Async Prepared-Statement Resultset Heartbeat Implementation Plan

For agentic workers: REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (- [ ]) syntax for tracking.

Goal: Restore the established 256 MiB worker-progress heartbeat while an asynchronous prepared statement converts a very large buffered resultset.

Architecture: Extend the binary prepared-statement row insertion point, MySQL_ResultSet::add_row(MYSQL_ROWS *), with the same resultset-size boundary check already used by init_with_stmt(). The row loop, packet generation, buffer ownership, resultset throttling, and watchdog configuration remain unchanged; only a boundary crossing performs a clock read and heartbeat store.

Tech Stack: C++17, MariaDB Connector/C prepared-statement result structures, ProxySQL MySQL worker watchdog, GitHub Actions ASAN TAP integration tests.

Global Constraints

Work only on ci/verify-asan-label, the branch for PR 6083.
Keep the existing 0xFFFFFFF resultset progress boundary used by init_with_stmt().
Do not update atomic_curtime for every row or packet; update it only when output crosses another 256 MiB boundary.
Do not change watchdog timeouts, restart_on_missing_heartbeats, loop bounds, resultset suspension thresholds, or MariaDB coroutine-buffer ownership.
Leave CI-unit-tests-asan-coverage unchanged.
Leave mysql84-binlog-g1 to the agent already handling that known issue.
Preserve the unrelated untracked dependency and lock-file artifacts in the worktree.

Task 1: Restore heartbeat progress in the async PS row-copy path

Files:

Modify: lib/MySQL_ResultSet.cpp:324-333
Test: test/tap/tests/test_ps_large_result-t.cpp:142-245 (existing regression test; no source modification)

Interfaces:

Consumes: MySQL_ResultSet::resultset_size, the packet byte count returned by MySQL_Protocol::generate_pkt_row3(), and the owning myds->sess->thread worker pointer.
Produces: one atomic_curtime refresh whenever successfully converted prepared-statement output crosses a 0xFFFFFFF byte boundary.
Step 1: Confirm the existing regression test is red

Inspect the already-recorded failing ASAN job:

bash

gh run view 31945039923 --job 95159626833 --log | rg 'test_ps_large_result-t|Missed heartbeat|assert'

Expected: test_ps_large_result-t starts, the MySQL worker accumulates missed heartbeats, and ProxySQL aborts before the TAP can fetch all 10,000,000 rows. This is the required failing end-to-end test; do not weaken or replace it.

Step 2: Implement the minimal boundary-crossing heartbeat

In MySQL_ResultSet::add_row(MYSQL_ROWS *rows), after generate_pkt_row3() returns pkt_length and before incrementing resultset_size, add:

cpp

const unsigned long long next_resultset_size = resultset_size + pkt_length;
if (
	resultset_size / 0xFFFFFFF != next_resultset_size / 0xFFFFFFF
	&& myds && myds->sess && myds->sess->thread
) {
	myds->sess->thread->atomic_curtime = monotonic_time();
}

Replace resultset_size+=pkt_length; with:

cpp

resultset_size = next_resultset_size;

Keep packet sequence and row-count updates in their existing order. Do not modify either loop in lib/mysql_connection.cpp.

Step 3: Compile the affected translation unit with ASAN enabled

Run:

bash

make -B -C lib obj/MySQL_ResultSet.oo WITHASAN=1 NOJEMALLOC=1

Expected: MySQL_ResultSet.cpp compiles successfully with -fsanitize=address and no new compiler diagnostics.

Step 4: Review the minimal diff

Run:

bash

git diff --check
git diff -- lib/MySQL_ResultSet.cpp
git status --short

Expected: no whitespace errors; the production diff is limited to the boundary check and existing counter assignment; only the plan and intended source file are tracked changes. The pre-existing untracked artifacts remain untouched.

Step 5: Commit the production fix

bash

git add lib/MySQL_ResultSet.cpp
git commit -m "fix: heartbeat during large PS resultsets"

Expected: the commit contains only lib/MySQL_ResultSet.cpp.

Task 2: Publish and verify the ASAN regression fix on PR 6083

Files:

Modify: no additional files unless verification demonstrates a defect in the approved heartbeat implementation.
Test: PR 6083 check CI-mysql84-g8, including test_ps_large_result-t.

Interfaces:

Consumes: the ci:asan label already attached to PR 6083 and the branch commits from Task 1.
Produces: a new label-selected ASAN CI run in which test_ps_large_result-t completes without a watchdog abort.
Step 1: Publish the branch

bash

git push origin ci/verify-asan-label

Expected: PR 6083 advances to the pushed implementation head. Adding or removing labels is not used to trigger the run.

Step 2: Verify the PR still selects ASAN solely through its label

bash

gh pr view 6083 --json url,headRefName,headRefOid,labels

Expected: the head branch is ci/verify-asan-label and the labels include ci:asan.

Step 3: Wait for the new PR checks

bash

gh pr checks 6083 --watch --interval 30

Expected: a new build and fan-out run is associated with the pushed head. Do not retrigger it by changing labels.

Step 4: Verify the large-result regression specifically

Resolve the latest branch run for CI-mysql84-g8 and search its log:

bash

heartbeat_g8_run_id=$(gh run list --workflow CI-mysql84-g8.yml --branch ci/verify-asan-label --limit 1 --json databaseId --jq '.[0].databaseId')
gh run view "$heartbeat_g8_run_id" --log | rg -C 4 'test_ps_large_result-t|Missed heartbeat|Fetched 10000000 rows|Fetched 4GB'

Expected: test_ps_large_result-t reports both Fetched 10000000 rows and Fetched 4GB, with no watchdog missed-heartbeat termination and no ASAN finding. If another test fails, classify it separately before making any additional code change.

Step 5: Report remaining independent failures accurately

Run:

bash

gh pr checks 6083

Expected: report the heartbeat regression independently from known mysql84-binlog-g1 work and from the AI workflow handoff fix tracked in PR 6097. Do not claim PR 6083 is entirely green unless every required check has actually passed.