appdynamics/lib/probes/cluster-probe.js

Performance Profiler and Monitor

/*
Copyright (c) AppDynamics, Inc., and its affiliates
2015
All Rights Reserved
 */
'use strict';

var fs = require('fs');


function ClusterProbe(agent) {
  this.agent = agent;

  this.packages = ['cluster'];
}
exports.ClusterProbe = ClusterProbe;



ClusterProbe.prototype.attach = function(obj) {
  var self = this;

  if(process.env.APPDYNAMICS_CLUSTER_PROBE_DISABLE == true || process.env.APPDYNAMICS_CLUSTER_PROBE_DISABLE == 'true') {
    return;
  }

  if(obj.__appdynamicsProbeAttached__) return;
  obj.__appdynamicsProbeAttached__ = true;
  self.agent.on('destroy', function() {
    if(obj.__appdynamicsProbeAttached__) {
      delete obj.__appdynamicsProbeAttached__;
      proxy.release(obj.fork);
    }
  });

  var proxy = self.agent.proxy;

  var indexDirExists = false;

  proxy.after(obj, 'fork', function(obj, args, ret) {
    var indexMap = {};
    var maxIndex = 0;
    for(var id in obj.workers) {
      var worker = obj.workers[id];

      if(worker.__appdNodeIndex !== undefined) {
        indexMap[worker.__appdNodeIndex] = true;

        if(worker.__appdNodeIndex > maxIndex) {
          maxIndex = worker.__appdNodeIndex;
        }
      }
    }

    var freeIndex;
    for(var i = 1; i <= maxIndex; i++) {
      if(!indexMap[i]) {
        freeIndex = i;
        break;
      }
    }

    if(freeIndex === undefined) {
      freeIndex = maxIndex + 1;
    }

    ret.__appdNodeIndex = freeIndex;

    var indexDir = self.agent.tmpDir + '/index';
    if(indexDirExists) {
      writeIndexPid();
    }
    else if(fs.existsSync(indexDir)) {
      indexDirExists = true;
      writeIndexPid();
    }
    else {
      fs.mkdirSync(indexDir);
      indexDirExists = true;
      writeIndexPid();
    }

    function writeIndexPid() {
      fs.writeFile(indexDir + '/' + freeIndex + '.pid', String(ret.process.pid), function(err) {
        if(err) return self.agent.logger.error(err);
      });
    }
  });
};