Fix optimizer crash in JDBC prepare by initializing active_query#1
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Fix optimizer crash in JDBC prepare by initializing active_query#1thijs-s wants to merge 1 commit into
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Initialize `active_query` in `ClientContext::PrepareInternal` to ensure the optimizer has a valid context during statement preparation. This fixes a null pointer dereference encountered by optimizer extensions when accessing `GetCurrentQuery()` via the JDBC driver. The implementation uses a new `ActiveQueryGuard` RAII helper to ensure strict exception safety and proper resource cleanup.
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In the current implementation, we suffer invalid memory access with the
unit test.
ASAN reports see below
```sh
hjiang@hjiangs-MacBook-Pro$ ./build/debug/test/unittest "[block_allocator]"
Filters: [block_allocator]
[0/1] (0%): BlockAllocator usage and de-allocation on different threads =================================================================
==23765==ERROR: AddressSanitizer: stack-use-after-scope on address 0x00016f4ff6f8 at pc 0x00010d437368 bp 0x00016f58abf0 sp 0x00016f58abe8
READ of size 8 at 0x00016f4ff6f8 thread T1
#0 0x00010d437364 in std::__1::unique_ptr<duckdb::BlockQueue, std::__1::default_delete<duckdb::BlockQueue>>::get[abi:ne200100]() const unique_ptr.h:281
#1 0x00010d2cddd4 in duckdb::unique_ptr<duckdb::BlockQueue, std::__1::default_delete<duckdb::BlockQueue>, false>::operator->() const unique_ptr.hpp:41
duckdb#2 0x00010d2cd000 in duckdb::BlockAllocatorThreadLocalState::Clear() block_allocator.cpp:141
duckdb#3 0x00010d434348 in duckdb::BlockAllocatorThreadLocalState::~BlockAllocatorThreadLocalState() block_allocator.cpp:97
duckdb#4 0x00010d2cb87c in duckdb::BlockAllocatorThreadLocalState::~BlockAllocatorThreadLocalState() block_allocator.cpp:96
duckdb#5 0x00019527fdc8 in invocation function for block in dyld::ThreadLocalVariables::finalizeList(void*)+0x34 (libdyld.dylib:arm64e+0x3dc8)
```
The root cause is (which is the plain english explanation for the unit
test)
- Assume we have two threads: A and B
- BlockAllocator is created in thread-A, and allocates memory in
thread-B, which means there's one [thread-local
state](https://github.com/duckdb/duckdb/blob/67a0a733f12119424dddee68aed6ad271792ec42/src/storage/block_allocator.cpp#L204)
created in thread-B and records free blocks
- When BlockAllocator is destructed in thread-A, a new thread-local
state will be created and cleared => thread-A's thread-local state is
unchanged
- Now when thread-A destructs, it [attempts to access
BlockAllocator](https://github.com/duckdb/duckdb/blob/67a0a733f12119424dddee68aed6ad271792ec42/src/storage/block_allocator.cpp#L139-L149),
which leads to invalid memory access
In one word, there's no guarantee on lifecycle for BlockAllocator and
threa-local state, this PR simply adds a guard to block possible invalid
access.
BlockAllocator is a [per-db
instance](https://github.com/duckdb/duckdb/blob/67a0a733f12119424dddee68aed6ad271792ec42/src/include/duckdb/main/config.hpp#L175-L176),
so the issue could happen in cases where user creates a DB in one worker
thread and performs query.
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Initialize
active_queryinClientContext::PrepareInternalto ensure the optimizer has a valid context during statement preparation. This fixes a null pointer dereference encountered by optimizer extensions when accessingGetCurrentQuery()via the JDBC driver.The implementation uses a new
ActiveQueryGuardRAII helper to ensure strict exception safety and proper resource cleanup.