From 99a495501c1e7b4614ed55ec7938b86fe980e0f8 Mon Sep 17 00:00:00 2001
From: Martin Holst Swende <martin@swende.se>
Date: Fri, 20 Mar 2020 10:57:12 +0100
Subject: [PATCH] squashmelater: add snaphash verifier function

---
 cmd/geth/chaincmd.go                     | 19 +++++---
 core/state/snapshot/hextrie_generator.go | 62 ++++++++++++++++++++++++
 2 files changed, 74 insertions(+), 7 deletions(-)

diff --git a/cmd/geth/chaincmd.go b/cmd/geth/chaincmd.go
index 219996d466..e04a4fa5c0 100644
--- a/cmd/geth/chaincmd.go
+++ b/cmd/geth/chaincmd.go
@@ -18,6 +18,7 @@ package main
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"github.com/ethereum/go-ethereum/core/state/snapshot"
 	"os"
@@ -616,14 +617,18 @@ func snapToHash(ctx *cli.Context) error {
 	if err != nil {
 		return fmt.Errorf("Could not create iterator for root %x: %v", root, err)
 	}
-	generatedRoot := snapshot.GenerateTrieRoot(it)
-	if err := it.Error(); err != nil {
-		fmt.Printf("Iterator error: %v\n", it.Error())
+	ollKorrekt := snapshot.CrosscheckTriehasher(it, 0, 10000)
+	//generatedRoot := snapshot.GenerateTrieRoot(it)
+	//if err := it.Error(); err != nil {
+	//	fmt.Printf("Iterator error: %v\n", it.Error())
+	//}
+	//if root != generatedRoot {
+	//	return fmt.Errorf("Wrong hash generated, expected %x, got %x", root, generatedRoot[:])
+	//}
+	if !ollKorrekt {
+		return errors.New("Computer says No, @gballet\n...come on man, fix me already!")
 	}
-	if root != generatedRoot {
-		return fmt.Errorf("Wrong hash generated, expected %x, got %x", root, generatedRoot[:])
-	}
-	log.Info("Generation done", "root", generatedRoot)
+	//log.Info("Generation done", "root", generatedRoot)
 	return nil
 }
 
diff --git a/core/state/snapshot/hextrie_generator.go b/core/state/snapshot/hextrie_generator.go
index d882bd6cb2..b7ab83e8b5 100644
--- a/core/state/snapshot/hextrie_generator.go
+++ b/core/state/snapshot/hextrie_generator.go
@@ -39,6 +39,10 @@ func GenerateTrieRoot(it AccountIterator) common.Hash {
 	return generateTrieRoot(it, StdGenerate)
 }
 
+func CrosscheckTriehasher(it AccountIterator, begin,end int) bool {
+	return verifyHasher(it, StackGenerate, begin, end)
+}
+
 func generateTrieRoot(it AccountIterator, generatorFn trieGeneratorFn) common.Hash {
 	var (
 		in  = make(chan leaf)        // chan to pass leaves
@@ -73,6 +77,64 @@ func generateTrieRoot(it AccountIterator, generatorFn trieGeneratorFn) common.Ha
 	return result
 }
 
+func verifyHasher(it AccountIterator, generatorFn trieGeneratorFn, begin, end int) bool {
+	var (
+		referenceFn = StdGenerate
+
+		inA  = make(chan leaf)        // chan to pass leaves
+		outA = make(chan common.Hash) // chan to collect result
+
+		inB  = make(chan leaf)        // chan to pass leaves
+		outB = make(chan common.Hash) // chan to collect result
+		wg   sync.WaitGroup
+	)
+	wg.Add(2)
+	go func() {
+		referenceFn(inA, outA)
+		wg.Done()
+	}()
+	go func() {
+		generatorFn(inB, outB)
+		wg.Done()
+	}()
+	// Feed leaves
+	start := time.Now()
+	logged := time.Now()
+	accounts := 0
+	for it.Next() {
+		if accounts < begin {
+			accounts++
+			continue
+		}
+		if end > 0 && accounts > end {
+			break
+		}
+		slimData := it.Account()
+		fullData := SlimToFull(slimData)
+		l := leaf{it.Hash(), fullData}
+		inA <- l
+		inB <- l
+		accounts++
+		if time.Since(logged) > 8*time.Second {
+			log.Info("Generating trie hash from snapshot",
+				"at", l.key, "accounts", accounts, "elapsed", time.Since(start))
+			logged = time.Now()
+		}
+	}
+	close(inA)
+	close(inB)
+	resultA := <-outA
+	resultB := <-outB
+	log.Info("Generated trie hash from snapshot", "accounts", accounts,
+		"elapsed", time.Since(start),
+		"start", begin,
+		"end", end,
+		"exp", resultA,
+		"got", resultB)
+	wg.Wait()
+	return resultA == resultB
+}
+
 // StackGenerate is a hexary trie builder which is built from the bottom-up as
 // keys are added.
 func StackGenerate(in chan (leaf), out chan (common.Hash)) {