openethereum/ethcore/src/engines/mod.rs

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// Copyright 2015-2017 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
// Parity 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.
// Parity 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 Parity. If not, see <http://www.gnu.org/licenses/>.
//! Consensus engine specification and basic implementations.
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mod authority_round;
mod basic_authority;
mod instant_seal;
mod null_engine;
mod signer;
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mod tendermint;
mod transition;
mod validator_set;
mod vote_collector;
pub mod epoch;
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pub use self::authority_round::AuthorityRound;
pub use self::basic_authority::BasicAuthority;
pub use self::epoch::{EpochVerifier, Transition as EpochTransition};
pub use self::instant_seal::InstantSeal;
pub use self::null_engine::NullEngine;
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pub use self::tendermint::Tendermint;
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use std::sync::{Weak, Arc};
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use std::collections::{BTreeMap, HashMap};
use std::fmt;
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use self::epoch::PendingTransition;
use account_provider::AccountProvider;
use block::ExecutedBlock;
use builtin::Builtin;
use client::EngineClient;
use vm::{EnvInfo, LastHashes, Schedule, CreateContractAddress};
use error::Error;
use header::{Header, BlockNumber};
use receipt::Receipt;
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use snapshot::SnapshotComponents;
use spec::CommonParams;
use transaction::{UnverifiedTransaction, SignedTransaction};
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use ethkey::Signature;
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use bigint::prelude::U256;
use bigint::hash::H256;
use semantic_version::SemanticVersion;
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use util::*;
/// Default EIP-210 contrat code.
/// As defined in https://github.com/ethereum/EIPs/pull/210/commits/9df24a3714af42e3bf350265bdc75b486c909d7f#diff-e02a92c2fb96c1a1bfb05e4c6e2ef5daR49
pub const DEFAULT_BLOCKHASH_CONTRACT: &'static str = "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";
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/// Voting errors.
#[derive(Debug)]
pub enum EngineError {
/// Signature or author field does not belong to an authority.
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NotAuthorized(Address),
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/// The same author issued different votes at the same step.
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DoubleVote(Address),
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/// The received block is from an incorrect proposer.
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NotProposer(Mismatch<Address>),
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/// Message was not expected.
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UnexpectedMessage,
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/// Seal field has an unexpected size.
BadSealFieldSize(OutOfBounds<usize>),
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/// Validation proof insufficient.
InsufficientProof(String),
/// Failed system call.
FailedSystemCall(String),
/// Requires client ref, but none registered.
RequiresClient,
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}
impl fmt::Display for EngineError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use self::EngineError::*;
let msg = match *self {
DoubleVote(ref address) => format!("Author {} issued too many blocks.", address),
NotProposer(ref mis) => format!("Author is not a current proposer: {}", mis),
NotAuthorized(ref address) => format!("Signer {} is not authorized.", address),
UnexpectedMessage => "This Engine should not be fed messages.".into(),
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BadSealFieldSize(ref oob) => format!("Seal field has an unexpected length: {}", oob),
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InsufficientProof(ref msg) => format!("Insufficient validation proof: {}", msg),
FailedSystemCall(ref msg) => format!("Failed to make system call: {}", msg),
RequiresClient => format!("Call requires client but none registered"),
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};
f.write_fmt(format_args!("Engine error ({})", msg))
}
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}
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/// Seal type.
#[derive(Debug, PartialEq, Eq)]
pub enum Seal {
/// Proposal seal; should be broadcasted, but not inserted into blockchain.
Proposal(Vec<Bytes>),
/// Regular block seal; should be part of the blockchain.
Regular(Vec<Bytes>),
/// Engine does generate seal for this block right now.
None,
}
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/// Type alias for a function we can make calls through synchronously.
/// Returns the call result and state proof for each call.
pub type Call<'a> = Fn(Address, Bytes) -> Result<(Bytes, Vec<Vec<u8>>), String> + 'a;
/// Type alias for a function we can get headers by hash through.
pub type Headers<'a> = Fn(H256) -> Option<Header> + 'a;
/// Type alias for a function we can query pending transitions by block hash through.
pub type PendingTransitionStore<'a> = Fn(H256) -> Option<PendingTransition> + 'a;
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/// Proof dependent on state.
pub trait StateDependentProof: Send + Sync {
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/// Generate a proof, given the state.
fn generate_proof(&self, caller: &Call) -> Result<Vec<u8>, String>;
/// Check a proof generated elsewhere (potentially by a peer).
// `engine` needed to check state proofs, while really this should
// just be state machine params.
fn check_proof(&self, engine: &Engine, proof: &[u8]) -> Result<(), String>;
}
/// Proof generated on epoch change.
pub enum Proof {
/// Known proof (extracted from signal)
Known(Vec<u8>),
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/// State dependent proof.
WithState(Arc<StateDependentProof>),
}
/// Generated epoch verifier.
pub enum ConstructedVerifier<'a> {
/// Fully trusted verifier.
Trusted(Box<EpochVerifier>),
/// Verifier unconfirmed. Check whether given finality proof finalizes given hash
/// under previous epoch.
Unconfirmed(Box<EpochVerifier>, &'a [u8], H256),
/// Error constructing verifier.
Err(Error),
}
impl<'a> ConstructedVerifier<'a> {
/// Convert to a result, indicating that any necessary confirmation has been done
/// already.
pub fn known_confirmed(self) -> Result<Box<EpochVerifier>, Error> {
match self {
ConstructedVerifier::Trusted(v) | ConstructedVerifier::Unconfirmed(v, _, _) => Ok(v),
ConstructedVerifier::Err(e) => Err(e),
}
}
}
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/// Results of a query of whether an epoch change occurred at the given block.
pub enum EpochChange {
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/// Cannot determine until more data is passed.
Unsure(Unsure),
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/// No epoch change.
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No,
/// The epoch will change, with proof.
Yes(Proof),
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}
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/// More data required to determine if an epoch change occurred at a given block.
#[derive(Debug, Clone, Copy, PartialEq)]
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pub enum Unsure {
/// Needs the body.
NeedsBody,
/// Needs the receipts.
NeedsReceipts,
/// Needs both body and receipts.
NeedsBoth,
}
/// A consensus mechanism for the chain. Generally either proof-of-work or proof-of-stake-based.
/// Provides hooks into each of the major parts of block import.
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pub trait Engine : Sync + Send {
/// The name of this engine.
fn name(&self) -> &str;
/// The version of this engine. Should be of the form
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fn version(&self) -> SemanticVersion { SemanticVersion::new(0, 0, 0) }
/// The number of additional header fields required for this engine.
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fn seal_fields(&self) -> usize { 0 }
/// Additional engine-specific information for the user/developer concerning `header`.
fn extra_info(&self, _header: &Header) -> BTreeMap<String, String> { BTreeMap::new() }
/// Additional information.
fn additional_params(&self) -> HashMap<String, String> { HashMap::new() }
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/// Get the general parameters of the chain.
fn params(&self) -> &CommonParams;
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/// Get the EVM schedule for the given `block_number`.
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fn schedule(&self, block_number: BlockNumber) -> Schedule {
self.params().schedule(block_number)
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}
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/// Builtin-contracts we would like to see in the chain.
/// (In principle these are just hints for the engine since that has the last word on them.)
fn builtins(&self) -> &BTreeMap<Address, Builtin>;
/// Some intrinsic operation parameters; by default they take their value from the `spec()`'s `engine_params`.
fn maximum_extra_data_size(&self) -> usize { self.params().maximum_extra_data_size }
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/// Maximum number of uncles a block is allowed to declare.
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fn maximum_uncle_count(&self) -> usize { 2 }
/// The number of generations back that uncles can be.
fn maximum_uncle_age(&self) -> usize { 6 }
/// The nonce with which accounts begin at given block.
fn account_start_nonce(&self, block: u64) -> U256 {
if block >= self.params().dust_protection_transition {
U256::from(self.params().nonce_cap_increment) * U256::from(block)
} else {
self.params().account_start_nonce
}
}
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/// Block transformation functions, before the transactions.
/// `epoch_begin` set to true if this block kicks off an epoch.
fn on_new_block(
&self,
block: &mut ExecutedBlock,
last_hashes: Arc<LastHashes>,
_epoch_begin: bool,
) -> Result<(), Error> {
let parent_hash = block.fields().header.parent_hash().clone();
common::push_last_hash(block, last_hashes, self, &parent_hash)
}
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/// Block transformation functions, after the transactions.
fn on_close_block(&self, _block: &mut ExecutedBlock) -> Result<(), Error> {
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Ok(())
}
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/// None means that it requires external input (e.g. PoW) to seal a block.
/// Some(true) means the engine is currently prime for seal generation (i.e. node is the current validator).
/// Some(false) means that the node might seal internally but is not qualified now.
fn seals_internally(&self) -> Option<bool> { None }
/// Attempt to seal the block internally.
///
/// If `Some` is returned, then you get a valid seal.
///
/// This operation is synchronous and may (quite reasonably) not be available, in which None will
/// be returned.
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fn generate_seal(&self, _block: &ExecutedBlock) -> Seal { Seal::None }
/// Phase 1 quick block verification. Only does checks that are cheap. `block` (the header's full block)
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/// may be provided for additional checks. Returns either a null `Ok` or a general error detailing the problem with import.
fn verify_block_basic(&self, _header: &Header, _block: Option<&[u8]>) -> Result<(), Error> { Ok(()) }
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/// Phase 2 verification. Perform costly checks such as transaction signatures. `block` (the header's full block)
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/// may be provided for additional checks. Returns either a null `Ok` or a general error detailing the problem with import.
fn verify_block_unordered(&self, _header: &Header, _block: Option<&[u8]>) -> Result<(), Error> { Ok(()) }
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/// Phase 3 verification. Check block information against parent and uncles. `block` (the header's full block)
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/// may be provided for additional checks. Returns either a null `Ok` or a general error detailing the problem with import.
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fn verify_block_family(&self, _header: &Header, _parent: &Header, _block: Option<&[u8]>) -> Result<(), Error> { Ok(()) }
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/// Phase 4 verification. Verify block header against potentially external data.
fn verify_block_external(&self, _header: &Header, _block: Option<&[u8]>) -> Result<(), Error> { Ok(()) }
/// Additional verification for transactions in blocks.
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// TODO: Add flags for which bits of the transaction to check.
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// TODO: consider including State in the params.
fn verify_transaction_basic(&self, t: &UnverifiedTransaction, _header: &Header) -> Result<(), Error> {
t.verify_basic(true, Some(self.params().chain_id), true)?;
Ok(())
}
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/// Verify a particular transaction is valid.
fn verify_transaction(&self, t: UnverifiedTransaction, _header: &Header) -> Result<SignedTransaction, Error> {
SignedTransaction::new(t)
}
/// The network ID that transactions should be signed with.
fn signing_chain_id(&self, _env_info: &EnvInfo) -> Option<u64> {
Some(self.params().chain_id)
}
/// Verify the seal of a block. This is an auxilliary method that actually just calls other `verify_` methods
/// to get the job done. By default it must pass `verify_basic` and `verify_block_unordered`. If more or fewer
/// methods are needed for an Engine, this may be overridden.
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fn verify_block_seal(&self, header: &Header) -> Result<(), Error> {
self.verify_block_basic(header, None).and_then(|_| self.verify_block_unordered(header, None))
}
/// Genesis epoch data.
fn genesis_epoch_data(&self, _header: &Header, _call: &Call) -> Result<Vec<u8>, String> { Ok(Vec::new()) }
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/// Whether an epoch change is signalled at the given header but will require finality.
/// If a change can be enacted immediately then return `No` from this function but
/// `Yes` from `is_epoch_end`.
///
/// If the block or receipts are required, return `Unsure` and the function will be
/// called again with them.
/// Return `Yes` or `No` when the answer is definitively known.
///
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/// Should not interact with state.
fn signals_epoch_end(&self, _header: &Header, _block: Option<&[u8]>, _receipts: Option<&[Receipt]>)
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-> EpochChange
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{
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EpochChange::No
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}
/// Whether a block is the end of an epoch.
///
/// This either means that an immediate transition occurs or a block signalling transition
/// has reached finality. The `Headers` given are not guaranteed to return any blocks
/// from any epoch other than the current.
///
/// Return optional transition proof.
fn is_epoch_end(
&self,
_chain_head: &Header,
_chain: &Headers,
_transition_store: &PendingTransitionStore,
) -> Option<Vec<u8>> {
None
}
/// Create an epoch verifier from validation proof and a flag indicating
/// whether finality is required.
fn epoch_verifier<'a>(&self, _header: &Header, _proof: &'a [u8]) -> ConstructedVerifier<'a> {
ConstructedVerifier::Trusted(Box::new(self::epoch::NoOp))
}
/// Populate a header's fields based on its parent's header.
/// Usually implements the chain scoring rule based on weight.
/// The gas floor target must not be lower than the engine's minimum gas limit.
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fn populate_from_parent(&self, header: &mut Header, parent: &Header, _gas_floor_target: U256, _gas_ceil_target: U256) {
header.set_difficulty(parent.difficulty().clone());
header.set_gas_limit(parent.gas_limit().clone());
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}
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/// Handle any potential consensus messages;
/// updating consensus state and potentially issuing a new one.
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fn handle_message(&self, _message: &[u8]) -> Result<(), Error> { Err(EngineError::UnexpectedMessage.into()) }
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/// Attempt to get a handle to a built-in contract.
/// Only returns references to activated built-ins.
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// TODO: builtin contract routing - to do this properly, it will require removing the built-in configuration-reading logic
// from Spec into here and removing the Spec::builtins field.
fn builtin(&self, a: &Address, block_number: ::header::BlockNumber) -> Option<&Builtin> {
self.builtins()
.get(a)
.and_then(|b| if b.is_active(block_number) { Some(b) } else { None })
}
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/// Find out if the block is a proposal block and should not be inserted into the DB.
/// Takes a header of a fully verified block.
fn is_proposal(&self, _verified_header: &Header) -> bool { false }
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/// Register an account which signs consensus messages.
fn set_signer(&self, _account_provider: Arc<AccountProvider>, _address: Address, _password: String) {}
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/// Sign using the EngineSigner, to be used for consensus tx signing.
fn sign(&self, _hash: H256) -> Result<Signature, Error> { unimplemented!() }
/// Add Client which can be used for sealing, querying the state and sending messages.
fn register_client(&self, _client: Weak<EngineClient>) {}
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/// Trigger next step of the consensus engine.
fn step(&self) {}
/// Stops any services that the may hold the Engine and makes it safe to drop.
fn stop(&self) {}
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/// Create a factory for building snapshot chunks and restoring from them.
/// Returning `None` indicates that this engine doesn't support snapshot creation.
fn snapshot_components(&self) -> Option<Box<SnapshotComponents>> {
None
}
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/// Whether this engine supports warp sync.
fn supports_warp(&self) -> bool {
self.snapshot_components().is_some()
}
/// If this engine supports wasm contracts.
fn supports_wasm(&self) -> bool {
self.params().wasm
}
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/// Returns new contract address generation scheme at given block number.
fn create_address_scheme(&self, number: BlockNumber) -> CreateContractAddress {
if number >= self.params().eip86_transition {
CreateContractAddress::FromCodeHash
} else {
CreateContractAddress::FromSenderAndNonce
}
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}
}
/// Common engine utilities
pub mod common {
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use std::sync::Arc;
use block::ExecutedBlock;
use error::Error;
use transaction::SYSTEM_ADDRESS;
use executive::Executive;
use vm::{CallType, ActionParams, ActionValue, EnvInfo, LastHashes};
use trace::{NoopTracer, NoopVMTracer, Tracer, ExecutiveTracer, RewardType};
use state::Substate;
use state::CleanupMode;
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use bigint::prelude::U256;
use bigint::hash::H256;
use util::*;
use super::Engine;
/// Execute a call as the system address.
pub fn execute_as_system<E: Engine + ?Sized>(
block: &mut ExecutedBlock,
last_hashes: Arc<LastHashes>,
engine: &E,
contract_address: Address,
gas: U256,
data: Option<Bytes>,
) -> Result<Bytes, Error> {
let env_info = {
let header = block.fields().header;
EnvInfo {
number: header.number(),
author: header.author().clone(),
timestamp: header.timestamp(),
difficulty: header.difficulty().clone(),
last_hashes: last_hashes,
gas_used: U256::zero(),
gas_limit: gas,
}
};
let mut state = block.fields_mut().state;
let params = ActionParams {
code_address: contract_address.clone(),
address: contract_address.clone(),
sender: SYSTEM_ADDRESS.clone(),
origin: SYSTEM_ADDRESS.clone(),
gas: gas,
gas_price: 0.into(),
value: ActionValue::Transfer(0.into()),
code: state.code(&contract_address)?,
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code_hash: Some(state.code_hash(&contract_address)?),
data: data,
call_type: CallType::Call,
};
let mut ex = Executive::new(&mut state, &env_info, engine);
let mut substate = Substate::new();
let mut output = Vec::new();
if let Err(e) = ex.call(params, &mut substate, BytesRef::Flexible(&mut output), &mut NoopTracer, &mut NoopVMTracer) {
warn!("Encountered error on making system call: {}", e);
}
Ok(output)
}
/// Push last known block hash to the state.
pub fn push_last_hash<E: Engine + ?Sized>(block: &mut ExecutedBlock, last_hashes: Arc<LastHashes>, engine: &E, hash: &H256) -> Result<(), Error> {
if block.fields().header.number() == engine.params().eip210_transition {
let state = block.fields_mut().state;
state.init_code(&engine.params().eip210_contract_address, engine.params().eip210_contract_code.clone())?;
}
if block.fields().header.number() >= engine.params().eip210_transition {
let _ = execute_as_system(
block,
last_hashes,
engine,
engine.params().eip210_contract_address,
engine.params().eip210_contract_gas,
Some(hash.to_vec()),
)?;
}
Ok(())
}
/// Trace rewards on closing block
pub fn bestow_block_reward<E: Engine + ?Sized>(block: &mut ExecutedBlock, engine: &E) -> Result<(), Error> {
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let fields = block.fields_mut();
// Bestow block reward
let reward = engine.params().block_reward;
let res = fields.state.add_balance(fields.header.author(), &reward, CleanupMode::NoEmpty)
.map_err(::error::Error::from)
.and_then(|_| fields.state.commit());
let block_author = fields.header.author().clone();
fields.traces.as_mut().map(|mut traces| {
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let mut tracer = ExecutiveTracer::default();
tracer.trace_reward(block_author, engine.params().block_reward, RewardType::Block);
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traces.push(tracer.drain())
});
// Commit state so that we can actually figure out the state root.
if let Err(ref e) = res {
warn!("Encountered error on bestowing reward: {}", e);
}
res
}
}