System contracts ckb_light_client and image_cell are saved into different MPT trie.

[yangby-cryptape]

Current Behavior

• Initialize system contracts when Axon starts.

  axon/core/run/src/lib.rs

  Line 480 in 8e5d567

  system_contract::init(db_group.inner_db(), &mut backend);

• Generate MPT changes.

  axon/core/executor/src/system_contract/mod.rs

  Lines 133 to 136 in 8e5d567

  	if current_cell_root.is_zero() {
  	let changes = generate_mpt_root_changes(adapter, IMAGE_CELL_CONTRACT_ADDRESS);
  	adapter.apply(changes, vec![], false);
  	}

• Two changes are created.

  axon/core/executor/src/system_contract/utils.rs

  Lines 73 to 88 in 8e5d567

  	vec![
  	Apply::Modify {
  	address: CKB_LIGHT_CLIENT_CONTRACT_ADDRESS,
  	basic: backend.basic(CKB_LIGHT_CLIENT_CONTRACT_ADDRESS),
  	code: None,
  	storage: storage_changes.clone(),
  	reset_storage: false,
  	},
  	Apply::Modify {
  	address: IMAGE_CELL_CONTRACT_ADDRESS,
  	basic: backend.basic(IMAGE_CELL_CONTRACT_ADDRESS),
  	code: None,
  	storage: storage_changes,
  	reset_storage: false,
  	},
  	]

• Two changes are applied one by one.

  axon/core/executor/src/adapter/backend/apply.rs

  Lines 235 to 248 in 8e5d567

  	for apply in values.into_iter() {
  	match apply {
  	Apply::Modify {
  	address,
  	basic,
  	code,
  	storage,
  	reset_storage,
  	} => {
  	let is_empty = self.apply(address, basic, code, storage, reset_storage);
  	if is_empty && delete_empty {
  	self.inner.trie.remove(address.as_bytes()).unwrap();
  	}
  	}

• Since there two changes have different addresses.

  • Each time a new old_account is initialized.

    axon/core/executor/src/adapter/backend/apply.rs

    Lines 155 to 163 in 8e5d567

    	let old_account = match self.inner.trie.get(address.as_bytes()) {
    	Ok(Some(raw)) => Account::decode(raw).unwrap(),
    	_ => Account {
    	nonce: U256::zero(),
    	balance: U256::zero(),
    	storage_root: RLP_NULL,
    	code_hash: NIL_DATA,
    	},
    	};

  • Then, each time a new storage_trie is initialized.

    axon/core/executor/src/adapter/backend/apply.rs

    Lines 165 to 169 in 8e5d567

    	let storage_root = if reset_storage {
    	RLP_NULL
    	} else {
    	old_account.storage_root
    	};

    
    

    axon/core/executor/src/adapter/backend/apply.rs

    Lines 171 to 175 in 8e5d567

    	let mut storage_trie = if storage_root == RLP_NULL {
    	MPTTrie::new(Arc::clone(&self.inner.db))
    	} else {
    	MPTTrie::from_root(old_account.storage_root, Arc::clone(&self.inner.db)).unwrap()
    	};

• So, these two system contracts are insert into two different MPT trie.

• Let's go back to the system contracts initialization.

  • When try to get the current_cell_root, only address CKB_LIGHT_CLIENT_CONTRACT_ADDRESS is used.

    axon/core/executor/src/system_contract/mod.rs

    Lines 130 to 131 in 8e5d567

    	let current_cell_root =
    	adapter.storage(CKB_LIGHT_CLIENT_CONTRACT_ADDRESS, *HEADER_CELL_ROOT_KEY);

    ❓ So, its storage_root won't contains the image cell contract. I'm not sure. Is this correct?

  • When try to generate MPT changes, only address IMAGE_CELL_CONTRACT_ADDRESS is used.

    axon/core/executor/src/system_contract/mod.rs

    Line 134 in 8e5d567

    let changes = generate_mpt_root_changes(adapter, IMAGE_CELL_CONTRACT_ADDRESS);

    ❓ Can anyone guess the fact this function call also generate changes for the ckb light client contract too, even just an address IMAGE_CELL_CONTRACT_ADDRESS is passed.

  • ❓ Can anyone guess that the above two function calls are a pair: one is getter, and one is setter, even they use different addresses as arguments.

Expected Behavior

.

Axon version

main branch