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core/evm: less iteration in blockhash (#20589) 

* core/vm/runtime: add test for blockhash

* core/evm: less iteration in blockhash

* core/vm/runtime: nitpickfix

Co-authored-by: Péter Szilágyi <peterke@gmail.com>
This commit is contained in:
Martin Holst Swende 2020-02-04 11:32:31 +01:00 committed by GitHub
parent 33791dbeb5
commit 058a4ac5f1
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 136 additions and 17 deletions
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32
core/evm.go
View File

@ -60,24 +60,32 @@ func NewEVMContext(msg Message, header *types.Header, chain ChainContext, author
// GetHashFn returns a GetHashFunc which retrieves header hashes by number
func GetHashFn(ref *types.Header, chain ChainContext) func(n uint64) common.Hash {
var cache map[uint64]common.Hash
// Cache will initially contain [refHash.parent],
// Then fill up with [refHash.p, refHash.pp, refHash.ppp, ...]
var cache []common.Hash
return func(n uint64) common.Hash {
// If there's no hash cache yet, make one
if cache == nil {
cache = map[uint64]common.Hash{
ref.Number.Uint64() - 1: ref.ParentHash,
if len(cache) == 0 {
cache = append(cache, ref.ParentHash)
}
if idx := ref.Number.Uint64() - n - 1; idx < uint64(len(cache)) {
return cache[idx]
}
// Try to fulfill the request from the cache
if hash, ok := cache[n]; ok {
return hash
// No luck in the cache, but we can start iterating from the last element we already know
lastKnownHash := cache[len(cache)-1]
lastKnownNumber := ref.Number.Uint64() - uint64(len(cache))
for {
header := chain.GetHeader(lastKnownHash, lastKnownNumber)
if header == nil {
break
}
// Not cached, iterate the blocks and cache the hashes
for header := chain.GetHeader(ref.ParentHash, ref.Number.Uint64()-1); header != nil; header = chain.GetHeader(header.ParentHash, header.Number.Uint64()-1) {
cache[header.Number.Uint64()-1] = header.ParentHash
if n == header.Number.Uint64()-1 {
return header.ParentHash
cache = append(cache, header.ParentHash)
lastKnownHash = header.ParentHash
lastKnownNumber = header.Number.Uint64() - 1
if n == lastKnownNumber {
return lastKnownHash
}
}
return common.Hash{}

4
core/vm/runtime/env.go
View File

@ -17,7 +17,6 @@
package runtime
import (
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core"
"github.com/ethereum/go-ethereum/core/vm"
)
@ -26,8 +25,7 @@ func NewEnv(cfg *Config) *vm.EVM {
context := vm.Context{
CanTransfer: core.CanTransfer,
Transfer: core.Transfer,
GetHash: func(uint64) common.Hash { return common.Hash{} },
GetHash: cfg.GetHashFn,
Origin: cfg.Origin,
Coinbase: cfg.Coinbase,
BlockNumber: cfg.BlockNumber,

113
core/vm/runtime/runtime_test.go
View File

@ -23,8 +23,11 @@ import (
"github.com/ethereum/go-ethereum/accounts/abi"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/consensus"
"github.com/ethereum/go-ethereum/core"
"github.com/ethereum/go-ethereum/core/rawdb"
"github.com/ethereum/go-ethereum/core/state"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/core/vm"
"github.com/ethereum/go-ethereum/params"
)
@ -203,3 +206,113 @@ func BenchmarkEVM_CREATE2_1200(bench *testing.B) {
// initcode size 1200K, repeatedly calls CREATE2 and then modifies the mem contents
benchmarkEVM_Create(bench, "5b5862124f80600080f5600152600056")
}
func fakeHeader(n uint64, parentHash common.Hash) *types.Header {
header := types.Header{
Coinbase: common.HexToAddress("0x00000000000000000000000000000000deadbeef"),
Number: big.NewInt(int64(n)),
ParentHash: parentHash,
Time: 1000,
Nonce: types.BlockNonce{0x1},
Extra: []byte{},
Difficulty: big.NewInt(0),
GasLimit: 100000,
}
return &header
}
type dummyChain struct {
counter int
}
// Engine retrieves the chain's consensus engine.
func (d *dummyChain) Engine() consensus.Engine {
return nil
}
// GetHeader returns the hash corresponding to their hash.
func (d *dummyChain) GetHeader(h common.Hash, n uint64) *types.Header {
d.counter++
parentHash := common.Hash{}
s := common.LeftPadBytes(big.NewInt(int64(n-1)).Bytes(), 32)
copy(parentHash[:], s)
//parentHash := common.Hash{byte(n - 1)}
//fmt.Printf("GetHeader(%x, %d) => header with parent %x\n", h, n, parentHash)
return fakeHeader(n, parentHash)
}
// TestBlockhash tests the blockhash operation. It's a bit special, since it internally
// requires access to a chain reader.
func TestBlockhash(t *testing.T) {
// Current head
n := uint64(1000)
parentHash := common.Hash{}
s := common.LeftPadBytes(big.NewInt(int64(n-1)).Bytes(), 32)
copy(parentHash[:], s)
header := fakeHeader(n, parentHash)
// This is the contract we're using. It requests the blockhash for current num (should be all zeroes),
// then iteratively fetches all blockhashes back to n-260.
// It returns
// 1. the first (should be zero)
// 2. the second (should be the parent hash)
// 3. the last non-zero hash
// By making the chain reader return hashes which correlate to the number, we can
// verify that it obtained the right hashes where it should
/*
pragma solidity ^0.5.3;
contract Hasher{
function test() public view returns (bytes32, bytes32, bytes32){
uint256 x = block.number;
bytes32 first;
bytes32 last;
bytes32 zero;
zero = blockhash(x); // Should be zeroes
first = blockhash(x-1);
for(uint256 i = 2 ; i < 260; i++){
bytes32 hash = blockhash(x - i);
if (uint256(hash) != 0){
last = hash;
}
}
return (zero, first, last);
}
}
*/
// The contract above
data := common.Hex2Bytes("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")
// The method call to 'test()'
input := common.Hex2Bytes("f8a8fd6d")
chain := &dummyChain{}
ret, _, err := Execute(data, input, &Config{
GetHashFn: core.GetHashFn(header, chain),
BlockNumber: new(big.Int).Set(header.Number),
})
if err != nil {
t.Fatalf("expected no error, got %v", err)
}
if len(ret) != 96 {
t.Fatalf("expected returndata to be 96 bytes, got %d", len(ret))
}
zero := new(big.Int).SetBytes(ret[0:32])
first := new(big.Int).SetBytes(ret[32:64])
last := new(big.Int).SetBytes(ret[64:96])
if zero.BitLen() != 0 {
t.Fatalf("expected zeroes, got %x", ret[0:32])
}
if first.Uint64() != 999 {
t.Fatalf("second block should be 999, got %d (%x)", first, ret[32:64])
}
if last.Uint64() != 744 {
t.Fatalf("last block should be 744, got %d (%x)", last, ret[64:96])
}
if exp, got := 255, chain.counter; exp != got {
t.Errorf("suboptimal; too much chain iteration, expected %d, got %d", exp, got)
}
}