[Code Origin for Spans] Refactor Fastify implementation

[watson]

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What does this PR do?

Use a WeakMap to store the Code Origin Entry Span location instead of polluting the Fastify route options config object.

Also limit when the onRoute handler is added, to only be when the version of Fastify supports getting the proper stack trace (requires v4.10.0+).

Motivation

Unfortunately DEBUG-3941 can't easily be fixed, but while working on that JIRA ticket, I refactored a few areas of the Fastify Code Origin implementation. This PR contains those refactorings. The rest of the work related to DEBUG-3941 has been tabled for now, until we know if enough users running versions of Fastify older than 4.10.0 wants the Code Origin for Spans feature (no need to spend time on that unless it's needed).

Plugin Checklist

• [ ] Unit tests.
• [ ] Integration tests.
• [ ] Benchmarks.
• [ ] TypeScript definitions.
• [ ] TypeScript tests.
• [ ] API documentation.
• [ ] CI jobs/workflows.

Additional Notes

If we ever continue with the work to support Code Origin for Spans below v4.10.0, we'll need this patch, which was developed as part of this work, but was excluded from this PR:

diff --git a/packages/datadog-instrumentations/src/fastify.js b/packages/datadog-instrumentations/src/fastify.js
index 3957c6795..58099f243 100644
--- a/packages/datadog-instrumentations/src/fastify.js
+++ b/packages/datadog-instrumentations/src/fastify.js
@@ -148,7 +148,9 @@ function getRes (reply) {
 }
 
 function getRouteConfig (request) {
-  return request?.routeOptions?.config
+  // The `request.routerOptions` object was added in Fastify v4.10.0.
+  // If not present, fallback to use the now deprecated `request.context` object to access the `config` object.
+  return request?.routeOptions?.config ?? request?.context?.config
 }
 
 function publishError (error, req) {

[watson]

• #5764 👈 (View in Graphite)
• master

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[github-actions[bot]]

Overall package size

Self size: 9.42 MB Deduped: 103.45 MB No deduping: 103.97 MB

Dependency sizes

| name | version | self size | total size | |------|---------|-----------|------------| | @datadog/libdatadog | 0.5.1 | 29.73 MB | 29.73 MB | | @datadog/native-appsec | 8.5.2 | 19.33 MB | 19.34 MB | | @datadog/pprof | 5.8.0 | 12.55 MB | 12.92 MB | | @datadog/native-iast-taint-tracking | 4.0.0 | 11.72 MB | 11.73 MB | | @opentelemetry/core | 1.30.1 | 908.66 kB | 7.16 MB | | protobufjs | 7.4.0 | 2.77 MB | 5.42 MB | | @datadog/wasm-js-rewriter | 4.0.1 | 2.85 MB | 3.58 MB | | @datadog/native-metrics | 3.1.1 | 1.02 MB | 1.43 MB | | @opentelemetry/api | 1.8.0 | 1.21 MB | 1.21 MB | | import-in-the-middle | 1.13.1 | 117.64 kB | 839.26 kB | | source-map | 0.7.4 | 226 kB | 226 kB | | opentracing | 0.14.7 | 194.81 kB | 194.81 kB | | lru-cache | 7.18.3 | 133.92 kB | 133.92 kB | | pprof-format | 2.1.0 | 111.69 kB | 111.69 kB | | @datadog/sketches-js | 2.1.1 | 109.9 kB | 109.9 kB | | lodash.sortby | 4.7.0 | 75.76 kB | 75.76 kB | | ignore | 5.3.2 | 53.63 kB | 53.63 kB | | istanbul-lib-coverage | 3.2.0 | 29.34 kB | 29.34 kB | | rfdc | 1.4.1 | 27.15 kB | 27.15 kB | | @isaacs/ttlcache | 1.4.1 | 25.2 kB | 25.2 kB | | dc-polyfill | 0.1.8 | 25.08 kB | 25.08 kB | | tlhunter-sorted-set | 0.1.0 | 24.94 kB | 24.94 kB | | shell-quote | 1.8.2 | 23.54 kB | 23.54 kB | | limiter | 1.1.5 | 23.17 kB | 23.17 kB | | retry | 0.13.1 | 18.85 kB | 18.85 kB | | semifies | 1.0.0 | 15.84 kB | 15.84 kB | | jest-docblock | 29.7.0 | 8.99 kB | 12.76 kB | | crypto-randomuuid | 1.0.0 | 11.18 kB | 11.18 kB | | ttl-set | 1.0.0 | 4.61 kB | 9.69 kB | | mutexify | 1.4.0 | 5.71 kB | 8.74 kB | | path-to-regexp | 0.1.12 | 6.6 kB | 6.6 kB | | koalas | 1.0.2 | 6.47 kB | 6.47 kB | | module-details-from-path | 1.0.3 | 4.47 kB | 4.47 kB |

_{🤖 This report was automatically generated by heaviest-objects-in-the-universe}

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 79.06%. Comparing base (86f1f53) to head (88fe776). Report is 106 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5764      +/-   ##
==========================================
- Coverage   79.15%   79.06%   -0.10%     
==========================================
  Files         520      516       -4     
  Lines       23729    23618     -111     
==========================================
- Hits        18783    18673     -110     
+ Misses       4946     4945       -1     

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Benchmarks

Benchmark execution time: 2025-05-23 10:34:35

Comparing candidate commit 88fe77613d35b2d3458c5ac94cdfeb5c0f1cc8bd in PR branch watson/DEBUG-3941/improve-co-fastify-version-limit with baseline commit 86f1f53648764b8a7e7d2bac06e2e67cab8dea4c in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 1268 metrics, 55 unstable metrics.

[datadog-datadog-prod-us1[bot]]

Datadog Report

Branch report: watson/DEBUG-3941/improve-co-fastify-version-limit Commit report: 255c310 Test service: dd-trace-js-integration-tests

:white_check_mark: 0 Failed, 1152 Passed, 0 Skipped, 22m 40.03s Total Time