[ypopovych]

Fixes #325.

Problem

Every swizzle in URLSessionInstrumentation followed this pattern:

var originalIMP: IMP?
let block = { ... unsafeBitCast(originalIMP, ...)(...) ... }
originalIMP = method_setImplementation(original, swizzledIMP)

method_setImplementation publishes the swizzled IMP before it returns, while originalIMP is assigned only afterwards. A thread calling the method in that window enters the block with originalIMP == nil and jumps to 0x0.

At bootstrap, DDTestMonitor runs network auto-instrumentation (startInstrumenting → startNetworkAutoInstrumentation) concurrently with the SDK's own tracer settings request (startTestOptimization → getTracerConfig), which hits that window.

The customer crash report, symbolicated with the 2.7.11 iphonesimulator arm64 dSYM (UUID 5C9387A6-AADD-3844-AAA3-1F5F7B5F33E4), confirms this:

• Crashed thread: getTracerConfig (DDTestMonitor.swift:337) → SettingsApiService.tracerSettings → HTTPClient._send → swizzled block in injectIntoNSURLSessionAsyncDataAndDownloadTaskMethods (URLSessionInstrumentation.swift:372) → 0x0
• Concurrent thread: startNetworkAutoInstrumentation (DDTestMonitor.swift:701) → injectIntoNSURLSessionAsyncDataAndDownloadTaskMethods (:305), inside method_setImplementation

Fix

At all 10 swizzle sites (session task creation methods, resume, and the delegate injections), the original IMP is now read with method_getImplementation and captured as a let before the swizzled IMP is published. This is the same pattern injectIntoNSURLSessionCreateTaskWithParameterMethods already used.

Testing

• macOS unit tests (DatadogSDKTestingTests): 464 tests, 0 failures

🤖 Generated with Claude Code

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-19T13:41:55.934267Z	ac0f080	PR opened
🔒 Security Review	✅ Completed 2026-10-19T13:43:47.237015Z	ac0f080	PR opened

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[datadog-datadog-prod-us1]

More details

Capturing each original implementation before publishing its swizzled replacement closes the reported nil-IMP window across all ten affected sites.

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