core: separate and contain POW verifier, extensive tests

1 files changed, 233 insertions, 0 deletions

diff --git a/core/chain_pow_test.go b/core/chain_pow_test.go
new file mode 100644
index 000000000..80c6a1cc0
--- /dev/null
+++ b/core/chain_pow_test.go
@@ -0,0 +1,233 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package core
+
+import (
+	"math/big"
+	"runtime"
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/pow"
+)
+
+// failPow is a non-validating proof of work implementation, that returns true
+// from Verify for all but one block.
+type failPow struct {
+	failing uint64
+}
+
+func (pow failPow) Search(pow.Block, <-chan struct{}) (uint64, []byte) {
+	return 0, nil
+}
+func (pow failPow) Verify(block pow.Block) bool { return block.NumberU64() != pow.failing }
+func (pow failPow) GetHashrate() int64          { return 0 }
+func (pow failPow) Turbo(bool)                  {}
+
+// delayedPow is a non-validating proof of work implementation, that returns true
+// from Verify for all blocks, but delays them the configured amount of time.
+type delayedPow struct {
+	delay time.Duration
+}
+
+func (pow delayedPow) Search(pow.Block, <-chan struct{}) (uint64, []byte) {
+	return 0, nil
+}
+func (pow delayedPow) Verify(block pow.Block) bool { time.Sleep(pow.delay); return true }
+func (pow delayedPow) GetHashrate() int64          { return 0 }
+func (pow delayedPow) Turbo(bool)                  {}
+
+// Tests that simple POW verification works, for both good and bad blocks.
+func TestPowVerification(t *testing.T) {
+	// Create a simple chain to verify
+	var (
+		testdb, _ = ethdb.NewMemDatabase()
+		genesis   = GenesisBlockForTesting(testdb, common.Address{}, new(big.Int))
+		blocks    = GenerateChain(genesis, testdb, 8, nil)
+	)
+	headers := make([]*types.Header, len(blocks))
+	for i, block := range blocks {
+		headers[i] = block.Header()
+	}
+	// Run the POW checker for blocks one-by-one, checking for both valid and invalid nonces
+	for i := 0; i < len(blocks); i++ {
+		for j, full := range []bool{true, false} {
+			for k, valid := range []bool{true, false} {
+				var results <-chan nonceCheckResult
+
+				switch {
+				case full && valid:
+					_, results = verifyNoncesFromBlocks(FakePow{}, []*types.Block{blocks[i]})
+				case full && !valid:
+					_, results = verifyNoncesFromBlocks(failPow{blocks[i].NumberU64()}, []*types.Block{blocks[i]})
+				case !full && valid:
+					_, results = verifyNoncesFromHeaders(FakePow{}, []*types.Header{headers[i]})
+				case !full && !valid:
+					_, results = verifyNoncesFromHeaders(failPow{headers[i].Number.Uint64()}, []*types.Header{headers[i]})
+				}
+				// Wait for the verification result
+				select {
+				case result := <-results:
+					if result.index != 0 {
+						t.Errorf("test %d.%d.%d: invalid index: have %d, want 0", i, j, k, result.index)
+					}
+					if result.valid != valid {
+						t.Errorf("test %d.%d.%d: validity mismatch: have %v, want %v", i, j, k, result.valid, valid)
+					}
+				case <-time.After(time.Second):
+					t.Fatalf("test %d.%d.%d: verification timeout", i, j, k)
+				}
+				// Make sure no more data is returned
+				select {
+				case result := <-results:
+					t.Fatalf("test %d.%d.%d: unexpected result returned: %v", i, j, k, result)
+				case <-time.After(25 * time.Millisecond):
+				}
+			}
+		}
+	}
+}
+
+// Tests that concurrent POW verification works, for both good and bad blocks.
+func TestPowConcurrentVerification2(t *testing.T)  { testPowConcurrentVerification(t, 2) }
+func TestPowConcurrentVerification8(t *testing.T)  { testPowConcurrentVerification(t, 8) }
+func TestPowConcurrentVerification32(t *testing.T) { testPowConcurrentVerification(t, 32) }
+
+func testPowConcurrentVerification(t *testing.T, threads int) {
+	// Create a simple chain to verify
+	var (
+		testdb, _ = ethdb.NewMemDatabase()
+		genesis   = GenesisBlockForTesting(testdb, common.Address{}, new(big.Int))
+		blocks    = GenerateChain(genesis, testdb, 8, nil)
+	)
+	headers := make([]*types.Header, len(blocks))
+	for i, block := range blocks {
+		headers[i] = block.Header()
+	}
+	// Set the number of threads to verify on
+	old := runtime.GOMAXPROCS(threads)
+	defer runtime.GOMAXPROCS(old)
+
+	// Run the POW checker for the entire block chain at once both for a valid and
+	// also an invalid chain (enough if one is invalid, last but one (arbitrary)).
+	for i, full := range []bool{true, false} {
+		for j, valid := range []bool{true, false} {
+			var results <-chan nonceCheckResult
+
+			switch {
+			case full && valid:
+				_, results = verifyNoncesFromBlocks(FakePow{}, blocks)
+			case full && !valid:
+				_, results = verifyNoncesFromBlocks(failPow{uint64(len(blocks) - 1)}, blocks)
+			case !full && valid:
+				_, results = verifyNoncesFromHeaders(FakePow{}, headers)
+			case !full && !valid:
+				_, results = verifyNoncesFromHeaders(failPow{uint64(len(headers) - 1)}, headers)
+			}
+			// Wait for all the verification results
+			checks := make(map[int]bool)
+			for k := 0; k < len(blocks); k++ {
+				select {
+				case result := <-results:
+					if _, ok := checks[result.index]; ok {
+						t.Fatalf("test %d.%d.%d: duplicate results for %d", i, j, k, result.index)
+					}
+					if result.index < 0 || result.index >= len(blocks) {
+						t.Fatalf("test %d.%d.%d: result %d out of bounds [%d, %d]", i, j, k, result.index, 0, len(blocks)-1)
+					}
+					checks[result.index] = result.valid
+
+				case <-time.After(time.Second):
+					t.Fatalf("test %d.%d.%d: verification timeout", i, j, k)
+				}
+			}
+			// Check nonce check validity
+			for k := 0; k < len(blocks); k++ {
+				want := valid || (k != len(blocks)-2) // We chose the last but one nonce in the chain to fail
+				if checks[k] != want {
+					t.Errorf("test %d.%d.%d: validity mismatch: have %v, want %v", i, j, k, checks[k], want)
+				}
+			}
+			// Make sure no more data is returned
+			select {
+			case result := <-results:
+				t.Fatalf("test %d.%d: unexpected result returned: %v", i, j, result)
+			case <-time.After(25 * time.Millisecond):
+			}
+		}
+	}
+}
+
+// Tests that aborting a POW validation indeed prevents further checks from being
+// run, as well as checks that no left-over goroutines are leaked.
+func TestPowConcurrentAbortion2(t *testing.T)  { testPowConcurrentAbortion(t, 2) }
+func TestPowConcurrentAbortion8(t *testing.T)  { testPowConcurrentAbortion(t, 8) }
+func TestPowConcurrentAbortion32(t *testing.T) { testPowConcurrentAbortion(t, 32) }
+
+func testPowConcurrentAbortion(t *testing.T, threads int) {
+	// Create a simple chain to verify
+	var (
+		testdb, _ = ethdb.NewMemDatabase()
+		genesis   = GenesisBlockForTesting(testdb, common.Address{}, new(big.Int))
+		blocks    = GenerateChain(genesis, testdb, 1024, nil)
+	)
+	headers := make([]*types.Header, len(blocks))
+	for i, block := range blocks {
+		headers[i] = block.Header()
+	}
+	// Set the number of threads to verify on
+	old := runtime.GOMAXPROCS(threads)
+	defer runtime.GOMAXPROCS(old)
+
+	// Run the POW checker for the entire block chain at once
+	for i, full := range []bool{true, false} {
+		var abort chan<- struct{}
+		var results <-chan nonceCheckResult
+
+		// Start the verifications and immediately abort
+		if full {
+			abort, results = verifyNoncesFromBlocks(delayedPow{time.Millisecond}, blocks)
+		} else {
+			abort, results = verifyNoncesFromHeaders(delayedPow{time.Millisecond}, headers)
+		}
+		close(abort)
+
+		// Deplete the results channel
+		verified := make(map[int]struct{})
+		for depleted := false; !depleted; {
+			select {
+			case result := <-results:
+				verified[result.index] = struct{}{}
+			case <-time.After(50 * time.Millisecond):
+				depleted = true
+			}
+		}
+		// Check that abortion was honored by not processing too many POWs
+		if len(verified) > 2*threads {
+			t.Errorf("test %d: verification count too large: have %d, want below %d", i, len(verified), 2*threads)
+		}
+		// Check that there are no gaps in the results
+		for j := 0; j < len(verified); j++ {
+			if _, ok := verified[j]; !ok {
+				t.Errorf("test %d.%d: gap found in verification results", i, j)
+			}
+		}
+	}
+}