refactor: simplify inference engine and backend dispatch

- merge _generate_streaming/_generate_non_streaming into single _generate() with stream flag
- delete dead GenerationRequest class and generate_with_request method
- inline _next_token helper into generate_async
- replace flash-attn double-checked locking with functools.lru_cache
- extract _write_and_gather_kv helper shared by TorchNative/FlashAttn backends
- inline _kv_cache_is_contiguous into its sole call site in FlashAttnBackend
- change default backend priority from flash>cuda>torch to cuda>flash>torch
- add ASTR_BACKEND env var to override default backend at resolve time
- add supports_graph() static method to AttentionBackend ABC, override in CudaBackend
- replace isinstance(get_backend(), CudaBackend) with get_backend().supports_graph() in executor
- add torch.cuda.is_available() guard to CudaBackend.supports()
This commit is contained in:
2026-08-07 22:28:48 +08:00
parent 05739629fc
commit 02469887f5
7 changed files with 119 additions and 299 deletions
+36 -155
View File
@@ -64,44 +64,6 @@ class GenerateResult:
return self.results.copy()
class GenerationRequest:
"""Request parameters for text generation."""
def __init__(
self,
messages: List[Dict[str, str]],
top_k: int = 50,
top_p: float = 1.0,
temperature: float = 1.0,
max_tokens: Optional[int] = None,
frequency_penalty: float = 0.0,
rep_window: int = 64,
stream: bool = False,
):
if not (isinstance(top_k, int) and top_k >= 0):
raise ValueError("top_k must be a non-negative integer")
if not (0.0 <= top_p <= 1.0):
raise ValueError("top_p must be a float between 0.0 and 1.0")
if not (isinstance(temperature, (int, float)) and temperature >= 0):
raise ValueError("temperature must be a non-negative number")
if not (
isinstance(frequency_penalty, (int, float))
and -2.0 <= frequency_penalty <= 2.0
):
raise ValueError("frequency_penalty must be between -2.0 and 2.0")
if not (isinstance(rep_window, int) and rep_window > 0):
raise ValueError("rep_window must be a positive integer")
self.messages = messages
self.top_k = top_k
self.top_p = top_p
self.temperature = temperature
self.max_tokens = max_tokens
self.frequency_penalty = frequency_penalty
self.rep_window = rep_window
self.stream = stream
class InferenceEngine:
"""Unified inference engine backed by continuous-batching scheduler."""
@@ -152,28 +114,17 @@ class InferenceEngine:
results = [""] * len(prompts)
return results if is_batch else results[0]
if stream:
return self._generate_streaming(
prompts,
is_batch,
max_tokens,
temperature,
top_p,
top_k,
frequency_penalty,
rep_window,
)
else:
return self._generate_non_streaming(
prompts,
is_batch,
max_tokens,
temperature,
top_p,
top_k,
frequency_penalty,
rep_window,
)
return self._generate(
prompts,
is_batch,
stream,
max_tokens,
temperature,
top_p,
top_k,
frequency_penalty,
rep_window,
)
def generate_async(
self,
@@ -185,9 +136,10 @@ class InferenceEngine:
frequency_penalty: float = 0.0,
rep_window: int = 64,
) -> AsyncGenerator[str, None]:
sync_gen = self._generate_streaming(
sync_gen = self._generate(
[prompt],
False,
True,
max_tokens,
temperature,
top_p,
@@ -199,51 +151,30 @@ class InferenceEngine:
async def _agen():
loop = asyncio.get_event_loop()
while True:
token = await loop.run_in_executor(None, self._next_token, sync_gen)
if token is None:
try:
token = await loop.run_in_executor(None, next, sync_gen)
except StopIteration:
break
yield token
return _agen()
@staticmethod
def _next_token(gen: Generator) -> Optional[str]:
try:
return next(gen)
except StopIteration:
return None
def generate_with_request(
self, request: GenerationRequest
) -> Union[Generator[str, None, None], str, List[str]]:
prompt = self.tokenizer.apply_chat_template(request.messages, tokenize=False)
return self.generate(
prompt=prompt,
stream=request.stream,
max_tokens=request.max_tokens,
temperature=request.temperature,
top_p=request.top_p,
top_k=request.top_k,
frequency_penalty=request.frequency_penalty,
rep_window=request.rep_window,
)
def _submit_tasks(
def _generate(
self,
prompts: List[str],
is_batch: bool,
stream: bool,
max_tokens: Optional[int],
temperature: float,
top_p: float,
top_k: int,
frequency_penalty: float,
rep_window: int,
) -> Tuple[GenerateResult, List[str]]:
) -> Union[Generator, str, List[str]]:
n = len(prompts)
result = GenerateResult(count=n)
task_ids = []
for i, p in enumerate(prompts):
cb = self._make_callback(result, i)
task_id = self.scheduler.add_task(
task_ids = [
self.scheduler.add_task(
prompt=p,
max_tokens=max_tokens,
temperature=temperature,
@@ -251,39 +182,23 @@ class InferenceEngine:
top_k=top_k,
frequency_penalty=frequency_penalty,
rep_window=rep_window,
stream_callback=cb,
stream_callback=lambda token, idx=i: result.append(token, idx),
)
task_ids.append(task_id)
return result, task_ids
for i, p in enumerate(prompts)
]
@staticmethod
def _make_callback(result: GenerateResult, idx: int):
def cb(token):
result.append(token, idx)
if not stream:
try:
result.wait_completion()
except TimeoutError:
for tid in task_ids:
self.scheduler.remove_task(tid)
raise
for tid in task_ids:
self.scheduler.remove_task(tid)
res = result.get_results()
return res if is_batch else res[0]
return cb
def _generate_streaming(
self,
prompts: List[str],
is_batch: bool,
max_tokens: Optional[int],
temperature: float,
top_p: float,
top_k: int,
frequency_penalty: float,
rep_window: int,
) -> Generator:
result, task_ids = self._submit_tasks(
prompts,
max_tokens,
temperature,
top_p,
top_k,
frequency_penalty,
rep_window,
)
n = len(prompts)
remaining = n
finished = [False] * n
@@ -307,40 +222,6 @@ class InferenceEngine:
return gen()
def _generate_non_streaming(
self,
prompts: List[str],
is_batch: bool,
max_tokens: Optional[int],
temperature: float,
top_p: float,
top_k: int,
frequency_penalty: float,
rep_window: int,
) -> Union[str, List[str]]:
result, task_ids = self._submit_tasks(
prompts,
max_tokens,
temperature,
top_p,
top_k,
frequency_penalty,
rep_window,
)
try:
result.wait_completion()
except TimeoutError:
for tid in task_ids:
self.scheduler.remove_task(tid)
raise
for tid in task_ids:
self.scheduler.remove_task(tid)
res = result.get_results()
return res if is_batch else res[0]
def get_stats(self) -> Dict[str, Any]:
return self.scheduler.get_stats()