[Bugfix] Fix size calculation of processing cache (#15114)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

tests/multimodal/test_processing.py

@@ -7,15 +7,20 @@ from unittest.mock import MagicMock
 
 import numpy as np
 import pytest
+import torch
 from transformers import ProcessorMixin
 
 from vllm.config import ModelConfig
 from vllm.multimodal import MULTIMODAL_REGISTRY
+from vllm.multimodal.inputs import (MultiModalFieldElem, MultiModalKwargs,
+                                    MultiModalKwargsItem,
+                                    MultiModalSharedField)
 # yapf conflicts with isort for this block
 # yapf: disable
 from vllm.multimodal.processing import (PlaceholderFeaturesInfo,
-                                        PromptIndexTargets, PromptInsertion,
-                                        PromptReplacement, apply_text_matches,
+                                        ProcessingCache, PromptIndexTargets,
+                                        PromptInsertion, PromptReplacement,
+                                        apply_text_matches,
                                         apply_token_matches,
                                         find_mm_placeholders,
                                         find_text_matches, find_token_matches,
@@ -890,6 +895,45 @@ def test_find_mm_placeholders(
     assert result == expected
 
 
+def _dummy_elem(modality: str, key: str, size: int):
+    return MultiModalFieldElem(
+        modality=modality,
+        key=key,
+        data=torch.empty((size, ), dtype=torch.int8),
+        field=MultiModalSharedField(1),
+    )
+
+
+def _dummy_item(modality: str, size_by_key: dict[str, int]):
+    return MultiModalKwargsItem.from_elems([
+        _dummy_elem(modality, key, size) for key, size in size_by_key.items()
+    ])
+
+
+def _dummy_kw(size_by_key_modality: dict[str, dict[str, int]]):
+    return MultiModalKwargs.from_items([
+        _dummy_item(modality, size_by_key)
+        for modality, size_by_key in size_by_key_modality.items()
+    ])
+
+
+# yapf: disable
+@pytest.mark.parametrize(
+    ("item", "expected_size"),
+    [
+        (_dummy_item("a", {"a1": 100}), 100),
+        (_dummy_item("a", {"a1": 100, "a2": 110}), 210),
+        (_dummy_kw({"a": {"a1": 100, "a2": 110}, "b": {"b1": 120, "b2": 130}}), 460),  # noqa: E501
+    ],
+)
+# yapf: enable
+def test_cache_item_size(item, expected_size):
+    cache = ProcessingCache.get_lru_cache(2048, type(item))
+    cache[""] = item
+
+    assert cache.currsize == expected_size
+
+
 @pytest.mark.parametrize("model_id", ["llava-hf/llava-v1.6-mistral-7b-hf"])
 @pytest.mark.parametrize(
     ("limit", "num_supported", "is_valid"),