chore(sampling): moves sampler.py and sampling_rule.py from ddtrace to ddtrace._trace [3.0]

[mabdinur]

Motivation

Deprecates support for samplers. Ensures sampling can only be configured via environment variables and remote configuration.

Changes

• Internalize the implementation details of the Datadog samplers by moving ddtrace/sampler.py and ddtrace/sampling_rule.py to ddtrace/_trace/
• Maintains backwards compatibility by continuing to export all objects in ddtrace._trace.[sampling_rule/sampler].py in ddtrace.[sampling_rule/sampler].py.
• Logs a warning if the internalized sampling modules are used.

Checklist

• 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
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[github-actions]

CODEOWNERS have been resolved as:

ddtrace/_trace/sampler.py                                               @DataDog/apm-sdk-api-python
ddtrace/_trace/sampling_rule.py                                         @DataDog/apm-sdk-api-python
releasenotes/notes/internalize-samplers-b4f014f680f872f9.yaml           @DataDog/apm-python
ddtrace/_trace/processor/__init__.py                                    @DataDog/apm-sdk-api-python
ddtrace/_trace/tracer.py                                                @DataDog/apm-sdk-api-python
ddtrace/appsec/_iast/_overhead_control_engine.py                        @DataDog/asm-python
ddtrace/internal/debug.py                                               @DataDog/apm-core-python
ddtrace/internal/sampling.py                                            @DataDog/apm-sdk-api-python
ddtrace/llmobs/_evaluators/sampler.py                                   @DataDog/ml-observability
ddtrace/llmobs/_integrations/base.py                                    @DataDog/ml-observability
ddtrace/sampler.py                                                      @DataDog/apm-sdk-api-python
ddtrace/sampling_rule.py                                                @DataDog/apm-sdk-api-python
tests/contrib/aiohttp/test_middleware.py                                @DataDog/apm-core-python @DataDog/apm-idm-python
tests/integration/test_debug.py                                         @DataDog/apm-core-python
tests/integration/test_sampling.py                                      @DataDog/apm-core-python
tests/integration/test_trace_stats.py                                   @DataDog/apm-core-python
tests/internal/remoteconfig/test_remoteconfig.py                        @DataDog/remote-config @DataDog/apm-core-python
tests/internal/test_settings.py                                         @DataDog/apm-core-python
tests/tracer/test_processors.py                                         @DataDog/apm-sdk-api-python
tests/tracer/test_sampler.py                                            @DataDog/apm-sdk-api-python

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-01-13 20:25:26

Comparing candidate commit a7c7485 in PR branch munir/deprecate-samplers with baseline commit 358a167 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 394 metrics, 2 unstable metrics.

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: munir/deprecate-samplers
Commit report: a7c7485
Test service: dd-trace-py

✅ 0 Failed, 87 Passed, 1468 Skipped, 4m 0.59s Total duration (35m 32.88s time saved)

[Yun-Kim]

Moving samplers to be internal-only lgtm from team ML Obs