benchmark: add `setImmediate()` benchmarks

Timings for sequential and concurren setImmediate() with and without
arguments, and set + clearImmediate().

PR-URL: https://github.com/nodejs/node/pull/6436
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

benchmark/timers/immediate.js

@@ -0,0 +1,113 @@
+'use strict';
+var common = require('../common.js');
+
+var bench = common.createBenchmark(main, {
+  thousands: [2000],
+  type: ['depth', 'depth1', 'breadth', 'breadth1', 'breadth4', 'clear']
+});
+
+function main(conf) {
+  var N = +conf.thousands * 1e3;
+  switch (conf.type) {
+    case 'depth':
+      depth(N);
+      break;
+    case 'depth1':
+      depth1(N);
+      break;
+    case 'breadth':
+      breadth(N);
+      break;
+    case 'breadth1':
+      breadth1(N);
+      break;
+    case 'breadth4':
+      breadth4(N);
+      break;
+    case 'clear':
+      clear(N);
+      break;
+  }
+}
+
+// setImmediate tail recursion, 0 arguments
+function depth(N) {
+  var n = 0;
+  bench.start();
+  setImmediate(cb);
+  function cb() {
+    n++;
+    if (n === N)
+      bench.end(N / 1e3);
+    else
+      setImmediate(cb);
+  }
+}
+
+// setImmediate tail recursion, 1 argument
+function depth1(N) {
+  var n = 0;
+  bench.start();
+  setImmediate(cb, 1);
+  function cb(a1) {
+    n++;
+    if (n === N)
+      bench.end(N / 1e3);
+    else
+      setImmediate(cb, 1);
+  }
+}
+
+// concurrent setImmediate, 0 arguments
+function breadth(N) {
+  var n = 0;
+  bench.start();
+  function cb() {
+    n++;
+    if (n === N)
+      bench.end(N / 1e3);
+  }
+  for (var i = 0; i < N; i++) {
+    setImmediate(cb);
+  }
+}
+
+// concurrent setImmediate, 1 argument
+function breadth1(N) {
+  var n = 0;
+  bench.start();
+  function cb(a1) {
+    n++;
+    if (n === N)
+      bench.end(N / 1e3);
+  }
+  for (var i = 0; i < N; i++) {
+    setImmediate(cb, 1);
+  }
+}
+
+// concurrent setImmediate, 4 arguments
+function breadth4(N) {
+  var n = 0;
+  bench.start();
+  function cb(a1, a2, a3, a4) {
+    n++;
+    if (n === N)
+      bench.end(N / 1e3);
+  }
+  for (var i = 0; i < N; i++) {
+    setImmediate(cb, 1, 2, 3, 4);
+  }
+}
+
+function clear(N) {
+  bench.start();
+  function cb(a1) {
+    if (a1 === 2)
+      bench.end(N / 1e3);
+  }
+  for (var i = 0; i < N; i++) {
+    clearImmediate(setImmediate(cb, 1));
+  }
+  setImmediate(cb, 2);
+}