[ISSUE #2188]💫Remove SyncUnsafeCellWrapper from mmapped_file🍻 #2189
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WalkthroughThe pull request focuses on simplifying the memory-mapped file handling in the RocketMQ Rust implementation. The primary change involves removing the Changes
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Actionable comments posted: 2
🧹 Nitpick comments (1)
rocketmq-store/src/log_file/mapped_file/default_mapped_file_impl.rs (1)
Line range hint
1-781: Consider adopting Rust's safe abstractions.The codebase could benefit from using Rust's safe abstractions to handle concurrent access to memory-mapped files:
- Replace raw pointer manipulation with safe alternatives like
RefCellorMutex- Consider using
parking_lotcrate for more efficient synchronization primitives- Document the safety invariants that must be upheld by unsafe code
- Add compile-time checks using
static_assertionscrateThis would improve maintainability and reduce the risk of memory safety issues.
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📒 Files selected for processing (1)
rocketmq-store/src/log_file/mapped_file/default_mapped_file_impl.rs(4 hunks)
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🔇 Additional comments (1)
rocketmq-store/src/log_file/mapped_file/default_mapped_file_impl.rs (1)
125-125: LGTM: Constructor assignments are consistent.The direct assignment of
MmapMutin both constructors is consistent with the field type change.Also applies to: 207-207
| #[allow(clippy::mut_from_ref)] | ||
| pub fn get_mapped_file_mut(&self) -> &mut MmapMut { | ||
| self.mmapped_file.mut_from_ref() | ||
| unsafe { &mut *(self.mmapped_file.as_ptr() as *mut MmapMut) } | ||
| } | ||
|
|
||
| #[inline] | ||
| pub fn get_mapped_file(&self) -> &MmapMut { | ||
| self.mmapped_file.as_ref() | ||
| unsafe { &*(self.mmapped_file.as_ptr() as *const MmapMut) } |
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Fix unsafe mutable reference handling.
The current implementation of get_mapped_file_mut violates Rust's aliasing rules by potentially creating multiple mutable references to the same data. Consider these alternatives:
- Use interior mutability with
RefCellorMutex - Make the method require
&mut self - Document why the current unsafe implementation is sound
Additionally, get_mapped_file could be simplified to avoid unnecessary pointer casting.
Consider this safer implementation:
-#[allow(clippy::mut_from_ref)]
-pub fn get_mapped_file_mut(&self) -> &mut MmapMut {
- unsafe { &mut *(self.mmapped_file.as_ptr() as *mut MmapMut) }
-}
+pub fn get_mapped_file_mut(&mut self) -> &mut MmapMut {
+ &mut self.mmapped_file
+}
-pub fn get_mapped_file(&self) -> &MmapMut {
- unsafe { &*(self.mmapped_file.as_ptr() as *const MmapMut) }
-}
+pub fn get_mapped_file(&self) -> &MmapMut {
+ &self.mmapped_file
+}Committable suggestion skipped: line range outside the PR's diff.
| @@ -58,7 +57,7 @@ | |||
| pub struct DefaultMappedFile { | |||
| reference_resource: ReferenceResourceImpl, | |||
| file: File, | |||
| mmapped_file: SyncUnsafeCellWrapper<MmapMut>, | |||
| mmapped_file: MmapMut, | |||
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💡 Codebase verification
Confirmed thread-safety issues after SyncUnsafeCellWrapper removal
The verification reveals serious thread-safety concerns:
- While metadata (positions, timestamps) is protected using atomic types, the actual memory-mapped file content lacks proper synchronization
get_mapped_file_mut()can create multiple mutable references toMmapMut, violating Rust's aliasing rules- Direct access to
MmapMutwithout synchronization could lead to data races in concurrent scenarios
Consider wrapping MmapMut in a proper synchronization primitive like RwLock to ensure thread-safe access to the memory-mapped content.
🔗 Analysis chain
Verify thread-safety after removing SyncUnsafeCellWrapper.
The removal of SyncUnsafeCellWrapper might impact thread-safety. Ensure that all access to mmapped_file is properly synchronized through other mechanisms.
🏁 Scripts executed
The following scripts were executed for the analysis:
Script:
#!/bin/bash
# Search for all concurrent access patterns to mmapped_file
rg -A 5 "mmapped_file" | rg -B 5 "async|thread|concurrent|parallel|sync|lock|mutex"
# Search for any synchronization mechanisms around MmapMut usage
ast-grep --pattern 'MmapMut'
Length of output: 701
Script:
#!/bin/bash
# Search for synchronization mechanisms around mmapped_file
rg -B 5 -A 10 "mmapped_file" rocketmq-store/src/log_file/mapped_file/default_mapped_file_impl.rs
# Look for method signatures and concurrent access patterns
ast-grep --pattern 'impl DefaultMappedFileImpl {
$$$
pub fn $_(&$_) {
$$$
}
$$$
}'
# Search for Mutex/RwLock usage
rg "Mutex|RwLock" rocketmq-store/src/log_file/mapped_file/default_mapped_file_impl.rs
Length of output: 2497
Codecov ReportAttention: Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #2189 +/- ##
==========================================
- Coverage 28.75% 28.75% -0.01%
==========================================
Files 498 498
Lines 71059 71059
==========================================
- Hits 20435 20430 -5
- Misses 50624 50629 +5 ☔ View full report in Codecov by Sentry. |
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Which Issue(s) This PR Fixes(Closes)
Fixes #2188
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