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// This file is part of Substrate.
// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
// This program 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.
// This program 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 this program. If not, see <https://www.gnu.org/licenses/>.
//! Transaction pool client facing API.
#![warn(missing_docs)]
pub mod error;
use async_trait::async_trait;
use codec::Codec;
use futures::{Future, Stream};
use serde::{de::DeserializeOwned, Deserialize, Serialize};
use sp_core::offchain::TransactionPoolExt;
use sp_runtime::traits::{Block as BlockT, Member, NumberFor};
use std::{collections::HashMap, hash::Hash, marker::PhantomData, pin::Pin, sync::Arc};
const LOG_TARGET: &str = "txpool::api";
pub use sp_runtime::transaction_validity::{
TransactionLongevity, TransactionPriority, TransactionSource, TransactionTag,
};
/// Transaction pool status.
#[derive(Debug)]
pub struct PoolStatus {
/// Number of transactions in the ready queue.
pub ready: usize,
/// Sum of bytes of ready transaction encodings.
pub ready_bytes: usize,
/// Number of transactions in the future queue.
pub future: usize,
/// Sum of bytes of ready transaction encodings.
pub future_bytes: usize,
}
impl PoolStatus {
/// Returns true if the are no transactions in the pool.
pub fn is_empty(&self) -> bool {
self.ready == 0 && self.future == 0
}
}
/// Possible transaction status events.
///
/// This events are being emitted by `TransactionPool` watchers,
/// which are also exposed over RPC.
///
/// The status events can be grouped based on their kinds as:
/// 1. Entering/Moving within the pool:
/// - [Future](TransactionStatus::Future)
/// - [Ready](TransactionStatus::Ready)
/// 2. Inside `Ready` queue:
/// - [Broadcast](TransactionStatus::Broadcast)
/// 3. Leaving the pool:
/// - [InBlock](TransactionStatus::InBlock)
/// - [Invalid](TransactionStatus::Invalid)
/// - [Usurped](TransactionStatus::Usurped)
/// - [Dropped](TransactionStatus::Dropped)
/// 4. Re-entering the pool:
/// - [Retracted](TransactionStatus::Retracted)
/// 5. Block finalized:
/// - [Finalized](TransactionStatus::Finalized)
/// - [FinalityTimeout](TransactionStatus::FinalityTimeout)
///
/// Transactions are first placed in either the `Ready` or `Future` queues of the transaction pool.
/// Substrate validates the transaction before it enters the pool.
///
/// A transaction is placed in the `Future` queue if it will become valid at a future time.
/// For example, submitting a transaction with a higher account nonce than the current
/// expected nonce will place the transaction in the `Future` queue.
///
/// The events will always be received in the order described above, however
/// there might be cases where transactions alternate between `Future` and `Ready`
/// pool, and are `Broadcast` in the meantime.
///
/// There is also only single event causing the transaction to leave the pool.
/// I.e. only one of the listed ones should be triggered.
///
/// Note that there are conditions that may cause transactions to reappear in the pool.
/// 1. Due to possible forks, the transaction that ends up being in included
/// in one block, may later re-enter the pool or be marked as invalid.
/// 2. Transaction `Dropped` at one point, may later re-enter the pool if some other
/// transactions are removed. A `Dropped` transaction may re-enter the pool only if it is
/// resubmitted.
/// 3. `Invalid` transaction may become valid at some point in the future.
/// (Note that runtimes are encouraged to use `UnknownValidity` to inform the pool about
/// such case). An `Invalid` transaction may re-enter the pool only if it is resubmitted.
/// 4. `Retracted` transactions might be included in some next block.
///
/// The `FinalityTimeout` event will be emitted when the block did not reach finality
/// within 512 blocks. This either indicates that finality is not available for your chain,
/// or that finality gadget is lagging behind. If you choose to wait for finality longer, you can
/// re-subscribe for a particular transaction hash manually again.
///
/// ### Last Event
///
/// The stream is considered finished when one of the following events happen:
/// - [Finalized](TransactionStatus::Finalized)
/// - [FinalityTimeout](TransactionStatus::FinalityTimeout)
/// - [Usurped](TransactionStatus::Usurped)
/// - [Invalid](TransactionStatus::Invalid)
/// - [Dropped](TransactionStatus::Dropped)
///
/// See [`TransactionStatus::is_final`] for more details.
///
/// ### Resubmit Transactions
///
/// Users might resubmit the transaction at a later time for the following events:
/// - [FinalityTimeout](TransactionStatus::FinalityTimeout)
/// - [Invalid](TransactionStatus::Invalid)
/// - [Dropped](TransactionStatus::Dropped)
///
/// See [`TransactionStatus::is_retriable`] for more details.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub enum TransactionStatus<Hash, BlockHash> {
/// Transaction is part of the future queue.
Future,
/// Transaction is part of the ready queue.
Ready,
/// The transaction has been broadcast to the given peers.
Broadcast(Vec<String>),
/// Transaction has been included in block with given hash
/// at the given position.
#[serde(with = "v1_compatible")]
InBlock((BlockHash, TxIndex)),
/// The block this transaction was included in has been retracted.
Retracted(BlockHash),
/// Maximum number of finality watchers has been reached,
/// old watchers are being removed.
FinalityTimeout(BlockHash),
/// Transaction has been finalized by a finality-gadget, e.g GRANDPA.
#[serde(with = "v1_compatible")]
Finalized((BlockHash, TxIndex)),
/// Transaction has been replaced in the pool, by another transaction
/// that provides the same tags. (e.g. same (sender, nonce)).
Usurped(Hash),
/// Transaction has been dropped from the pool because of the limit.
Dropped,
/// Transaction is no longer valid in the current state.
Invalid,
}
impl<Hash, BlockHash> TransactionStatus<Hash, BlockHash> {
/// Returns true if this is the last event emitted by [`TransactionStatusStream`].
pub fn is_final(&self) -> bool {
// The state must be kept in sync with `crate::graph::Sender`.
match self {
Self::Usurped(_) |
Self::Finalized(_) |
Self::FinalityTimeout(_) |
Self::Invalid |
Self::Dropped => true,
_ => false,
}
}
/// Returns true if the transaction could be re-submitted to the pool in the future.
///
/// For example, `TransactionStatus::Dropped` is retriable, because the transaction
/// may enter the pool if there is space for it in the future.
pub fn is_retriable(&self) -> bool {
match self {
// The number of finality watchers has been reached.
Self::FinalityTimeout(_) |
// An invalid transaction might be valid at a later time.
Self::Invalid |
// The transaction was dropped because of the limits of the pool.
// It can reenter the pool when other transactions are removed / finalized.
Self::Dropped => true,
_ => false,
}
}
}
/// The stream of transaction events.
pub type TransactionStatusStream<Hash, BlockHash> =
dyn Stream<Item = TransactionStatus<Hash, BlockHash>> + Send;
/// The import notification event stream.
pub type ImportNotificationStream<H> = futures::channel::mpsc::Receiver<H>;
/// Transaction hash type for a pool.
pub type TxHash<P> = <P as TransactionPool>::Hash;
/// Block hash type for a pool.
pub type BlockHash<P> = <<P as TransactionPool>::Block as BlockT>::Hash;
/// Transaction type for a pool.
pub type TransactionFor<P> = <<P as TransactionPool>::Block as BlockT>::Extrinsic;
/// Type of transactions event stream for a pool.
pub type TransactionStatusStreamFor<P> = TransactionStatusStream<TxHash<P>, BlockHash<P>>;
/// Transaction type for a local pool.
pub type LocalTransactionFor<P> = <<P as LocalTransactionPool>::Block as BlockT>::Extrinsic;
/// Transaction's index within the block in which it was included.
pub type TxIndex = usize;
/// Typical future type used in transaction pool api.
pub type PoolFuture<T, E> = std::pin::Pin<Box<dyn Future<Output = Result<T, E>> + Send>>;
/// In-pool transaction interface.
///
/// The pool is container of transactions that are implementing this trait.
/// See `sp_runtime::ValidTransaction` for details about every field.
pub trait InPoolTransaction {
/// Transaction type.
type Transaction;
/// Transaction hash type.
type Hash;
/// Get the reference to the transaction data.
fn data(&self) -> &Self::Transaction;
/// Get hash of the transaction.
fn hash(&self) -> &Self::Hash;
/// Get priority of the transaction.
fn priority(&self) -> &TransactionPriority;
/// Get longevity of the transaction.
fn longevity(&self) -> &TransactionLongevity;
/// Get transaction dependencies.
fn requires(&self) -> &[TransactionTag];
/// Get tags that transaction provides.
fn provides(&self) -> &[TransactionTag];
/// Return a flag indicating if the transaction should be propagated to other peers.
fn is_propagable(&self) -> bool;
}
/// Transaction pool interface.
pub trait TransactionPool: Send + Sync {
/// Block type.
type Block: BlockT;
/// Transaction hash type.
type Hash: Hash + Eq + Member + Serialize + DeserializeOwned + Codec;
/// In-pool transaction type.
type InPoolTransaction: InPoolTransaction<
Transaction = TransactionFor<Self>,
Hash = TxHash<Self>,
>;
/// Error type.
type Error: From<crate::error::Error> + crate::error::IntoPoolError;
// *** RPC
/// Returns a future that imports a bunch of unverified transactions to the pool.
fn submit_at(
&self,
at: <Self::Block as BlockT>::Hash,
source: TransactionSource,
xts: Vec<TransactionFor<Self>>,
) -> PoolFuture<Vec<Result<TxHash<Self>, Self::Error>>, Self::Error>;
/// Returns a future that imports one unverified transaction to the pool.
fn submit_one(
&self,
at: <Self::Block as BlockT>::Hash,
source: TransactionSource,
xt: TransactionFor<Self>,
) -> PoolFuture<TxHash<Self>, Self::Error>;
/// Returns a future that import a single transaction and starts to watch their progress in the
/// pool.
fn submit_and_watch(
&self,
at: <Self::Block as BlockT>::Hash,
source: TransactionSource,
xt: TransactionFor<Self>,
) -> PoolFuture<Pin<Box<TransactionStatusStreamFor<Self>>>, Self::Error>;
// *** Block production / Networking
/// Get an iterator for ready transactions ordered by priority.
///
/// Guarantees to return only when transaction pool got updated at `at` block.
/// Guarantees to return immediately when `None` is passed.
fn ready_at(
&self,
at: NumberFor<Self::Block>,
) -> Pin<
Box<
dyn Future<
Output = Box<dyn ReadyTransactions<Item = Arc<Self::InPoolTransaction>> + Send>,
> + Send,
>,
>;
/// Get an iterator for ready transactions ordered by priority.
fn ready(&self) -> Box<dyn ReadyTransactions<Item = Arc<Self::InPoolTransaction>> + Send>;
// *** Block production
/// Remove transactions identified by given hashes (and dependent transactions) from the pool.
fn remove_invalid(&self, hashes: &[TxHash<Self>]) -> Vec<Arc<Self::InPoolTransaction>>;
// *** logging
/// Get futures transaction list.
fn futures(&self) -> Vec<Self::InPoolTransaction>;
/// Returns pool status.
fn status(&self) -> PoolStatus;
// *** logging / RPC / networking
/// Return an event stream of transactions imported to the pool.
fn import_notification_stream(&self) -> ImportNotificationStream<TxHash<Self>>;
// *** networking
/// Notify the pool about transactions broadcast.
fn on_broadcasted(&self, propagations: HashMap<TxHash<Self>, Vec<String>>);
/// Returns transaction hash
fn hash_of(&self, xt: &TransactionFor<Self>) -> TxHash<Self>;
/// Return specific ready transaction by hash, if there is one.
fn ready_transaction(&self, hash: &TxHash<Self>) -> Option<Arc<Self::InPoolTransaction>>;
}
/// An iterator of ready transactions.
///
/// The trait extends regular [`std::iter::Iterator`] trait and allows reporting
/// last-returned element as invalid.
///
/// The implementation is then allowed, for performance reasons, to change the elements
/// returned next, by e.g. skipping elements that are known to depend on the reported
/// transaction, which yields them invalid as well.
pub trait ReadyTransactions: Iterator {
/// Report given transaction as invalid.
///
/// This might affect subsequent elements returned by the iterator, so dependent transactions
/// are skipped for performance reasons.
fn report_invalid(&mut self, _tx: &Self::Item);
}
/// A no-op implementation for an empty iterator.
impl<T> ReadyTransactions for std::iter::Empty<T> {
fn report_invalid(&mut self, _tx: &T) {}
}
/// Events that the transaction pool listens for.
pub enum ChainEvent<B: BlockT> {
/// New best block have been added to the chain.
NewBestBlock {
/// Hash of the block.
hash: B::Hash,
/// Tree route from old best to new best parent that was calculated on import.
///
/// If `None`, no re-org happened on import.
tree_route: Option<Arc<sp_blockchain::TreeRoute<B>>>,
},
/// An existing block has been finalized.
Finalized {
/// Hash of just finalized block.
hash: B::Hash,
/// Path from old finalized to new finalized parent.
tree_route: Arc<[B::Hash]>,
},
}
impl<B: BlockT> ChainEvent<B> {
/// Returns the block hash associated to the event.
pub fn hash(&self) -> B::Hash {
match self {
Self::NewBestBlock { hash, .. } | Self::Finalized { hash, .. } => *hash,
}
}
/// Is `self == Self::Finalized`?
pub fn is_finalized(&self) -> bool {
matches!(self, Self::Finalized { .. })
}
}
/// Trait for transaction pool maintenance.
#[async_trait]
pub trait MaintainedTransactionPool: TransactionPool {
/// Perform maintenance
async fn maintain(&self, event: ChainEvent<Self::Block>);
}
/// Transaction pool interface for submitting local transactions that exposes a
/// blocking interface for submission.
pub trait LocalTransactionPool: Send + Sync {
/// Block type.
type Block: BlockT;
/// Transaction hash type.
type Hash: Hash + Eq + Member + Serialize;
/// Error type.
type Error: From<crate::error::Error> + crate::error::IntoPoolError;
/// Submits the given local unverified transaction to the pool blocking the
/// current thread for any necessary pre-verification.
/// NOTE: It MUST NOT be used for transactions that originate from the
/// network or RPC, since the validation is performed with
/// `TransactionSource::Local`.
fn submit_local(
&self,
at: <Self::Block as BlockT>::Hash,
xt: LocalTransactionFor<Self>,
) -> Result<Self::Hash, Self::Error>;
}
impl<T: LocalTransactionPool> LocalTransactionPool for Arc<T> {
type Block = T::Block;
type Hash = T::Hash;
type Error = T::Error;
fn submit_local(
&self,
at: <Self::Block as BlockT>::Hash,
xt: LocalTransactionFor<Self>,
) -> Result<Self::Hash, Self::Error> {
(**self).submit_local(at, xt)
}
}
/// An abstraction for [`LocalTransactionPool`]
///
/// We want to use a transaction pool in [`OffchainTransactionPoolFactory`] in a `Arc` without
/// bleeding the associated types besides the `Block`. Thus, this abstraction here exists to achieve
/// the wrapping in a `Arc`.
trait OffchainSubmitTransaction<Block: BlockT>: Send + Sync {
/// Submit transaction.
///
/// The transaction will end up in the pool and be propagated to others.
fn submit_at(&self, at: Block::Hash, extrinsic: Block::Extrinsic) -> Result<(), ()>;
}
impl<TPool: LocalTransactionPool> OffchainSubmitTransaction<TPool::Block> for TPool {
fn submit_at(
&self,
at: <TPool::Block as BlockT>::Hash,
extrinsic: <TPool::Block as BlockT>::Extrinsic,
) -> Result<(), ()> {
log::debug!(
target: LOG_TARGET,
"(offchain call) Submitting a transaction to the pool: {:?}",
extrinsic
);
let result = self.submit_local(at, extrinsic);
result.map(|_| ()).map_err(|e| {
log::warn!(
target: LOG_TARGET,
"(offchain call) Error submitting a transaction to the pool: {}",
e
)
})
}
}
/// Factory for creating [`TransactionPoolExt`]s.
///
/// This provides an easy way for creating [`TransactionPoolExt`] extensions for registering them in
/// the wasm execution environment to send transactions from an offchain call to the runtime.
#[derive(Clone)]
pub struct OffchainTransactionPoolFactory<Block: BlockT> {
pool: Arc<dyn OffchainSubmitTransaction<Block>>,
}
impl<Block: BlockT> OffchainTransactionPoolFactory<Block> {
/// Creates a new instance using the given `tx_pool`.
pub fn new<T: LocalTransactionPool<Block = Block> + 'static>(tx_pool: T) -> Self {
Self { pool: Arc::new(tx_pool) as Arc<_> }
}
/// Returns an instance of [`TransactionPoolExt`] bound to the given `block_hash`.
///
/// Transactions that are being submitted by this instance will be submitted with `block_hash`
/// as context for validation.
pub fn offchain_transaction_pool(&self, block_hash: Block::Hash) -> TransactionPoolExt {
TransactionPoolExt::new(OffchainTransactionPool { pool: self.pool.clone(), block_hash })
}
}
/// Wraps a `pool` and `block_hash` to implement [`sp_core::offchain::TransactionPool`].
struct OffchainTransactionPool<Block: BlockT> {
block_hash: Block::Hash,
pool: Arc<dyn OffchainSubmitTransaction<Block>>,
}
impl<Block: BlockT> sp_core::offchain::TransactionPool for OffchainTransactionPool<Block> {
fn submit_transaction(&mut self, extrinsic: Vec<u8>) -> Result<(), ()> {
let extrinsic = match codec::Decode::decode(&mut &extrinsic[..]) {
Ok(t) => t,
Err(e) => {
log::error!(
target: LOG_TARGET,
"Failed to decode extrinsic in `OffchainTransactionPool::submit_transaction`: {e:?}"
);
return Err(())
},
};
self.pool.submit_at(self.block_hash, extrinsic)
}
}
/// Wrapper functions to keep the API backwards compatible over the wire for the old RPC spec.
mod v1_compatible {
use serde::{Deserialize, Deserializer, Serialize, Serializer};
pub fn serialize<S, H>(data: &(H, usize), serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
H: Serialize,
{
let (hash, _) = data;
serde::Serialize::serialize(&hash, serializer)
}
pub fn deserialize<'de, D, H>(deserializer: D) -> Result<(H, usize), D::Error>
where
D: Deserializer<'de>,
H: Deserialize<'de>,
{
let hash: H = serde::Deserialize::deserialize(deserializer)?;
Ok((hash, 0))
}
}
/// Transaction pool that rejects all submitted transactions.
///
/// Could be used for example in tests.
pub struct RejectAllTxPool<Block>(PhantomData<Block>);
impl<Block> Default for RejectAllTxPool<Block> {
fn default() -> Self {
Self(PhantomData)
}
}
impl<Block: BlockT> LocalTransactionPool for RejectAllTxPool<Block> {
type Block = Block;
type Hash = Block::Hash;
type Error = error::Error;
fn submit_local(&self, _: Block::Hash, _: Block::Extrinsic) -> Result<Self::Hash, Self::Error> {
Err(error::Error::ImmediatelyDropped)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn tx_status_compatibility() {
let event: TransactionStatus<u8, u8> = TransactionStatus::InBlock((1, 2));
let ser = serde_json::to_string(&event).unwrap();
let exp = r#"{"inBlock":1}"#;
assert_eq!(ser, exp);
let event_dec: TransactionStatus<u8, u8> = serde_json::from_str(exp).unwrap();
assert_eq!(event_dec, TransactionStatus::InBlock((1, 0)));
let event: TransactionStatus<u8, u8> = TransactionStatus::Finalized((1, 2));
let ser = serde_json::to_string(&event).unwrap();
let exp = r#"{"finalized":1}"#;
assert_eq!(ser, exp);
let event_dec: TransactionStatus<u8, u8> = serde_json::from_str(exp).unwrap();
assert_eq!(event_dec, TransactionStatus::Finalized((1, 0)));
}
}