1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of OpenEthereum.

// OpenEthereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// OpenEthereum 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 General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.

//! Single account in the system.

use bytes::{Bytes, ToPretty};
use error::Error;
use ethereum_types::{Address, BigEndianHash, H256, U256};
use ethtrie::{Result as TrieResult, SecTrieDB, TrieDB, TrieFactory};
use hash::{keccak, KECCAK_EMPTY, KECCAK_NULL_RLP};
use hash_db::HashDB;
use keccak_hasher::KeccakHasher;
use kvdb::DBValue;
use lru_cache::LruCache;
use pod_account::*;
use rlp::{encode, RlpStream};
use std::{
    collections::{BTreeMap, HashMap},
    fmt,
    sync::Arc,
};
use trie::{Recorder, Trie};
use types::basic_account::BasicAccount;

use std::cell::{Cell, RefCell};

const STORAGE_CACHE_ITEMS: usize = 8192;

/// Boolean type for clean/dirty status.
#[derive(PartialEq, Eq, Clone, Copy, Debug)]
pub enum Filth {
    /// Data has not been changed.
    Clean,
    /// Data has been changed.
    Dirty,
}

/// Single account in the system.
/// Keeps track of changes to the code and storage.
/// The changes are applied in `commit_storage` and `commit_code`
pub struct Account {
    // Balance of the account.
    balance: U256,
    // Nonce of the account.
    nonce: U256,
    // Trie-backed storage.
    storage_root: H256,
    // LRU Cache of the trie-backed storage.
    // This is limited to `STORAGE_CACHE_ITEMS` recent queries
    storage_cache: RefCell<LruCache<H256, H256>>,
    // LRU Cache of the trie-backed storage for original value.
    // This is only used when the initial storage root is different compared to
    // what is in the database. That is, it is only used for new contracts.
    original_storage_cache: Option<(H256, RefCell<LruCache<H256, H256>>)>,
    // Modified storage. Accumulates changes to storage made in `set_storage`
    // Takes precedence over `storage_cache`.
    storage_changes: HashMap<H256, H256>,
    // Code hash of the account.
    code_hash: H256,
    // Size of the account code.
    code_size: Option<usize>,
    // Code cache of the account.
    code_cache: Arc<Bytes>,
    // Account code new or has been modified.
    code_filth: Filth,
    // Cached address hash.
    address_hash: Cell<Option<H256>>,
}

impl From<BasicAccount> for Account {
    fn from(basic: BasicAccount) -> Self {
        Account {
            balance: basic.balance,
            nonce: basic.nonce,
            storage_root: basic.storage_root,
            storage_cache: Self::empty_storage_cache(),
            original_storage_cache: None,
            storage_changes: HashMap::new(),
            code_hash: basic.code_hash,
            code_size: None,
            code_cache: Arc::new(vec![]),
            code_filth: Filth::Clean,
            address_hash: Cell::new(None),
        }
    }
}

impl Account {
    #[cfg(test)]
    /// General constructor.
    pub fn new(balance: U256, nonce: U256, storage: HashMap<H256, H256>, code: Bytes) -> Account {
        Account {
            balance: balance,
            nonce: nonce,
            storage_root: KECCAK_NULL_RLP,
            storage_cache: Self::empty_storage_cache(),
            original_storage_cache: None,
            storage_changes: storage,
            code_hash: keccak(&code),
            code_size: Some(code.len()),
            code_cache: Arc::new(code),
            code_filth: Filth::Dirty,
            address_hash: Cell::new(None),
        }
    }

    fn empty_storage_cache() -> RefCell<LruCache<H256, H256>> {
        RefCell::new(LruCache::new(STORAGE_CACHE_ITEMS))
    }

    /// General constructor.
    pub fn from_pod(pod: PodAccount) -> Account {
        Account {
            balance: pod.balance,
            nonce: pod.nonce,
            storage_root: KECCAK_NULL_RLP,
            storage_cache: Self::empty_storage_cache(),
            original_storage_cache: None,
            storage_changes: pod.storage.into_iter().collect(),
            code_hash: pod.code.as_ref().map_or(KECCAK_EMPTY, |c| keccak(c)),
            code_filth: Filth::Dirty,
            code_size: Some(pod.code.as_ref().map_or(0, |c| c.len())),
            code_cache: Arc::new(pod.code.map_or_else(
                || {
                    warn!("POD account with unknown code is being created! Assuming no code.");
                    vec![]
                },
                |c| c,
            )),
            address_hash: Cell::new(None),
        }
    }

    /// Create a new account with the given balance.
    pub fn new_basic(balance: U256, nonce: U256) -> Account {
        Account {
            balance: balance,
            nonce: nonce,
            storage_root: KECCAK_NULL_RLP,
            storage_cache: Self::empty_storage_cache(),
            original_storage_cache: None,
            storage_changes: HashMap::new(),
            code_hash: KECCAK_EMPTY,
            code_cache: Arc::new(vec![]),
            code_size: Some(0),
            code_filth: Filth::Clean,
            address_hash: Cell::new(None),
        }
    }

    /// Create a new account from RLP.
    pub fn from_rlp(rlp: &[u8]) -> Result<Account, Error> {
        ::rlp::decode::<BasicAccount>(rlp)
            .map(|ba| ba.into())
            .map_err(|e| e.into())
    }

    /// Create a new contract account.
    /// NOTE: make sure you use `init_code` on this before `commit`ing.
    pub fn new_contract(balance: U256, nonce: U256, original_storage_root: H256) -> Account {
        Account {
            balance: balance,
            nonce: nonce,
            storage_root: KECCAK_NULL_RLP,
            storage_cache: Self::empty_storage_cache(),
            original_storage_cache: if original_storage_root == KECCAK_NULL_RLP {
                None
            } else {
                Some((original_storage_root, Self::empty_storage_cache()))
            },
            storage_changes: HashMap::new(),
            code_hash: KECCAK_EMPTY,
            code_cache: Arc::new(vec![]),
            code_size: None,
            code_filth: Filth::Clean,
            address_hash: Cell::new(None),
        }
    }

    /// Set this account's code to the given code.
    /// NOTE: Account should have been created with `new_contract()`
    pub fn init_code(&mut self, code: Bytes) {
        self.code_hash = keccak(&code);
        self.code_cache = Arc::new(code);
        self.code_size = Some(self.code_cache.len());
        self.code_filth = Filth::Dirty;
    }

    /// Reset this account's code to the given code.
    pub fn reset_code(&mut self, code: Bytes) {
        self.init_code(code);
    }

    /// Reset this account's code and storage to given values.
    pub fn reset_code_and_storage(&mut self, code: Arc<Bytes>, storage: HashMap<H256, H256>) {
        self.code_hash = keccak(&*code);
        self.code_cache = code;
        self.code_size = Some(self.code_cache.len());
        self.code_filth = Filth::Dirty;
        self.storage_cache = Self::empty_storage_cache();
        self.storage_changes = storage;
        if self.storage_root != KECCAK_NULL_RLP {
            self.original_storage_cache = Some((self.storage_root, Self::empty_storage_cache()));
        }
        self.storage_root = KECCAK_NULL_RLP;
    }

    /// Set (and cache) the contents of the trie's storage at `key` to `value`.
    pub fn set_storage(&mut self, key: H256, value: H256) {
        self.storage_changes.insert(key, value);
    }

    /// Get (and cache) the contents of the trie's storage at `key`.
    /// Takes modified storage into account.
    pub fn storage_at(
        &self,
        db: &dyn HashDB<KeccakHasher, DBValue>,
        key: &H256,
    ) -> TrieResult<H256> {
        if let Some(value) = self.cached_storage_at(key) {
            return Ok(value);
        }
        Self::get_and_cache_storage(
            &self.storage_root,
            &mut self.storage_cache.borrow_mut(),
            db,
            key,
        )
    }

    /// Get (and cache) the contents of the trie's storage at `key`.
    /// Does not take modified storage into account.
    pub fn original_storage_at(
        &self,
        db: &dyn HashDB<KeccakHasher, DBValue>,
        key: &H256,
    ) -> TrieResult<H256> {
        if let Some(value) = self.cached_original_storage_at(key) {
            return Ok(value);
        }
        match &self.original_storage_cache {
            Some((ref original_storage_root, ref original_storage_cache)) => {
                Self::get_and_cache_storage(
                    original_storage_root,
                    &mut original_storage_cache.borrow_mut(),
                    db,
                    key,
                )
            }
            None => Self::get_and_cache_storage(
                &self.storage_root,
                &mut self.storage_cache.borrow_mut(),
                db,
                key,
            ),
        }
    }

    fn get_and_cache_storage(
        storage_root: &H256,
        storage_cache: &mut LruCache<H256, H256>,
        db: &dyn HashDB<KeccakHasher, DBValue>,
        key: &H256,
    ) -> TrieResult<H256> {
        let db = SecTrieDB::new(&db, storage_root)?;
        let panicky_decoder =
            |bytes: &[u8]| ::rlp::decode(&bytes).expect("decoding db value failed");
        let item: U256 = db
            .get_with(key.as_bytes(), panicky_decoder)?
            .unwrap_or_else(U256::zero);
        let value: H256 = BigEndianHash::from_uint(&item);
        storage_cache.insert(key.clone(), value.clone());
        Ok(value)
    }

    /// Get cached storage value if any. Returns `None` if the
    /// key is not in the cache.
    pub fn cached_storage_at(&self, key: &H256) -> Option<H256> {
        if let Some(value) = self.storage_changes.get(key) {
            return Some(value.clone());
        }
        self.cached_moved_original_storage_at(key)
    }

    /// Get cached original storage value after last state commitment. Returns `None` if the key is not in the cache.
    pub fn cached_original_storage_at(&self, key: &H256) -> Option<H256> {
        match &self.original_storage_cache {
            Some((_, ref original_storage_cache)) => original_storage_cache
                .borrow_mut()
                .get_mut(key)
                .map(|value| value.clone()),
            None => self.cached_moved_original_storage_at(key),
        }
    }

    /// Get cached original storage value since last contract creation on this address. Returns `None` if the key is not in the cache.
    fn cached_moved_original_storage_at(&self, key: &H256) -> Option<H256> {
        // If storage root is empty RLP, then early return zero value. Practically, this makes it so that if
        // `original_storage_cache` is used, then `storage_cache` will always remain empty.
        if self.storage_root == KECCAK_NULL_RLP {
            return Some(H256::default());
        }

        self.storage_cache
            .borrow_mut()
            .get_mut(key)
            .map(|value| value.clone())
    }

    /// return the balance associated with this account.
    pub fn balance(&self) -> &U256 {
        &self.balance
    }

    /// return the nonce associated with this account.
    pub fn nonce(&self) -> &U256 {
        &self.nonce
    }

    /// return the code hash associated with this account.
    pub fn code_hash(&self) -> H256 {
        self.code_hash.clone()
    }

    /// return and cache `keccak(address)`, `address` must be the address of this
    /// account.
    pub fn address_hash(&self, address: &Address) -> H256 {
        let hash = self.address_hash.get();
        hash.unwrap_or_else(|| {
            let hash = keccak(address);
            self.address_hash.set(Some(hash.clone()));
            hash
        })
    }

    /// returns the account's code. If `None` then the code cache isn't available -
    /// get someone who knows to call `note_code`.
    pub fn code(&self) -> Option<Arc<Bytes>> {
        if self.code_hash != KECCAK_EMPTY && self.code_cache.is_empty() {
            return None;
        }
        Some(self.code_cache.clone())
    }

    /// returns the account's code size. If `None` then the code cache or code size cache isn't available -
    /// get someone who knows to call `note_code`.
    pub fn code_size(&self) -> Option<usize> {
        self.code_size.clone()
    }

    #[cfg(test)]
    /// Provide a byte array which hashes to the `code_hash`. returns the hash as a result.
    pub fn note_code(&mut self, code: Bytes) -> Result<(), H256> {
        let h = keccak(&code);
        if self.code_hash == h {
            self.code_cache = Arc::new(code);
            self.code_size = Some(self.code_cache.len());
            Ok(())
        } else {
            Err(h)
        }
    }

    /// Is `code_cache` valid; such that code is going to return Some?
    pub fn is_cached(&self) -> bool {
        !self.code_cache.is_empty()
            || (self.code_cache.is_empty() && self.code_hash == KECCAK_EMPTY)
    }

    /// Provide a database to get `code_hash`. Should not be called if it is a contract without code. Returns the cached code, if successful.
    #[must_use]
    pub fn cache_code(&mut self, db: &dyn HashDB<KeccakHasher, DBValue>) -> Option<Arc<Bytes>> {
        // TODO: fill out self.code_cache;
        trace!(
            "Account::cache_code: ic={}; self.code_hash={:?}, self.code_cache={}",
            self.is_cached(),
            self.code_hash,
            self.code_cache.pretty()
        );

        if self.is_cached() {
            return Some(self.code_cache.clone());
        }

        match db.get(&self.code_hash) {
            Some(x) => {
                self.code_size = Some(x.len());
                self.code_cache = Arc::new(x.into_vec());
                Some(self.code_cache.clone())
            }
            _ => {
                warn!("Failed reverse get of {}", self.code_hash);
                None
            }
        }
    }

    /// Provide code to cache. For correctness, should be the correct code for the account.
    pub fn cache_given_code(&mut self, code: Arc<Bytes>) {
        trace!(
            "Account::cache_given_code: ic={}; self.code_hash={:?}, self.code_cache={}",
            self.is_cached(),
            self.code_hash,
            self.code_cache.pretty()
        );

        self.code_size = Some(code.len());
        self.code_cache = code;
    }

    /// Provide a database to get `code_size`. Should not be called if it is a contract without code. Returns whether
    /// the cache succeeds.
    #[must_use]
    pub fn cache_code_size(&mut self, db: &dyn HashDB<KeccakHasher, DBValue>) -> bool {
        // TODO: fill out self.code_cache;
        trace!(
            "Account::cache_code_size: ic={}; self.code_hash={:?}, self.code_cache={}",
            self.is_cached(),
            self.code_hash,
            self.code_cache.pretty()
        );
        self.code_size.is_some()
            || if self.code_hash != KECCAK_EMPTY {
                match db.get(&self.code_hash) {
                    Some(x) => {
                        self.code_size = Some(x.len());
                        true
                    }
                    _ => {
                        warn!("Failed reverse get of {}", self.code_hash);
                        false
                    }
                }
            } else {
                // If the code hash is empty hash, then the code size is zero.
                self.code_size = Some(0);
                true
            }
    }

    /// Determine whether there are any un-`commit()`-ed storage-setting operations.
    pub fn storage_is_clean(&self) -> bool {
        self.storage_changes.is_empty()
    }

    /// Check if account has zero nonce, balance, no code and no storage.
    ///
    /// NOTE: Will panic if `!self.storage_is_clean()`
    pub fn is_empty(&self) -> bool {
        assert!(
            self.storage_is_clean(),
            "Account::is_empty() may only legally be called when storage is clean."
        );
        self.is_null() && self.storage_root == KECCAK_NULL_RLP
    }

    /// Check if account has zero nonce, balance, no code.
    pub fn is_null(&self) -> bool {
        self.balance.is_zero() && self.nonce.is_zero() && self.code_hash == KECCAK_EMPTY
    }

    /// Check if account is basic (Has no code).
    pub fn is_basic(&self) -> bool {
        self.code_hash == KECCAK_EMPTY
    }

    /// Return the storage root associated with this account or None if it has been altered via the overlay.
    pub fn storage_root(&self) -> Option<H256> {
        if self.storage_is_clean() {
            Some(self.storage_root)
        } else {
            None
        }
    }

    /// Return the original storage root of this account.
    pub fn original_storage_root(&self) -> H256 {
        if let Some((original_storage_root, _)) = self.original_storage_cache {
            original_storage_root
        } else {
            self.storage_root
        }
    }

    /// Whether the base storage root of this account is unchanged.
    pub fn is_base_storage_root_unchanged(&self) -> bool {
        self.original_storage_cache.is_none()
    }

    /// Storage root where the account changes are based upon.
    pub fn base_storage_root(&self) -> H256 {
        self.storage_root
    }

    /// Return the storage overlay.
    pub fn storage_changes(&self) -> &HashMap<H256, H256> {
        &self.storage_changes
    }

    /// Increment the nonce of the account by one.
    pub fn inc_nonce(&mut self) {
        self.nonce = self.nonce.saturating_add(U256::from(1u8));
    }

    /// Increase account balance.
    pub fn add_balance(&mut self, x: &U256) {
        self.balance = self.balance.saturating_add(*x);
    }

    /// Decrease account balance.
    /// Panics if balance is less than `x`
    pub fn sub_balance(&mut self, x: &U256) {
        assert!(self.balance >= *x);
        self.balance = self.balance - *x;
    }

    /// Commit the `storage_changes` to the backing DB and update `storage_root`.
    pub fn commit_storage(
        &mut self,
        trie_factory: &TrieFactory,
        db: &mut dyn HashDB<KeccakHasher, DBValue>,
    ) -> TrieResult<()> {
        let mut t = trie_factory.from_existing(db, &mut self.storage_root)?;
        for (k, v) in self.storage_changes.drain() {
            // cast key and value to trait type,
            // so we can call overloaded `to_bytes` method
            match v.is_zero() {
                true => t.remove(k.as_bytes())?,
                false => t.insert(k.as_bytes(), &encode(&v.into_uint()))?,
            };

            self.storage_cache.borrow_mut().insert(k, v);
        }
        self.original_storage_cache = None;
        Ok(())
    }

    /// Commit any unsaved code. `code_hash` will always return the hash of the `code_cache` after this.
    pub fn commit_code(&mut self, db: &mut dyn HashDB<KeccakHasher, DBValue>) {
        trace!(
            "Commiting code of {:?} - {:?}, {:?}",
            self,
            self.code_filth == Filth::Dirty,
            self.code_cache.is_empty()
        );
        match (self.code_filth == Filth::Dirty, self.code_cache.is_empty()) {
            (true, true) => {
                self.code_size = Some(0);
                self.code_filth = Filth::Clean;
            }
            (true, false) => {
                db.emplace(
                    self.code_hash.clone(),
                    DBValue::from_slice(&*self.code_cache),
                );
                self.code_size = Some(self.code_cache.len());
                self.code_filth = Filth::Clean;
            }
            (false, _) => {}
        }
    }

    /// Export to RLP.
    pub fn rlp(&self) -> Bytes {
        let mut stream = RlpStream::new_list(4);
        stream.append(&self.nonce);
        stream.append(&self.balance);
        stream.append(&self.storage_root);
        stream.append(&self.code_hash);
        stream.out()
    }

    /// Clone basic account data
    pub fn clone_basic(&self) -> Account {
        Account {
            balance: self.balance.clone(),
            nonce: self.nonce.clone(),
            storage_root: self.storage_root.clone(),
            storage_cache: Self::empty_storage_cache(),
            original_storage_cache: self
                .original_storage_cache
                .as_ref()
                .map(|(r, _)| (*r, Self::empty_storage_cache())),
            storage_changes: HashMap::new(),
            code_hash: self.code_hash.clone(),
            code_size: self.code_size.clone(),
            code_cache: self.code_cache.clone(),
            code_filth: self.code_filth,
            address_hash: self.address_hash.clone(),
        }
    }

    /// Clone account data and dirty storage keys
    pub fn clone_dirty(&self) -> Account {
        let mut account = self.clone_basic();
        account.storage_changes = self.storage_changes.clone();
        account
    }

    /// Clone account data, dirty storage keys and cached storage keys.
    pub fn clone_all(&self) -> Account {
        let mut account = self.clone_dirty();
        account.storage_cache = self.storage_cache.clone();
        account.original_storage_cache = self.original_storage_cache.clone();
        account
    }

    /// Replace self with the data from other account merging storage cache.
    /// Basic account data and all modifications are overwritten
    /// with new values.
    pub fn overwrite_with(&mut self, other: Account) {
        self.balance = other.balance;
        self.nonce = other.nonce;
        self.code_hash = other.code_hash;
        self.code_filth = other.code_filth;
        self.code_cache = other.code_cache;
        self.code_size = other.code_size;
        self.address_hash = other.address_hash;
        if self.storage_root == other.storage_root {
            let mut cache = self.storage_cache.borrow_mut();
            for (k, v) in other.storage_cache.into_inner() {
                cache.insert(k, v);
            }
        } else {
            self.storage_cache = other.storage_cache;
        }
        self.original_storage_cache = other.original_storage_cache;
        self.storage_root = other.storage_root;
        self.storage_changes = other.storage_changes;
    }
}

// light client storage proof.
impl Account {
    /// Prove a storage key's existence or nonexistence in the account's storage
    /// trie.
    /// `storage_key` is the hash of the desired storage key, meaning
    /// this will only work correctly under a secure trie.
    pub fn prove_storage(
        &self,
        db: &dyn HashDB<KeccakHasher, DBValue>,
        storage_key: H256,
    ) -> TrieResult<(Vec<Bytes>, H256)> {
        let mut recorder = Recorder::new();

        let trie = TrieDB::new(&db, &self.storage_root)?;
        let item: U256 = {
            let panicky_decoder =
                |bytes: &[u8]| ::rlp::decode(bytes).expect("decoding db value failed");
            let query = (&mut recorder, panicky_decoder);
            trie.get_with(storage_key.as_bytes(), query)?
                .unwrap_or_else(U256::zero)
        };

        Ok((
            recorder.drain().into_iter().map(|r| r.data).collect(),
            BigEndianHash::from_uint(&item),
        ))
    }
}

impl fmt::Debug for Account {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_struct("Account")
            .field("balance", &self.balance)
            .field("nonce", &self.nonce)
            .field("code", &self.code())
            .field(
                "storage",
                &self.storage_changes.iter().collect::<BTreeMap<_, _>>(),
            )
            .finish()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use account_db::*;
    use bytes::Bytes;
    use ethereum_types::{Address, H256};
    use journaldb::new_memory_db;
    use rlp_compress::{compress, decompress, snapshot_swapper};
    use std::str::FromStr;

    #[test]
    fn account_compress() {
        let raw = Account::new_basic(2.into(), 4.into()).rlp();
        let compact_vec = compress(&raw, snapshot_swapper());
        assert!(raw.len() > compact_vec.len());
        let again_raw = decompress(&compact_vec, snapshot_swapper());
        assert_eq!(raw, again_raw.into_vec());
    }

    #[test]
    fn storage_at() {
        let mut db = new_memory_db();
        let mut db = AccountDBMut::new(&mut db, &Address::default());
        let rlp = {
            let mut a = Account::new_contract(69.into(), 0.into(), KECCAK_NULL_RLP);
            a.set_storage(
                H256::from_low_u64_be(0x00u64),
                H256::from_low_u64_be(0x1234u64),
            );
            a.commit_storage(&Default::default(), &mut db).unwrap();
            a.init_code(vec![]);
            a.commit_code(&mut db);
            a.rlp()
        };

        let a = Account::from_rlp(&rlp).expect("decoding db value failed");
        assert_eq!(
            a.storage_root().unwrap(),
            H256::from_str("c57e1afb758b07f8d2c8f13a3b6e44fa5ff94ab266facc5a4fd3f062426e50b2")
                .unwrap()
        );
        assert_eq!(
            a.storage_at(&db.immutable(), &H256::from_low_u64_be(0x00u64))
                .unwrap(),
            H256::from_low_u64_be(0x1234u64)
        );
        assert_eq!(
            a.storage_at(&db.immutable(), &H256::from_low_u64_be(0x01u64))
                .unwrap(),
            H256::default()
        );
    }

    #[test]
    fn note_code() {
        let mut db = new_memory_db();
        let mut db = AccountDBMut::new(&mut db, &Address::default());

        let rlp = {
            let mut a = Account::new_contract(69.into(), 0.into(), KECCAK_NULL_RLP);
            a.init_code(vec![0x55, 0x44, 0xffu8]);
            a.commit_code(&mut db);
            a.rlp()
        };

        let mut a = Account::from_rlp(&rlp).expect("decoding db value failed");
        assert!(a.cache_code(&db.immutable()).is_some());

        let mut a = Account::from_rlp(&rlp).expect("decoding db value failed");
        assert_eq!(a.note_code(vec![0x55, 0x44, 0xffu8]), Ok(()));
    }

    #[test]
    fn commit_storage() {
        let mut a = Account::new_contract(69.into(), 0.into(), KECCAK_NULL_RLP);
        let mut db = new_memory_db();
        let mut db = AccountDBMut::new(&mut db, &Address::default());
        a.set_storage(H256::from_low_u64_be(0), H256::from_low_u64_be(0x1234));
        assert_eq!(a.storage_root(), None);
        a.commit_storage(&Default::default(), &mut db).unwrap();
        assert_eq!(
            a.storage_root().unwrap(),
            H256::from_str("c57e1afb758b07f8d2c8f13a3b6e44fa5ff94ab266facc5a4fd3f062426e50b2")
                .unwrap()
        );
    }

    #[test]
    fn commit_remove_commit_storage() {
        let mut a = Account::new_contract(69.into(), 0.into(), KECCAK_NULL_RLP);
        let mut db = new_memory_db();
        let mut db = AccountDBMut::new(&mut db, &Address::default());
        a.set_storage(H256::from_low_u64_be(0), H256::from_low_u64_be(0x1234));
        a.commit_storage(&Default::default(), &mut db).unwrap();
        a.set_storage(H256::from_low_u64_be(1), H256::from_low_u64_be(0x1234));
        a.commit_storage(&Default::default(), &mut db).unwrap();
        a.set_storage(H256::from_low_u64_be(1), H256::from_low_u64_be(0));
        a.commit_storage(&Default::default(), &mut db).unwrap();
        assert_eq!(
            a.storage_root().unwrap(),
            H256::from_str("c57e1afb758b07f8d2c8f13a3b6e44fa5ff94ab266facc5a4fd3f062426e50b2")
                .unwrap()
        );
    }

    #[test]
    fn commit_code() {
        let mut a = Account::new_contract(69.into(), 0.into(), KECCAK_NULL_RLP);
        let mut db = new_memory_db();
        let mut db = AccountDBMut::new(&mut db, &Address::default());
        a.init_code(vec![0x55, 0x44, 0xffu8]);
        assert_eq!(a.code_filth, Filth::Dirty);
        assert_eq!(a.code_size(), Some(3));
        a.commit_code(&mut db);
        assert_eq!(
            a.code_hash(),
            H256::from_str("af231e631776a517ca23125370d542873eca1fb4d613ed9b5d5335a46ae5b7eb")
                .unwrap()
        );
    }

    #[test]
    fn reset_code() {
        let mut a = Account::new_contract(69.into(), 0.into(), KECCAK_NULL_RLP);
        let mut db = new_memory_db();
        let mut db = AccountDBMut::new(&mut db, &Address::default());
        a.init_code(vec![0x55, 0x44, 0xffu8]);
        assert_eq!(a.code_filth, Filth::Dirty);
        a.commit_code(&mut db);
        assert_eq!(a.code_filth, Filth::Clean);
        assert_eq!(
            a.code_hash(),
            H256::from_str("af231e631776a517ca23125370d542873eca1fb4d613ed9b5d5335a46ae5b7eb")
                .unwrap()
        );
        a.reset_code(vec![0x55]);
        assert_eq!(a.code_filth, Filth::Dirty);
        a.commit_code(&mut db);
        assert_eq!(
            a.code_hash(),
            H256::from_str("37bf2238b11b68cdc8382cece82651b59d3c3988873b6e0f33d79694aa45f1be")
                .unwrap()
        );
    }

    #[test]
    fn rlpio() {
        let a = Account::new(69u8.into(), 0u8.into(), HashMap::new(), Bytes::new());
        let b = Account::from_rlp(&a.rlp()).unwrap();
        assert_eq!(a.balance(), b.balance());
        assert_eq!(a.nonce(), b.nonce());
        assert_eq!(a.code_hash(), b.code_hash());
        assert_eq!(a.storage_root(), b.storage_root());
    }

    #[test]
    fn new_account() {
        let a = Account::new(69u8.into(), 0u8.into(), HashMap::new(), Bytes::new());
        assert_eq!(a.rlp().to_hex(), "f8448045a056e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421a0c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470");
        assert_eq!(*a.balance(), 69u8.into());
        assert_eq!(*a.nonce(), 0u8.into());
        assert_eq!(a.code_hash(), KECCAK_EMPTY);
        assert_eq!(a.storage_root().unwrap(), KECCAK_NULL_RLP);
    }
}