package fetcher
import (
"encoding/binary"
"errors"
"math/big"
"sync/atomic"
"testing"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
)
var (
knownHash = common.Hash{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}
unknownHash = common.Hash{2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2}
bannedHash = common.Hash{3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3}
genesis = createBlock(1, common.Hash{}, knownHash)
)
// idCounter is used by the createHashes method the generate deterministic but unique hashes
var idCounter = int64(2) // #1 is the genesis block
// createHashes generates a batch of hashes rooted at a specific point in the chain.
func createHashes(amount int, root common.Hash) (hashes []common.Hash) {
hashes = make([]common.Hash, amount+1)
hashes[len(hashes)-1] = root
for i := 0; i < len(hashes)-1; i++ {
binary.BigEndian.PutUint64(hashes[i][:8], uint64(idCounter))
idCounter++
}
return
}
// createBlock assembles a new block at the given chain height.
func createBlock(i int, parent, hash common.Hash) *types.Block {
header := &types.Header{Number: big.NewInt(int64(i))}
block := types.NewBlockWithHeader(header)
block.HeaderHash = hash
block.ParentHeaderHash = parent
return block
}
// copyBlock makes a deep copy of a block suitable for local modifications.
func copyBlock(block *types.Block) *types.Block {
return createBlock(int(block.Number().Int64()), block.ParentHeaderHash, block.HeaderHash)
}
// createBlocksFromHashes assembles a collection of blocks, each having a correct
// place in the given hash chain.
func createBlocksFromHashes(hashes []common.Hash) map[common.Hash]*types.Block {
blocks := make(map[common.Hash]*types.Block)
for i := 0; i < len(hashes); i++ {
parent := knownHash
if i < len(hashes)-1 {
parent = hashes[i+1]
}
blocks[hashes[i]] = createBlock(len(hashes)-i, parent, hashes[i])
}
return blocks
}
// fetcherTester is a test simulator for mocking out local block chain.
type fetcherTester struct {
fetcher *Fetcher
ownHashes []common.Hash // Hash chain belonging to the tester
ownBlocks map[common.Hash]*types.Block // Blocks belonging to the tester
}
// newTester creates a new fetcher test mocker.
func newTester() *fetcherTester {
tester := &fetcherTester{
ownHashes: []common.Hash{knownHash},
ownBlocks: map[common.Hash]*types.Block{knownHash: genesis},
}
tester.fetcher = New(tester.hasBlock, tester.importBlock)
tester.fetcher.Start()
return tester
}
// hasBlock checks if a block is pres ent in the testers canonical chain.
func (f *fetcherTester) hasBlock(hash common.Hash) bool {
_, ok := f.ownBlocks[hash]
return ok
}
// importBlock injects a new blocks into the simulated chain.
func (f *fetcherTester) importBlock(peer string, block *types.Block) error {
if _, ok := f.ownBlocks[block.ParentHash()]; !ok {
return errors.New("unknown parent")
}
f.ownHashes = append(f.ownHashes, block.Hash())
f.ownBlocks[block.Hash()] = block
return nil
}
// peerFetcher retrieves a fetcher associated with a simulated peer.
func (f *fetcherTester) makeFetcher(blocks map[common.Hash]*types.Block) blockRequesterFn {
// Copy all the blocks to ensure they are not tampered with
closure := make(map[common.Hash]*types.Block)
for hash, block := range blocks {
closure[hash] = copyBlock(block)
}
// Create a function that returns blocks from the closure
return func(hashes []common.Hash) error {
// Gather the blocks to return
blocks := make([]*types.Block, 0, len(hashes))
for _, hash := range hashes {
if block, ok := closure[hash]; ok {
blocks = append(blocks, block)
}
}
// Return on a new thread
go f.fetcher.Filter(blocks)
return nil
}
}
// Tests that a fetcher accepts block announcements and initiates retrievals for
// them, successfully importing into the local chain.
func TestSequentialAnnouncements(t *testing.T) {
// Create a chain of blocks to import
targetBlocks := 24
hashes := createHashes(targetBlocks, knownHash)
blocks := createBlocksFromHashes(hashes)
tester := newTester()
fetcher := tester.makeFetcher(blocks)
// Iteratively announce blocks until all are imported
for i := len(hashes) - 1; i >= 0; i-- {
tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher)
time.Sleep(50 * time.Millisecond)
}
if imported := len(tester.ownBlocks); imported != targetBlocks+1 {
t.Fatalf("synchronised block mismatch: have %v, want %v", imported, targetBlocks+1)
}
}
// Tests that if blocks are announced by multiple peers (or even the same buggy
// peer), they will only get downloaded at most once.
func TestConcurrentAnnouncements(t *testing.T) {
// Create a chain of blocks to import
targetBlocks := 24
hashes := createHashes(targetBlocks, knownHash)
blocks := createBlocksFromHashes(hashes)
// Assemble a tester with a built in counter for the requests
tester := newTester()
fetcher := tester.makeFetcher(blocks)
counter := uint32(0)
wrapper := func(hashes []common.Hash) error {
atomic.AddUint32(&counter, uint32(len(hashes)))
return fetcher(hashes)
}
// Iteratively announce blocks until all are imported
for i := len(hashes) - 1; i >= 0; i-- {
tester.fetcher.Notify("first", hashes[i], time.Now().Add(-arriveTimeout), wrapper)
tester.fetcher.Notify("second", hashes[i], time.Now().Add(-arriveTimeout+time.Millisecond), wrapper)
tester.fetcher.Notify("second", hashes[i], time.Now().Add(-arriveTimeout-time.Millisecond), wrapper)
time.Sleep(50 * time.Millisecond)
}
if imported := len(tester.ownBlocks); imported != targetBlocks+1 {
t.Fatalf("synchronised block mismatch: have %v, want %v", imported, targetBlocks+1)
}
// Make sure no blocks were retrieved twice
if int(counter) != targetBlocks {
t.Fatalf("retrieval count mismatch: have %v, want %v", counter, targetBlocks)
}
}
// Tests that announcements arriving while a previous is being fetched still
// results in a valid import.
func TestOverlappingAnnouncements(t *testing.T) {
// Create a chain of blocks to import
targetBlocks := 24
hashes := createHashes(targetBlocks, knownHash)
blocks := createBlocksFromHashes(hashes)
tester := newTester()
fetcher := tester.makeFetcher(blocks)
// Iteratively announce blocks, but overlap them continuously
delay, overlap := 50*time.Millisecond, time.Duration(5)
for i := len(hashes) - 1; i >= 0; i-- {
tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout+overlap*delay), fetcher)
time.Sleep(delay)
}
time.Sleep(overlap * delay)
if imported := len(tester.ownBlocks); imported != targetBlocks+1 {
t.Fatalf("synchronised block mismatch: have %v, want %v", imported, targetBlocks+1)
}
}
