[FRAME] Use 'ready' pages in XCMP suspend logic

cumulus/pallets/xcmp-queue/src/lib.rs

@@ -600,7 +600,7 @@ impl<T: Config> Pallet<T> {
 		let QueueConfigData { drop_threshold, .. } = <QueueConfig<T>>::get();
 		let fp = T::XcmpQueue::footprint(sender);
 		// Assume that it will not fit into the current page:
-		let new_pages = fp.pages.saturating_add(1);
+		let new_pages = fp.ready_pages.saturating_add(1);
 		if new_pages > drop_threshold {
 			// This should not happen since the channel should have been suspended in
 			// [`on_queue_changed`].
@@ -663,12 +663,12 @@ impl<T: Config> OnQueueChanged<ParaId> for Pallet<T> {
 		let mut suspended_channels = <InboundXcmpSuspended<T>>::get();
 		let suspended = suspended_channels.contains(&para);
 
-		if suspended && fp.pages <= resume_threshold {
+		if suspended && fp.ready_pages <= resume_threshold {
 			Self::send_signal(para, ChannelSignal::Resume);
 
 			suspended_channels.remove(&para);
 			<InboundXcmpSuspended<T>>::put(suspended_channels);
-		} else if !suspended && fp.pages >= suspend_threshold {
+		} else if !suspended && fp.ready_pages >= suspend_threshold {
 			log::warn!("XCMP queue for sibling {:?} is full; suspending channel.", para);
 			Self::send_signal(para, ChannelSignal::Suspend);
 

cumulus/pallets/xcmp-queue/src/mock.rs

@@ -247,6 +247,7 @@ impl<T: OnQueueChanged<ParaId>> EnqueueMessage<ParaId> for EnqueueToLocalStorage
 			}
 		}
 		footprint.pages = footprint.storage.size as u32 / 16; // Number does not matter
+		footprint.ready_pages = footprint.pages;
 		footprint
 	}
 }

cumulus/pallets/xcmp-queue/src/tests.rs

@@ -116,7 +116,11 @@ fn xcm_enqueueing_starts_dropping_on_overflow() {
 		// The drop threshold for pages is 48, the others numbers dont really matter:
 		assert_eq!(
 			<Test as Config>::XcmpQueue::footprint(1000.into()),
-			QueueFootprint { storage: Footprint { count: 256, size: 768 }, pages: 48 }
+			QueueFootprint {
+				storage: Footprint { count: 256, size: 768 },
+				pages: 48,
+				ready_pages: 48
+			}
 		);
 	})
 }

substrate/frame/message-queue/src/integration_test.rs

@@ -289,6 +289,11 @@ fn process_some_messages(num_msgs: u32) {
 	ServiceWeight::set(Some(weight));
 	let consumed = next_block();
 
+	for origin in BookStateFor::<Test>::iter_keys() {
+		let fp = MessageQueue::footprint(origin);
+		assert_eq!(fp.pages, fp.ready_pages);
+	}
+
 	assert_eq!(consumed, weight, "\n{}", MessageQueue::debug_info());
 	assert_eq!(NumMessagesProcessed::take(), num_msgs as usize);
 }

substrate/frame/message-queue/src/lib.rs

@@ -194,8 +194,9 @@ use frame_support::{
 	defensive,
 	pallet_prelude::*,
 	traits::{
-		DefensiveTruncateFrom, EnqueueMessage, ExecuteOverweightError, Footprint, ProcessMessage,
-		ProcessMessageError, QueueFootprint, QueuePausedQuery, ServiceQueues,
+		DefensiveSaturating, DefensiveTruncateFrom, EnqueueMessage, ExecuteOverweightError,
+		Footprint, ProcessMessage, ProcessMessageError, QueueFootprint, QueuePausedQuery,
+		ServiceQueues,
 	},
 	BoundedSlice, CloneNoBound, DefaultNoBound,
 };
@@ -427,6 +428,7 @@ 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 },
 		}
 	}
@@ -1181,6 +1183,13 @@ impl<T: Config> Pallet<T> {
 			"Memory Corruption in Pages"
 		);
 
+		// Basic checks for each book
+		for book in BookStateFor::<T>::iter_values() {
+			let fp: QueueFootprint = book.into();
+
+			ensure!(fp.ready_pages <= fp.pages, "There can be no more ready than total pages");
+		}
+
 		// No state to check
 		if ServiceHead::<T>::get().is_none() {
 			return Ok(())

substrate/frame/message-queue/src/mock.rs

@@ -369,6 +369,6 @@ pub fn num_overweight_enqueued_events() -> u32 {
 		.count() as u32
 }
 
-pub fn fp(pages: u32, count: u64, size: u64) -> QueueFootprint {
-	QueueFootprint { storage: Footprint { count, size }, pages }
+pub fn fp(pages: u32, ready_pages: u32, count: u64, size: u64) -> QueueFootprint {
+	QueueFootprint { storage: Footprint { count, size }, pages, ready_pages }
 }

substrate/frame/message-queue/src/tests.rs

@@ -1064,28 +1064,33 @@ fn footprint_num_pages_works() {
 		MessageQueue::enqueue_message(msg("weight=2"), Here);
 		MessageQueue::enqueue_message(msg("weight=3"), Here);
 
-		assert_eq!(MessageQueue::footprint(Here), fp(2, 2, 16));
+		assert_eq!(MessageQueue::footprint(Here), fp(2, 2, 2, 16));
 
 		// Mark the messages as overweight.
 		assert_eq!(MessageQueue::service_queues(1.into_weight()), 0.into_weight());
 		assert_eq!(System::events().len(), 2);
-		// Overweight does not change the footprint.
-		assert_eq!(MessageQueue::footprint(Here), fp(2, 2, 16));
+		// `ready_pages` decreases but `page` count does not.
+		assert_eq!(MessageQueue::footprint(Here), fp(2, 0, 2, 16));
 
 		// Now execute the second message.
 		assert_eq!(
 			<MessageQueue as ServiceQueues>::execute_overweight(3.into_weight(), (Here, 1, 0))
 				.unwrap(),
 			3.into_weight()
 		);
-		assert_eq!(MessageQueue::footprint(Here), fp(1, 1, 8));
+		assert_eq!(MessageQueue::footprint(Here), fp(1, 0, 1, 8));
 		// And the first one:
 		assert_eq!(
 			<MessageQueue as ServiceQueues>::execute_overweight(2.into_weight(), (Here, 0, 0))
 				.unwrap(),
 			2.into_weight()
 		);
 		assert_eq!(MessageQueue::footprint(Here), Default::default());
+		assert_eq!(MessageQueue::footprint(Here), fp(0, 0, 0, 0));
+
+		// `ready_pages` and normal `pages` increases again:
+		MessageQueue::enqueue_message(msg("weight=3"), Here);
+		assert_eq!(MessageQueue::footprint(Here), fp(1, 1, 1, 8));
 	})
 }
 

substrate/frame/support/src/traits/messages.rs

@@ -121,6 +121,8 @@ impl<OverweightAddr> ServiceQueues for NoopServiceQueues<OverweightAddr> {
 pub struct QueueFootprint {
 	/// The number of pages in the queue (including overweight pages).
 	pub pages: u32,
+	/// The number of pages that are ready (not yet processed and also not overweight).
+	pub ready_pages: u32,
 	/// The storage footprint of the queue (including overweight messages).
 	pub storage: Footprint,
 }