refactor(tracing): break span-sampling cycle

[P403n1x87]

We break the cycle between the span object and the sampling logic by moving some methods and functions around

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/processor/__init__.py                                    @DataDog/apm-sdk-api-python
ddtrace/_trace/sampler.py                                               @DataDog/apm-sdk-api-python
ddtrace/_trace/sampling_rule.py                                         @DataDog/apm-sdk-api-python
ddtrace/_trace/span.py                                                  @DataDog/apm-sdk-api-python
ddtrace/appsec/_trace_utils.py                                          @DataDog/asm-python
ddtrace/internal/ci_visibility/filters.py                               @DataDog/ci-app-libraries
ddtrace/internal/sampling.py                                            @DataDog/apm-sdk-api-python
ddtrace/propagation/http.py                                             @DataDog/apm-sdk-api-python
tests/integration/test_sampling.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
tests/tracer/test_single_span_sampling_rules.py                         @DataDog/apm-sdk-api-python

[github-actions]

Bootstrap import analysis

Comparison of import times between this PR and base.

Summary

The average import time from this PR is: 237 ± 6 ms.

The average import time from base is: 235 ± 4 ms.

The import time difference between this PR and base is: 1.9 ± 0.2 ms.

Import time breakdown

The following import paths have appeared:

ddtrace.auto 0.629 ms (0.27%)

ddtrace 0.629 ms (0.27%)

ddtrace.trace 0.629 ms (0.27%)

ddtrace._trace.filters 0.629 ms (0.27%)

ddtrace._trace.processor 0.629 ms (0.27%)

ddtrace._trace.sampler 0.629 ms (0.27%)

ddtrace._trace.span 0.629 ms (0.27%)

ddtrace._trace.sampling_rule 0.629 ms (0.27%)

ddtrace.internal.glob_matching 0.264 ms (0.11%)

The following import paths have disappeared:

ddtrace.auto 0.719 ms (0.30%)

ddtrace 0.719 ms (0.30%)

ddtrace.trace 0.719 ms (0.30%)

ddtrace._trace.filters 0.719 ms (0.30%)

ddtrace._trace.processor 0.719 ms (0.30%)

ddtrace._trace.sampler 0.719 ms (0.30%)

ddtrace._trace.span 0.719 ms (0.30%)

ddtrace.internal.sampling 0.719 ms (0.30%)

ddtrace._trace.sampling_rule 0.719 ms (0.30%)

ddtrace.internal.glob_matching 0.274 ms (0.12%)

The following import paths have grown:

ddtrace.auto 0.471 ms (0.20%)

ddtrace.bootstrap.sitecustomize 0.317 ms (0.13%)

ddtrace.bootstrap.preload 0.317 ms (0.13%)

ddtrace.internal.products 0.317 ms (0.13%)

importlib.metadata 0.213 ms (0.09%)

importlib.metadata._meta 0.070 ms (0.03%)

ddtrace.internal.remoteconfig._connectors 0.104 ms (0.04%)

ctypes 0.104 ms (0.04%)

_ctypes 0.104 ms (0.04%)

ddtrace 0.154 ms (0.07%)

ddtrace.trace 0.154 ms (0.07%)

ddtrace._trace.filters 0.154 ms (0.07%)

ddtrace._trace.processor 0.154 ms (0.07%)

ddtrace._trace.sampler 0.154 ms (0.07%)

ddtrace._trace.span 0.154 ms (0.07%)

ddtrace.internal._rand 0.105 ms (0.04%)

The following import paths have shrunk:

ddtrace.auto 1.379 ms (0.58%)

ddtrace.bootstrap.sitecustomize 0.716 ms (0.30%)

ddtrace.bootstrap.preload 0.716 ms (0.30%)

ddtrace.internal.products 0.716 ms (0.30%)

ddtrace.internal.remoteconfig.client 0.558 ms (0.24%)

importlib.metadata 0.158 ms (0.07%)

csv 0.096 ms (0.04%)

importlib.metadata._collections 0.062 ms (0.03%)

ddtrace 0.663 ms (0.28%)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-04-15 15:45:02

Comparing candidate commit 758ae26 in PR branch refactor/span-sampling with baseline commit 70e052b in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 392 metrics, 2 unstable metrics.

[github-actions]

This pull request has been automatically closed after a period of inactivity.
After this much time, it will likely be easier to open a new pull request with the
same changes than to update this one from the base branch. Please comment or reopen
if you think this pull request was closed in error.