state.py (in src/ethereum/forks/tangerine

ethereum.forks.tangerine_whistle.state

State.

.. contents:: Table of Contents :backlinks: none :local:

Introduction

The state contains all information that is preserved between transactions.

It consists of a main account trie and storage tries for each contract.

There is a distinction between an account that does not exist and EMPTY_ACCOUNT.

State ¶

Contains all information that is preserved between transactions.

30	@dataclass

class State:

_main_trie ¶

36	_main_trie: Trie[Address, Optional[Account]] = field(
37	default_factory=lambda: Trie(secured=True, default=None)
38	)

_storage_tries ¶

39	_storage_tries: Dict[Address, Trie[Bytes32, U256]] = field(
40	default_factory=dict
41	)

_snapshots ¶

42	_snapshots: List[
43	Tuple[
44	Trie[Address, Optional[Account]],
45	Dict[Address, Trie[Bytes32, U256]],
46	]
47	] = field(default_factory=list)

close_state ¶

Free resources held by the state. Used by optimized implementations to release file descriptors.

def close_state(state: State) -> None:

51	"""
52	Free resources held by the state. Used by optimized implementations to
53	release file descriptors.
54	"""
55	del state._main_trie
56	del state._storage_tries
57	del state._snapshots

begin_transaction ¶

Start a state transaction.

Transactions are entirely implicit and can be nested. It is not possible to calculate the state root during a transaction.

Parameters

state : State The state.

def begin_transaction(state: State) -> None:

61	"""
62	Start a state transaction.
63
64	Transactions are entirely implicit and can be nested. It is not possible to
65	calculate the state root during a transaction.
66
67	Parameters
68	----------
69	state : State
70	The state.
71
72	"""
73	state._snapshots.append(
74	(
75	copy_trie(state._main_trie),
76	{k: copy_trie(t) for (k, t) in state._storage_tries.items()},
77	)
78	)

commit_transaction ¶

Commit a state transaction.

Parameters

state : State The state.

def commit_transaction(state: State) -> None:

82	"""
83	Commit a state transaction.
84
85	Parameters
86	----------
87	state : State
88	The state.
89
90	"""
91	state._snapshots.pop()

rollback_transaction ¶

Rollback a state transaction, resetting the state to the point when the corresponding begin_transaction() call was made.

Parameters

state : State The state.

def rollback_transaction(state: State) -> None:

95	"""
96	Rollback a state transaction, resetting the state to the point when the
97	corresponding `begin_transaction()` call was made.
98
99	Parameters
100	----------
101	state : State
102	The state.
103
104	"""
105	state._main_trie, state._storage_tries = state._snapshots.pop()

get_account ¶

Get the Account object at an address. Returns EMPTY_ACCOUNT if there is no account at the address.

Use get_account_optional() if you care about the difference between a non-existent account and EMPTY_ACCOUNT.

Parameters

state: State The state address : Address Address to lookup.

Returns

account : Account Account at address.

def get_account(state: State, address: Address) -> Account:

109	"""
110	Get the `Account` object at an address. Returns `EMPTY_ACCOUNT` if there
111	is no account at the address.
112
113	Use `get_account_optional()` if you care about the difference between a
114	non-existent account and `EMPTY_ACCOUNT`.
115
116	Parameters
117	----------
118	state: `State`
119	The state
120	address : `Address`
121	Address to lookup.
122
123	Returns
124	-------
125	account : `Account`
126	Account at address.
127
128	"""
129	account = get_account_optional(state, address)
130	if isinstance(account, Account):
131	return account
132	else:
133	return EMPTY_ACCOUNT

get_account_optional ¶

Get the Account object at an address. Returns None (rather than EMPTY_ACCOUNT) if there is no account at the address.

Parameters

state: State The state address : Address Address to lookup.

Returns

account : Account Account at address.

def get_account_optional(state: State, address: Address) -> Optional[Account]:

137	"""
138	Get the `Account` object at an address. Returns `None` (rather than
139	`EMPTY_ACCOUNT`) if there is no account at the address.
140
141	Parameters
142	----------
143	state: `State`
144	The state
145	address : `Address`
146	Address to lookup.
147
148	Returns
149	-------
150	account : `Account`
151	Account at address.
152
153	"""
154	account = trie_get(state._main_trie, address)
155	return account

set_account ¶

Set the Account object at an address. Setting to None deletes the account (but not its storage, see destroy_account()).

Parameters

state: State The state address : Address Address to set. account : Account Account to set at address.

def set_account(state: State, address: Address, account: Optional[Account]) -> None:

161	"""
162	Set the `Account` object at an address. Setting to `None` deletes
163	the account (but not its storage, see `destroy_account()`).
164
165	Parameters
166	----------
167	state: `State`
168	The state
169	address : `Address`
170	Address to set.
171	account : `Account`
172	Account to set at address.
173
174	"""
175	trie_set(state._main_trie, address, account)

destroy_account ¶

Completely remove the account at address and all of its storage.

This function is made available exclusively for the SELFDESTRUCT opcode. It is expected that SELFDESTRUCT will be disabled in a future hardfork and this function will be removed.

Parameters

state: State The state address : Address Address of account to destroy.

def destroy_account(state: State, address: Address) -> None:

179	"""
180	Completely remove the account at `address` and all of its storage.
181
182	This function is made available exclusively for the `SELFDESTRUCT`
183	opcode. It is expected that `SELFDESTRUCT` will be disabled in a future
184	hardfork and this function will be removed.
185
186	Parameters
187	----------
188	state: `State`
189	The state
190	address : `Address`
191	Address of account to destroy.
192
193	"""
194	destroy_storage(state, address)
195	set_account(state, address, None)

destroy_storage ¶

Completely remove the storage at address.

Parameters

state: State The state address : Address Address of account whose storage is to be deleted.

def destroy_storage(state: State, address: Address) -> None:

199	"""
200	Completely remove the storage at `address`.
201
202	Parameters
203	----------
204	state: `State`
205	The state
206	address : `Address`
207	Address of account whose storage is to be deleted.
208
209	"""
210	if address in state._storage_tries:
211	del state._storage_tries[address]

get_storage ¶

Get a value at a storage key on an account. Returns U256(0) if the storage key has not been set previously.

Parameters

state: State The state address : Address Address of the account. key : Bytes Key to lookup.

Returns

value : U256 Value at the key.

def get_storage(state: State, address: Address, key: Bytes32) -> U256:

215	"""
216	Get a value at a storage key on an account. Returns `U256(0)` if the
217	storage key has not been set previously.
218
219	Parameters
220	----------
221	state: `State`
222	The state
223	address : `Address`
224	Address of the account.
225	key : `Bytes`
226	Key to lookup.
227
228	Returns
229	-------
230	value : `U256`
231	Value at the key.
232
233	"""
234	trie = state._storage_tries.get(address)
235	if trie is None:
236	return U256(0)
237
238	value = trie_get(trie, key)
239
240	assert isinstance(value, U256)
241	return value

set_storage ¶

Set a value at a storage key on an account. Setting to U256(0) deletes the key.

Parameters

state: State The state address : Address Address of the account. key : Bytes Key to set. value : U256 Value to set at the key.

def set_storage(state: State, address: Address, key: Bytes32, value: U256) -> None:

247	"""
248	Set a value at a storage key on an account. Setting to `U256(0)` deletes
249	the key.
250
251	Parameters
252	----------
253	state: `State`
254	The state
255	address : `Address`
256	Address of the account.
257	key : `Bytes`
258	Key to set.
259	value : `U256`
260	Value to set at the key.
261
262	"""
263	assert trie_get(state._main_trie, address) is not None
264
265	trie = state._storage_tries.get(address)
266	if trie is None:
267	trie = Trie(secured=True, default=U256(0))
268	state._storage_tries[address] = trie
269	trie_set(trie, key, value)
270	if trie._data == {}:
271	del state._storage_tries[address]

storage_root ¶

Calculate the storage root of an account.

Parameters

state: The state address : Address of the account.

Returns

root : Root Storage root of the account.

def storage_root(state: State, address: Address) -> Root:

275	"""
276	Calculate the storage root of an account.
277
278	Parameters
279	----------
280	state:
281	The state
282	address :
283	Address of the account.
284
285	Returns
286	-------
287	root : `Root`
288	Storage root of the account.
289
290	"""
291	assert not state._snapshots
292	if address in state._storage_tries:
293	return root(state._storage_tries[address])
294	else:
295	return EMPTY_TRIE_ROOT

state_root ¶

Calculate the state root.

Parameters

state: The current state.

Returns

root : Root The state root.

def state_root(state: State) -> Root:

299	"""
300	Calculate the state root.
301
302	Parameters
303	----------
304	state:
305	The current state.
306
307	Returns
308	-------
309	root : `Root`
310	The state root.
311
312	"""
313	assert not state._snapshots
314
315	def get_storage_root(address: Address) -> Root:
316	return storage_root(state, address)
317
318	return root(state._main_trie, get_storage_root=get_storage_root)

account_exists ¶

Checks if an account exists in the state trie.

Parameters

state: The state address: Address of the account that needs to be checked.

Returns

account_exists : bool True if account exists in the state trie, False otherwise

def account_exists(state: State, address: Address) -> bool:

322	"""
323	Checks if an account exists in the state trie.
324
325	Parameters
326	----------
327	state:
328	The state
329	address:
330	Address of the account that needs to be checked.
331
332	Returns
333	-------
334	account_exists : `bool`
335	True if account exists in the state trie, False otherwise
336
337	"""
338	return get_account_optional(state, address) is not None

account_has_code_or_nonce ¶

Checks if an account has non-zero nonce or non-empty code.

Parameters

state: The state address: Address of the account that needs to be checked.

Returns

has_code_or_nonce : bool True if the account has non-zero nonce or non-empty code, False otherwise.

def account_has_code_or_nonce(state: State, address: Address) -> bool:

342	"""
343	Checks if an account has non-zero nonce or non-empty code.
344
345	Parameters
346	----------
347	state:
348	The state
349	address:
350	Address of the account that needs to be checked.
351
352	Returns
353	-------
354	has_code_or_nonce : `bool`
355	True if the account has non-zero nonce or non-empty code,
356	False otherwise.
357
358	"""
359	account = get_account(state, address)
360	return account.nonce != Uint(0) or account.code != b""

account_has_storage ¶

Checks if an account has storage.

Parameters

state: The state address: Address of the account that needs to be checked.

Returns

has_storage : bool True if the account has storage, False otherwise.

def account_has_storage(state: State, address: Address) -> bool:

364	"""
365	Checks if an account has storage.
366
367	Parameters
368	----------
369	state:
370	The state
371	address:
372	Address of the account that needs to be checked.
373
374	Returns
375	-------
376	has_storage : `bool`
377	True if the account has storage, False otherwise.
378
379	"""
380	return address in state._storage_tries

modify_state ¶

Modify an Account in the State.

def modify_state(state: State, address: Address, f: Callable[[Account], None]) -> None:

386	"""
387	Modify an `Account` in the `State`.
388	"""
389	set_account(state, address, modify(get_account(state, address), f))

move_ether ¶

Move funds between accounts.

def move_ether(state: State, sender_address: Address, recipient_address: Address, amount: U256) -> None:

398	"""
399	Move funds between accounts.
400	"""
401
402	def reduce_sender_balance(sender: Account) -> None:
403	if sender.balance < amount:
404	raise AssertionError
405	sender.balance -= amount
406
407	def increase_recipient_balance(recipient: Account) -> None:
408	recipient.balance += amount
409
410	modify_state(state, sender_address, reduce_sender_balance)
411	modify_state(state, recipient_address, increase_recipient_balance)

set_account_balance ¶

Sets the balance of an account.

Parameters

state: The current state.

address: Address of the account whose nonce needs to be incremented.

amount: The amount that needs to be set in the balance.

def set_account_balance(state: State, address: Address, amount: U256) -> None:

415	"""
416	Sets the balance of an account.
417
418	Parameters
419	----------
420	state:
421	The current state.
422
423	address:
424	Address of the account whose nonce needs to be incremented.
425
426	amount:
427	The amount that needs to be set in the balance.
428
429	"""
430
431	def set_balance(account: Account) -> None:
432	account.balance = amount
433
434	modify_state(state, address, set_balance)

touch_account ¶

Initializes an account to state.

Parameters

state: The current state.

address: The address of the account that needs to be initialized.

def touch_account(state: State, address: Address) -> None:

438	"""
439	Initializes an account to state.
440
441	Parameters
442	----------
443	state:
444	The current state.
445
446	address:
447	The address of the account that needs to be initialized.
448
449	"""
450	if not account_exists(state, address):
451	set_account(state, address, EMPTY_ACCOUNT)

increment_nonce ¶

Increments the nonce of an account.

Parameters

state: The current state.

address: Address of the account whose nonce needs to be incremented.

def increment_nonce(state: State, address: Address) -> None:

455	"""
456	Increments the nonce of an account.
457
458	Parameters
459	----------
460	state:
461	The current state.
462
463	address:
464	Address of the account whose nonce needs to be incremented.
465
466	"""
467
468	def increase_nonce(sender: Account) -> None:
469	sender.nonce += Uint(1)
470
471	modify_state(state, address, increase_nonce)

set_code ¶

Sets Account code.

Parameters

state: The current state.

address: Address of the account whose code needs to be updated.

code: The bytecode that needs to be set.

def set_code(state: State, address: Address, code: Bytes) -> None:

475	"""
476	Sets Account code.
477
478	Parameters
479	----------
480	state:
481	The current state.
482
483	address:
484	Address of the account whose code needs to be updated.
485
486	code:
487	The bytecode that needs to be set.
488
489	"""
490
491	def write_code(sender: Account) -> None:
492	sender.code = code
493
494	modify_state(state, address, write_code)

create_ether ¶

Add newly created ether to an account.

Parameters

state: The current state. address: Address of the account to which ether is added. amount: The amount of ether to be added to the account of interest.

def create_ether(state: State, address: Address, amount: U256) -> None:

498	"""
499	Add newly created ether to an account.
500
501	Parameters
502	----------
503	state:
504	The current state.
505	address:
506	Address of the account to which ether is added.
507	amount:
508	The amount of ether to be added to the account of interest.
509
510	"""
511
512	def increase_balance(account: Account) -> None:
513	account.balance += amount
514
515	modify_state(state, address, increase_balance)

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