From 90f2269276fdec71aac7be30b0f1e6603d27659c Mon Sep 17 00:00:00 2001
From: Chris Matheson <chris@matheson.it>
Date: Thu, 26 Jul 2018 14:17:44 +0100
Subject: [PATCH 1/4] introduction of function which understands async return
 and instruments appropriately

---
 lib/statsFunctions.js | 38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/lib/statsFunctions.js b/lib/statsFunctions.js
index 6a667470..bd5bd947 100644
--- a/lib/statsFunctions.js
+++ b/lib/statsFunctions.js
@@ -48,6 +48,42 @@ function applyStatsFns (Client) {
     };
   };
 
+  /**
+   * Decorates an async function with timing recording behaviour.
+   *
+   * This version of `timer` will record the time take for the asyncronus action returned by `func`
+   * not just the execution time of `func` itself.
+   *
+   * @param func {<T,A>(...A):Promise<T>} The function to run
+   * @param stat {String|Array} The stat(s) to send
+   * @param sampleRate {Number=} The Number of times to sample (0 to 1). Optional.
+   * @param tags {Array=} The Array of tags to add to metrics. Optional.
+   * @param callback {Function=} Callback when message is done being delivered. Optional.
+   */
+  Client.prototype.asyncTimer = function (func, stat, sampleRate, tags, callback) {
+    var self = this;
+    return function() {
+      var end = hrtimer();
+      var p = func.apply(null, arguments);
+      var recordStat = () => self.timing(stat, end(), sampleRate, tags, callback);
+
+      return p.then(recordStat, recordStat);
+    };
+  };
+
+  function hrtimer() {
+    var start = process.hrtime();
+
+    return function () {
+      var durationComponents = process.hrtime(start);
+      var seconds = durationComponents[0];
+      var nanoseconds = durationComponents[1];
+      var duration = seconds * 1000 + nanoseconds / 1E6;
+      return duration;
+    };
+  }
+
+
   /**
    * Increments a stat by a specified amount
    * @param stat {String|Array} The stat(s) to send
@@ -267,4 +303,4 @@ function applyStatsFns (Client) {
   };
 }
 
-module.exports = applyStatsFns;
\ No newline at end of file
+module.exports = applyStatsFns;

From fdf9a9c903d74c87edb3d4eccd2f2c9a269a3ba9 Mon Sep 17 00:00:00 2001
From: Chris Matheson <chris@matheson.it>
Date: Thu, 26 Jul 2018 14:34:37 +0100
Subject: [PATCH 2/4] adding tests (should have done sooner as it wasnt
 working)

---
 lib/statsFunctions.js |  2 +-
 test/timer.js         | 29 ++++++++++++++++++++++++++++-
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/lib/statsFunctions.js b/lib/statsFunctions.js
index bd5bd947..36228d5c 100644
--- a/lib/statsFunctions.js
+++ b/lib/statsFunctions.js
@@ -65,7 +65,7 @@ function applyStatsFns (Client) {
     return function() {
       var end = hrtimer();
       var p = func.apply(null, arguments);
-      var recordStat = () => self.timing(stat, end(), sampleRate, tags, callback);
+      var recordStat = function() { self.timing(stat, end(), sampleRate, tags, callback); };
 
       return p.then(recordStat, recordStat);
     };
diff --git a/test/timer.js b/test/timer.js
index d3813280..8fdcb1df 100644
--- a/test/timer.js
+++ b/test/timer.js
@@ -1,5 +1,5 @@
 'use strict';
-
+var StatsD = require('../lib/statsd');
 var assert = require('assert');
 
 var createStatsdClient = require('./helpers').createStatsdClient;
@@ -105,5 +105,32 @@ module.exports = function runTimerTestSuite() {
         });
       });
     });
+
+    it('should record "user time" of promise', function () {
+      /* globals Promise */
+      var statsd = new StatsD({mock:true});
+
+      var onehundredMsFunc = function () { return delay(100); };
+
+      var instrumented = statsd.asyncTimer(onehundredMsFunc, 'name-thingy');
+
+      return instrumented().then(function() {
+
+        var stat = statsd.mockBuffer[0];
+        var name = stat.split(/:|\|/)[0];
+        var time = stat.split(/:|\|/)[1];
+
+        assert.equal(name, 'name-thingy');
+        assert.ok(parseFloat(time) >= 100);
+        assert.ok(parseFloat(time) < 110);
+      });
+    });
   });
 };
+
+
+function delay(n) {
+  return new Promise(function (resolve, reject) {
+    setTimeout(resolve, n);
+  });
+}

From 5d1f7eb0c9f1a3242109d4eb85e9beb1feef77fd Mon Sep 17 00:00:00 2001
From: Chris Matheson <chris@matheson.it>
Date: Thu, 26 Jul 2018 16:00:10 +0100
Subject: [PATCH 3/4] whoops, actually return the correct promise

---
 lib/statsFunctions.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/statsFunctions.js b/lib/statsFunctions.js
index 36228d5c..bd82a2b9 100644
--- a/lib/statsFunctions.js
+++ b/lib/statsFunctions.js
@@ -66,8 +66,8 @@ function applyStatsFns (Client) {
       var end = hrtimer();
       var p = func.apply(null, arguments);
       var recordStat = function() { self.timing(stat, end(), sampleRate, tags, callback); };
-
-      return p.then(recordStat, recordStat);
+      p.then(recordStat, recordStat);
+      return p;
     };
   };
 

From c8ea82212c6b95d1f086286051be4b2bf4cd9a1b Mon Sep 17 00:00:00 2001
From: Chris Matheson <chris@matheson.it>
Date: Fri, 27 Jul 2018 08:50:51 +0100
Subject: [PATCH 4/4] raise upper theshold of sanity check (review feedback)

---
 test/timer.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/timer.js b/test/timer.js
index 8fdcb1df..24cae592 100644
--- a/test/timer.js
+++ b/test/timer.js
@@ -122,7 +122,7 @@ module.exports = function runTimerTestSuite() {
 
         assert.equal(name, 'name-thingy');
         assert.ok(parseFloat(time) >= 100);
-        assert.ok(parseFloat(time) < 110);
+        assert.ok(parseFloat(time) < 200);
       });
     });
   });