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fix(storage): Resolve potential race condition in AsyncWriterConnectionImpl#16099
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This pull request introduces a mutex to protect the impl_ member variable during destruction and within the Finish method of AsyncWriterConnectionImpl to prevent data races. While these changes improve thread safety, the reviewer noted that the fix is incomplete as other methods accessing impl_ and shared state like latest_write_handle_ remain unprotected, potentially leading to race conditions or null pointer dereferences.
v-pratap
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May 19, 2026
v-pratap
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May 19, 2026
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This change addresses a potential race condition in
AsyncWriterConnectionImplbetween the destructor and asynchronous callback operations.The
impl_member variable could be moved in the destructor while simultaneously being accessed by a callback function (e.g., withinOnPartialUploadwhich can callimpl_->Finish()). This concurrent access could lead to a use-after-free error under certain timing conditions. To resolve this, this commit introduces astd::mutexto protect accesses to theimpl_member.Why other methods (Write, Flush, etc.) are not protected:
The library's public API contract forbids users from calling methods like Write(), Flush(), Query(), or Finalize() while destruction is in progress or while another operation is already pending. As long as the user follows this contract, these methods will never run concurrently with the destructor.
The only reason we need protection in Finish() and OnFinalUpload() is because they are called by the library's own internal asynchronous callbacks (running on the Completion Queue thread), which can execute concurrently with the destructor (running on the user's thread) if an operation completes or fails just as the object is being destroyed.