[Perf][DreamZero]dreamzero supports CUDA graph, torch.compile, and DiT Caching. (#4213)

Signed-off-by: amy-why-3459 <wuhaiyan17@huawei.com>

vllm_omni/diffusion/cache/stepcache/__init__.py

@@ -0,0 +1,66 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+"""
+StepCache: velocity-based step skipping for DreamZero-style DiT denoising.
+
+Unlike block-level Cache-DiT, this backend skips entire DiT forwards during the
+pipeline denoise loop when successive velocity predictions are highly aligned.
+
+Usage:
+    from vllm_omni import Omni
+
+    omni = Omni(
+        model="...",
+        cache_backend="step_cache",
+    )
+
+    # Alternative: environment variable
+    # export DIFFUSION_CACHE_BACKEND=step_cache
+"""
+
+from vllm_omni.diffusion.cache.stepcache.backend import (
+    CUSTOM_STEP_CACHE_DIT_ENABLERS,
+    CUSTOM_STEPCACHE_ENABLERS,
+    STEP_CACHE_CONFIG_ATTR,
+    STEP_CACHE_DIT_CONFIG_ATTR,
+    STEP_CACHE_DIT_STATE_ATTR,
+    STEP_CACHE_STATE_ATTR,
+    StepCacheBackend,
+    StepCacheDiTBackend,
+    StepCacheDiTConfig,
+    StepCacheDiTState,
+    enable_dreamzero_step_cache_dit,
+    enable_dreamzero_stepcache,
+    get_step_cache_dit_config,
+    get_step_cache_dit_state,
+    get_stepcache_config,
+    get_stepcache_state,
+    is_step_cache_dit_active,
+    is_stepcache_active,
+)
+from vllm_omni.diffusion.cache.stepcache.config import StepCacheConfig
+from vllm_omni.diffusion.cache.stepcache.state import StepCacheState
+
+__all__ = [
+    "CUSTOM_STEP_CACHE_DIT_ENABLERS",
+    "CUSTOM_STEPCACHE_ENABLERS",
+    "STEP_CACHE_CONFIG_ATTR",
+    "STEP_CACHE_DIT_CONFIG_ATTR",
+    "STEP_CACHE_DIT_STATE_ATTR",
+    "STEP_CACHE_STATE_ATTR",
+    "StepCacheBackend",
+    "StepCacheConfig",
+    "StepCacheDiTBackend",
+    "StepCacheDiTConfig",
+    "StepCacheDiTState",
+    "StepCacheState",
+    "enable_dreamzero_step_cache_dit",
+    "enable_dreamzero_stepcache",
+    "get_step_cache_dit_config",
+    "get_step_cache_dit_state",
+    "get_stepcache_config",
+    "get_stepcache_state",
+    "is_step_cache_dit_active",
+    "is_stepcache_active",
+]