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// This file is part of Substrate.
// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//! # Generalized Message Queue Pallet
//!
//! Provides generalized message queuing and processing capabilities on a per-queue basis for
//! arbitrary use-cases.
//!
//! # Design Goals
//!
//! 1. Minimal assumptions about `Message`s and `MessageOrigin`s. Both should be MEL bounded blobs.
//! This ensures the generality and reusability of the pallet.
//! 2. Well known and tightly limited pre-dispatch PoV weights, especially for message execution.
//! This is paramount for the success of the pallet since message execution is done in
//! `on_initialize` which must _never_ under-estimate its PoV weight. It also needs a frugal PoV
//! footprint since PoV is scarce and this is (possibly) done in every block. This must also hold
//! in the presence of unpredictable message size distributions.
//! 3. Usable as XCMP, DMP and UMP message/dispatch queue - possibly through adapter types.
//!
//! # Design
//!
//! The pallet has means to enqueue, store and process messages. This is implemented by having
//! *queues* which store enqueued messages and can be *served* to process said messages. A queue is
//! identified by its origin in the `BookStateFor`. Each message has an origin which defines into
//! which queue it will be stored. Messages are stored by being appended to the last [`Page`] of a
//! book. Each book keeps track of its pages by indexing `Pages`. The `ReadyRing` contains all
//! queues which hold at least one unprocessed message and are thereby *ready* to be serviced. The
//! `ServiceHead` indicates which *ready* queue is the next to be serviced.
//! The pallet implements [`frame_support::traits::EnqueueMessage`],
//! [`frame_support::traits::ServiceQueues`] and has [`frame_support::traits::ProcessMessage`] and
//! [`OnQueueChanged`] hooks to communicate with the outside world.
//!
//! NOTE: The storage items are not linked since they are not public.
//!
//! **Message Execution**
//!
//! Executing a message is offloaded to the [`Config::MessageProcessor`] which contains the actual
//! logic of how to handle the message since they are blobs. Storage changes are not rolled back on
//! error.
//!
//! A failed message can be temporarily or permanently overweight. The pallet will perpetually try
//! to execute a temporarily overweight message. A permanently overweight message is skipped and
//! must be executed manually.
//!
//! **Reentrancy**
//!
//! This pallet has two entry points for executing (possibly recursive) logic;
//! [`Pallet::service_queues`] and [`Pallet::execute_overweight`]. Both entry points are guarded by
//! the same mutex to error on reentrancy. The only functions that are explicitly **allowed** to be
//! called by a message processor are: [`Pallet::enqueue_message`] and
//! [`Pallet::enqueue_messages`]. All other functions are forbidden and error with
//! [`Error::RecursiveDisallowed`].
//!
//! **Pagination**
//!
//! Queues are stored in a *paged* manner by splitting their messages into [`Page`]s. This results
//! in a lot of complexity when implementing the pallet but is completely necessary to achieve the
//! second #[Design Goal](design-goals). The problem comes from the fact a message can *possibly* be
//! quite large, lets say 64KiB. This then results in a *MEL* of at least 64KiB which results in a
//! PoV of at least 64KiB. Now we have the assumption that most messages are much shorter than their
//! maximum allowed length. This would result in most messages having a pre-dispatch PoV size which
//! is much larger than their post-dispatch PoV size, possibly by a factor of thousand. Disregarding
//! this observation would cripple the processing power of the pallet since it cannot straighten out
//! this discrepancy at runtime. Conceptually, the implementation is packing as many messages into a
//! single bounded vec, as actually fit into the bounds. This reduces the wasted PoV.
//!
//! **Page Data Layout**
//!
//! A Page contains a heap which holds all its messages. The heap is built by concatenating
//! `(ItemHeader, Message)` pairs. The [`ItemHeader`] contains the length of the message which is
//! needed for retrieving it. This layout allows for constant access time of the next message and
//! linear access time for any message in the page. The header must remain minimal to reduce its PoV
//! impact.
//!
//! **Weight Metering**
//!
//! The pallet utilizes the [`sp_weights::WeightMeter`] to manually track its consumption to always
//! stay within the required limit. This implies that the message processor hook can calculate the
//! weight of a message without executing it. This restricts the possible use-cases but is necessary
//! since the pallet runs in `on_initialize` which has a hard weight limit. The weight meter is used
//! in a way that `can_accrue` and `check_accrue` are always used to check the remaining weight of
//! an operation before committing to it. The process of exiting due to insufficient weight is
//! termed "bailing".
//!
//! # Scenario: Message enqueuing
//!
//! A message `m` is enqueued for origin `o` into queue `Q[o]` through
//! [`frame_support::traits::EnqueueMessage::enqueue_message`]`(m, o)`.
//!
//! First the queue is either loaded if it exists or otherwise created with empty default values.
//! The message is then inserted to the queue by appended it into its last `Page` or by creating a
//! new `Page` just for `m` if it does not fit in there. The number of messages in the `Book` is
//! incremented.
//!
//! `Q[o]` is now *ready* which will eventually result in `m` being processed.
//!
//! # Scenario: Message processing
//!
//! The pallet runs each block in `on_initialize` or when being manually called through
//! [`frame_support::traits::ServiceQueues::service_queues`].
//!
//! First it tries to "rotate" the `ReadyRing` by one through advancing the `ServiceHead` to the
//! next *ready* queue. It then starts to service this queue by servicing as many pages of it as
//! possible. Servicing a page means to execute as many message of it as possible. Each executed
//! message is marked as *processed* if the [`Config::MessageProcessor`] return Ok. An event
//! [`Event::Processed`] is emitted afterwards. It is possible that the weight limit of the pallet
//! will never allow a specific message to be executed. In this case it remains as unprocessed and
//! is skipped. This process stops if either there are no more messages in the queue or the
//! remaining weight became insufficient to service this queue. If there is enough weight it tries
//! to advance to the next *ready* queue and service it. This continues until there are no more
//! queues on which it can make progress or not enough weight to check that.
//!
//! # Scenario: Overweight execution
//!
//! A permanently over-weight message which was skipped by the message processing will never be
//! executed automatically through `on_initialize` nor by calling
//! [`frame_support::traits::ServiceQueues::service_queues`].
//!
//! Manual intervention in the form of
//! [`frame_support::traits::ServiceQueues::execute_overweight`] is necessary. Overweight messages
//! emit an [`Event::OverweightEnqueued`] event which can be used to extract the arguments for
//! manual execution. This only works on permanently overweight messages. There is no guarantee that
//! this will work since the message could be part of a stale page and be reaped before execution
//! commences.
//!
//! # Terminology
//!
//! - `Message`: A blob of data into which the pallet has no introspection, defined as
//! [`BoundedSlice<u8, MaxMessageLenOf<T>>`]. The message length is limited by [`MaxMessageLenOf`]
//! which is calculated from [`Config::HeapSize`] and [`ItemHeader::max_encoded_len()`].
//! - `MessageOrigin`: A generic *origin* of a message, defined as [`MessageOriginOf`]. The
//! requirements for it are kept minimal to remain as generic as possible. The type is defined in
//! [`frame_support::traits::ProcessMessage::Origin`].
//! - `Page`: An array of `Message`s, see [`Page`]. Can never be empty.
//! - `Book`: A list of `Page`s, see [`BookState`]. Can be empty.
//! - `Queue`: A `Book` together with an `MessageOrigin` which can be part of the `ReadyRing`. Can
//! be empty.
//! - `ReadyRing`: A double-linked list which contains all *ready* `Queue`s. It chains together the
//! queues via their `ready_neighbours` fields. A `Queue` is *ready* if it contains at least one
//! `Message` which can be processed. Can be empty.
//! - `ServiceHead`: A pointer into the `ReadyRing` to the next `Queue` to be serviced.
//! - (`un`)`processed`: A message is marked as *processed* after it was executed by the pallet. A
//! message which was either: not yet executed or could not be executed remains as `unprocessed`
//! which is the default state for a message after being enqueued.
//! - `knitting`/`unknitting`: The means of adding or removing a `Queue` from the `ReadyRing`.
//! - `MEL`: The Max Encoded Length of a type, see [`codec::MaxEncodedLen`].
//! - `Reentrance`: To enter an execution context again before it has completed.
//!
//! # Properties
//!
//! **Liveness - Enqueueing**
//!
//! It is always possible to enqueue any message for any `MessageOrigin`.
//!
//! **Liveness - Processing**
//!
//! `on_initialize` always respects its finite weight-limit.
//!
//! **Progress - Enqueueing**
//!
//! An enqueued message immediately becomes *unprocessed* and thereby eligible for execution.
//!
//! **Progress - Processing**
//!
//! The pallet will execute at least one unprocessed message per block, if there is any. Ensuring
//! this property needs careful consideration of the concrete weights, since it is possible that the
//! weight limit of `on_initialize` never allows for the execution of even one message; trivially if
//! the limit is set to zero. `integrity_test` can be used to ensure that this property holds.
//!
//! **Fairness - Enqueuing**
//!
//! Enqueueing a message for a specific `MessageOrigin` does not influence the ability to enqueue a
//! message for the same of any other `MessageOrigin`; guaranteed by **Liveness - Enqueueing**.
//!
//! **Fairness - Processing**
//!
//! The average amount of weight available for message processing is the same for each queue if the
//! number of queues is constant. Creating a new queue must therefore be, possibly economically,
//! expensive. Currently this is archived by having one queue per para-chain/thread, which keeps the
//! number of queues within `O(n)` and should be "good enough".
#![deny(missing_docs)]
#![cfg_attr(not(feature = "std"), no_std)]
mod benchmarking;
mod integration_test;
mod mock;
pub mod mock_helpers;
mod tests;
pub mod weights;
extern crate alloc;
use alloc::{vec, vec::Vec};
use codec::{Codec, Decode, Encode, MaxEncodedLen};
use core::{fmt::Debug, ops::Deref};
use frame_support::{
defensive,
pallet_prelude::*,
traits::{
Defensive, DefensiveSaturating, DefensiveTruncateFrom, EnqueueMessage,
ExecuteOverweightError, Footprint, ProcessMessage, ProcessMessageError, QueueFootprint,
QueuePausedQuery, ServiceQueues,
},
BoundedSlice, CloneNoBound, DefaultNoBound,
};
use frame_system::pallet_prelude::*;
pub use pallet::*;
use scale_info::TypeInfo;
use sp_arithmetic::traits::{BaseArithmetic, Unsigned};
use sp_core::{defer, H256};
use sp_runtime::{
traits::{One, Zero},
SaturatedConversion, Saturating, TransactionOutcome,
};
use sp_weights::WeightMeter;
pub use weights::WeightInfo;
/// Type for identifying a page.
type PageIndex = u32;
/// Data encoded and prefixed to the encoded `MessageItem`.
#[derive(Encode, Decode, PartialEq, MaxEncodedLen, Debug)]
pub struct ItemHeader<Size> {
/// The length of this item, not including the size of this header. The next item of the page
/// follows immediately after the payload of this item.
payload_len: Size,
/// Whether this item has been processed.
is_processed: bool,
}
/// A page of messages. Pages always contain at least one item.
#[derive(
CloneNoBound, Encode, Decode, RuntimeDebugNoBound, DefaultNoBound, TypeInfo, MaxEncodedLen,
)]
#[scale_info(skip_type_params(HeapSize))]
#[codec(mel_bound(Size: MaxEncodedLen))]
pub struct Page<Size: Into<u32> + Debug + Clone + Default, HeapSize: Get<Size>> {
/// Messages remaining to be processed; this includes overweight messages which have been
/// skipped.
remaining: Size,
/// The size of all remaining messages to be processed.
///
/// Includes overweight messages outside of the `first` to `last` window.
remaining_size: Size,
/// The number of items before the `first` item in this page.
first_index: Size,
/// The heap-offset of the header of the first message item in this page which is ready for
/// processing.
first: Size,
/// The heap-offset of the header of the last message item in this page.
last: Size,
/// The heap. If `self.offset == self.heap.len()` then the page is empty and should be deleted.
heap: BoundedVec<u8, IntoU32<HeapSize, Size>>,
}
impl<
Size: BaseArithmetic + Unsigned + Copy + Into<u32> + Codec + MaxEncodedLen + Debug + Default,
HeapSize: Get<Size>,
> Page<Size, HeapSize>
{
/// Create a [`Page`] from one unprocessed message.
fn from_message<T: Config>(message: BoundedSlice<u8, MaxMessageLenOf<T>>) -> Self {
let payload_len = message.len();
let data_len = ItemHeader::<Size>::max_encoded_len().saturating_add(payload_len);
let payload_len = payload_len.saturated_into();
let header = ItemHeader::<Size> { payload_len, is_processed: false };
let mut heap = Vec::with_capacity(data_len);
header.using_encoded(|h| heap.extend_from_slice(h));
heap.extend_from_slice(message.deref());
Page {
remaining: One::one(),
remaining_size: payload_len,
first_index: Zero::zero(),
first: Zero::zero(),
last: Zero::zero(),
heap: BoundedVec::defensive_truncate_from(heap),
}
}
/// Try to append one message to a page.
fn try_append_message<T: Config>(
&mut self,
message: BoundedSlice<u8, MaxMessageLenOf<T>>,
) -> Result<(), ()> {
let pos = self.heap.len();
let payload_len = message.len();
let data_len = ItemHeader::<Size>::max_encoded_len().saturating_add(payload_len);
let payload_len = payload_len.saturated_into();
let header = ItemHeader::<Size> { payload_len, is_processed: false };
let heap_size: u32 = HeapSize::get().into();
if (heap_size as usize).saturating_sub(self.heap.len()) < data_len {
// Can't fit.
return Err(())
}
let mut heap = core::mem::take(&mut self.heap).into_inner();
header.using_encoded(|h| heap.extend_from_slice(h));
heap.extend_from_slice(message.deref());
self.heap = BoundedVec::defensive_truncate_from(heap);
self.last = pos.saturated_into();
self.remaining.saturating_inc();
self.remaining_size.saturating_accrue(payload_len);
Ok(())
}
/// Returns the first message in the page without removing it.
///
/// SAFETY: Does not panic even on corrupted storage.
fn peek_first(&self) -> Option<BoundedSlice<u8, IntoU32<HeapSize, Size>>> {
if self.first > self.last {
return None
}
let f = (self.first.into() as usize).min(self.heap.len());
let mut item_slice = &self.heap[f..];
if let Ok(h) = ItemHeader::<Size>::decode(&mut item_slice) {
let payload_len = h.payload_len.into() as usize;
if payload_len <= item_slice.len() {
// impossible to truncate since is sliced up from `self.heap: BoundedVec<u8,
// HeapSize>`
return Some(BoundedSlice::defensive_truncate_from(&item_slice[..payload_len]))
}
}
defensive!("message-queue: heap corruption");
None
}
/// Point `first` at the next message, marking the first as processed if `is_processed` is true.
fn skip_first(&mut self, is_processed: bool) {
let f = (self.first.into() as usize).min(self.heap.len());
if let Ok(mut h) = ItemHeader::decode(&mut &self.heap[f..]) {
if is_processed && !h.is_processed {
h.is_processed = true;
h.using_encoded(|d| self.heap[f..f + d.len()].copy_from_slice(d));
self.remaining.saturating_dec();
self.remaining_size.saturating_reduce(h.payload_len);
}
self.first
.saturating_accrue(ItemHeader::<Size>::max_encoded_len().saturated_into());
self.first.saturating_accrue(h.payload_len);
self.first_index.saturating_inc();
}
}
/// Return the message with index `index` in the form of `(position, processed, message)`.
fn peek_index(&self, index: usize) -> Option<(usize, bool, &[u8])> {
let mut pos = 0;
let mut item_slice = &self.heap[..];
let header_len: usize = ItemHeader::<Size>::max_encoded_len().saturated_into();
for _ in 0..index {
let h = ItemHeader::<Size>::decode(&mut item_slice).ok()?;
let item_len = h.payload_len.into() as usize;
if item_slice.len() < item_len {
return None
}
item_slice = &item_slice[item_len..];
pos.saturating_accrue(header_len.saturating_add(item_len));
}
let h = ItemHeader::<Size>::decode(&mut item_slice).ok()?;
if item_slice.len() < h.payload_len.into() as usize {
return None
}
item_slice = &item_slice[..h.payload_len.into() as usize];
Some((pos, h.is_processed, item_slice))
}
/// Set the `is_processed` flag for the item at `pos` to be `true` if not already and decrement
/// the `remaining` counter of the page.
///
/// Does nothing if no [`ItemHeader`] could be decoded at the given position.
fn note_processed_at_pos(&mut self, pos: usize) {
if let Ok(mut h) = ItemHeader::<Size>::decode(&mut &self.heap[pos..]) {
if !h.is_processed {
h.is_processed = true;
h.using_encoded(|d| self.heap[pos..pos + d.len()].copy_from_slice(d));
self.remaining.saturating_dec();
self.remaining_size.saturating_reduce(h.payload_len);
}
}
}
/// Returns whether the page is *complete* which means that no messages remain.
fn is_complete(&self) -> bool {
self.remaining.is_zero()
}
}
/// A single link in the double-linked Ready Ring list.
#[derive(Clone, Encode, Decode, MaxEncodedLen, TypeInfo, RuntimeDebug, PartialEq)]
pub struct Neighbours<MessageOrigin> {
/// The previous queue.
prev: MessageOrigin,
/// The next queue.
next: MessageOrigin,
}
/// The state of a queue as represented by a book of its pages.
///
/// Each queue has exactly one book which holds all of its pages. All pages of a book combined
/// contain all of the messages of its queue; hence the name *Book*.
/// Books can be chained together in a double-linked fashion through their `ready_neighbours` field.
#[derive(Clone, Encode, Decode, MaxEncodedLen, TypeInfo, RuntimeDebug)]
pub struct BookState<MessageOrigin> {
/// The first page with some items to be processed in it. If this is `>= end`, then there are
/// no pages with items to be processing in them.
begin: PageIndex,
/// One more than the last page with some items to be processed in it.
end: PageIndex,
/// The number of pages stored at present.
///
/// This might be larger than `end-begin`, because we keep pages with unprocessed overweight
/// messages outside of the end/begin window.
count: PageIndex,
/// If this book has any ready pages, then this will be `Some` with the previous and next
/// neighbours. This wraps around.
ready_neighbours: Option<Neighbours<MessageOrigin>>,
/// The number of unprocessed messages stored at present.
message_count: u64,
/// The total size of all unprocessed messages stored at present.
size: u64,
}
impl<MessageOrigin> Default for BookState<MessageOrigin> {
fn default() -> Self {
Self { begin: 0, end: 0, count: 0, ready_neighbours: None, message_count: 0, size: 0 }
}
}
impl<MessageOrigin> From<BookState<MessageOrigin>> for QueueFootprint {
fn from(book: BookState<MessageOrigin>) -> Self {
QueueFootprint {
pages: book.count,
ready_pages: book.end.defensive_saturating_sub(book.begin),
storage: Footprint { count: book.message_count, size: book.size },
}
}
}
/// Handler code for when the items in a queue change.
pub trait OnQueueChanged<Id> {
/// Note that the queue `id` now has `item_count` items in it, taking up `items_size` bytes.
fn on_queue_changed(id: Id, fp: QueueFootprint);
}
impl<Id> OnQueueChanged<Id> for () {
fn on_queue_changed(_: Id, _: QueueFootprint) {}
}
#[frame_support::pallet]
pub mod pallet {
use super::*;
#[pallet::pallet]
pub struct Pallet<T>(_);
/// The module configuration trait.
#[pallet::config]
pub trait Config: frame_system::Config {
/// The overarching event type.
type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;
/// Weight information for extrinsics in this pallet.
type WeightInfo: WeightInfo;
/// Processor for a message.
///
/// Storage changes are not rolled back on error.
///
/// # Benchmarking
///
/// Must be set to [`mock_helpers::NoopMessageProcessor`] for benchmarking.
/// Other message processors that consumes exactly (1, 1) weight for any give message will
/// work as well. Otherwise the benchmarking will also measure the weight of the message
/// processor, which is not desired.
type MessageProcessor: ProcessMessage;
/// Page/heap size type.
type Size: BaseArithmetic
+ Unsigned
+ Copy
+ Into<u32>
+ Member
+ Encode
+ Decode
+ MaxEncodedLen
+ TypeInfo
+ Default;
/// Code to be called when a message queue changes - either with items introduced or
/// removed.
type QueueChangeHandler: OnQueueChanged<<Self::MessageProcessor as ProcessMessage>::Origin>;
/// Queried by the pallet to check whether a queue can be serviced.
///
/// This also applies to manual servicing via `execute_overweight` and `service_queues`. The
/// value of this is only polled once before servicing the queue. This means that changes to
/// it that happen *within* the servicing will not be reflected.
type QueuePausedQuery: QueuePausedQuery<<Self::MessageProcessor as ProcessMessage>::Origin>;
/// The size of the page; this implies the maximum message size which can be sent.
///
/// A good value depends on the expected message sizes, their weights, the weight that is
/// available for processing them and the maximal needed message size. The maximal message
/// size is slightly lower than this as defined by [`MaxMessageLenOf`].
#[pallet::constant]
type HeapSize: Get<Self::Size>;
/// The maximum number of stale pages (i.e. of overweight messages) allowed before culling
/// can happen. Once there are more stale pages than this, then historical pages may be
/// dropped, even if they contain unprocessed overweight messages.
#[pallet::constant]
type MaxStale: Get<u32>;
/// The amount of weight (if any) which should be provided to the message queue for
/// servicing enqueued items `on_initialize`.
///
/// This may be legitimately `None` in the case that you will call
/// `ServiceQueues::service_queues` manually or set [`Self::IdleMaxServiceWeight`] to have
/// it run in `on_idle`.
#[pallet::constant]
type ServiceWeight: Get<Option<Weight>>;
/// The maximum amount of weight (if any) to be used from remaining weight `on_idle` which
/// should be provided to the message queue for servicing enqueued items `on_idle`.
/// Useful for parachains to process messages at the same block they are received.
///
/// If `None`, it will not call `ServiceQueues::service_queues` in `on_idle`.
#[pallet::constant]
type IdleMaxServiceWeight: Get<Option<Weight>>;
}
#[pallet::event]
#[pallet::generate_deposit(pub(super) fn deposit_event)]
pub enum Event<T: Config> {
/// Message discarded due to an error in the `MessageProcessor` (usually a format error).
ProcessingFailed {
/// The `blake2_256` hash of the message.
id: H256,
/// The queue of the message.
origin: MessageOriginOf<T>,
/// The error that occurred.
///
/// This error is pretty opaque. More fine-grained errors need to be emitted as events
/// by the `MessageProcessor`.
error: ProcessMessageError,
},
/// Message is processed.
Processed {
/// The `blake2_256` hash of the message.
id: H256,
/// The queue of the message.
origin: MessageOriginOf<T>,
/// How much weight was used to process the message.
weight_used: Weight,
/// Whether the message was processed.
///
/// Note that this does not mean that the underlying `MessageProcessor` was internally
/// successful. It *solely* means that the MQ pallet will treat this as a success
/// condition and discard the message. Any internal error needs to be emitted as events
/// by the `MessageProcessor`.
success: bool,
},
/// Message placed in overweight queue.
OverweightEnqueued {
/// The `blake2_256` hash of the message.
id: [u8; 32],
/// The queue of the message.
origin: MessageOriginOf<T>,
/// The page of the message.
page_index: PageIndex,
/// The index of the message within the page.
message_index: T::Size,
},
/// This page was reaped.
PageReaped {
/// The queue of the page.
origin: MessageOriginOf<T>,
/// The index of the page.
index: PageIndex,
},
}
#[pallet::error]
pub enum Error<T> {
/// Page is not reapable because it has items remaining to be processed and is not old
/// enough.
NotReapable,
/// Page to be reaped does not exist.
NoPage,
/// The referenced message could not be found.
NoMessage,
/// The message was already processed and cannot be processed again.
AlreadyProcessed,
/// The message is queued for future execution.
Queued,
/// There is temporarily not enough weight to continue servicing messages.
InsufficientWeight,
/// This message is temporarily unprocessable.
///
/// Such errors are expected, but not guaranteed, to resolve themselves eventually through
/// retrying.
TemporarilyUnprocessable,
/// The queue is paused and no message can be executed from it.
///
/// This can change at any time and may resolve in the future by re-trying.
QueuePaused,
/// Another call is in progress and needs to finish before this call can happen.
RecursiveDisallowed,
}
/// The index of the first and last (non-empty) pages.
#[pallet::storage]
pub(super) type BookStateFor<T: Config> =
StorageMap<_, Twox64Concat, MessageOriginOf<T>, BookState<MessageOriginOf<T>>, ValueQuery>;
/// The origin at which we should begin servicing.
#[pallet::storage]
pub(super) type ServiceHead<T: Config> = StorageValue<_, MessageOriginOf<T>, OptionQuery>;
/// The map of page indices to pages.
#[pallet::storage]
pub(super) type Pages<T: Config> = StorageDoubleMap<
_,
Twox64Concat,
MessageOriginOf<T>,
Twox64Concat,
PageIndex,
Page<T::Size, T::HeapSize>,
OptionQuery,
>;
#[pallet::hooks]
impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {
fn on_initialize(_n: BlockNumberFor<T>) -> Weight {
if let Some(weight_limit) = T::ServiceWeight::get() {
Self::service_queues_impl(weight_limit, ServiceQueuesContext::OnInitialize)
} else {
Weight::zero()
}
}
fn on_idle(_n: BlockNumberFor<T>, remaining_weight: Weight) -> Weight {
if let Some(weight_limit) = T::IdleMaxServiceWeight::get() {
// Make use of the remaining weight to process enqueued messages.
Self::service_queues_impl(
weight_limit.min(remaining_weight),
ServiceQueuesContext::OnIdle,
)
} else {
Weight::zero()
}
}
#[cfg(feature = "try-runtime")]
fn try_state(_: BlockNumberFor<T>) -> Result<(), sp_runtime::TryRuntimeError> {
Self::do_try_state()
}
/// Check all compile-time assumptions about [`crate::Config`].
#[cfg(test)]
fn integrity_test() {
Self::do_integrity_test().expect("Pallet config is valid; qed")
}
}
#[pallet::call]
impl<T: Config> Pallet<T> {
/// Remove a page which has no more messages remaining to be processed or is stale.
#[pallet::call_index(0)]
#[pallet::weight(T::WeightInfo::reap_page())]
pub fn reap_page(
origin: OriginFor<T>,
message_origin: MessageOriginOf<T>,
page_index: PageIndex,
) -> DispatchResult {
let _ = ensure_signed(origin)?;
Self::do_reap_page(&message_origin, page_index)
}
/// Execute an overweight message.
///
/// Temporary processing errors will be propagated whereas permanent errors are treated
/// as success condition.
///
/// - `origin`: Must be `Signed`.
/// - `message_origin`: The origin from which the message to be executed arrived.
/// - `page`: The page in the queue in which the message to be executed is sitting.
/// - `index`: The index into the queue of the message to be executed.
/// - `weight_limit`: The maximum amount of weight allowed to be consumed in the execution
/// of the message.
///
/// Benchmark complexity considerations: O(index + weight_limit).
#[pallet::call_index(1)]
#[pallet::weight(
T::WeightInfo::execute_overweight_page_updated().max(
T::WeightInfo::execute_overweight_page_removed()).saturating_add(*weight_limit)
)]
pub fn execute_overweight(
origin: OriginFor<T>,
message_origin: MessageOriginOf<T>,
page: PageIndex,
index: T::Size,
weight_limit: Weight,
) -> DispatchResultWithPostInfo {
let _ = ensure_signed(origin)?;
let actual_weight =
Self::do_execute_overweight(message_origin, page, index, weight_limit)?;
Ok(Some(actual_weight).into())
}
}
}
/// The status of a page after trying to execute its next message.
#[derive(PartialEq, Debug)]
enum PageExecutionStatus {
/// The execution bailed because there was not enough weight remaining.
Bailed,
/// The page did not make any progress on its execution.
///
/// This is a transient condition and can be handled by retrying - exactly like [Bailed].
NoProgress,
/// No more messages could be loaded. This does _not_ imply `page.is_complete()`.
///
/// The reasons for this status are:
/// - The end of the page is reached but there could still be skipped messages.
/// - The storage is corrupted.
NoMore,
}
/// The status after trying to execute the next item of a [`Page`].
#[derive(PartialEq, Debug)]
enum ItemExecutionStatus {
/// The execution bailed because there was not enough weight remaining.
Bailed,
/// The item did not make any progress on its execution.
///
/// This is a transient condition and can be handled by retrying - exactly like [Bailed].
NoProgress,
/// The item was not found.
NoItem,
/// Whether the execution of an item resulted in it being processed.
///
/// One reason for `false` would be permanently overweight.
Executed(bool),
}
/// The status of an attempt to process a message.
#[derive(PartialEq)]
enum MessageExecutionStatus {
/// There is not enough weight remaining at present.
InsufficientWeight,
/// There will never be enough weight.
Overweight,
/// The message was processed successfully.
Processed,
/// The message was processed and resulted in a, possibly permanent, error.
Unprocessable { permanent: bool },
/// The stack depth limit was reached.
///
/// We cannot just return `Unprocessable` in this case, because the processability of the
/// message depends on how the function was called. This may be a permanent error if it was
/// called by a top-level function, or a transient error if it was already called in a nested
/// function.
StackLimitReached,
}
/// The context to pass to [`Pallet::service_queues_impl`] through on_idle and on_initialize hooks
/// We don't want to throw the defensive message if called from on_idle hook
#[derive(PartialEq)]
enum ServiceQueuesContext {
/// Context of on_idle hook.
OnIdle,
/// Context of on_initialize hook.
OnInitialize,
/// Context `service_queues` trait function.
ServiceQueues,
}
impl<T: Config> Pallet<T> {
/// Knit `origin` into the ready ring right at the end.
///
/// Return the two ready ring neighbours of `origin`.
fn ready_ring_knit(origin: &MessageOriginOf<T>) -> Result<Neighbours<MessageOriginOf<T>>, ()> {
if let Some(head) = ServiceHead::<T>::get() {
let mut head_book_state = BookStateFor::<T>::get(&head);
let mut head_neighbours = head_book_state.ready_neighbours.take().ok_or(())?;
let tail = head_neighbours.prev;
head_neighbours.prev = origin.clone();
head_book_state.ready_neighbours = Some(head_neighbours);
BookStateFor::<T>::insert(&head, head_book_state);
let mut tail_book_state = BookStateFor::<T>::get(&tail);
let mut tail_neighbours = tail_book_state.ready_neighbours.take().ok_or(())?;
tail_neighbours.next = origin.clone();
tail_book_state.ready_neighbours = Some(tail_neighbours);
BookStateFor::<T>::insert(&tail, tail_book_state);
Ok(Neighbours { next: head, prev: tail })
} else {
ServiceHead::<T>::put(origin);
Ok(Neighbours { next: origin.clone(), prev: origin.clone() })
}
}
fn ready_ring_unknit(origin: &MessageOriginOf<T>, neighbours: Neighbours<MessageOriginOf<T>>) {
if origin == &neighbours.next {
debug_assert!(
origin == &neighbours.prev,
"unknitting from single item ring; outgoing must be only item"
);
// Service queue empty.
ServiceHead::<T>::kill();
} else {
BookStateFor::<T>::mutate(&neighbours.next, |book_state| {
if let Some(ref mut n) = book_state.ready_neighbours {
n.prev = neighbours.prev.clone()
}
});
BookStateFor::<T>::mutate(&neighbours.prev, |book_state| {
if let Some(ref mut n) = book_state.ready_neighbours {
n.next = neighbours.next.clone()
}
});
if let Some(head) = ServiceHead::<T>::get() {
if &head == origin {
ServiceHead::<T>::put(neighbours.next);
}
} else {
defensive!("`ServiceHead` must be some if there was a ready queue");
}
}
}
/// Tries to bump the current `ServiceHead` to the next ready queue.
///
/// Returns the current head if it got be bumped and `None` otherwise.
fn bump_service_head(weight: &mut WeightMeter) -> Option<MessageOriginOf<T>> {
if weight.try_consume(T::WeightInfo::bump_service_head()).is_err() {
return None
}
if let Some(head) = ServiceHead::<T>::get() {
let mut head_book_state = BookStateFor::<T>::get(&head);
if let Some(head_neighbours) = head_book_state.ready_neighbours.take() {
ServiceHead::<T>::put(&head_neighbours.next);
Some(head)
} else {
None
}
} else {
None
}
}
/// The maximal weight that a single message ever can consume.
///
/// Any message using more than this will be marked as permanently overweight and not
/// automatically re-attempted. Returns `None` if the servicing of a message cannot begin.
/// `Some(0)` means that only messages with no weight may be served.
fn max_message_weight(limit: Weight) -> Option<Weight> {
let service_weight = T::ServiceWeight::get().unwrap_or_default();
let on_idle_weight = T::IdleMaxServiceWeight::get().unwrap_or_default();
// Whatever weight is set, the one with the biggest one is used as the maximum weight. If a
// message is tried in one context and fails, it will be retried in the other context later.
let max_message_weight =
if service_weight.any_gt(on_idle_weight) { service_weight } else { on_idle_weight };
if max_message_weight.is_zero() {
// If no service weight is set, we need to use the given limit as max message weight.
limit.checked_sub(&Self::single_msg_overhead())
} else {
max_message_weight.checked_sub(&Self::single_msg_overhead())
}
}
/// The overhead of servicing a single message.
fn single_msg_overhead() -> Weight {
T::WeightInfo::bump_service_head()
.saturating_add(T::WeightInfo::service_queue_base())
.saturating_add(
T::WeightInfo::service_page_base_completion()
.max(T::WeightInfo::service_page_base_no_completion()),
)
.saturating_add(T::WeightInfo::service_page_item())
.saturating_add(T::WeightInfo::ready_ring_unknit())
}
/// Checks invariants of the pallet config.
///
/// The results of this can only be relied upon if the config values are set to constants.
#[cfg(test)]
fn do_integrity_test() -> Result<(), String> {
ensure!(!MaxMessageLenOf::<T>::get().is_zero(), "HeapSize too low");
let max_block = T::BlockWeights::get().max_block;
if let Some(service) = T::ServiceWeight::get() {
if Self::max_message_weight(service).is_none() {
return Err(format!(
"ServiceWeight too low: {}. Must be at least {}",
service,
Self::single_msg_overhead(),
))
}
if service.any_gt(max_block) {
return Err(format!(
"ServiceWeight {service} is bigger than max block weight {max_block}"
))
}
}
if let Some(on_idle) = T::IdleMaxServiceWeight::get() {
if on_idle.any_gt(max_block) {
return Err(format!(
"IdleMaxServiceWeight {on_idle} is bigger than max block weight {max_block}"
))
}
}
if let (Some(service_weight), Some(on_idle)) =
(T::ServiceWeight::get(), T::IdleMaxServiceWeight::get())
{
if !(service_weight.all_gt(on_idle) ||
on_idle.all_gt(service_weight) ||
service_weight == on_idle)
{
return Err("One of `ServiceWeight` or `IdleMaxServiceWeight` needs to be `all_gt` or both need to be equal.".into())
}
}
Ok(())
}
fn do_enqueue_message(
origin: &MessageOriginOf<T>,
message: BoundedSlice<u8, MaxMessageLenOf<T>>,
) {
let mut book_state = BookStateFor::<T>::get(origin);
book_state.message_count.saturating_inc();
book_state
.size
// This should be payload size, but here the payload *is* the message.
.saturating_accrue(message.len() as u64);
if book_state.end > book_state.begin {
debug_assert!(book_state.ready_neighbours.is_some(), "Must be in ready ring if ready");
// Already have a page in progress - attempt to append.
let last = book_state.end - 1;
let mut page = match Pages::<T>::get(origin, last) {
Some(p) => p,
None => {
defensive!("Corruption: referenced page doesn't exist.");
return
},
};
if page.try_append_message::<T>(message).is_ok() {
Pages::<T>::insert(origin, last, &page);
BookStateFor::<T>::insert(origin, book_state);
return
}
} else {
debug_assert!(
book_state.ready_neighbours.is_none(),
"Must not be in ready ring if not ready"
);
// insert into ready queue.
match Self::ready_ring_knit(origin) {
Ok(neighbours) => book_state.ready_neighbours = Some(neighbours),
Err(()) => {
defensive!("Ring state invalid when knitting");
},
}
}
// No room on the page or no page - link in a new page.
book_state.end.saturating_inc();
book_state.count.saturating_inc();
let page = Page::from_message::<T>(message);
Pages::<T>::insert(origin, book_state.end - 1, page);
// NOTE: `T::QueueChangeHandler` is called by the caller.
BookStateFor::<T>::insert(origin, book_state);
}
/// Try to execute a single message that was marked as overweight.
///
/// The `weight_limit` is the weight that can be consumed to execute the message. The base
/// weight of the function it self must be measured by the caller.
pub fn do_execute_overweight(
origin: MessageOriginOf<T>,
page_index: PageIndex,
index: T::Size,
weight_limit: Weight,
) -> Result<Weight, Error<T>> {
match with_service_mutex(|| {
Self::do_execute_overweight_inner(origin, page_index, index, weight_limit)
}) {
Err(()) => Err(Error::<T>::RecursiveDisallowed),
Ok(x) => x,
}
}
/// Same as `do_execute_overweight` but must be called while holding the `service_mutex`.
fn do_execute_overweight_inner(
origin: MessageOriginOf<T>,
page_index: PageIndex,
index: T::Size,
weight_limit: Weight,
) -> Result<Weight, Error<T>> {
let mut book_state = BookStateFor::<T>::get(&origin);
ensure!(!T::QueuePausedQuery::is_paused(&origin), Error::<T>::QueuePaused);
let mut page = Pages::<T>::get(&origin, page_index).ok_or(Error::<T>::NoPage)?;
let (pos, is_processed, payload) =
page.peek_index(index.into() as usize).ok_or(Error::<T>::NoMessage)?;
let payload_len = payload.len() as u64;
ensure!(
page_index < book_state.begin ||
(page_index == book_state.begin && pos < page.first.into() as usize),
Error::<T>::Queued
);
ensure!(!is_processed, Error::<T>::AlreadyProcessed);
use MessageExecutionStatus::*;
let mut weight_counter = WeightMeter::with_limit(weight_limit);
match Self::process_message_payload(
origin.clone(),
page_index,
index,
payload,
&mut weight_counter,
Weight::MAX,
// ^^^ We never recognise it as permanently overweight, since that would result in an
// additional overweight event being deposited.
) {
Overweight | InsufficientWeight => Err(Error::<T>::InsufficientWeight),
StackLimitReached | Unprocessable { permanent: false } =>
Err(Error::<T>::TemporarilyUnprocessable),
Unprocessable { permanent: true } | Processed => {
page.note_processed_at_pos(pos);
book_state.message_count.saturating_dec();
book_state.size.saturating_reduce(payload_len);
let page_weight = if page.remaining.is_zero() {
debug_assert!(
page.remaining_size.is_zero(),
"no messages remaining; no space taken; qed"
);
Pages::<T>::remove(&origin, page_index);
debug_assert!(book_state.count >= 1, "page exists, so book must have pages");
book_state.count.saturating_dec();
T::WeightInfo::execute_overweight_page_removed()
// no need to consider .first or ready ring since processing an overweight page
// would not alter that state.
} else {
Pages::<T>::insert(&origin, page_index, page);
T::WeightInfo::execute_overweight_page_updated()
};
BookStateFor::<T>::insert(&origin, &book_state);
T::QueueChangeHandler::on_queue_changed(origin, book_state.into());
Ok(weight_counter.consumed().saturating_add(page_weight))
},
}
}
/// Remove a stale page or one which has no more messages remaining to be processed.
fn do_reap_page(origin: &MessageOriginOf<T>, page_index: PageIndex) -> DispatchResult {
match with_service_mutex(|| Self::do_reap_page_inner(origin, page_index)) {
Err(()) => Err(Error::<T>::RecursiveDisallowed.into()),
Ok(x) => x,
}
}
/// Same as `do_reap_page` but must be called while holding the `service_mutex`.
fn do_reap_page_inner(origin: &MessageOriginOf<T>, page_index: PageIndex) -> DispatchResult {
let mut book_state = BookStateFor::<T>::get(origin);
// definitely not reapable if the page's index is no less than the `begin`ning of ready
// pages.
ensure!(page_index < book_state.begin, Error::<T>::NotReapable);
let page = Pages::<T>::get(origin, page_index).ok_or(Error::<T>::NoPage)?;
// definitely reapable if the page has no messages in it.
let reapable = page.remaining.is_zero();
// also reapable if the page index has dropped below our watermark.
let cullable = || {
let total_pages = book_state.count;
let ready_pages = book_state.end.saturating_sub(book_state.begin).min(total_pages);
// The number of stale pages - i.e. pages which contain unprocessed overweight messages.
// We would prefer to keep these around but will restrict how far into history they can
// extend if we notice that there's too many of them.
//
// We don't know *where* in history these pages are so we use a dynamic formula which
// reduces the historical time horizon as the stale pages pile up and increases it as
// they reduce.
let stale_pages = total_pages - ready_pages;
// The maximum number of stale pages (i.e. of overweight messages) allowed before
// culling can happen at all. Once there are more stale pages than this, then historical
// pages may be dropped, even if they contain unprocessed overweight messages.
let max_stale = T::MaxStale::get();
// The amount beyond the maximum which are being used. If it's not beyond the maximum
// then we exit now since no culling is needed.
let overflow = match stale_pages.checked_sub(max_stale + 1) {
Some(x) => x + 1,
None => return false,
};
// The special formula which tells us how deep into index-history we will pages. As
// the overflow is greater (and thus the need to drop items from storage is more urgent)
// this is reduced, allowing a greater range of pages to be culled.
// With a minimum `overflow` (`1`), this returns `max_stale ** 2`, indicating we only
// cull beyond that number of indices deep into history.
// At this overflow increases, our depth reduces down to a limit of `max_stale`. We
// never want to reduce below this since this will certainly allow enough pages to be
// culled in order to bring `overflow` back to zero.
let backlog = (max_stale * max_stale / overflow).max(max_stale);
let watermark = book_state.begin.saturating_sub(backlog);
page_index < watermark
};
ensure!(reapable || cullable(), Error::<T>::NotReapable);
Pages::<T>::remove(origin, page_index);
debug_assert!(book_state.count > 0, "reaping a page implies there are pages");
book_state.count.saturating_dec();
book_state.message_count.saturating_reduce(page.remaining.into() as u64);
book_state.size.saturating_reduce(page.remaining_size.into() as u64);
BookStateFor::<T>::insert(origin, &book_state);
T::QueueChangeHandler::on_queue_changed(origin.clone(), book_state.into());
Self::deposit_event(Event::PageReaped { origin: origin.clone(), index: page_index });
Ok(())
}
/// Execute any messages remaining to be processed in the queue of `origin`, using up to
/// `weight_limit` to do so. Any messages which would take more than `overweight_limit` to
/// execute are deemed overweight and ignored.
fn service_queue(
origin: MessageOriginOf<T>,
weight: &mut WeightMeter,
overweight_limit: Weight,
) -> (bool, Option<MessageOriginOf<T>>) {
use PageExecutionStatus::*;
if weight
.try_consume(
T::WeightInfo::service_queue_base()
.saturating_add(T::WeightInfo::ready_ring_unknit()),
)
.is_err()
{
return (false, None)
}
let mut book_state = BookStateFor::<T>::get(&origin);
let mut total_processed = 0;
if T::QueuePausedQuery::is_paused(&origin) {
let next_ready = book_state.ready_neighbours.as_ref().map(|x| x.next.clone());
return (false, next_ready)
}
while book_state.end > book_state.begin {
let (processed, status) =
Self::service_page(&origin, &mut book_state, weight, overweight_limit);
total_processed.saturating_accrue(processed);
match status {
// Store the page progress and do not go to the next one.
Bailed | NoProgress => break,
// Go to the next page if this one is at the end.
NoMore => (),
};
book_state.begin.saturating_inc();
}
let next_ready = book_state.ready_neighbours.as_ref().map(|x| x.next.clone());
if book_state.begin >= book_state.end {
// No longer ready - unknit.
if let Some(neighbours) = book_state.ready_neighbours.take() {
Self::ready_ring_unknit(&origin, neighbours);
} else if total_processed > 0 {
defensive!("Freshly processed queue must have been ready");
}
}
BookStateFor::<T>::insert(&origin, &book_state);
if total_processed > 0 {
T::QueueChangeHandler::on_queue_changed(origin, book_state.into());
}
(total_processed > 0, next_ready)
}
/// Service as many messages of a page as possible.
///
/// Returns how many messages were processed and the page's status.
fn service_page(
origin: &MessageOriginOf<T>,
book_state: &mut BookStateOf<T>,
weight: &mut WeightMeter,
overweight_limit: Weight,
) -> (u32, PageExecutionStatus) {
use PageExecutionStatus::*;
if weight
.try_consume(
T::WeightInfo::service_page_base_completion()
.max(T::WeightInfo::service_page_base_no_completion()),
)
.is_err()
{
return (0, Bailed)
}
let page_index = book_state.begin;
let mut page = match Pages::<T>::get(origin, page_index) {
Some(p) => p,
None => {
defensive!("message-queue: referenced page not found");
return (0, NoMore)
},
};
let mut total_processed = 0;
// Execute as many messages as possible.
let status = loop {
use ItemExecutionStatus::*;
match Self::service_page_item(
origin,
page_index,
book_state,
&mut page,
weight,
overweight_limit,
) {
Bailed => break PageExecutionStatus::Bailed,
NoItem => break PageExecutionStatus::NoMore,
NoProgress => break PageExecutionStatus::NoProgress,
// Keep going as long as we make progress...
Executed(true) => total_processed.saturating_inc(),
Executed(false) => (),
}
};
if page.is_complete() {
debug_assert!(status != Bailed, "we never bail if a page became complete");
Pages::<T>::remove(origin, page_index);
debug_assert!(book_state.count > 0, "completing a page implies there are pages");
book_state.count.saturating_dec();
} else {
Pages::<T>::insert(origin, page_index, page);
}
(total_processed, status)
}
/// Execute the next message of a page.
pub(crate) fn service_page_item(
origin: &MessageOriginOf<T>,
page_index: PageIndex,
book_state: &mut BookStateOf<T>,
page: &mut PageOf<T>,
weight: &mut WeightMeter,
overweight_limit: Weight,
) -> ItemExecutionStatus {
use MessageExecutionStatus::*;
// This ugly pre-checking is needed for the invariant
// "we never bail if a page became complete".
if page.is_complete() {
return ItemExecutionStatus::NoItem
}
if weight.try_consume(T::WeightInfo::service_page_item()).is_err() {
return ItemExecutionStatus::Bailed
}
let payload = &match page.peek_first() {
Some(m) => m,
None => return ItemExecutionStatus::NoItem,
}[..];
let payload_len = payload.len() as u64;
// Store these for the case that `process_message_payload` is recursive.
Pages::<T>::insert(origin, page_index, &*page);
BookStateFor::<T>::insert(origin, &*book_state);
let res = Self::process_message_payload(
origin.clone(),
page_index,
page.first_index,
payload,
weight,
overweight_limit,
);
// And restore them afterwards to see the changes of a recursive call.
*book_state = BookStateFor::<T>::get(origin);
if let Some(new_page) = Pages::<T>::get(origin, page_index) {
*page = new_page;
} else {
defensive!("page must exist since we just inserted it and recursive calls are not allowed to remove anything");
return ItemExecutionStatus::NoItem
};
let is_processed = match res {
InsufficientWeight => return ItemExecutionStatus::Bailed,
Unprocessable { permanent: false } => return ItemExecutionStatus::NoProgress,
Processed | Unprocessable { permanent: true } | StackLimitReached => true,
Overweight => false,
};
if is_processed {
book_state.message_count.saturating_dec();
book_state.size.saturating_reduce(payload_len as u64);
}
page.skip_first(is_processed);
ItemExecutionStatus::Executed(is_processed)
}
/// Ensure the correctness of state of this pallet.
///
/// # Assumptions-
///
/// If `serviceHead` points to a ready Queue, then BookState of that Queue has:
///
/// * `message_count` > 0
/// * `size` > 0
/// * `end` > `begin`
/// * Some(ready_neighbours)
/// * If `ready_neighbours.next` == self.origin, then `ready_neighbours.prev` == self.origin
/// (only queue in ring)
///
/// For Pages(begin to end-1) in BookState:
///
/// * `remaining` > 0
/// * `remaining_size` > 0
/// * `first` <= `last`
/// * Every page can be decoded into peek_* functions
#[cfg(any(test, feature = "try-runtime", feature = "std"))]
pub fn do_try_state() -> Result<(), sp_runtime::TryRuntimeError> {
// Checking memory corruption for BookStateFor
ensure!(
BookStateFor::<T>::iter_keys().count() == BookStateFor::<T>::iter_values().count(),
"Memory Corruption in BookStateFor"
);
// Checking memory corruption for Pages
ensure!(
Pages::<T>::iter_keys().count() == Pages::<T>::iter_values().count(),
"Memory Corruption in Pages"
);
// Basic checks for each book
for book in BookStateFor::<T>::iter_values() {
ensure!(book.end >= book.begin, "Invariant");
ensure!(book.end < 1 << 30, "Likely overflow or corruption");
ensure!(book.message_count < 1 << 30, "Likely overflow or corruption");
ensure!(book.size < 1 << 30, "Likely overflow or corruption");
ensure!(book.count < 1 << 30, "Likely overflow or corruption");
let fp: QueueFootprint = book.into();
ensure!(fp.ready_pages <= fp.pages, "There cannot be more ready than total pages");
}
//loop around this origin
let Some(starting_origin) = ServiceHead::<T>::get() else { return Ok(()) };
while let Some(head) = Self::bump_service_head(&mut WeightMeter::new()) {
ensure!(
BookStateFor::<T>::contains_key(&head),
"Service head must point to an existing book"
);
let head_book_state = BookStateFor::<T>::get(&head);
ensure!(
head_book_state.message_count > 0,
"There must be some messages if in ReadyRing"
);
ensure!(head_book_state.size > 0, "There must be some message size if in ReadyRing");
ensure!(
head_book_state.end > head_book_state.begin,
"End > Begin if unprocessed messages exists"
);
ensure!(
head_book_state.ready_neighbours.is_some(),
"There must be neighbours if in ReadyRing"
);
if head_book_state.ready_neighbours.as_ref().unwrap().next == head {
ensure!(
head_book_state.ready_neighbours.as_ref().unwrap().prev == head,
"Can only happen if only queue in ReadyRing"
);
}
for page_index in head_book_state.begin..head_book_state.end {
let page = Pages::<T>::get(&head, page_index).unwrap();
let remaining_messages = page.remaining;
let mut counted_remaining_messages: u32 = 0;
ensure!(
remaining_messages > 0.into(),
"These must be some messages that have not been processed yet!"
);
for i in 0..u32::MAX {
if let Some((_, processed, _)) = page.peek_index(i as usize) {
if !processed {
counted_remaining_messages += 1;
}
} else {
break
}
}
ensure!(
remaining_messages.into() == counted_remaining_messages,
"Memory Corruption"
);
}
if head_book_state.ready_neighbours.as_ref().unwrap().next == starting_origin {
break
}
}
Ok(())
}
/// Print the pages in each queue and the messages in each page.
///
/// Processed messages are prefixed with a `*` and the current `begin`ning page with a `>`.
///
/// # Example output
///
/// ```text
/// queue Here:
/// page 0: []
/// > page 1: []
/// page 2: ["\0weight=4", "\0c", ]
/// page 3: ["\0bigbig 1", ]
/// page 4: ["\0bigbig 2", ]
/// page 5: ["\0bigbig 3", ]
/// ```
#[cfg(feature = "std")]
pub fn debug_info() -> String {
let mut info = String::new();
for (origin, book_state) in BookStateFor::<T>::iter() {
let mut queue = format!("queue {:?}:\n", &origin);
let mut pages = Pages::<T>::iter_prefix(&origin).collect::<Vec<_>>();
pages.sort_by(|(a, _), (b, _)| a.cmp(b));
for (page_index, mut page) in pages.into_iter() {
let page_info = if book_state.begin == page_index { ">" } else { " " };
let mut page_info = format!(
"{} page {} ({:?} first, {:?} last, {:?} remain): [ ",
page_info, page_index, page.first, page.last, page.remaining
);
for i in 0..u32::MAX {
if let Some((_, processed, message)) =
page.peek_index(i.try_into().expect("std-only code"))
{
let msg = String::from_utf8_lossy(message);
if processed {
page_info.push('*');
}
page_info.push_str(&format!("{:?}, ", msg));
page.skip_first(true);
} else {
break
}
}
page_info.push_str("]\n");
queue.push_str(&page_info);
}
info.push_str(&queue);
}
info
}
/// Process a single message.
///
/// The base weight of this function needs to be accounted for by the caller. `weight` is the
/// remaining weight to process the message. `overweight_limit` is the maximum weight that a
/// message can ever consume. Messages above this limit are marked as permanently overweight.
/// This process is also transactional, any form of error that occurs in processing a message
/// causes storage changes to be rolled back.
fn process_message_payload(
origin: MessageOriginOf<T>,
page_index: PageIndex,
message_index: T::Size,
message: &[u8],
meter: &mut WeightMeter,
overweight_limit: Weight,
) -> MessageExecutionStatus {
let mut id = sp_io::hashing::blake2_256(message);
use ProcessMessageError::*;
let prev_consumed = meter.consumed();
let transaction =
storage::with_transaction(|| -> TransactionOutcome<Result<_, DispatchError>> {
let res =
T::MessageProcessor::process_message(message, origin.clone(), meter, &mut id);
match &res {
Ok(_) => TransactionOutcome::Commit(Ok(res)),
Err(_) => TransactionOutcome::Rollback(Ok(res)),
}
});
let transaction = match transaction {
Ok(result) => result,
_ => {
defensive!(
"Error occurred processing message, storage changes will be rolled back"
);
return MessageExecutionStatus::Unprocessable { permanent: true }
},
};
match transaction {
Err(Overweight(w)) if w.any_gt(overweight_limit) => {
// Permanently overweight.
Self::deposit_event(Event::<T>::OverweightEnqueued {
id,
origin,
page_index,
message_index,
});
MessageExecutionStatus::Overweight
},
Err(Overweight(_)) => {
// Temporarily overweight - save progress and stop processing this
// queue.
MessageExecutionStatus::InsufficientWeight
},
Err(Yield) => {
// Processing should be reattempted later.
MessageExecutionStatus::Unprocessable { permanent: false }
},
Err(error @ BadFormat | error @ Corrupt | error @ Unsupported) => {
// Permanent error - drop
Self::deposit_event(Event::<T>::ProcessingFailed { id: id.into(), origin, error });
MessageExecutionStatus::Unprocessable { permanent: true }
},
Err(error @ StackLimitReached) => {
Self::deposit_event(Event::<T>::ProcessingFailed { id: id.into(), origin, error });
MessageExecutionStatus::StackLimitReached
},
Ok(success) => {
// Success
let weight_used = meter.consumed().saturating_sub(prev_consumed);
Self::deposit_event(Event::<T>::Processed {
id: id.into(),
origin,
weight_used,
success,
});
MessageExecutionStatus::Processed
},
}
}
fn service_queues_impl(weight_limit: Weight, context: ServiceQueuesContext) -> Weight {
let mut weight = WeightMeter::with_limit(weight_limit);
// Get the maximum weight that processing a single message may take:
let overweight_limit = Self::max_message_weight(weight_limit).unwrap_or_else(|| {
if matches!(context, ServiceQueuesContext::OnInitialize) {
defensive!("Not enough weight to service a single message.");
}
Weight::zero()
});
match with_service_mutex(|| {
let mut next = match Self::bump_service_head(&mut weight) {
Some(h) => h,
None => return weight.consumed(),
};
// The last queue that did not make any progress.
// The loop aborts as soon as it arrives at this queue again without making any progress
// on other queues in between.
let mut last_no_progress = None;
loop {
let (progressed, n) =
Self::service_queue(next.clone(), &mut weight, overweight_limit);
next = match n {
Some(n) =>
if !progressed {
if last_no_progress == Some(n.clone()) {
break
}
if last_no_progress.is_none() {
last_no_progress = Some(next.clone())
}
n
} else {
last_no_progress = None;
n
},
None => break,
}
}
weight.consumed()
}) {
Err(()) => weight.consumed(),
Ok(w) => w,
}
}
}
/// Run a closure that errors on re-entrance. Meant to be used by anything that services queues.
pub(crate) fn with_service_mutex<F: FnOnce() -> R, R>(f: F) -> Result<R, ()> {
// Holds the singleton token instance.
environmental::environmental!(token: Option<()>);
token::using_once(&mut Some(()), || {
// The first `ok_or` should always be `Ok` since we are inside a `using_once`.
let hold = token::with(|t| t.take()).ok_or(()).defensive()?.ok_or(())?;
// Put the token back when we're done.
defer! {
token::with(|t| {
*t = Some(hold);
});
}
Ok(f())
})
}
/// Provides a [`sp_core::Get`] to access the `MEL` of a [`codec::MaxEncodedLen`] type.
pub struct MaxEncodedLenOf<T>(core::marker::PhantomData<T>);
impl<T: MaxEncodedLen> Get<u32> for MaxEncodedLenOf<T> {
fn get() -> u32 {
T::max_encoded_len() as u32
}
}
/// Calculates the maximum message length and exposed it through the [`codec::MaxEncodedLen`] trait.
pub struct MaxMessageLen<Origin, Size, HeapSize>(
core::marker::PhantomData<(Origin, Size, HeapSize)>,
);
impl<Origin: MaxEncodedLen, Size: MaxEncodedLen + Into<u32>, HeapSize: Get<Size>> Get<u32>
for MaxMessageLen<Origin, Size, HeapSize>
{
fn get() -> u32 {
(HeapSize::get().into()).saturating_sub(ItemHeader::<Size>::max_encoded_len() as u32)
}
}
/// The maximal message length.
pub type MaxMessageLenOf<T> =
MaxMessageLen<MessageOriginOf<T>, <T as Config>::Size, <T as Config>::HeapSize>;
/// The maximal encoded origin length.
pub type MaxOriginLenOf<T> = MaxEncodedLenOf<MessageOriginOf<T>>;
/// The `MessageOrigin` of this pallet.
pub type MessageOriginOf<T> = <<T as Config>::MessageProcessor as ProcessMessage>::Origin;
/// The maximal heap size of a page.
pub type HeapSizeU32Of<T> = IntoU32<<T as Config>::HeapSize, <T as Config>::Size>;
/// The [`Page`] of this pallet.
pub type PageOf<T> = Page<<T as Config>::Size, <T as Config>::HeapSize>;
/// The [`BookState`] of this pallet.
pub type BookStateOf<T> = BookState<MessageOriginOf<T>>;
/// Converts a [`sp_core::Get`] with returns a type that can be cast into an `u32` into a `Get`
/// which returns an `u32`.
pub struct IntoU32<T, O>(core::marker::PhantomData<(T, O)>);
impl<T: Get<O>, O: Into<u32>> Get<u32> for IntoU32<T, O> {
fn get() -> u32 {
T::get().into()
}
}
impl<T: Config> ServiceQueues for Pallet<T> {
type OverweightMessageAddress = (MessageOriginOf<T>, PageIndex, T::Size);
fn service_queues(weight_limit: Weight) -> Weight {
Self::service_queues_impl(weight_limit, ServiceQueuesContext::ServiceQueues)
}
/// Execute a single overweight message.
///
/// The weight limit must be enough for `execute_overweight` and the message execution itself.
fn execute_overweight(
weight_limit: Weight,
(message_origin, page, index): Self::OverweightMessageAddress,
) -> Result<Weight, ExecuteOverweightError> {
let mut weight = WeightMeter::with_limit(weight_limit);
if weight
.try_consume(
T::WeightInfo::execute_overweight_page_removed()
.max(T::WeightInfo::execute_overweight_page_updated()),
)
.is_err()
{
return Err(ExecuteOverweightError::InsufficientWeight)
}
Pallet::<T>::do_execute_overweight(message_origin, page, index, weight.remaining()).map_err(
|e| match e {
Error::<T>::InsufficientWeight => ExecuteOverweightError::InsufficientWeight,
Error::<T>::AlreadyProcessed => ExecuteOverweightError::AlreadyProcessed,
Error::<T>::QueuePaused => ExecuteOverweightError::QueuePaused,
Error::<T>::NoPage | Error::<T>::NoMessage | Error::<T>::Queued =>
ExecuteOverweightError::NotFound,
Error::<T>::RecursiveDisallowed => ExecuteOverweightError::RecursiveDisallowed,
_ => ExecuteOverweightError::Other,
},
)
}
}
impl<T: Config> EnqueueMessage<MessageOriginOf<T>> for Pallet<T> {
type MaxMessageLen =
MaxMessageLen<<T::MessageProcessor as ProcessMessage>::Origin, T::Size, T::HeapSize>;
fn enqueue_message(
message: BoundedSlice<u8, Self::MaxMessageLen>,
origin: <T::MessageProcessor as ProcessMessage>::Origin,
) {
Self::do_enqueue_message(&origin, message);
let book_state = BookStateFor::<T>::get(&origin);
T::QueueChangeHandler::on_queue_changed(origin, book_state.into());
}
fn enqueue_messages<'a>(
messages: impl Iterator<Item = BoundedSlice<'a, u8, Self::MaxMessageLen>>,
origin: <T::MessageProcessor as ProcessMessage>::Origin,
) {
for message in messages {
Self::do_enqueue_message(&origin, message);
}
let book_state = BookStateFor::<T>::get(&origin);
T::QueueChangeHandler::on_queue_changed(origin, book_state.into());
}
fn sweep_queue(origin: MessageOriginOf<T>) {
if !BookStateFor::<T>::contains_key(&origin) {
return
}
let mut book_state = BookStateFor::<T>::get(&origin);
book_state.begin = book_state.end;
if let Some(neighbours) = book_state.ready_neighbours.take() {
Self::ready_ring_unknit(&origin, neighbours);
}
BookStateFor::<T>::insert(&origin, &book_state);
}
fn footprint(origin: MessageOriginOf<T>) -> QueueFootprint {
BookStateFor::<T>::get(&origin).into()
}
}