Fix some models treated as having size 0 in the model cache (#6571)

## Summary

This PR fixes a regression that caused the following models to be
treated as having size 0 in the model cache: `(TextualInversionModelRaw,
IPAdapter, LoRAModelRaw)`.

Changes:
- Call the correct model size calculation for all supported model types.
- Log an error message if an unexpected model type is loaded, to prevent
similar regressions in the future.

## QA Instructions

I tested the following features and verified that no models fell back to
using a size of 0 unexpectedly:
- Test-to-image
- Textual Inversion
- LoRA
- IP-Adapter
- ControlNet
(All tested with both SD1.5 and SDXL.)

I compared the model cache switching behavior before and after this
change with a large number of LoRAs (10). Since LoRAs are small compared
to the main models, the changes in behaviour are minimal. Nonetheless,
it makes sense to get this in for correctness. And it might make a
difference for some usage patterns with limited RAM.

## Merge Plan

No special instructions.

## Checklist

- [x] _The PR has a short but descriptive title, suitable for a
changelog_
- [x] _Tests added / updated (if applicable)_
- [x] _Documentation added / updated (if applicable)_

invokeai/backend/ip_adapter/ip_adapter.py

@@ -136,11 +136,11 @@ class IPAdapter(RawModel):
         self._image_proj_model.to(device=self.device, dtype=self.dtype, non_blocking=non_blocking)
         self.attn_weights.to(device=self.device, dtype=self.dtype, non_blocking=non_blocking)
 
-    def calc_size(self):
+    def calc_size(self) -> int:
-        # workaround for circular import
+        # HACK(ryand): Fix this issue with circular imports.
-        from invokeai.backend.model_manager.load.model_util import calc_model_size_by_data
+        from invokeai.backend.model_manager.load.model_util import calc_module_size
 
-        return calc_model_size_by_data(self._image_proj_model) + calc_model_size_by_data(self.attn_weights)
+        return calc_module_size(self._image_proj_model) + calc_module_size(self.attn_weights)
 
     def _init_image_proj_model(
         self, state_dict: dict[str, torch.Tensor]

invokeai/backend/model_manager/load/model_cache/model_cache_default.py

@@ -160,7 +160,7 @@ class ModelCache(ModelCacheBase[AnyModel]):
         key = self._make_cache_key(key, submodel_type)
         if key in self._cached_models:
             return
-        size = calc_model_size_by_data(model)
+        size = calc_model_size_by_data(self.logger, model)
         self.make_room(size)
 
         state_dict = model.state_dict() if isinstance(model, torch.nn.Module) else None

invokeai/backend/model_manager/load/model_util.py

@@ -2,25 +2,46 @@
 """Various utility functions needed by the loader and caching system."""
 
 import json
+import logging
 from pathlib import Path
 from typing import Optional
 
 import torch
-from diffusers import DiffusionPipeline
+from diffusers.pipelines.pipeline_utils import DiffusionPipeline
+from diffusers.schedulers.scheduling_utils import SchedulerMixin
+from transformers import CLIPTokenizer
 
+from invokeai.backend.ip_adapter.ip_adapter import IPAdapter
+from invokeai.backend.lora import LoRAModelRaw
 from invokeai.backend.model_manager.config import AnyModel
 from invokeai.backend.onnx.onnx_runtime import IAIOnnxRuntimeModel
+from invokeai.backend.textual_inversion import TextualInversionModelRaw
 
 
-def calc_model_size_by_data(model: AnyModel) -> int:
+def calc_model_size_by_data(logger: logging.Logger, model: AnyModel) -> int:
     """Get size of a model in memory in bytes."""
+    # TODO(ryand): We should create a CacheableModel interface for all models, and move the size calculations down to
+    # the models themselves.
     if isinstance(model, DiffusionPipeline):
         return _calc_pipeline_by_data(model)
     elif isinstance(model, torch.nn.Module):
-        return _calc_model_by_data(model)
+        return calc_module_size(model)
     elif isinstance(model, IAIOnnxRuntimeModel):
         return _calc_onnx_model_by_data(model)
+    elif isinstance(model, SchedulerMixin):
+        return 0
+    elif isinstance(model, CLIPTokenizer):
+        # TODO(ryand): Accurately calculate the tokenizer's size. It's small enough that it shouldn't matter for now.
+        return 0
+    elif isinstance(model, (TextualInversionModelRaw, IPAdapter, LoRAModelRaw)):
+        return model.calc_size()
     else:
+        # TODO(ryand): Promote this from a log to an exception once we are confident that we are handling all of the
+        # supported model types.
+        logger.error(
+            f"Failed to calculate model size for unexpected model type: {type(model)}. The model will be treated as "
+            "having size 0."
+        )
         return 0
 
 
@@ -30,11 +51,12 @@ def _calc_pipeline_by_data(pipeline: DiffusionPipeline) -> int:
     for submodel_key in pipeline.components.keys():
         submodel = getattr(pipeline, submodel_key)
         if submodel is not None and isinstance(submodel, torch.nn.Module):
-            res += _calc_model_by_data(submodel)
+            res += calc_module_size(submodel)
     return res
 
 
-def _calc_model_by_data(model: torch.nn.Module) -> int:
+def calc_module_size(model: torch.nn.Module) -> int:
+    """Calculate the size (in bytes) of a torch.nn.Module."""
     mem_params = sum([param.nelement() * param.element_size() for param in model.parameters()])
     mem_bufs = sum([buf.nelement() * buf.element_size() for buf in model.buffers()])
     mem: int = mem_params + mem_bufs  # in bytes

invokeai/backend/textual_inversion.py

@@ -77,6 +77,14 @@ class TextualInversionModelRaw(RawModel):
             if emb is not None:
                 emb.to(device=device, dtype=dtype, non_blocking=non_blocking)
 
+    def calc_size(self) -> int:
+        """Get the size of this model in bytes."""
+        embedding_size = self.embedding.element_size() * self.embedding.nelement()
+        embedding_2_size = 0
+        if self.embedding_2 is not None:
+            embedding_2_size = self.embedding_2.element_size() * self.embedding_2.nelement()
+        return embedding_size + embedding_2_size
+
 
 class TextualInversionManager(BaseTextualInversionManager):
     """TextualInversionManager implements the BaseTextualInversionManager ABC from the compel library."""