// Copyright (C) Parity Technologies (UK) Ltd.
// This file is part of Parity Bridges Common.
// Parity Bridges Common 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 Bridges Common 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 Bridges Common. If not, see .
//! Bridge transaction priority calculator.
//!
//! We want to prioritize message delivery transactions with more messages over
//! transactions with less messages. That's because we reject delivery transactions
//! if it contains already delivered message. And if some transaction delivers
//! single message with nonce `N`, then the transaction with nonces `N..=N+100` will
//! be rejected. This can lower bridge throughput down to one message per block.
use bp_messages::MessageNonce;
use frame_support::traits::Get;
use sp_runtime::transaction_validity::TransactionPriority;
// reexport everything from `integrity_tests` module
#[allow(unused_imports)]
pub use integrity_tests::*;
/// Compute priority boost for message delivery transaction that delivers
/// given number of messages.
pub fn compute_priority_boost(
messages: MessageNonce,
) -> TransactionPriority
where
PriorityBoostPerMessage: Get,
{
// we don't want any boost for transaction with single message => minus one
PriorityBoostPerMessage::get().saturating_mul(messages.saturating_sub(1))
}
#[cfg(not(feature = "integrity-test"))]
mod integrity_tests {}
#[cfg(feature = "integrity-test")]
mod integrity_tests {
use super::compute_priority_boost;
use bp_messages::MessageNonce;
use bp_runtime::PreComputedSize;
use frame_support::{
dispatch::{DispatchClass, DispatchInfo, Pays, PostDispatchInfo},
traits::Get,
};
use pallet_bridge_messages::WeightInfoExt;
use pallet_transaction_payment::OnChargeTransaction;
use sp_runtime::{
traits::{Dispatchable, UniqueSaturatedInto, Zero},
transaction_validity::TransactionPriority,
FixedPointOperand, SaturatedConversion, Saturating,
};
type BalanceOf =
<::OnChargeTransaction as OnChargeTransaction<
T,
>>::Balance;
/// Ensures that the value of `PriorityBoostPerMessage` matches the value of
/// `tip_boost_per_message`.
///
/// We want two transactions, `TX1` with `N` messages and `TX2` with `N+1` messages, have almost
/// the same priority if we'll add `tip_boost_per_message` tip to the `TX1`. We want to be sure
/// that if we add plain `PriorityBoostPerMessage` priority to `TX1`, the priority will be close
/// to `TX2` as well.
pub fn ensure_priority_boost_is_sane(
tip_boost_per_message: BalanceOf,
) where
Runtime:
pallet_transaction_payment::Config + pallet_bridge_messages::Config,
MessagesInstance: 'static,
PriorityBoostPerMessage: Get,
Runtime::RuntimeCall: Dispatchable,
BalanceOf: Send + Sync + FixedPointOperand,
{
let priority_boost_per_message = PriorityBoostPerMessage::get();
let maximal_messages_in_delivery_transaction =
Runtime::MaxUnconfirmedMessagesAtInboundLane::get();
for messages in 1..=maximal_messages_in_delivery_transaction {
let base_priority = estimate_message_delivery_transaction_priority::<
Runtime,
MessagesInstance,
>(messages, Zero::zero());
let priority_boost = compute_priority_boost::(messages);
let priority_with_boost = base_priority + priority_boost;
let tip = tip_boost_per_message.saturating_mul((messages - 1).unique_saturated_into());
let priority_with_tip =
estimate_message_delivery_transaction_priority::(1, tip);
const ERROR_MARGIN: TransactionPriority = 5; // 5%
if priority_with_boost.abs_diff(priority_with_tip).saturating_mul(100) /
priority_with_tip >
ERROR_MARGIN
{
panic!(
"The PriorityBoostPerMessage value ({}) must be fixed to: {}",
priority_boost_per_message,
compute_priority_boost_per_message::(
tip_boost_per_message
),
);
}
}
}
/// Compute priority boost that we give to message delivery transaction for additional message.
#[cfg(feature = "integrity-test")]
fn compute_priority_boost_per_message(
tip_boost_per_message: BalanceOf,
) -> TransactionPriority
where
Runtime:
pallet_transaction_payment::Config + pallet_bridge_messages::Config,
MessagesInstance: 'static,
Runtime::RuntimeCall: Dispatchable,
BalanceOf: Send + Sync + FixedPointOperand,
{
// esimate priority of transaction that delivers one message and has large tip
let maximal_messages_in_delivery_transaction =
Runtime::MaxUnconfirmedMessagesAtInboundLane::get();
let small_with_tip_priority =
estimate_message_delivery_transaction_priority::(
1,
tip_boost_per_message
.saturating_mul(maximal_messages_in_delivery_transaction.saturated_into()),
);
// estimate priority of transaction that delivers maximal number of messages, but has no tip
let large_without_tip_priority = estimate_message_delivery_transaction_priority::<
Runtime,
MessagesInstance,
>(maximal_messages_in_delivery_transaction, Zero::zero());
small_with_tip_priority
.saturating_sub(large_without_tip_priority)
.saturating_div(maximal_messages_in_delivery_transaction - 1)
}
/// Estimate message delivery transaction priority.
#[cfg(feature = "integrity-test")]
fn estimate_message_delivery_transaction_priority(
messages: MessageNonce,
tip: BalanceOf,
) -> TransactionPriority
where
Runtime:
pallet_transaction_payment::Config + pallet_bridge_messages::Config,
MessagesInstance: 'static,
Runtime::RuntimeCall: Dispatchable,
BalanceOf: Send + Sync + FixedPointOperand,
{
// just an estimation of extra transaction bytes that are added to every transaction
// (including signature, signed extensions extra and etc + in our case it includes
// all call arguments extept the proof itself)
let base_tx_size = 512;
// let's say we are relaying similar small messages and for every message we add more trie
// nodes to the proof (x0.5 because we expect some nodes to be reused)
let estimated_message_size = 512;
// let's say all our messages have the same dispatch weight
let estimated_message_dispatch_weight =
Runtime::WeightInfo::message_dispatch_weight(estimated_message_size);
// messages proof argument size is (for every message) messages size + some additional
// trie nodes. Some of them are reused by different messages, so let's take 2/3 of default
// "overhead" constant
let messages_proof_size = Runtime::WeightInfo::expected_extra_storage_proof_size()
.saturating_mul(2)
.saturating_div(3)
.saturating_add(estimated_message_size)
.saturating_mul(messages as _);
// finally we are able to estimate transaction size and weight
let transaction_size = base_tx_size.saturating_add(messages_proof_size);
let transaction_weight = Runtime::WeightInfo::receive_messages_proof_weight(
&PreComputedSize(transaction_size as _),
messages as _,
estimated_message_dispatch_weight.saturating_mul(messages),
);
pallet_transaction_payment::ChargeTransactionPayment::::get_priority(
&DispatchInfo {
weight: transaction_weight,
class: DispatchClass::Normal,
pays_fee: Pays::Yes,
},
transaction_size as _,
tip,
Zero::zero(),
)
}
}