/**
* MySQL Resource - Locks
*/
import type { MySQLAdapter } from '../MySQLAdapter.js';
import type { ResourceDefinition, RequestContext } from '../../../types/index.js';
export function createLocksResource(adapter: MySQLAdapter): ResourceDefinition {
return {
uri: 'mysql://locks',
name: 'Lock Contention',
title: 'MySQL Lock Contention',
description: 'Current InnoDB lock waits and blocking transactions',
mimeType: 'application/json',
annotations: {
audience: ['user', 'assistant'],
priority: 0.8
},
handler: async (_uri: string, _context: RequestContext) => {
try {
// Get current lock waits from performance_schema
const lockWaitsResult = await adapter.executeQuery(`
SELECT
r.trx_id AS waiting_trx_id,
r.trx_mysql_thread_id AS waiting_thread,
r.trx_query AS waiting_query,
b.trx_id AS blocking_trx_id,
b.trx_mysql_thread_id AS blocking_thread,
b.trx_query AS blocking_query,
TIMESTAMPDIFF(SECOND, r.trx_wait_started, NOW()) AS wait_seconds
FROM performance_schema.data_lock_waits w
JOIN information_schema.innodb_trx r ON r.trx_id = w.REQUESTING_ENGINE_TRANSACTION_ID
JOIN information_schema.innodb_trx b ON b.trx_id = w.BLOCKING_ENGINE_TRANSACTION_ID
LIMIT 20
`);
// Get global lock status
const lockStatusResult = await adapter.executeQuery(`
SHOW STATUS LIKE 'Innodb_row_lock%'
`);
const lockStats: Record<string, unknown> = {};
for (const row of (lockStatusResult.rows ?? [])) {
const varName = row['Variable_name'];
if (typeof varName === 'string') {
lockStats[varName] = row['Value'];
}
}
return {
currentLockWaits: lockWaitsResult.rows?.length ?? 0,
lockWaits: lockWaitsResult.rows ?? [],
lockStatistics: lockStats
};
} catch {
return {
currentLockWaits: 0,
lockWaits: [],
lockStatistics: {},
error: 'Unable to retrieve lock information'
};
}
}
};
}
