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Simplify backend imports and initialization #153

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Merged
merged 1 commit into from
Sep 7, 2025
Merged

Simplify backend imports and initialization #153

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83 changes: 27 additions & 56 deletions flash_dmattn/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2,72 +2,33 @@

from typing import Optional

__version__ = "1.0.0"
__version__ = "1.0.3"


# Import CUDA functions when available
try:
from flash_dmattn.flash_dmattn_interface import flash_dmattn_func
CUDA_AVAILABLE = True
except ImportError:
CUDA_AVAILABLE = False
flash_dmattn_func = None

# Import Triton functions when available
try:
from .flash_dmattn_triton import triton_dmattn_func
from flash_dmattn.flash_dmattn_triton import triton_dmattn_func
TRITON_AVAILABLE = True
except ImportError:
TRITON_AVAILABLE = False
triton_dmattn_func = None

# Import Flex functions when available
try:
from .flash_dmattn_flex import flex_dmattn_func
from flash_dmattn.flash_dmattn_flex import flex_dmattn_func
FLEX_AVAILABLE = True
except ImportError:
FLEX_AVAILABLE = False
flex_dmattn_func = None

# Check if CUDA extension is available
try:
import flash_dmattn_cuda # type: ignore[import]
CUDA_AVAILABLE = True
except ImportError:
CUDA_AVAILABLE = False

# Import CUDA functions when available
if CUDA_AVAILABLE:
try:
from .flash_dmattn_interface import (
flash_dmattn_func,
flash_dmattn_kvpacked_func,
flash_dmattn_qkvpacked_func,
flash_dmattn_varlen_func,
flash_dmattn_varlen_kvpacked_func,
flash_dmattn_varlen_qkvpacked_func,
)
except ImportError:
# Fallback if interface module is not available
flash_dmattn_func = None
flash_dmattn_kvpacked_func = None
flash_dmattn_qkvpacked_func = None
flash_dmattn_varlen_func = None
flash_dmattn_varlen_kvpacked_func = None
flash_dmattn_varlen_qkvpacked_func = None
else:
flash_dmattn_func = None
flash_dmattn_kvpacked_func = None
flash_dmattn_qkvpacked_func = None
flash_dmattn_varlen_func = None
flash_dmattn_varlen_kvpacked_func = None
flash_dmattn_varlen_qkvpacked_func = None

__all__ = [
"triton_dmattn_func",
"flex_dmattn_func",
"flash_dmattn_func",
"flash_dmattn_kvpacked_func",
"flash_dmattn_qkvpacked_func",
"flash_dmattn_varlen_func",
"flash_dmattn_varlen_kvpacked_func",
"flash_dmattn_varlen_qkvpacked_func",
"flash_dmattn_func_auto",
"get_available_backends",
"TRITON_AVAILABLE",
"FLEX_AVAILABLE",
"CUDA_AVAILABLE",
]


def get_available_backends():
"""Return a list of available backends."""
Expand All @@ -87,7 +48,7 @@ def flash_dmattn_func_auto(backend: Optional[str] = None, **kwargs):

Args:
backend (str, optional): Backend to use ('cuda', 'triton', 'flex').
If None, will use the first available backend in order: cuda, triton, flex.
If None, will use the first available backend in order: cuda, triton, flex.
**kwargs: Arguments to pass to the attention function.

Returns:
Expand All @@ -107,8 +68,6 @@ def flash_dmattn_func_auto(backend: Optional[str] = None, **kwargs):
if backend == "cuda":
if not CUDA_AVAILABLE:
raise RuntimeError("CUDA backend is not available. Please build the CUDA extension.")
if flash_dmattn_func is None:
raise RuntimeError("CUDA flash_dmattn_func is not available. Please check the installation.")
return flash_dmattn_func

elif backend == "triton":
Expand All @@ -123,3 +82,15 @@ def flash_dmattn_func_auto(backend: Optional[str] = None, **kwargs):

else:
raise ValueError(f"Unknown backend: {backend}. Available backends: {get_available_backends()}")


__all__ = [
"CUDA_AVAILABLE",
"TRITON_AVAILABLE",
"FLEX_AVAILABLE",
"flash_dmattn_func",
"triton_dmattn_func",
"flex_dmattn_func",
"get_available_backends",
"flash_dmattn_func_auto",
]