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fix(pinned events): make sure to initialize ordering before reloading events from disk #6466

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9b97723
refactor(sdk): move `load_linked_chunk_metadata` to a file where it c…
bnjbvr Apr 20, 2026
4892c81
fix(pinned events): initialize events ordering before reloading from …
bnjbvr Apr 20, 2026
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11 changes: 10 additions & 1 deletion crates/matrix-sdk/src/event_cache/caches/pinned_events/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,10 @@ use super::{
room::RoomEventCacheLinkedChunkUpdate,
};
use crate::{
Room, client::WeakClient, config::RequestConfig, event_cache::TimelineVectorDiffs,
Room,
client::WeakClient,
config::RequestConfig,
event_cache::{TimelineVectorDiffs, persistence::load_linked_chunk_metadata},
room::WeakRoom,
};

Expand Down Expand Up @@ -124,6 +127,12 @@ impl<'a> PinnedEventCacheStateLockWriteGuard<'a> {
return Ok(());
};

let linked_chunk_metadata =
load_linked_chunk_metadata(&self.store, linked_chunk_id).await?;

// Reload the metadata first.
self.state.chunk = EventLinkedChunk::with_initial_linked_chunk(None, linked_chunk_metadata);

{
let mut current_chunk_identifier = last_chunk.identifier;
self.state.chunk.replace_with(Some(last_chunk), chunk_id_gen)?;
Expand Down
128 changes: 2 additions & 126 deletions crates/matrix-sdk/src/event_cache/caches/room/state.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,8 +31,7 @@ use matrix_sdk_base::{
store::{EventCacheStoreLock, EventCacheStoreLockGuard, EventCacheStoreLockState},
},
linked_chunk::{
ChunkIdentifierGenerator, ChunkMetadata, LinkedChunkId, OwnedLinkedChunkId, Position,
Update, lazy_loader,
ChunkIdentifierGenerator, LinkedChunkId, OwnedLinkedChunkId, Position, Update, lazy_loader,
},
serde_helpers::{extract_edit_target, extract_thread_root},
sync::Timeline,
Expand Down Expand Up @@ -76,6 +75,7 @@ use crate::{
Room,
event_cache::{
automatic_pagination::AutomaticPagination, caches::pagination::SharedPaginationStatus,
persistence::load_linked_chunk_metadata,
},
room::WeakRoom,
};
Expand Down Expand Up @@ -1430,127 +1430,3 @@ fn get_event_focused_cache(
let key = EventFocusedCacheKey { focused: event_id, thread_mode };
state.event_focused_caches.get(&key).cloned()
}

/// Load a linked chunk's full metadata, making sure the chunks are
/// according to their their links.
///
/// Returns `None` if there's no such linked chunk in the store, or an
/// error if the linked chunk is malformed.
async fn load_linked_chunk_metadata(
store_guard: &EventCacheStoreLockGuard,
linked_chunk_id: LinkedChunkId<'_>,
) -> Result<Option<Vec<ChunkMetadata>>, EventCacheError> {
let mut all_chunks = store_guard
.load_all_chunks_metadata(linked_chunk_id)
.await
.map_err(EventCacheError::from)?;

if all_chunks.is_empty() {
// There are no chunks, so there's nothing to do.
return Ok(None);
}

// Transform the vector into a hashmap, for quick lookup of the predecessors.
let chunk_map: HashMap<_, _> = all_chunks.iter().map(|meta| (meta.identifier, meta)).collect();

// Find a last chunk.
let mut iter = all_chunks.iter().filter(|meta| meta.next.is_none());
let Some(last) = iter.next() else {
return Err(EventCacheError::InvalidLinkedChunkMetadata {
details: "no last chunk found".to_owned(),
});
};

// There must at most one last chunk.
if let Some(other_last) = iter.next() {
return Err(EventCacheError::InvalidLinkedChunkMetadata {
details: format!(
"chunks {} and {} both claim to be last chunks",
last.identifier.index(),
other_last.identifier.index()
),
});
}

// Rewind the chain back to the first chunk, and do some checks at the same
// time.
let mut seen = HashSet::new();
let mut current = last;
loop {
// If we've already seen this chunk, there's a cycle somewhere.
if !seen.insert(current.identifier) {
return Err(EventCacheError::InvalidLinkedChunkMetadata {
details: format!(
"cycle detected in linked chunk at {}",
current.identifier.index()
),
});
}

let Some(prev_id) = current.previous else {
// If there's no previous chunk, we're done.
if seen.len() != all_chunks.len() {
return Err(EventCacheError::InvalidLinkedChunkMetadata {
details: format!(
"linked chunk likely has multiple components: {} chunks seen through the chain of predecessors, but {} expected",
seen.len(),
all_chunks.len()
),
});
}
break;
};

// If the previous chunk is not in the map, then it's unknown
// and missing.
let Some(pred_meta) = chunk_map.get(&prev_id) else {
return Err(EventCacheError::InvalidLinkedChunkMetadata {
details: format!(
"missing predecessor {} chunk for {}",
prev_id.index(),
current.identifier.index()
),
});
};

// If the previous chunk isn't connected to the next, then the link is invalid.
if pred_meta.next != Some(current.identifier) {
return Err(EventCacheError::InvalidLinkedChunkMetadata {
details: format!(
"chunk {}'s next ({:?}) doesn't match the current chunk ({})",
pred_meta.identifier.index(),
pred_meta.next.map(|chunk_id| chunk_id.index()),
current.identifier.index()
),
});
}

current = *pred_meta;
}

// At this point, `current` is the identifier of the first chunk.
//
// Reorder the resulting vector, by going through the chain of `next` links, and
// swapping items into their final position.
//
// Invariant in this loop: all items in [0..i[ are in their final, correct
// position.
let mut current = current.identifier;
for i in 0..all_chunks.len() {
// Find the target metadata.
let j = all_chunks
.iter()
.rev()
.position(|meta| meta.identifier == current)
.map(|j| all_chunks.len() - 1 - j)
.expect("the target chunk must be present in the metadata");
if i != j {
all_chunks.swap(i, j);
}
if let Some(next) = all_chunks[i].next {
current = next;
}
}

Ok(Some(all_chunks))
}
130 changes: 128 additions & 2 deletions crates/matrix-sdk/src/event_cache/persistence.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,17 +12,19 @@
// See the License for the specific language governing permissions and
// limitations under the License.

use std::collections::{HashMap, HashSet};

use matrix_sdk_base::{
deserialized_responses::TimelineEventKind,
event_cache::{Event, Gap, store::EventCacheStoreLockGuard},
executor::spawn,
linked_chunk::{OwnedLinkedChunkId, Update},
linked_chunk::{ChunkMetadata, LinkedChunkId, OwnedLinkedChunkId, Update},
};
use ruma::serde::Raw;
use tokio::sync::broadcast::Sender;
use tracing::trace;

use crate::event_cache::{Result, caches::room::RoomEventCacheLinkedChunkUpdate};
use crate::event_cache::{EventCacheError, Result, caches::room::RoomEventCacheLinkedChunkUpdate};

/// Propagate linked chunk updates to the store and to the linked chunk update
/// observers.
Expand Down Expand Up @@ -136,3 +138,127 @@ fn strip_relations_if_present<T>(event: &mut Raw<T>) {
};
let _ = closure();
}

/// Load a linked chunk's full metadata, making sure the chunks are
/// according to their their links.
///
/// Returns `None` if there's no such linked chunk in the store, or an
/// error if the linked chunk is malformed.
pub(super) async fn load_linked_chunk_metadata(
store_guard: &EventCacheStoreLockGuard,
linked_chunk_id: LinkedChunkId<'_>,
) -> Result<Option<Vec<ChunkMetadata>>> {
let mut all_chunks = store_guard
.load_all_chunks_metadata(linked_chunk_id)
.await
.map_err(EventCacheError::from)?;

if all_chunks.is_empty() {
// There are no chunks, so there's nothing to do.
return Ok(None);
}

// Transform the vector into a hashmap, for quick lookup of the predecessors.
let chunk_map: HashMap<_, _> = all_chunks.iter().map(|meta| (meta.identifier, meta)).collect();

// Find a last chunk.
let mut iter = all_chunks.iter().filter(|meta| meta.next.is_none());
let Some(last) = iter.next() else {
return Err(EventCacheError::InvalidLinkedChunkMetadata {
details: "no last chunk found".to_owned(),
});
};

// There must at most one last chunk.
if let Some(other_last) = iter.next() {
return Err(EventCacheError::InvalidLinkedChunkMetadata {
details: format!(
"chunks {} and {} both claim to be last chunks",
last.identifier.index(),
other_last.identifier.index()
),
});
}

// Rewind the chain back to the first chunk, and do some checks at the same
// time.
let mut seen = HashSet::new();
let mut current = last;
loop {
// If we've already seen this chunk, there's a cycle somewhere.
if !seen.insert(current.identifier) {
return Err(EventCacheError::InvalidLinkedChunkMetadata {
details: format!(
"cycle detected in linked chunk at {}",
current.identifier.index()
),
});
}

let Some(prev_id) = current.previous else {
// If there's no previous chunk, we're done.
if seen.len() != all_chunks.len() {
return Err(EventCacheError::InvalidLinkedChunkMetadata {
details: format!(
"linked chunk likely has multiple components: {} chunks seen through the chain of predecessors, but {} expected",
seen.len(),
all_chunks.len()
),
});
}
break;
};

// If the previous chunk is not in the map, then it's unknown
// and missing.
let Some(pred_meta) = chunk_map.get(&prev_id) else {
return Err(EventCacheError::InvalidLinkedChunkMetadata {
details: format!(
"missing predecessor {} chunk for {}",
prev_id.index(),
current.identifier.index()
),
});
};

// If the previous chunk isn't connected to the next, then the link is invalid.
if pred_meta.next != Some(current.identifier) {
return Err(EventCacheError::InvalidLinkedChunkMetadata {
details: format!(
"chunk {}'s next ({:?}) doesn't match the current chunk ({})",
pred_meta.identifier.index(),
pred_meta.next.map(|chunk_id| chunk_id.index()),
current.identifier.index()
),
});
}

current = *pred_meta;
}

// At this point, `current` is the identifier of the first chunk.
//
// Reorder the resulting vector, by going through the chain of `next` links, and
// swapping items into their final position.
//
// Invariant in this loop: all items in [0..i[ are in their final, correct
// position.
let mut current = current.identifier;
for i in 0..all_chunks.len() {
// Find the target metadata.
let j = all_chunks
.iter()
.rev()
.position(|meta| meta.identifier == current)
.map(|j| all_chunks.len() - 1 - j)
.expect("the target chunk must be present in the metadata");
if i != j {
all_chunks.swap(i, j);
}
if let Some(next) = all_chunks[i].next {
current = next;
}
}

Ok(Some(all_chunks))
}
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