fix block manager interface for can_allocate

vllm/core/block_manager_v1.py

@@ -281,10 +281,15 @@ def __init__(
     def _get_seq_num_required_blocks(self, seq: Optional[Sequence]) -> int:
         return 0 if seq is None else seq.n_blocks
 
-    def can_allocate(self, seq_group: SequenceGroup) -> AllocStatus:
+    def can_allocate(self,
+                     seq_group: SequenceGroup,
+                     num_lookahead_slots: int = 0) -> AllocStatus:
         # FIXME(woosuk): Here we assume that all sequences in the group share
         # the same prompt. This may not be true for preempted sequences.
 
+        assert (num_lookahead_slots == 0
+                ), "lookahead allocation not supported in BlockSpaceManagerV1"
+
         check_no_caching_or_swa_for_blockmgr_encdec(self, seq_group)
 
         self_num_required_blocks = self._get_seq_num_required_blocks(

vllm/core/embedding_model_block_manager.py

@@ -21,7 +21,9 @@ def __init__(
     ) -> None:
         pass
 
-    def can_allocate(self, seq_group: SequenceGroup) -> AllocStatus:
+    def can_allocate(self,
+                     seq_group: SequenceGroup,
+                     num_lookahead_slots: int = 0) -> AllocStatus:
         # Always return OK for dummy purposes
         return AllocStatus.OK
 

vllm/core/interfaces.py

@@ -44,7 +44,9 @@ def get_block_space_manager_class(version: str):
         raise ValueError(f"Unknown version {version=}")
 
     @abstractmethod
-    def can_allocate(self, seq_group: SequenceGroup) -> AllocStatus:
+    def can_allocate(self,
+                     seq_group: SequenceGroup,
+                     num_lookahead_slots: int = 0) -> AllocStatus:
         pass
 
     @abstractmethod