data addr = %s\n", addr)
    //chunk2, err := fileStore.Get(addr)
    //fmt.Printf("fileStore chunk = %s\n", chunk2)

    // print demoData before modifying it
    demoData.Reset()
    demoData.WriteString("567")
    //fmt.Printf("demoData = %s\n", demoData.Bytes())

    newAddr, wait, err := fileStore.Append(addr, demoData, false)
    if err != nil {
        panic("Append Error!")
    }
    wait()

    fmt.Printf("Appended data Address= %s\n", newAddr)
    // chunk, err := fileStore.Get(newAddr)
    // fmt.Printf("fileStore chunk = %s\n", chunk)

    // Retrieve the appended data to display it.
    reader, _ := fileStore.Retrieve(newAddr)
    quitC := make(chan bool)
    size, err := reader.Size(quitC)
    if err != nil {
        panic("reader.Size Error")
    }

    s := make([]byte, size)
    _, err = reader.Read(s)
    if err != io.EOF {
        panic("Read Error!")
    }

    fmt.Printf("🔴 Appended Data: %v \n", string(s))

    ctx, cancel = context.WithCancel(context.Background())
    defer cancel()
    mruAddr2, err := mruHandler.Update(ctx, "awesomemru.eth", newAddr)
    if err != nil {
        panic("Oh mruAddr2!")
    }
    fmt.Printf("mruAddr2 = %s\n", mruAddr2)

    // My hypothesis is that this fails because the block height hasn't progressed to be able to represent the update.
    // since we've essentially stubbed out our backend.
    addr3, data, err :=mruHandler.GetContent("awesomemru.eth")
    if err != nil {
        fmt.Printf("err = %s\n", err)
        panic("Oh mruAddr2!")
    }
    fmt.Printf("addr3 = %s\n", addr3)
    fmt.Printf("data = %s\n", data)
}

func defaultHandlerParams() (*mru.HandlerParams) {
    privateKey, err := crypto.GenerateKey()
    if err != nil {
        panic("Oh No GenerateKey!")
    }
    qMaxPeriods := &mru.LookupParams{}
    signer := &mru.GenericSigner{PrivKey: privateKey}
    headerGetter := &fakeBackend{}
    var ownerValidator owner
    mruParams := &mru.HandlerParams{
        qMaxPeriods,
        signer,
        headerGetter,
        &ownerValidator,
    }
    return mruParams
}

func setupLogging() {
    // setup Logging
    hs := log.StreamHandler(os.Stderr, log.TerminalFormat(true))
    hf := log.LvlFilterHandler(log.LvlTrace, hs)
    h := log.CallerFileHandler(hf)
    log.Root().SetHandler(h)
}