From 5f8322c964a5b43c8ec8684af2e5ccb96d153af0 Mon Sep 17 00:00:00 2001
From: Gary Rong <garyrong0905@gmail.com>
Date: Wed, 27 Nov 2024 16:18:23 +0800
Subject: [PATCH] core/state: remove Copy function

---
 core/state/reader.go  | 37 -------------------------------------
 core/state/statedb.go |  3 ++-
 2 files changed, 2 insertions(+), 38 deletions(-)

diff --git a/core/state/reader.go b/core/state/reader.go
index 85842adde8..f86eb71e84 100644
--- a/core/state/reader.go
+++ b/core/state/reader.go
@@ -18,7 +18,6 @@ package state
 
 import (
 	"errors"
-	"maps"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -47,9 +46,6 @@ type Reader interface {
 	// - Returns an error only if an unexpected issue occurs
 	// - The returned storage slot is safe to modify after the call
 	Storage(addr common.Address, slot common.Hash) (common.Hash, error)
-
-	// Copy returns a deep-copied state reader.
-	Copy() Reader
 }
 
 // stateReader wraps a database state reader.
@@ -123,14 +119,6 @@ func (r *stateReader) Storage(addr common.Address, key common.Hash) (common.Hash
 	return value, nil
 }
 
-// Copy implements Reader, returning a deep-copied snap reader.
-func (r *stateReader) Copy() Reader {
-	return &stateReader{
-		reader: r.reader,
-		buff:   crypto.NewKeccakState(),
-	}
-}
-
 // trieReader implements the Reader interface, providing functions to access
 // state from the referenced trie.
 type trieReader struct {
@@ -227,22 +215,6 @@ func (r *trieReader) Storage(addr common.Address, key common.Hash) (common.Hash,
 	return value, nil
 }
 
-// Copy implements Reader, returning a deep-copied trie reader.
-func (r *trieReader) Copy() Reader {
-	tries := make(map[common.Address]Trie)
-	for addr, tr := range r.subTries {
-		tries[addr] = mustCopyTrie(tr)
-	}
-	return &trieReader{
-		root:     r.root,
-		db:       r.db,
-		buff:     crypto.NewKeccakState(),
-		mainTrie: mustCopyTrie(r.mainTrie),
-		subRoots: maps.Clone(r.subRoots),
-		subTries: tries,
-	}
-}
-
 // multiReader is the aggregation of a list of Reader interface, providing state
 // access by leveraging all readers. The checking priority is determined by the
 // position in the reader list.
@@ -297,12 +269,3 @@ func (r *multiReader) Storage(addr common.Address, slot common.Hash) (common.Has
 	}
 	return common.Hash{}, errors.Join(errs...)
 }
-
-// Copy implementing Reader interface, returning a deep-copied state reader.
-func (r *multiReader) Copy() Reader {
-	var readers []Reader
-	for _, reader := range r.readers {
-		readers = append(readers, reader.Copy())
-	}
-	return &multiReader{readers: readers}
-}
diff --git a/core/state/statedb.go b/core/state/statedb.go
index 9cc91c9332..b0603db7f0 100644
--- a/core/state/statedb.go
+++ b/core/state/statedb.go
@@ -650,10 +650,11 @@ func (s *StateDB) CreateContract(addr common.Address) {
 // Snapshots of the copied state cannot be applied to the copy.
 func (s *StateDB) Copy() *StateDB {
 	// Copy all the basic fields, initialize the memory ones
+	reader, _ := s.db.Reader(s.originalRoot) // impossible to fail
 	state := &StateDB{
 		db:                   s.db,
 		trie:                 mustCopyTrie(s.trie),
-		reader:               s.reader.Copy(),
+		reader:               reader,
 		originalRoot:         s.originalRoot,
 		stateObjects:         make(map[common.Address]*stateObject, len(s.stateObjects)),
 		stateObjectsDestruct: make(map[common.Address]*stateObject, len(s.stateObjectsDestruct)),