From 519e021a655cfd73f7a17a87820f5228b680a7d1 Mon Sep 17 00:00:00 2001
From: Samuron <samuronchik@gmail.com>
Date: Wed, 20 Mar 2024 08:24:23 +0200
Subject: [PATCH] perf(tracer): reduce overhead of attribute sanitization

---
 .../src/common/attributes.ts                  | 12 ++++++-----
 .../src/Tracer.ts                             |  5 ++---
 .../test/performance/benchmark/span.js        | 21 +++++++++++++++++--
 3 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/packages/opentelemetry-core/src/common/attributes.ts b/packages/opentelemetry-core/src/common/attributes.ts
index 0726acd5813..c3dc1594c12 100644
--- a/packages/opentelemetry-core/src/common/attributes.ts
+++ b/packages/opentelemetry-core/src/common/attributes.ts
@@ -16,24 +16,26 @@
 
 import { diag, SpanAttributeValue, SpanAttributes } from '@opentelemetry/api';
 
-export function sanitizeAttributes(attributes: unknown): SpanAttributes {
-  const out: SpanAttributes = {};
-
+export function sanitizeAttributes(
+  attributes: unknown,
+  out: SpanAttributes = {}
+): SpanAttributes {
   if (typeof attributes !== 'object' || attributes == null) {
     return out;
   }
 
-  for (const [key, val] of Object.entries(attributes)) {
+  for (const key in attributes) {
     if (!isAttributeKey(key)) {
       diag.warn(`Invalid attribute key: ${key}`);
       continue;
     }
+    const val = attributes[key as keyof typeof attributes] as unknown;
     if (!isAttributeValue(val)) {
       diag.warn(`Invalid attribute value set for key: ${key}`);
       continue;
     }
     if (Array.isArray(val)) {
-      out[key] = val.slice();
+      out[key] = out[key] == val ? val : val.slice();
     } else {
       out[key] = val;
     }
diff --git a/packages/opentelemetry-sdk-trace-base/src/Tracer.ts b/packages/opentelemetry-sdk-trace-base/src/Tracer.ts
index f943e6a11cc..454d3ff0fc9 100644
--- a/packages/opentelemetry-sdk-trace-base/src/Tracer.ts
+++ b/packages/opentelemetry-sdk-trace-base/src/Tracer.ts
@@ -134,9 +134,8 @@ export class Tracer implements api.Tracer {
 
     // Set initial span attributes. The attributes object may have been mutated
     // by the sampler, so we sanitize the merged attributes before setting them.
-    const initAttributes = sanitizeAttributes(
-      Object.assign(attributes, samplingResult.attributes)
-    );
+    Object.assign(attributes, samplingResult.attributes);
+    const initAttributes = sanitizeAttributes(attributes, attributes);
 
     const span = new Span(
       this,
diff --git a/packages/opentelemetry-sdk-trace-base/test/performance/benchmark/span.js b/packages/opentelemetry-sdk-trace-base/test/performance/benchmark/span.js
index 851123c392f..8f2171a9e37 100644
--- a/packages/opentelemetry-sdk-trace-base/test/performance/benchmark/span.js
+++ b/packages/opentelemetry-sdk-trace-base/test/performance/benchmark/span.js
@@ -18,7 +18,7 @@ const Benchmark = require('benchmark');
 const { BasicTracerProvider } = require('../../../build/src');
 
 const tracerProvider = new BasicTracerProvider();
-const tracer = tracerProvider.getTracer('test')
+const tracer = tracerProvider.getTracer('test');
 
 const suite = new Benchmark.Suite();
 
@@ -26,7 +26,7 @@ suite.on('cycle', event => {
   console.log(String(event.target));
 });
 
-suite.add('create spans (10 attributes)', function() {
+suite.add('create spans (10 attributes)', function () {
   const span = tracer.startSpan('span');
   span.setAttribute('aaaaaaaaaaaaaaaaaaaa', 'aaaaaaaaaaaaaaaaaaaa');
   span.setAttribute('bbbbbbbbbbbbbbbbbbbb', 'aaaaaaaaaaaaaaaaaaaa');
@@ -41,4 +41,21 @@ suite.add('create spans (10 attributes)', function() {
   span.end();
 });
 
+suite.add('create spans (10 attributes) passed as options', function () {
+  const span = tracer.startSpan('span', {
+    attributes: {
+      aaaaaaaaaaaaaaaaaaaa: 'aaaaaaaaaaaaaaaaaaaa',
+      bbbbbbbbbbbbbbbbbbbb: 'aaaaaaaaaaaaaaaaaaaa',
+      cccccccccccccccccccc: 'aaaaaaaaaaaaaaaaaaaa',
+      dddddddddddddddddddd: 'aaaaaaaaaaaaaaaaaaaa',
+      eeeeeeeeeeeeeeeeeeee: 'aaaaaaaaaaaaaaaaaaaa',
+      ffffffffffffffffffff: 'aaaaaaaaaaaaaaaaaaaa',
+      gggggggggggggggggggg: 'aaaaaaaaaaaaaaaaaaaa',
+      hhhhhhhhhhhhhhhhhhhh: 'aaaaaaaaaaaaaaaaaaaa',
+      iiiiiiiiiiiiiiiiiiii: 'aaaaaaaaaaaaaaaaaaaa',
+      jjjjjjjjjjjjjjjjjjjj: 'aaaaaaaaaaaaaaaaaaaa',
+    },
+  });
+});
+
 suite.run();