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vllm-omni/tests/diffusion/ar_diffusion/test_pipeline_bridge.py
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# SPDX-License-Identifier: Apache-2.0
"""Tests for the ARDiffusionKVState paged-attention pipeline bridge."""
import pytest
import torch
from vllm_omni.experimental.ar_diffusion.capability import ARDiffusionKVBranchSpec
from vllm_omni.experimental.ar_diffusion.kv_cache import (
ARDiffusionKVCache,
ARDiffusionKVConfig,
ARDiffusionPagedLayerContext,
)
from vllm_omni.experimental.ar_diffusion.kv_cache.state import ARDiffusionKVState
pytestmark = [pytest.mark.core_model, pytest.mark.diffusion, pytest.mark.cpu]
BLOCK = 16
N_HEADS = 4
HEAD_DIM = 64
POS = "positive"
NEG = "negative"
def make_state(num_layers=1, window_chunks=4, cross_attn_length=0, shared_local_index=False):
cfg = ARDiffusionKVConfig(enable=True, chunk_size=BLOCK, window_chunks=window_chunks)
kv = ARDiffusionKVCache(
cfg,
num_layers=num_layers,
num_kv_heads=N_HEADS,
head_size=HEAD_DIM,
dtype=torch.float32,
block_size=BLOCK,
max_model_len=4096,
available_bytes=1 << 24,
kv_branches=(
ARDiffusionKVBranchSpec(POS, 0),
ARDiffusionKVBranchSpec(NEG, 0 if shared_local_index else 1),
),
session_capacity=2,
cross_attention_lengths={"text": cross_attn_length} if cross_attn_length else None,
device=torch.device("cpu"),
)
pos = kv.begin_request("r-pos")
neg = kv.begin_request("r-neg")
return kv, ARDiffusionKVState(kv, "s1", {POS: pos, NEG: neg}, num_layers=num_layers)
def _prepare_and_commit(st: ARDiffusionKVState, kv_branch: str, n_chunks: int) -> None:
ctx = st.get_kv_caches(kv_branch, seq_len=n_chunks * BLOCK, commit_current=True)[0].forward_ctx
ctx.ensure_video_slots(torch.device("cpu"))
st.commit_paged_context(kv_branch)
def test_get_returns_paged_layer_contexts_when_nothing_committed():
_, st = make_state(num_layers=2)
for kv_branch in (POS, NEG):
contexts = st.get_kv_caches(kv_branch, seq_len=BLOCK, commit_current=False)
assert len(contexts) == 2
assert all(isinstance(ctx, ARDiffusionPagedLayerContext) for ctx in contexts)
assert contexts[0].history_block_ids == []
def test_managed_paged_context_commits_only_after_forward():
kv, st = make_state(num_layers=1)
contexts = st.get_kv_caches(POS, seq_len=2 * BLOCK, commit_current=True)
ctx = contexts[0].forward_ctx
assert st.adapter(POS).completed_chunks == 0
assert kv.window_block_ids(st.adapter(POS)) == []
ctx.ensure_video_slots(torch.device("cpu"))
assert st.adapter(POS).completed_chunks == 0
assert len(ctx.current_video_block_ids) == 2
st.commit_paged_context(POS)
assert st.adapter(POS).completed_chunks == 2
assert st._committed[POS] == 2 * BLOCK
assert len(kv.window_block_ids(st.adapter(POS))) == 2
def test_scratch_paged_context_does_not_commit():
kv, st = make_state(num_layers=1)
contexts = st.get_kv_caches(POS, seq_len=BLOCK, commit_current=False)
ctx = contexts[0].forward_ctx
ctx.ensure_video_slots(torch.device("cpu"))
assert ctx.current_video_block_ids == kv.scratch_block_ids(POS, 0, 1)
st.commit_paged_context(POS)
assert st.adapter(POS).completed_chunks == 0
assert st._committed[POS] == 0
assert kv.window_block_ids(st.adapter(POS)) == []
def test_eviction_bounds_resident_window():
kv, st = make_state(num_layers=1, window_chunks=3)
_prepare_and_commit(st, POS, 3)
assert len(kv.window_block_ids(st.adapter(POS))) == 3
_prepare_and_commit(st, POS, 2)
ctx = st.get_kv_caches(POS, seq_len=BLOCK, commit_current=False)[0].forward_ctx
visible_blocks, video_len = ctx.video_block_table(torch.device("cpu"))
assert len(visible_blocks) == 3
assert video_len == 3 * BLOCK
def test_branches_are_independent():
kv, st = make_state()
_prepare_and_commit(st, POS, 1)
assert len(kv.window_block_ids(st.adapter(POS))) == 1
assert kv.window_block_ids(st.adapter(NEG)) == []
def test_reset_clears_session_window():
kv, st = make_state(num_layers=1, window_chunks=4)
_prepare_and_commit(st, POS, 2)
_prepare_and_commit(st, NEG, 1)
assert st._committed[POS] == 2 * BLOCK and st._committed[NEG] == BLOCK
free_before = kv.manager.block_pool.get_num_free_blocks()
st.reset()
assert st._committed == {POS: 0, NEG: 0}
assert st._paged_pending == {POS: None, NEG: None}
assert kv.window_block_ids(st.adapter(POS)) == []
assert kv.window_block_ids(st.adapter(NEG)) == []
assert kv.manager.block_pool.get_num_free_blocks() > free_before
_prepare_and_commit(st, POS, 1)
assert len(kv.window_block_ids(st.adapter(POS))) == 1
def test_get_cross_attention_kv_raises_before_populate():
_, st = make_state(cross_attn_length=8)
for kv_branch in (POS, NEG):
with pytest.raises(RuntimeError, match="before it was populated"):
st.get_cross_attention_kv(kv_branch, "text")
def test_get_cross_attention_kv_returns_session_pool_dicts_when_populated():
L = 8
kv, st = make_state(num_layers=2, cross_attn_length=L)
written = []
for _ in range(2):
k = torch.randn(1, L, N_HEADS, HEAD_DIM)
v = torch.randn(1, L, N_HEADS, HEAD_DIM)
written.append((k, v))
st.populate_cross_attention(POS, "text", written)
out = st.get_cross_attention_kv(POS, "text")
assert len(out) == 2
for i, (k, v) in enumerate(written):
assert out[i]["is_init"] is True
assert out[i]["k"].shape == (1, L, N_HEADS, HEAD_DIM)
assert torch.equal(out[i]["k"], k)
assert torch.equal(out[i]["v"], v)
def test_window_reset_can_keep_named_cross_attention_cache():
kv, st = make_state(num_layers=1, cross_attn_length=8)
k = torch.randn(1, 8, N_HEADS, HEAD_DIM)
v = torch.randn(1, 8, N_HEADS, HEAD_DIM)
st.populate_cross_attention(POS, "text", [(k, v)])
old_adapter = st.adapter(POS)
st.reset(keep_cross_attention=("text",))
assert st.adapter(POS) is not old_adapter
assert torch.equal(st.get_cross_attention_kv(POS, "text")[0]["k"], k)
assert "s1" in kv._cross_sessions
st.reset()
assert "s1" not in kv._cross_sessions
assert not st.is_cross_attention_populated(POS, "text")
def test_cross_attention_uses_logical_branch_when_local_slot_is_shared():
_, st = make_state(num_layers=2, cross_attn_length=8, shared_local_index=True)
assert st.kv_cache.num_local_kv_branches == 1
pos_layers = [
(torch.full((1, 8, N_HEADS, HEAD_DIM), 1.0), torch.full((1, 8, N_HEADS, HEAD_DIM), 2.0)) for _ in range(2)
]
neg_layers = [
(torch.full((1, 8, N_HEADS, HEAD_DIM), 3.0), torch.full((1, 8, N_HEADS, HEAD_DIM), 4.0)) for _ in range(2)
]
st.populate_cross_attention(POS, "text", pos_layers)
st.populate_cross_attention(NEG, "text", neg_layers)
for layer in st.get_cross_attention_kv(POS, "text"):
assert torch.count_nonzero(layer["k"] != 1.0) == 0
assert torch.count_nonzero(layer["v"] != 2.0) == 0
for layer in st.get_cross_attention_kv(NEG, "text"):
assert torch.count_nonzero(layer["k"] != 3.0) == 0
assert torch.count_nonzero(layer["v"] != 4.0) == 0
def test_cross_attention_population_is_transactional():
kv, st = make_state(num_layers=2, cross_attn_length=8)
original = [
(torch.full((1, 8, N_HEADS, HEAD_DIM), value), torch.full((1, 8, N_HEADS, HEAD_DIM), -value))
for value in (1.0, 2.0)
]
replacement = (
torch.full((1, 8, N_HEADS, HEAD_DIM), 9.0),
torch.full((1, 8, N_HEADS, HEAD_DIM), -9.0),
)
def interrupted_population():
yield replacement
raise RuntimeError("projection failed")
with pytest.raises(RuntimeError, match="projection failed"):
st.populate_cross_attention(POS, "text", interrupted_population())
assert not st.is_cross_attention_populated(POS, "text")
assert "s1" not in kv._cross_sessions
st.populate_cross_attention(POS, "text", original)
with pytest.raises(RuntimeError, match="projection failed"):
st.populate_cross_attention(POS, "text", interrupted_population())
out = st.get_cross_attention_kv(POS, "text")
for layer_index, layer in enumerate(out):
assert torch.equal(layer["k"], original[layer_index][0])
assert torch.equal(layer["v"], original[layer_index][1])
for invalid_layers in (original[:1], [*original, replacement]):
with pytest.raises(ValueError, match="expected 2 layers"):
st.populate_cross_attention(POS, "text", invalid_layers)
out = st.get_cross_attention_kv(POS, "text")
for layer_index, layer in enumerate(out):
assert torch.equal(layer["k"], original[layer_index][0])
assert torch.equal(layer["v"], original[layer_index][1])
invalid_shape = (torch.empty(1, 7, N_HEADS, HEAD_DIM), original[0][1])
with pytest.raises(ValueError, match="expected k/v shape"):
st.populate_cross_attention(POS, "text", [invalid_shape, original[1]])
out = st.get_cross_attention_kv(POS, "text")
assert torch.equal(out[0]["k"], original[0][0])
def test_closed_state_cannot_repopulate_cross_attention():
kv, st = make_state(num_layers=1, cross_attn_length=8)
layer = (torch.ones(1, 8, N_HEADS, HEAD_DIM), torch.ones(1, 8, N_HEADS, HEAD_DIM))
st.close()
with pytest.raises(RuntimeError, match="is closed"):
st.populate_cross_attention(POS, "text", [layer])
assert "s1" not in kv._cross_sessions
def test_kv_create_is_noop_engine_owns_allocation():
from unittest.mock import MagicMock
from vllm_omni.diffusion.models.dreamzero.pipeline_dreamzero import DreamZeroPipeline
p = DreamZeroPipeline.__new__(DreamZeroPipeline)
p._ar_diffusion_kv_state = object()
state = MagicMock()
p._kv_create(state, 1, "float32", "cpu", 24, 4, 64)
state.create_kv_caches.assert_not_called()
def test_get_kv_cache_requires_frame_aligned_seqlen():
_, st = make_state()
with pytest.raises(AssertionError, match="frame-aligned"):
st.get_kv_caches(POS, seq_len=BLOCK + 1, commit_current=True)
def test_prepare_one_branch_allocates_nothing_for_the_other():
"""CFG-parallel laziness: a rank prepares only the kv_branch it runs."""
kv, st = make_state(num_layers=1, window_chunks=4)
pos_ctx = st.get_kv_caches(POS, seq_len=BLOCK, commit_current=True)[0].forward_ctx
neg_ctx = st.get_kv_caches(NEG, seq_len=BLOCK, commit_current=True)[0].forward_ctx
pos_ctx.prepare(device=torch.device("cpu"), action_len=0, query_len=BLOCK)
assert pos_ctx._allocated_video
assert not neg_ctx._allocated_video
assert kv.window_block_ids(st.adapter(NEG)) == []