WIP: Stream DAG

[edgarrmondragon]

Summary by Sourcery

Update the RESTStream backoff_runtime signature and introduce comprehensive Stream DAG functionality for orchestrating complex inter-stream dependencies.

New Features:

• Update RESTStream.backoff_runtime type annotation to support both int and float backoff values
• Introduce StreamDAG engine with StreamDependency, SyncTrigger, and relation types for DAG-driven stream orchestration
• Integrate DAG support into Stream and Tap classes with per-record processing and finalization hooks

Enhancements:

• Add helper module with common DAG pattern builders (dag_examples.py)

Documentation:

• Add Stream DAG user guide (docs/stream_dag.md) detailing core concepts, usage patterns, and API

Tests:

• Add extensive tests for StreamDAG covering dependency management, cycle detection, sync triggers, and Tap integration

[sourcery-ai]

Reviewer's Guide

Integrates a StreamDAG system into the core SDK to orchestrate complex inter-stream dependencies, extends Tap to configure and expose the DAG, updates a RESTStream type annotation for numeric backoff, and adds comprehensive tests, examples, helper patterns, and documentation for the new DAG API.

File-Level Changes

Change	Details	Files
Integrate StreamDAG into base Stream class	Imported StreamDAG and added _dag field Hooked into _sync_records to call _process_record_with_dag Called _finalize_with_dag at end of sync Implemented set_dag, _process_record_with_dag, and _finalize_with_dag methods	singer_sdk/streams/core.py
Add DAG setup and accessors in Tap class	Introduced _dag field in Tap Defined setup_dag to initialize StreamDAG, register streams, and inject into each stream Added dag property to retrieve the DAG instance	singer_sdk/tap_base.py
Generalize backoff_runtime to support any numeric type	Changed _TNum type variable to int	float Updated backoff_runtime signature to return Generator[_TNum, None, None]
Add comprehensive StreamDAG tests	Created MockStream/MockTap test fixtures Covered adding streams, dependencies, cycles, topological sort Tested all SyncTrigger behaviors and multi-parent scenarios	tests/core/test_stream_dag.py
Provide a full usage example with DAG patterns	Added an example tap demonstrating multiple DAG patterns Included sample Stream classes, setup_dag implementations, and main runner	examples/dag_usage_example.py
Supply helper functions for common DAG relationships	Added create_one_to_one, one_to_many, many_to_one, many_to_many, conditional dependency generators Packaged higher-level DAGPatterns for fan-in/fan-out hierarchies	singer_sdk/helpers/dag_examples.py
Document StreamDAG functionality and patterns	Created docs/stream_dag.md with overview, API reference, examples Outlined SyncTrigger and relation types, usage, best practices	docs/stream_dag.md

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[read-the-docs-community]

Documentation build overview

📚 Meltano SDK | 🛠️ Build #29427370 | 📁 Comparing 7cb1fe5 against latest (f8b69b5)

🔍 Preview build

Show files changed (5 files in total): 📝 4 modified | ➕ 1 added | ➖ 0 deleted

File	Status
genindex.html	📝 modified
stream_dag.html	➕ added
classes/singer_sdk.SQLTap.html	📝 modified
classes/singer_sdk.Stream.html	📝 modified
classes/singer_sdk.Tap.html	📝 modified

[codecov]

Codecov Report

❌ Patch coverage is 54.92424% with 119 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.18%. Comparing base (f8b69b5) to head (7cb1fe5).
⚠️ Report is 374 commits behind head on main.

Files with missing lines	Patch %	Lines
singer_sdk/helpers/dag_examples.py	0.00%	82 Missing ⚠️
singer_sdk/helpers/stream_dag.py	77.35%	23 Missing and 13 partials ⚠️
singer_sdk/tap_base.py	91.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3259      +/-   ##
==========================================
- Coverage   92.93%   91.18%   -1.76%     
==========================================
  Files          63       65       +2     
  Lines        5453     5717     +264     
  Branches      682      728      +46     
==========================================
+ Hits         5068     5213     +145     
- Misses        280      385     +105     
- Partials      105      119      +14     

Flag	Coverage Δ
core	78.10% <54.92%> (-1.09%)	⬇️
end-to-end	74.91% <23.10%> (-2.51%)	⬇️
optional-components	42.18% <21.59%> (-1.00%)	⬇️

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[codspeed-hq]

CodSpeed Performance Report

Merging #3259 will not alter performance

_{Comparing feat/sdk-stream-dag (7cb1fe5) with main (b8e0d5b)¹}

Summary

✅ 8 untouched benchmarks

Footnotes

1. No successful run was found on main (f8b69b5) during the generation of this report, so b8e0d5b was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩