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103 lines
3.0 KiB
103 lines
3.0 KiB
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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cluster = require("cluster"); //eslint-disable-line
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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 = () => disabled || 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.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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