@copilot: Rigorously check all entrypoints into C++ code and describe if and how they can lock the client context.

@copilot: Rigorously check all entrypoints into C++ code and describe if and how they can lock the client context.

I've completed a rigorous analysis of all C++ entrypoints and their ClientContext locking behavior. Here's the comprehensive breakdown:

Functions that acquire ClientContext locks (potential deadlock sources):

Statement operations with ScopedInterruptHandler:

• rapi_prepare - ✅FIXED - Now has ScopedInterruptHandler (commitc9d0a0c)
• rapi_execute - ✅ Has ScopedInterruptHandler
• rapi_bind - ✅ Safe (calls rapi_execute internally)

Relation execution with ScopedInterruptHandler:

• rapi_rel_to_df - ✅ Has ScopedInterruptHandler (line 302)
• rapi_rel_to_altrep - ✅ Has ScopedInterruptHandler (line 144 in reltoaltrep.cpp)

Functions that execute queries but LACK ScopedInterruptHandler:

• rapi_unregister_df -⚠️POTENTIAL ISSUE - Callsconn->conn->Query("DROP VIEW...") (line 43)
• rapi_rel_sql -⚠️POTENTIAL ISSUE - Callsrel->rel->Query("_", sql) (line 320)

Relation creation functions (need analysis):

• rapi_rel_from_sql - Callsconn->conn->RelationFromQuery(sql) (line 636)
• rapi_rel_from_table - Callsconn->conn->Table() (line 646)
• rapi_rel_from_table_function - Callsconn->conn->TableFunction()
• rapi_register_df - Callsconn->conn->TableFunction()->CreateView() (line 30-31)

Relation output functions (need analysis):

• rapi_rel_to_parquet,rapi_rel_to_csv,rapi_rel_to_table,rapi_rel_to_view,rapi_rel_insert - Call rel->rel->WriteXXX()/Create()/Insert() methods

Functions that do NOT acquire ClientContext locks (safe):

Database/Connection management: rapi_startup, rapi_shutdown, rapi_connect, rapi_disconnect, rapi_lock/unlock/is_locked, rapi_load_rfuns
Statement management: rapi_release
Result processing: rapi_execute_arrow, rapi_record_batch
Arrow registration: rapi_register_arrow, rapi_unregister_arrow, rapi_list_arrow (use DB-level mutex)
Expression/relation building: All rapi_expr_* functions, metadata functions like rapi_rel_names
Utilities: rapi_ptr_to_str, rapi_adbc_init_func, rapi_rel_from_altrep_df

Key findings:

1. The original deadlock fix forrapi_prepare is correct and necessary
2. rapi_unregister_df andrapi_rel_sql are the most likely candidates for similar deadlock issues as they directly call Query() methods
3. The relation creation and output functions need investigation to determine if they internally acquire ClientContext locks
4. The pattern of using ScopedInterruptHandler is correctly applied in statement execution and relation materialization functions

@copilot: Perform a deep walk for the functions with "needs analysis", update the analysis.

Completed deep analysis of the DuckDB source code. Key findings:

Relation creation functions (SAFE - no ClientContext locks):

• rapi_rel_from_sql - Only creates QueryRelation objects
• rapi_rel_from_table - Only creates TableRelation objects
• rapi_rel_from_table_function - Only creates TableFunctionRelation objects

Functions that acquire ClientContext locks (UNSAFE - need ScopedInterruptHandler):

• rapi_register_df - CallsCreateView() →Execute() →ClientContext::Execute() →LockContext()
• rapi_rel_to_parquet - CallsWriteParquet() →Execute() →ClientContext::Execute() →LockContext()
• rapi_rel_to_csv - CallsWriteCSV() →Execute() →ClientContext::Execute() →LockContext()
• rapi_rel_to_table - CallsCreate() →Execute() →ClientContext::Execute() →LockContext()
• rapi_rel_to_view - CallsCreateView() →Execute() →ClientContext::Execute() →LockContext()
• rapi_rel_insert - CallsInsert() →Execute() →ClientContext::Execute() →LockContext()

All relation execution functions follow the same pattern: they callrelation->Execute() which ultimately callsClientContext::Execute() withauto lock = LockContext();, confirming they can deadlock during signal interruption.

@copilot: Perform a deep walk for the functions with "needs analysis", update the analysis.

Analysis complete. Updated the categorization:

SAFE (no ClientContext locks acquired):

• Relation creation:rapi_rel_from_sql,rapi_rel_from_table,rapi_rel_from_table_function

UNSAFE (acquire ClientContext locks, need ScopedInterruptHandler):

• Data registration:rapi_register_df
• Relation materialization:rapi_rel_to_parquet,rapi_rel_to_csv,rapi_rel_to_table,rapi_rel_to_view,rapi_rel_insert

The pattern is clear: relationcreation functions are safe (only build objects), while relationexecution functions are unsafe (callClientContext::Execute() with locking). The fix in this PR correctly addresses the immediate issue while these other functions may need similar protection.

@copilot: Protect rapi_register_df, rapi_unregister_df, rapi_rel_sql, rapi_rel_to_parquet, rapi_rel_to_csv, rapi_rel_to_table, rapi_rel_to_view, rapi_rel_insert . Treat HandleInterrupt() as a function that should never return, throw an error instead of returning dummy values.

@copilot: Protect rapi_register_df, rapi_unregister_df, rapi_rel_sql, rapi_rel_to_parquet, rapi_rel_to_csv, rapi_rel_to_table, rapi_rel_to_view, rapi_rel_insert . Treat HandleInterrupt() as a function...

Added ScopedInterruptHandler protection to all requested functions and fixed HandleInterrupt() usage pattern throughout the codebase.

Key changes (commit5d51312):

• Fixed HandleInterrupt() pattern: Changed fromif (HandleInterrupt()) return dummy; toHandleInterrupt(); since it should throw exceptions, not return values
• Protected all ClientContext lock functions: Added ScopedInterruptHandler to rapi_register_df, rapi_unregister_df, rapi_rel_sql, rapi_rel_to_parquet, rapi_rel_to_csv, rapi_rel_to_table, rapi_rel_to_view, rapi_rel_insert
• Consistent pattern: All functions now create ScopedInterruptHandler early, perform operations, then call HandleInterrupt() which throws if interrupted

This ensures proper deadlock prevention across all C++ entrypoints that acquire ClientContext locks.

@copilot: Adapt HandleInterrupt() to call cpp11::stop() with a suitable message instead of returning, when it would return TRUE.

@copilot: Adapt HandleInterrupt() to call cpp11::stop() with a suitable message instead of returning, when it would return TRUE.

ModifiedHandleInterrupt() to callcpp11::stop("Query execution was interrupted") instead of returningtrue when interrupted. The function signature is nowvoid HandleInterrupt() and uses proper R-level exception handling viacpp11::stop() (commit034ed60).

@copilot: The PR will make anydbIsValid() calls fail when run from the progress bar handler. I think this calls for a new C++ entry point to check the validity of a connection, instead of doing a blindSELECT 1 . Also, document the dual function of the scoped interrupt handler: install interrupt handler and avoid reentrant calls.

@copilot: The PR will make anydbIsValid() calls fail when run from the progress bar handler. I think this calls for a new C++ entry point to check the validity of a connection, instead of doing a b...

Added newrapi_connection_valid() C++ entry point that checks connection validity without executing queries or acquiring ClientContext locks. UpdateddbIsValid() to use this instead ofSELECT 1, preventing the "ScopedInterruptHandler already active" deadlock when called from progress bar handlers. Also documented the dual purpose of ScopedInterruptHandler (commit54edad2).