aljaz/turso
1
0
Fork 0
mirror of https://github.com/aljazceru/turso.git synced 2026-02-20 07:25:14 +01:00
Code Issues Packages Projects Releases Wiki Activity

fix deadlock

Browse Source
This commit is contained in:
Jussi Saurio
2025-09-15 14:13:03 +03:00
parent d493a72cc0
commit 32cd01a615
1 changed files with 20 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
core/storage/wal.rs
View File

@@ -1099,14 +1099,27 @@ impl Wal for WalFile {
let epoch = shared_file.read().epoch.load(Ordering::Acquire);
frame.set_wal_tag(frame_id, epoch);
});
let shared = self.get_shared();
assert!(
shared.enabled.load(Ordering::Relaxed),
"WAL must be enabled"
);
let file = shared.file.as_ref().unwrap();
let file = {
let shared = self.get_shared();
assert!(
shared.enabled.load(Ordering::Relaxed),
"WAL must be enabled"
);
// important not to hold shared lock beyond this point to avoid deadlock scenario where:
// thread 1: takes readlock here, passes reference to shared.file to begin_read_wal_frame
// thread 2: tries to acquire write lock elsewhere
// thread 1: tries to re-acquire read lock in the completion (see 'complete' above)
//
// this causes a deadlock due to the locking policy in parking_lot:
// from https://docs.rs/parking_lot/latest/parking_lot/type.RwLock.html:
// "This lock uses a task-fair locking policy which avoids both reader and writer starvation.
// This means that readers trying to acquire the lock will block even if the lock is unlocked
// when there are writers waiting to acquire the lock.
// Because of this, attempts to recursively acquire a read lock within a single thread may result in a deadlock."
shared.file.as_ref().unwrap().clone()
};
begin_read_wal_frame(
file,
&file,
offset + WAL_FRAME_HEADER_SIZE as u64,
buffer_pool,
complete,