[BUG]: AsyncGenerators are not wrapped correctly by tracer.wrap()

[pfaion]

Tracer Version(s)

3.12.2

Python Version(s)

3.13.5

Pip Version(s)

Using "uv" as package manager, version 0.7.13

Bug Report

Thank you for maintaining datadog and it's Python SDK, I am generally very happy with the tooling!

However, I noticed the SDK does not correctly wrap async "generators" (!). It only handles iterators correctly. A generator is a generalization of an iterator that can also receive values, not only yield them.

See the following code:

import asyncio
from collections.abc import AsyncGenerator
from ddtrace.trace import tracer

# @tracer.wrap()
async def accumulator() -> AsyncGenerator[int, int]:
    total = 0
    while True:
        incoming = yield total
        total += incoming

async def main() -> None:
    acc = accumulator()
    await anext(acc)  # Start the generator

    for i in range(5):
        print(f"Current value: {await acc.asend(i)}")

asyncio.run(main())

If you run this as-is, it will sum up the values from range(5):

Current value: 0
Current value: 1
Current value: 3
Current value: 6
Current value: 10

However, if you uncomment the @tracer.wrap() decorator, it will crash with:

Traceback (most recent call last):
  File "/redacted/tmp.py", line 23, in <module>
    asyncio.run(main())
    ~~~~~~~~~~~^^^^^^^^
  File "~/.local/share/uv/python/cpython-3.13.5-macos-aarch64-none/lib/python3.13/asyncio/runners.py", line 195, in run
    return runner.run(main)
           ~~~~~~~~~~^^^^^^
  File "~/.local/share/uv/python/cpython-3.13.5-macos-aarch64-none/lib/python3.13/asyncio/runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "~/.local/share/uv/python/cpython-3.13.5-macos-aarch64-none/lib/python3.13/asyncio/base_events.py", line 725, in run_until_complete
    return future.result()
           ~~~~~~~~~~~~~^^
  File "/redacted/tmp.py", line 20, in main
    print(f"Current value: {await acc.asend(i)}")
                            ^^^^^^^^^^^^^^^^^^
  File "/redacted/.venv/lib/python3.13/site-packages/ddtrace/_trace/tracer.py", line 793, in func_wrapper
    async for value in f(*args, **kwargs):
        yield value
  File "/redacted/tmp.py", line 12, in accumulator
    total += incoming
TypeError: unsupported operand type(s) for +=: 'int' and 'NoneType'

Looking at the implementation, I saw that you only process iterators correctly (that don't receive values from the outside), but not generic generators:

dd-trace-py/ddtrace/_trace/tracer.py

Lines 732 to 748 in 77dc3ae

	def _wrap_generator_async(
	self,
	f: AnyCallable,
	span_name: str,
	service: Optional[str] = None,
	resource: Optional[str] = None,
	span_type: Optional[str] = None,
	) -> AnyCallable:
	"""Wrap a generator function with tracing."""
	@functools.wraps(f)
	async def func_wrapper(*args, **kwargs):
	with self.trace(span_name, service=service, resource=resource, span_type=span_type):
	async for value in f(*args, **kwargs):
	yield value
	return cast(AnyCallable, func_wrapper)

Reproduction Code

No response

Error Logs

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Libraries in Use

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Operating System

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