RUSageMeter: remove C++ class and associated bindings and tests

The native CPU metric instrumentation isn't needed anymore since
Node.js version 12 provides bindings of its own for this data. We
don't use the non-CPU metrics provided by RUSageMeter (memory, context
switches, etc) so it's okay to remove this feature wholesale.

A corresponding change in the calling code in the main agent repo is
forthcoming.

Fixes #154

binding.gyp

@@ -7,9 +7,7 @@
       "src/GCBinder.cpp",
       "src/LoopChecker.hpp",
       "src/LoopChecker.cpp",
-      "src/Metric.hpp",
-      "src/RUsageMeter.hpp",
-      "src/RUsageMeter.cpp"
+      "src/Metric.hpp"
     ],
     "defines": [
       "NOMINMAX"

index.js

@@ -39,9 +39,6 @@ function NativeMetricEmitter(opts) {
   this.bound = false
   this._timeout = null
 
-  this._rusageMeter = new natives.RUsageMeter()
-  this.usageEnabled = true
-
   this._gcBinder = new natives.GCBinder()
   this.gcEnabled = true
 
@@ -52,36 +49,6 @@ function NativeMetricEmitter(opts) {
 }
 util.inherits(NativeMetricEmitter, EventEmitter)
 
-/**
- * @interface RUsageStats
- *
- * @description
- *  Resource usage statistics.
- *
- *  Properties marked (X) are unmaintained by the operating system and are
- *  likely to be just `0`.
- *
- * @property {number} ru_utime    - user CPU time used in milliseconds
- * @property {number} ru_stime    - system CPU time used in milliseconds
- * @property {number} ru_maxrss   - maximum resident set size in bytes
- * @property {number} ru_ixrss    - integral shared memory size (X)
- * @property {number} ru_idrss    - integral unshared data size (X)
- * @property {number} ru_isrss    - integral unshared stack size (X)
- * @property {number} ru_minflt   - page reclaims (soft page faults) (X)
- * @property {number} ru_majflt   - page faults (hard page faults)
- * @property {number} ru_nswap    - swaps (X)
- * @property {number} ru_inblock  - block input operations
- * @property {number} ru_oublock  - block output operations
- * @property {number} ru_msgsnd   - IPC messages sent (X)
- * @property {number} ru_msgrcv   - IPC messages received (X)
- * @property {number} ru_nsignals - signals received (X)
- * @property {number} ru_nvcsw    - voluntary context switches (X)
- * @property {number} ru_nivcsw   - involuntary context switches (X)
- *
- * @see http://docs.libuv.org/en/v1.x/misc.html#c.uv_getrusage
- * @see http://docs.libuv.org/en/v1.x/misc.html#c.uv_rusage_t
- */
-
 /**
  * @interface LoopMetrics
  *
@@ -125,34 +92,14 @@ util.inherits(NativeMetricEmitter, EventEmitter)
  * @param {number} [timeout]
  *  The number of milliseconds between samplings. Defaults to 15 seconds.
  */
-NativeMetricEmitter.prototype.bind = function bind(timeout) {
+NativeMetricEmitter.prototype.bind = function bind() {
   if (this.bound) {
     return
   }
 
-  timeout = timeout || DEFAULT_TIMEOUT
   this._gcBinder.bind()
   this._loopChecker.bind()
 
-  this._timeout = setTimeout(nativeMetricTimeout.bind(this), timeout).unref()
-  function nativeMetricTimeout() {
-    if (this._rusageMeter) {
-      /**
-       * Resource usage sampling event.
-       *
-       * @event NativeMetricEmitter#usage
-       * @type {object}
-       *
-       * @property {RUsageStats} diff     - The change in stats since last sampling.
-       * @property {RUsageStats} current  - The current usage statistics.
-       */
-      this.emit('usage', this._rusageMeter.read())
-    }
-    if (this.bound) {
-      this._timeout = setTimeout(nativeMetricTimeout.bind(this), timeout).unref()
-    }
-  }
-
   this.bound = true
 }
 
@@ -166,7 +113,6 @@ NativeMetricEmitter.prototype.unbind = function unbind() {
 
   this._gcBinder.unbind()
   this._loopChecker.unbind()
-  clearTimeout(this._timeout)
   this.bound = false
 }
 

src/native_metrics.cpp

@@ -8,14 +8,12 @@
 
 #include "GCBinder.hpp"
 #include "LoopChecker.hpp"
-#include "RUsageMeter.hpp"
 
 namespace nr {
 
 NAN_MODULE_INIT(Init) {
   Nan::HandleScope scope;
   GCBinder::Init(target);
-  RUsageMeter::Init(target);
   LoopChecker::Init(target);
 }