March 2

node-7-scaling/child-exec.js

@@ -0,0 +1,11 @@
+var exec = require('child_process').exec;
+
+var child = exec('uptime | 23cut -d "," -f 1', function(err, stdout, stderr) {
+  if (err) {
+    console.log(stderr);
+  } else {
+    console.log('Output is: ' + stdout);
+  }
+});
+
+console.log("PID is: " + child.pid);

node-7-scaling/child-fork.js

@@ -0,0 +1,13 @@
+var fork = require('child_process').fork;
+
+var child = fork(__dirname + '/honourstudent.js');
+
+child.on('message', function(m) {
+  console.log('The answer is: ', m.answer);
+  child.send({cmd: 'done'});
+});
+
+child.send({cmd: 'double', number:20});
+
+
+console.log('PID is ' + child.pid);

node-7-scaling/child-spawn.js

@@ -0,0 +1,14 @@
+var spawn = require('child_process').spawn,
+    ps = spawn('ps', ['ax']),
+    grep = spawn('grep', ['node']);
+
+ps.stdout.pipe(grep.stdin);
+grep.stdout.pipe(process.stdout);
+
+ps.stderr.on('data', function(data) {
+  console.log('ps stderr: ' + data);
+});
+
+grep.stderr.on('data', function (data) {
+  console.log('grep stderr: ' + data);
+});

node-7-scaling/cluster.js

@@ -0,0 +1,47 @@
+var cluster = require('cluster');
+var http = require('http');
+var numWorkers = 2;
+
+if (cluster.isMaster) {
+  // Fork Workers
+  for (var i=0; i<numWorkers; i++) {
+    console.log('master: about to fork a worker');
+    cluster.fork();
+  }
+
+  cluster.on('fork', function(worker) {
+    console.log('master: fork event (worker ' + worker.id + ')');
+  });
+
+  cluster.on('online', function(worker) {
+    console.log('master: online event (worker ' + worker.id + ')');
+  });
+
+  cluster.on('listening', function(worker, address) {
+    console.log('master: listening event (worker ' + worker.id + ', pid ' + worker.process.pid  + ', ' + address.address + ':' + address.port + ')');
+  });  
+
+  cluster.on('exit', function(worker, code, signal) {
+    console.log('master: exit event (worker ' + worker.id + ')');
+  });
+} else {
+
+    console.log('worker: worker#' + cluster.worker.id + ' ready!');
+
+    var count = 0;
+
+    // Workers can share any TCP connection
+    // In this case its a HTTP server
+    http.createServer(function(req, res) {
+      res.writeHead(200);
+      // count.dir(req);
+      count++;
+      console.log('Worker # ' + cluster.worker.id + 'is incrementing count to ' + count);
+      res.end('Hello world from worker #' + cluster.worker.id + ' (pid ' + cluster.worker.process.id + ')');
+      if (count === 3) {
+        cluster.worker.destroy();
+      }
+    }).listen(process.env.PORT, process.env.IP);
+
+}
+

node-7-scaling/honourstudent.js

@@ -0,0 +1,13 @@
+var fun = require('./mathfun');
+
+process.on('message', function(m) {
+  console.log("Child pid is: " + process.pid);
+  if (m.cmd === 'double') {
+    console.log('hs: I was asked to double ' + m.number);
+    fun.evenDoubler(m.number, function(err, res) {
+      process.send({answer: res});
+    });
+  } else if (m.cmd === 'done') {
+    process.exit();
+  }
+});

node-7-scaling/mathfun.js

@@ -0,0 +1,27 @@
+var maxTime = 200;
+
+var evenDoubler = function(v, callback){
+  var randomTime = Math.floor(Math.random()*(maxTime+1));
+  if( v % 2 == 0) {
+    setTimeout(function(){
+      callback(null, v * 2, randomTime);
+    }, randomTime);
+  } else {
+    var err = new Error("odd number");
+    setTimeout(function(){
+      callback(err);
+    }, randomTime);
+  }
+};
+
+var evenDoublerSync = function(v) {
+  if (v%2) throw (new Error("ODD INPUT"));
+  else return v*2;
+}
+
+module.exports.evenDoubler = evenDoubler;
+module.exports.evenDoublerSync = evenDoublerSync;
+module.exports.foo = "bar";
+
+//evenDoubler(2, handleResults);
+//evenDoubler(1, handleResults);