From 058a4ac5f13f49a67d4b28111dd0ad3eea387c8c Mon Sep 17 00:00:00 2001 From: Martin Holst Swende Date: Tue, 4 Feb 2020 11:32:31 +0100 Subject: [PATCH] core/evm: less iteration in blockhash (#20589) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit * core/vm/runtime: add test for blockhash * core/evm: less iteration in blockhash * core/vm/runtime: nitpickfix Co-authored-by: Péter Szilágyi --- core/evm.go | 34 ++++++---- core/vm/runtime/env.go | 4 +- core/vm/runtime/runtime_test.go | 113 ++++++++++++++++++++++++++++++++ 3 files changed, 135 insertions(+), 16 deletions(-) diff --git a/core/evm.go b/core/evm.go index b654bbd479..8abe5a0477 100644 --- a/core/evm.go +++ b/core/evm.go @@ -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) } - // Try to fulfill the request from the cache - if hash, ok := cache[n]; ok { - return hash + if idx := ref.Number.Uint64() - n - 1; idx < uint64(len(cache)) { + return cache[idx] } - // 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 + // 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 + } + cache = append(cache, header.ParentHash) + lastKnownHash = header.ParentHash + lastKnownNumber = header.Number.Uint64() - 1 + if n == lastKnownNumber { + return lastKnownHash } } return common.Hash{} diff --git a/core/vm/runtime/env.go b/core/vm/runtime/env.go index 31c9b9cf9d..38ee448904 100644 --- a/core/vm/runtime/env.go +++ b/core/vm/runtime/env.go @@ -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, diff --git a/core/vm/runtime/runtime_test.go b/core/vm/runtime/runtime_test.go index 15f545ddca..f2d05118ce 100644 --- a/core/vm/runtime/runtime_test.go +++ b/core/vm/runtime/runtime_test.go @@ -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) + } +}