First commit

vllm/core/block/utils.py

@@ -0,0 +1,48 @@
+"""Block manager utils."""
+from vllm.sequence import SequenceGroup
+from vllm.utils import (STR_NOT_IMPL_ENC_DEC_PREFIX_CACHE,
+                        STR_NOT_IMPL_ENC_DEC_SWA)
+
+
+def _get_block_mgr_sliding_window_attr(block_mgr):
+    '''
+    BlockManagerV1 and BlockManagerV2 have slightly different
+    members related to sliding window attention (SWA). This
+    function extracts the appropriate member to use for determining
+    whether SWA is enabled.
+
+    Arguments:
+
+    * block_mgr: BlockManagerV1 or BlockManagerV2 instance
+    '''
+
+    if hasattr(block_mgr, 'block_sliding_window'):
+        return block_mgr.block_sliding_window
+    if hasattr(block_mgr, 'max_block_sliding_window'):
+        return block_mgr.max_block_sliding_window
+
+    raise AttributeError("Block manager instance has neither " + \
+                         "block_sliding_window nor " + \
+                         "max_block_sliding_window attributes.")
+
+
+def check_no_caching_or_swa_for_blockmgr_encdec(
+        block_mgr, seq_group: SequenceGroup) -> None:
+    '''
+    Enforce that prefix caching & sliding-window attention (SWA)
+    are currently unsupported *specifically* for encoder/decoder models.
+
+    Raises NotImplementedError if unsupported scenario is detected.
+
+    Arguments:
+
+    * block_mgr: BlockSpaceManager instance
+    * seq_group: SequenceGroup passed to block_mgr
+    '''
+
+    if seq_group.is_encoder_decoder():
+        if _get_block_mgr_sliding_window_attr(block_mgr) is not None:
+            raise NotImplementedError(STR_NOT_IMPL_ENC_DEC_SWA)
+
+        if block_mgr.enable_caching:
+            raise NotImplementedError(STR_NOT_IMPL_ENC_DEC_PREFIX_CACHE)