polkadot_runtime_parachains/dmp/
migration.rs

1// Copyright (C) Parity Technologies (UK) Ltd.
2// This file is part of Polkadot.
3
4// Polkadot is free software: you can redistribute it and/or modify
5// it under the terms of the GNU General Public License as published by
6// the Free Software Foundation, either version 3 of the License, or
7// (at your option) any later version.
8
9// Polkadot is distributed in the hope that it will be useful,
10// but WITHOUT ANY WARRANTY; without even the implied warranty of
11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12// GNU General Public License for more details.
13
14// You should have received a copy of the GNU General Public License
15// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
16
17//! Storage migrations for the dmp pallet.
18//!
19//! [`MigrateV0ToV1`] translates the old `Vec`-per-para layout
20//! ([`v0::DownwardMessageQueues`]) into the paged layout
21//! ([`DownwardMessageQueueMeta`] + [`DownwardMessageQueuePages`]).
22
23use super::{inbound_downward_queue::InboundDownwardQueue, *};
24#[cfg(feature = "try-runtime")]
25use alloc::collections::btree_map::BTreeMap;
26use alloc::vec::Vec;
27use codec::{Decode, Encode, MaxEncodedLen};
28use frame_support::{
29	migrations::{MigrationId, SteppedMigration, SteppedMigrationError},
30	pallet_prelude::ValueQuery,
31	storage_alias,
32	weights::WeightMeter,
33	Twox64Concat,
34};
35use scale_info::TypeInfo;
36
37/// Resume position for [`MigrateV0ToV1`]. Returning `Ok(None)` ends the migration; while
38/// `v0::DownwardMessageQueues` has data, return `Some(_)`.
39#[derive(Encode, Decode, MaxEncodedLen, TypeInfo, PartialEq, Eq, Clone, Debug)]
40pub enum MigrationCursor {
41	/// Resume by taking the next entry from `v0::DownwardMessageQueues::iter()`.
42	Iterate,
43	/// Resume mid-para: progress is encoded in the v0 entry itself (the unmigrated suffix
44	/// has been written back into `v0::DownwardMessageQueues[para]`).
45	InProgress { para: ParaId },
46}
47
48/// The in-code storage version.
49pub const STORAGE_VERSION: StorageVersion = StorageVersion::new(1);
50
51/// Identifier for migrations of this pallet.
52const PALLET_MIGRATIONS_ID: &[u8; 21] = b"cumulus-dmp-queue-mbm";
53
54/// The OLD (pre-paged) storage layout.
55pub mod v0 {
56	use super::*;
57
58	#[storage_alias]
59	pub type DownwardMessageQueues<T: Config> = StorageMap<
60		crate::dmp::Pallet<T>,
61		Twox64Concat,
62		ParaId,
63		Vec<InboundDownwardMessage<BlockNumberFor<T>>>,
64		ValueQuery,
65	>;
66}
67
68/// Migrate `v0::DownwardMessageQueues` into the paged layout.
69pub struct MigrateV0ToV1<T>(core::marker::PhantomData<T>);
70
71impl<T: Config> SteppedMigration for MigrateV0ToV1<T> {
72	type Cursor = MigrationCursor;
73	type Identifier = MigrationId<21>;
74
75	fn id() -> Self::Identifier {
76		MigrationId { pallet_id: *PALLET_MIGRATIONS_ID, version_from: 0, version_to: 1 }
77	}
78
79	fn step(
80		mut cursor: Option<Self::Cursor>,
81		meter: &mut WeightMeter,
82	) -> Result<Option<Self::Cursor>, SteppedMigrationError> {
83		if Pallet::<T>::on_chain_storage_version() != Self::id().version_from as u16 {
84			return Ok(None);
85		}
86		let base = <T as Config>::WeightInfo::migrate_v0_to_v1_step_base();
87		let per_iter = <T as Config>::WeightInfo::migrate_v0_to_v1_step_iter();
88		let per_msg = <T as Config>::WeightInfo::migrate_v0_to_v1_step_msg();
89
90		// Headroom for at least one full iteration; otherwise this call makes no progress.
91		let minimum = base.saturating_add(per_iter).saturating_add(per_msg);
92		if meter.remaining().any_lt(minimum) {
93			return Err(SteppedMigrationError::InsufficientWeight { required: minimum });
94		}
95		meter.consume(base);
96
97		loop {
98			if meter.try_consume(per_iter).is_err() {
99				break;
100			}
101
102			let para = match cursor.take() {
103				Some(MigrationCursor::InProgress { para }) => para,
104				Some(MigrationCursor::Iterate) | None => {
105					let Some(p) = v0::DownwardMessageQueues::<T>::iter_keys().next() else {
106						cursor = None;
107						break;
108					};
109					p
110				},
111			};
112
113			let msgs = v0::DownwardMessageQueues::<T>::take(para);
114			if msgs.is_empty() {
115				cursor = Some(MigrationCursor::Iterate);
116				continue;
117			}
118
119			let total = msgs.len();
120			let mut migrated = 0usize;
121
122			for msg in &msgs {
123				if migrated > 0 && meter.try_consume(per_msg).is_err() {
124					break;
125				}
126				if InboundDownwardQueue::<T>::push_back_inbound_v1(para, msg).is_err() {
127					v0::DownwardMessageQueues::<T>::insert(para, msgs[migrated..].to_vec());
128					cursor = Some(MigrationCursor::InProgress { para });
129					return Ok(cursor);
130				}
131				migrated = migrated.saturating_add(1);
132			}
133
134			if migrated < total {
135				v0::DownwardMessageQueues::<T>::insert(para, msgs[migrated..].to_vec());
136				cursor = Some(MigrationCursor::InProgress { para });
137				break;
138			}
139
140			super::Pallet::<T>::deposit_event(Event::DmpQueueV0Cleaned { para });
141			cursor = Some(MigrationCursor::Iterate);
142		}
143
144		if cursor.is_none() {
145			StorageVersion::new(Self::id().version_to as u16).put::<Pallet<T>>();
146		}
147		Ok(cursor)
148	}
149
150	#[cfg(feature = "try-runtime")]
151	fn pre_upgrade() -> Result<Vec<u8>, sp_runtime::TryRuntimeError> {
152		// Idempotent: snapshot whatever v0 holds now.
153		let snapshot: BTreeMap<ParaId, Vec<InboundDownwardMessage<BlockNumberFor<T>>>> =
154			v0::DownwardMessageQueues::<T>::iter().collect();
155
156		Ok(snapshot.encode())
157	}
158
159	#[cfg(feature = "try-runtime")]
160	fn post_upgrade(_prev: Vec<u8>) -> Result<(), sp_runtime::TryRuntimeError> {
161		assert_eq!(
162			v0::DownwardMessageQueues::<T>::iter().count(),
163			0,
164			"v0::DownwardMessageQueues still has entries after MigrateV0ToV1",
165		);
166
167		Ok(())
168	}
169}
polkadot_runtime_parachains/dmp/migration.rs

polkadot_runtime_parachains/dmp/
migration.rs
