Add input metadata

cacheflow/models/__init__.py

-from cacheflow.worker.models.model_utils import get_model
+from cacheflow.models.input_metadata import InputMetadata
+from cacheflow.models.model_utils import get_model
 
 
 __all__ = [
     'get_model',
-    
+    'InputMetadata',
 ]

cacheflow/models/input_metadata.py

+from typing import List
+
+import torch
+
+
+class InputMetadata:
+
+    def __init__(
+        self,
+        prompt_lens: List[int],
+        slot_mapping: torch.Tensor,
+        context_lens: torch.Tensor,
+        max_context_len: int,
+        block_tables: torch.Tensor,
+    ) -> None:
+        self.prompt_lens = prompt_lens
+        self.prompt_block_table = slot_mapping
+        self.context_lens = context_lens
+        self.max_context_len = max_context_len
+        self.block_tables = block_tables
+
+        self.num_prompts = len(prompt_lens)
+        self.num_generation_tokens = context_lens.shape[0]
+        self.max_num_blocks_per_seq = block_tables.shape[1]
+        assert self.num_generation_tokens == block_tables.shape[0]