CydandClaude Opus 4.8
df04ab4eb7
- dev/migrations/001-innodb.sql: convert pqs_queue + pqs_mission to InnoDB. - includes/queue.php: pqs_enqueue_player() seats a player in the next open mission (creating one if needed), serialized with GET_LOCK and wrapped in a transaction; capacity judged by real COUNT(*), numplayers rewritten from it so the counter self-heals and can't drift. - callsign.php: normal registration path now calls pqs_enqueue_player instead of the non-atomic read-check-insert. Verified on the local stack: 140 concurrent registrations -> 24 missions, zero overfill, zero counter drift. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
97 lines
3.5 KiB
PHP
97 lines
3.5 KiB
PHP
<?php
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/**
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* Queue domain logic for PQS.
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*
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* The core operation is "seat a player in the next open mission" — the thing
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* that races when the kiosk (callsign.php) and the staff console
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* (registration.php) add players at the same time. See docs/ARCHITECTURE.md §7.
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*/
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require_once __DIR__ . '/db.php';
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/**
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* Atomically seat a player in the lowest-numbered open mission, creating a new
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* mission (sized to the current pod count) if none has room. Returns the
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* MissionID the player landed in.
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*
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* Concurrency safety comes from two layers:
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* 1. GET_LOCK serializes the whole find-or-create-insert critical section, so
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* no two registrations can interleave their capacity check and insert —
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* this is what prevents overfilling a mission or racing to create
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* duplicate missions.
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* 2. An InnoDB transaction makes the mission update + queue insert commit (or
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* roll back) as a unit, so a mid-way failure can't leave numplayers and
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* the queue out of sync.
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*
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* Capacity is checked against the real COUNT(*) of queued rows, and numplayers
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* is rewritten to that count after inserting, so the denormalized counter is
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* self-healing and can't drift the mission into over/under-fill.
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*/
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function pqs_enqueue_player(string $callsign, string $mech, int $merc = 0): int
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{
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$db = pqs_db();
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if ((int) pqs_val("SELECT GET_LOCK('pqs_enqueue', 10)") !== 1) {
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throw new RuntimeException('Could not acquire enqueue lock (timeout)');
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}
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try {
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$db->begin_transaction();
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// Lowest open mission that still has a free seat, judged by actual
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// occupancy rather than the cached counter.
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$mission = pqs_row(
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"SELECT MissionID, MissionSize
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FROM pqs_mission
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WHERE Completed = 0
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AND locked = 0
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AND (SELECT COUNT(*) FROM pqs_queue WHERE MissionID = pqs_mission.MissionID) < MissionSize
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ORDER BY MissionID ASC
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LIMIT 1"
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);
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if ($mission === null) {
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// Nothing open: start a fresh mission sized to the current pods.
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$size = (int) pqs_val("SELECT numpods FROM pqs_gameconfig WHERE gamechoiceid = 1");
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if ($size < 1) {
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$size = 1;
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}
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// nummercs is NOT NULL without a default; set it explicitly (a new
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// mission has 0 mercs) so this works under strict SQL mode too.
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pqs_exec(
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"INSERT INTO pqs_mission (MissionDate, MissionSize, numplayers, nummercs, MissionTime)
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VALUES (?, ?, 0, 0, ?)",
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'iii',
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[(int) date('Ymd'), $size, (int) date('Hi')]
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);
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$missionid = (int) $db->insert_id;
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} else {
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$missionid = (int) $mission['MissionID'];
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}
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pqs_exec(
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"INSERT INTO pqs_queue (CallSign, Mech, MissionID, Merc) VALUES (?, ?, ?, ?)",
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'ssii',
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[$callsign, $mech, $missionid, $merc]
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);
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// Rewrite the cached counter from the truth, so it can never drift.
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pqs_exec(
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"UPDATE pqs_mission
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SET numplayers = (SELECT COUNT(*) FROM pqs_queue WHERE MissionID = ?)
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WHERE MissionID = ?",
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'ii',
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[$missionid, $missionid]
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);
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$db->commit();
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} catch (Throwable $e) {
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$db->rollback();
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pqs_val("SELECT RELEASE_LOCK('pqs_enqueue')");
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throw $e;
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}
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pqs_val("SELECT RELEASE_LOCK('pqs_enqueue')");
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return $missionid;
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}
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