unsloth/studio/backend/tests/test_diffusion_cache.py
Daniel Han 1d289aab61 Studio diffusion (Phase 12): only engage FBCache on context-aware transformers; quantized threshold for GGUF
- apply_step_cache now engages only via the transformer's native enable_cache (the diffusers
  CacheMixin path), which exists exactly when the pipeline wraps the transformer call in a
  cache_context. The standalone apply_first_block_cache fallback installed on non-CacheMixin
  transformers too (e.g. Z-Image), whose pipeline opens no cache_context, so the load reported
  transformer_cache=fbcache and then the first generation crashed inside the hook. Such a model
  now runs uncached per the best-effort contract.
- GGUF transformers are quantized (the default Studio load path), so they now use the higher
  quantized FBCache threshold when the caller leaves it unset, instead of the dense default
  that could keep the cache from triggering.
- fbcache_flux_probe.py: compile cached runs with fullgraph=False (FBCache is a graph break, so
  fullgraph=True failed warmup and silently measured an eager cached run); output dir is now
  relative to the script, not a hardcoded path.
2026-06-28 06:02:12 +00:00

149 lines
5.4 KiB
Python

# SPDX-License-Identifier: AGPL-3.0-only
# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
"""Hermetic CPU tests for opt-in step caching (First-Block-Cache).
``diffusers`` is stubbed via ``sys.modules`` (the module under test imports
``FirstBlockCacheConfig`` lazily), and the pipeline is a fake that records the engaged config.
So normalisation, the CacheMixin (``enable_cache``) gating, threshold selection, and the
best-effort failure handling are all exercised without torch or a real diffusers model.
"""
from __future__ import annotations
import sys
import types
import pytest
from core.inference.diffusion_cache import (
DEFAULT_FBCACHE_THRESHOLD,
QUANT_FBCACHE_THRESHOLD,
TC_FBCACHE,
apply_step_cache,
normalize_transformer_cache,
)
# ── normalize_transformer_cache ────────────────────────────────────────────────────
def test_normalize_disabled_values_are_none():
for value in (None, "", " ", "none", "off", "OFF", "None"):
assert normalize_transformer_cache(value) is None
def test_normalize_fbcache_and_casing():
assert normalize_transformer_cache("fbcache") == TC_FBCACHE
assert normalize_transformer_cache("FBCache") == TC_FBCACHE
assert normalize_transformer_cache(" fbcache ") == TC_FBCACHE
def test_normalize_rejects_unknown():
with pytest.raises(ValueError):
normalize_transformer_cache("deepcache")
# ── apply_step_cache ───────────────────────────────────────────────────────────────
class _Config:
def __init__(self, threshold):
self.threshold = threshold
class _MixinTransformer:
"""A CacheMixin-style transformer: exposes ``enable_cache``."""
def __init__(self, *, fail = False):
self.fail = fail
self.enabled_with = None
def enable_cache(self, config):
if self.fail:
raise RuntimeError("block signature not recognised")
self.enabled_with = config
class _NonCacheMixinTransformer:
"""A transformer with no ``enable_cache`` (not a CacheMixin) -> must run uncached.
Its pipeline opens no ``cache_context``, so installing FBCache would crash at generation;
the load runs uncached instead (e.g. Z-Image)."""
def _pipe(transformer):
return types.SimpleNamespace(transformer = transformer)
def _stub_diffusers(monkeypatch, *, hook_recorder = None):
diffusers = types.ModuleType("diffusers")
diffusers.FirstBlockCacheConfig = _Config
monkeypatch.setitem(sys.modules, "diffusers", diffusers)
hooks = types.ModuleType("diffusers.hooks")
def _apply_first_block_cache(transformer, config):
if hook_recorder is not None:
hook_recorder["transformer"] = transformer
hook_recorder["config"] = config
hooks.apply_first_block_cache = _apply_first_block_cache
monkeypatch.setitem(sys.modules, "diffusers.hooks", hooks)
def test_disabled_mode_is_noop(monkeypatch):
_stub_diffusers(monkeypatch)
t = _MixinTransformer()
assert apply_step_cache(_pipe(t), mode = None) is None
assert apply_step_cache(_pipe(t), mode = "off") is None
assert t.enabled_with is None
def test_enable_cache_path_default_threshold(monkeypatch):
_stub_diffusers(monkeypatch)
t = _MixinTransformer()
engaged = apply_step_cache(_pipe(t), mode = "fbcache")
assert engaged == TC_FBCACHE
assert t.enabled_with.threshold == DEFAULT_FBCACHE_THRESHOLD
assert t._unsloth_step_cache == f"fbcache@{DEFAULT_FBCACHE_THRESHOLD}"
def test_quant_active_raises_default_threshold(monkeypatch):
_stub_diffusers(monkeypatch)
t = _MixinTransformer()
apply_step_cache(_pipe(t), mode = "fbcache", quant_active = True)
assert t.enabled_with.threshold == QUANT_FBCACHE_THRESHOLD
def test_explicit_threshold_overrides_quant(monkeypatch):
_stub_diffusers(monkeypatch)
t = _MixinTransformer()
apply_step_cache(_pipe(t), mode = "fbcache", threshold = 0.2, quant_active = True)
assert t.enabled_with.threshold == 0.2
def test_non_cachemixin_runs_uncached(monkeypatch):
# A transformer without enable_cache (e.g. Z-Image) must NOT install the standalone hook
# -- its pipeline opens no cache_context, so it runs uncached instead of crashing at gen.
rec: dict = {}
_stub_diffusers(monkeypatch, hook_recorder = rec)
t = _NonCacheMixinTransformer()
assert apply_step_cache(_pipe(t), mode = "fbcache") is None
assert rec == {} # the standalone hook was never called
def test_incompatible_model_runs_uncached(monkeypatch):
# enable_cache raising (e.g. unrecognised block signature) must not fail the load.
_stub_diffusers(monkeypatch)
t = _MixinTransformer(fail = True)
assert apply_step_cache(_pipe(t), mode = "fbcache") is None
def test_missing_transformer_is_none(monkeypatch):
_stub_diffusers(monkeypatch)
pipe = types.SimpleNamespace(transformer = None)
assert apply_step_cache(pipe, mode = "fbcache") is None
def test_diffusers_unavailable_runs_uncached(monkeypatch):
# no diffusers import -> best-effort returns None, load proceeds uncached.
monkeypatch.setitem(sys.modules, "diffusers", None)
t = _MixinTransformer()
assert apply_step_cache(_pipe(t), mode = "fbcache") is None