106 lines
3.1 KiB
JavaScript
106 lines
3.1 KiB
JavaScript
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const debug = require('debug')('log4js:clustering');
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const LoggingEvent = require('./LoggingEvent');
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const configuration = require('./configuration');
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let disabled = false;
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let cluster = null;
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try {
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// eslint-disable-next-line global-require
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cluster = require('cluster');
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} catch (e) {
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debug('cluster module not present');
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disabled = true;
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}
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const listeners = [];
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let pm2 = false;
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let pm2InstanceVar = 'NODE_APP_INSTANCE';
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const isPM2Master = () => pm2 && process.env[pm2InstanceVar] === '0';
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const isMaster = () =>
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disabled || (cluster && cluster.isMaster) || isPM2Master();
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const sendToListeners = (logEvent) => {
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listeners.forEach((l) => l(logEvent));
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};
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// in a multi-process node environment, worker loggers will use
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// process.send
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const receiver = (worker, message) => {
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// prior to node v6, the worker parameter was not passed (args were message, handle)
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debug('cluster message received from worker ', worker, ': ', message);
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if (worker.topic && worker.data) {
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message = worker;
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worker = undefined;
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}
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if (message && message.topic && message.topic === 'log4js:message') {
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debug('received message: ', message.data);
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const logEvent = LoggingEvent.deserialise(message.data);
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sendToListeners(logEvent);
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}
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};
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if (!disabled) {
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configuration.addListener((config) => {
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// clear out the listeners, because configure has been called.
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listeners.length = 0;
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({
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pm2,
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disableClustering: disabled,
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pm2InstanceVar = 'NODE_APP_INSTANCE',
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} = config);
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debug(`clustering disabled ? ${disabled}`);
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debug(`cluster.isMaster ? ${cluster && cluster.isMaster}`);
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debug(`pm2 enabled ? ${pm2}`);
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debug(`pm2InstanceVar = ${pm2InstanceVar}`);
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debug(`process.env[${pm2InstanceVar}] = ${process.env[pm2InstanceVar]}`);
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// just in case configure is called after shutdown
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if (pm2) {
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process.removeListener('message', receiver);
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}
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if (cluster && cluster.removeListener) {
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cluster.removeListener('message', receiver);
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}
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if (disabled || config.disableClustering) {
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debug('Not listening for cluster messages, because clustering disabled.');
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} else if (isPM2Master()) {
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// PM2 cluster support
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// PM2 runs everything as workers - install pm2-intercom for this to work.
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// we only want one of the app instances to write logs
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debug('listening for PM2 broadcast messages');
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process.on('message', receiver);
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} else if (cluster && cluster.isMaster) {
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debug('listening for cluster messages');
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cluster.on('message', receiver);
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} else {
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debug('not listening for messages, because we are not a master process');
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}
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});
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}
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module.exports = {
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onlyOnMaster: (fn, notMaster) => (isMaster() ? fn() : notMaster),
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isMaster,
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send: (msg) => {
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if (isMaster()) {
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sendToListeners(msg);
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} else {
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if (!pm2) {
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msg.cluster = {
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workerId: cluster.worker.id,
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worker: process.pid,
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};
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}
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process.send({ topic: 'log4js:message', data: msg.serialise() });
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}
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},
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onMessage: (listener) => {
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listeners.push(listener);
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},
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};
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