chore: refactor SpanAggregator <> TraceWriter interface

[brettlangdon]

Help remove some implementation details from SpanAggregator into a the writer module.

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

[brettlangdon]

This is going to have conflicts with #13876

[github-actions]

CODEOWNERS have been resolved as:

ddtrace/_trace/processor/__init__.py                                    @DataDog/apm-sdk-api-python
ddtrace/internal/ci_visibility/writer.py                                @DataDog/ci-app-libraries
ddtrace/internal/writer/__init__.py                                     @DataDog/apm-core-python
ddtrace/internal/writer/writer.py                                       @DataDog/apm-core-python
tests/utils.py                                                          @DataDog/python-guild

[github-actions]

Bootstrap import analysis

Comparison of import times between this PR and base.

Summary

The average import time from this PR is: 277 ± 2 ms.

The average import time from base is: 278 ± 3 ms.

The import time difference between this PR and base is: -1.9 ± 0.1 ms.

Import time breakdown

The following import paths have appeared:

ddtrace.auto 4.805 ms (1.74%)

ddtrace 4.805 ms (1.74%)

ddtrace.trace 4.805 ms (1.74%)

ddtrace._trace.filters 4.805 ms (1.74%)

ddtrace._trace.processor 4.805 ms (1.74%)

ddtrace.internal.writer 4.805 ms (1.74%)

ddtrace.internal.writer.writer 4.805 ms (1.74%)

ddtrace.internal.dogstatsd 4.805 ms (1.74%)

ddtrace.vendor.dogstatsd 4.521 ms (1.63%)

ddtrace.vendor.dogstatsd.base 4.266 ms (1.54%)

queue 1.347 ms (0.49%)

heapq 0.566 ms (0.20%)

_heapq 0.285 ms (0.10%)

_queue 0.294 ms (0.11%)

ddtrace.vendor.dogstatsd.context 0.785 ms (0.28%)

ddtrace.vendor.dogstatsd.context_async 0.469 ms (0.17%)

ddtrace.vendor.dogstatsd.container 0.560 ms (0.20%)

ddtrace.vendor.dogstatsd.format 0.323 ms (0.12%)

ddtrace.vendor.dogstatsd.route 0.275 ms (0.10%)

ddtrace.vendor.dogstatsd.compat 0.247 ms (0.09%)

The following import paths have disappeared:

ddtrace.auto 4.792 ms (1.73%)

ddtrace 4.792 ms (1.73%)

ddtrace.trace 4.792 ms (1.73%)

ddtrace._trace.filters 4.792 ms (1.73%)

ddtrace._trace.processor 4.792 ms (1.73%)

ddtrace.internal.dogstatsd 4.792 ms (1.73%)

ddtrace.vendor.dogstatsd 4.494 ms (1.63%)

ddtrace.vendor.dogstatsd.base 4.240 ms (1.53%)

queue 1.236 ms (0.45%)

heapq 0.564 ms (0.20%)

_heapq 0.283 ms (0.10%)

_queue 0.295 ms (0.11%)

ddtrace.vendor.dogstatsd.context 0.783 ms (0.28%)

ddtrace.vendor.dogstatsd.context_async 0.464 ms (0.17%)

ddtrace.vendor.dogstatsd.container 0.665 ms (0.24%)

ddtrace.vendor.dogstatsd.format 0.317 ms (0.11%)

ddtrace.vendor.dogstatsd.route 0.276 ms (0.10%)

ddtrace.vendor.dogstatsd.compat 0.250 ms (0.09%)

The following import paths have grown:

ddtrace.auto 0.017 ms (0.01%)

ddtrace 0.017 ms (0.01%)

ddtrace.trace 0.017 ms (0.01%)

ddtrace._trace.filters 0.017 ms (0.01%)

ddtrace._trace.processor 0.017 ms (0.01%)

ddtrace.internal.writer 0.017 ms (0.01%)

ddtrace.internal.writer.writer 0.017 ms (0.01%)

ddtrace.internal.sma 0.017 ms (0.01%)

The following import paths have shrunk:

ddtrace.auto 2.052 ms (0.74%)

ddtrace.bootstrap.sitecustomize 1.333 ms (0.48%)

ddtrace.bootstrap.preload 1.333 ms (0.48%)

ddtrace.internal.remoteconfig.client 0.654 ms (0.24%)

ddtrace.debugging._import 0.016 ms (0.01%)

ddtrace.debugging._function.discovery 0.016 ms (0.01%)

ddtrace.debugging._function 0.016 ms (0.01%)

ddtrace 0.719 ms (0.26%)

ddtrace.trace 0.046 ms (0.02%)

ddtrace._trace.filters 0.046 ms (0.02%)

ddtrace._trace.processor 0.046 ms (0.02%)

ddtrace.internal._unpatched 0.028 ms (0.01%)

json 0.028 ms (0.01%)

json.decoder 0.028 ms (0.01%)

re 0.028 ms (0.01%)

enum 0.028 ms (0.01%)

types 0.028 ms (0.01%)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-07-15 16:51:10

Comparing candidate commit a705cfc in PR branch LANGPLAT-134/abstract-writer-create with baseline commit 1250b2f in branch main.

Found 0 performance improvements and 1 performance regressions! Performance is the same for 547 metrics, 2 unstable metrics.

scenario:iastaspectsospath-ospathsplitdrive_aspect

• 🟥 execution_time [+410.324ns; +491.674ns] or [+11.179%; +13.395%]

[VianneyRuhlmann]

LGTM, this will also be helpful for the DummyWriter creation with NativeWriter