Improve shimmer instrumentation performance (#5593)

* Improve shimmer instrumentation performance

The following improvements are implemented:

1. The prototype has to only be looked up in case the constructor
   is not identical. That is a rare case, so it'll be
   faster in average.
2. Copying the property descriptors is now done by skipping
  entries that may not be set. There is also no try / catch needed
  anymore.
4. The assertions are now faster by preventing duplicated lookups
   in the positive case.
5. Reusing the existing descriptor instead of creating a new object.

* Minor benchmark improvements

* Remove outdated benchmarks

* Fix basic benchmarks

These are now possible to run again and the benchmark script is
also fixed.

* Fast path for enumerable, writable, configurable properties

* Improve shimmer.wrap performance and add TODO entry

The wrap performance now has an additional fast path and the
noAssert argument is removed due to always being false.

Non configurable but writable properties are now instrumented
properly.

Author: BridgeAR

benchmark/benchmark.js

@@ -6,7 +6,7 @@ const Benchmark = require('benchmark')
 const nock = require('nock')
 
 Benchmark.options.maxTime = 0
-Benchmark.options.minSamples = 5
+Benchmark.options.minSamples = 100
 
 nock.disableNetConnect()
 

benchmark/e2e/README.md

@@ -4,6 +4,13 @@ const id = require('../../packages/dd-trace/src/id')
 
 const spanId = id('1234567812345678')
 
+const tags = {
+  'resource.name': '/resource',
+  'service.name': 'benchmark',
+  'span.type': 'web',
+  error: true
+}
+
 const span = {
   tracer: () => ({
     scope: () => ({
@@ -12,27 +19,27 @@ const span = {
     _service: 'service'
   }),
   addTags: () => {},
+  _addTags: () => {},
   context: () => ({
     _traceId: spanId,
     _spanId: spanId,
     _parentId: spanId,
     _trace: {
       started: [span, span],
-      finished: [span, span]
-    },
-    _tags: {
-      'resource.name': '/resource',
-      'service.name': 'benchmark',
-      'span.type': 'web',
-      error: true
+      finished: [span, span],
+      tags
     },
+    _tags: tags,
     _sampling: {},
     _name: 'operation'
   }),
   _startTime: 1500000000000.123,
   _duration: 100,
   _spanContext: {
     _name: 'operation'
+  },
+  setTag (key, value) {
+    this._addTags({ [key]: value })
   }
 }