try removing a dispatch_with_results call

[emmettbutler]

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• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
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[github-actions]

CODEOWNERS have been resolved as:

ddtrace/_trace/trace_handlers.py                                        @DataDog/apm-sdk-api-python
ddtrace/appsec/_asm_request_context.py                                  @DataDog/asm-python
ddtrace/appsec/_handlers.py                                             @DataDog/asm-python
ddtrace/appsec/_trace_utils.py                                          @DataDog/asm-python
ddtrace/contrib/dbapi/__init__.py                                       @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/dbapi_async/__init__.py                                 @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/aiomysql/patch.py                              @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/asgi/middleware.py                             @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/asyncpg/patch.py                               @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/django/patch.py                                @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/django/utils.py                                @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/flask/patch.py                                 @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/flask/wrappers.py                              @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/wsgi/wsgi.py                                   @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/ext/test_visibility/_utils.py                                   @DataDog/ci-app-libraries
ddtrace/ext/test_visibility/api.py                                      @DataDog/ci-app-libraries
ddtrace/internal/ci_visibility/recorder.py                              @DataDog/ci-app-libraries
ddtrace/internal/core/__init__.py                                       @DataDog/apm-core-python
ddtrace/internal/core/event_hub.py                                      @DataDog/apm-core-python
ddtrace/internal/test_visibility/_atr_mixins.py                         @DataDog/ci-app-libraries
ddtrace/internal/test_visibility/_efd_mixins.py                         @DataDog/ci-app-libraries
ddtrace/internal/test_visibility/_itr_mixins.py                         @DataDog/ci-app-libraries
ddtrace/internal/test_visibility/_utils.py                              @DataDog/ci-app-libraries
ddtrace/internal/test_visibility/api.py                                 @DataDog/ci-app-libraries
ddtrace/internal/utils/__init__.py                                      @DataDog/apm-core-python
ddtrace/propagation/_database_monitoring.py                             @DataDog/apm-sdk-api-python

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-12-06 20:44:47

Comparing candidate commit 601f456 in PR branch emmett.butler/no-dispatch-with-results with baseline commit 00440f5 in branch main.

Found 0 performance improvements and 2 performance regressions! Performance is the same for 386 metrics, 2 unstable metrics.

scenario:iast_aspects-ospathdirname_aspect

• 🟥 execution_time [+555.925ns; +622.536ns] or [+15.258%; +17.086%]

scenario:iast_aspects-ospathsplitext_aspect

• 🟥 execution_time [+417.076ns; +475.049ns] or [+11.352%; +12.930%]

[romainkomorn-exdatadog]

I know this is a draft/WIP but I worry about the usage for this, where one could conceivably:

• call get_item() without ever calling dispatch()
• call dispatch(), call get_item(), then call get_item() a second time and get a possibly unexpectedly-stale result
• runaway set_item()s could end up leaking memory (eg: set_item(f"my_unique_object_id"))

I like the idea of cleaning up the syntax around dispatch_with_results(), though, but I think its current approach makes sense, and I think anyone who wants to have behavior where the item isn't recomputed multiple times could (or should) implement a caching mechanism for it.