Stage 2: ODBC pooling primitives (ADO #47338) - #296
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Add SQL_ATTR_CONNECTION_DEAD and SQL_ATTR_RESET_CONNECTION support for connection pooling (Stage 2, ADO #47338). - B1: add SQL_ATTR_CONNECTION_DEAD/SQL_CD_TRUE/SQL_CD_FALSE and SQL_ATTR_RESET_CONNECTION/SQL_RESET_CONNECTION_YES constants. - B2: SQLGetConnectAttr(SQL_ATTR_CONNECTION_DEAD) returns a cached, never-probe liveness read; disconnected/never-connected reads DEAD. - B3: SQLSetConnectAttr(SQL_ATTR_RESET_CONNECTION) validates the value (HY024 otherwise), rolls back a live local transaction, arms the full RESETCONNECTION bit via prepare_reset_connection(false), and clears local_tran_started; disconnected surfaces 08003, busy is rejected. - Unit tests cover both attributes. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 63e24621-7665-4572-a5b8-e5dfa55060a0
This was referenced Aug 15, 2026
Saurabh Singh (saurabh500)
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enhancement
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Summary
Stage 2 of the mssql-odbc connection pooling effort (
[AB#47338](https://sqlclientdrivers.visualstudio.com/b95cf060-8083-439d-8ef1-405d5bf219d8/_workitems/edit/47338)). Wires the two ODBC pooling attributes intomssql-odbc, building on the Stage 1 TDS reset/liveness primitives.B1 — Constants (
api/odbc_types.rs)SQL_ATTR_CONNECTION_DEAD = 1209,SQL_CD_TRUE = 1,SQL_CD_FALSE = 0SQL_ATTR_RESET_CONNECTION = 116,SQL_RESET_CONNECTION_YES = 1B2 —
SQLGetConnectAttr(SQL_ATTR_CONNECTION_DEAD)(api/get_connect_attr.rs)SQL_CD_FALSEonly when the DBC is connected andclient.is_connection_dead()is false; otherwiseSQL_CD_TRUE.SQL_CD_TRUE(D1: msodbcsql defaults DEAD until a successful token read).take()s it (D8).B3 —
SQLSetConnectAttr(SQL_ATTR_RESET_CONNECTION, YES)(api/set_connect_attr.rs+api/txn.rs)set_connect_attr.rsinto a newreset_connectionhandler intxn.rs.SQL_RESET_CONNECTION_YESaccepted; any other value ⇒ HY024.claim_dbc_client(busy/active_stmt⇒ connection-busy; disconnected ⇒ 08003, D7).prepare_reset_connection(false)(pool checkout does not preserve).state.local_tran_started. Never holds the DBC mutex across I/O.B7 (partial) — Tests
SQL_ATTR_CONNECTION_DEAD:SQL_CD_TRUEwhen disconnected / connected-without-client;SQL_CD_FALSEwhen connected-and-alive; null-pointer rejected.SQL_ATTR_RESET_CONNECTION: non-YES ⇒ HY024; disconnected ⇒ 08003; busy (active_stmt) rejected; success clearslocal_tran_startedand leaves the idle client in place.Validation
cargo bfmt✅cargo bclippy✅ (warnings-as-errors)cargo nextest run -p mssql-odbc✅ 573 passedStacking
This PR targets
saurabh500-stage-1-tds-reset-correctness, notmain. It is stacked on Stage 1 PR #294 (which stacks on base PR #293).[AB#47338](https://sqlclientdrivers.visualstudio.com/b95cf060-8083-439d-8ef1-405d5bf219d8/_workitems/edit/47338)