switch to js implementation of orchestrion

[rochdev]

What does this PR do?

Switch to JavaScript implementation of Orchestrion.

Motivation

In its current form, Orchestrion is too heavy to be usable for instrumentation. It also lacks a good query engine to be powerful enough for any transformations, and it requires 2 distinct Rust projects to be updated and released every time we need to make any change. While this is still the direction we want to be going long-term, I don't see a path forward short-term so I wrote a JS version that enables our integrations team to start using the rewriter approach.

Startup time impact goes from +46-104% with Orchestrion to +6-11% with the JS based rewriter. Of course lazy loading can help with these numbers in both cases, but that's only true when no instrumentation is done using the rewriter, which will be less and less common as we start adding and updating integrations.

Instrumentation time is a bit slower but since we don't instrument a lot of files that's fine, especially since the time to parse is relative to the size of the file, and larger files are also slower to load for Node and v8, so parsing is only slow for an already slow to load file. For example, parsing langchain goes from 7ms to 14ms, but the library itself takes 100ms+ to load so we're still pretty insignificant in comparison.

Additional Notes

The goal of this PR is not to replace Orchestrion, quite the opposite. The JS implementation simply enables us to ship this now without having to make the many changes that are needed to get Orchestrion work for our needs. This is especially true since some of our needs are not known yet and may require larger changes. Once our usage becomes stable, everything should be backported to Orchestrion and we should switch back.

[github-actions]

Overall package size

Self size: 3.59 MB
Deduped: 4.47 MB
No deduping: 4.47 MB

Dependency sizes

| name | version | self size | total size | |------|---------|-----------|------------| | import-in-the-middle | 1.15.0 | 127.66 kB | 856.24 kB | | dc-polyfill | 0.1.10 | 26.73 kB | 26.73 kB |

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

[codecov]

Codecov Report

❌ Patch coverage is 75.38462% with 32 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.77%. Comparing base (5856d72) to head (47e5adb).
⚠️ Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
...nstrumentations/src/helpers/rewriter/transforms.js	65.90%	15 Missing ⚠️
...dog-instrumentations/src/helpers/rewriter/index.js	79.31%	12 Missing ⚠️
...datadog-instrumentations/src/helpers/instrument.js	28.57%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6877      +/-   ##
==========================================
- Coverage   84.83%   84.77%   -0.07%     
==========================================
  Files         515      521       +6     
  Lines       22022    22149     +127     
==========================================
+ Hits        18683    18776      +93     
- Misses       3339     3373      +34     

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[pr-commenter]

Benchmarks

Benchmark execution time: 2025-12-11 22:38:56

Comparing candidate commit 47e5adb in PR branch orchestrion-js with baseline commit 5856d72 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 290 metrics, 30 unstable metrics.