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Recover from stale PID file

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Mononaut 2023-11-10 07:45:02 +00:00
parent 28113d1141
commit 3639dcc92a
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1 changed files with 25 additions and 7 deletions
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32
backend/src/database.ts
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@ -4,6 +4,7 @@ import config from './config';
import { createPool, Pool, PoolConnection } from 'mysql2/promise';
import logger from './logger';
import { FieldPacket, OkPacket, PoolOptions, ResultSetHeader, RowDataPacket } from 'mysql2/typings/mysql';
import { execSync } from 'child_process';
class DB {
constructor() {
@ -105,18 +106,34 @@ import { FieldPacket, OkPacket, PoolOptions, ResultSetHeader, RowDataPacket } fr
public getPidLock(): boolean {
const filePath = path.join(config.DATABASE.PID_DIR || __dirname, `/mempool-${config.DATABASE.DATABASE}.pid`);
this.enforcePidLock(filePath);
fs.writeFileSync(filePath, `${process.pid}`);
return true;
}
private enforcePidLock(filePath: string): void {
if (fs.existsSync(filePath)) {
const pid = fs.readFileSync(filePath).toString();
if (pid !== `${process.pid}`) {
const msg = `Already running on PID ${pid} (or pid file '${filePath}' is stale)`;
const pid = parseInt(fs.readFileSync(filePath, 'utf-8'));
if (pid === process.pid) {
logger.warn('PID file already exists for this process');
return;
}
let cmd;
try {
cmd = execSync(`ps -p ${pid} -o args=`);
} catch (e) {
logger.warn(`Stale PID file at ${filePath}, but no process running on that PID ${pid}`);
return;
}
if (cmd && cmd.toString()?.includes('node')) {
const msg = `Another mempool nodejs process is already running on PID ${pid}`;
logger.err(msg);
throw new Error(msg);
} else {
return true;
logger.warn(`Stale PID file at ${filePath}, but the PID ${pid} does not belong to a running mempool instance`);
}
} else {
fs.writeFileSync(filePath, `${process.pid}`);
return true;
}
}
@ -124,6 +141,7 @@ import { FieldPacket, OkPacket, PoolOptions, ResultSetHeader, RowDataPacket } fr
const filePath = path.join(config.DATABASE.PID_DIR || __dirname, `/mempool-${config.DATABASE.DATABASE}.pid`);
if (fs.existsSync(filePath)) {
const pid = fs.readFileSync(filePath).toString();
// only release our own pid file
if (pid === `${process.pid}`) {
fs.unlinkSync(filePath);
}