flashinfer: switch to plan API (#2904)

This change doesn't switch `forward` to `run` yet, since it requires
that we have access to the softmax scale and the logit softcap outside
the model.

Author: danieldk

server/text_generation_server/layers/attention/cuda.py

@@ -235,7 +235,6 @@ def attention(
             paged_kv_cache=(kv_cache.key, kv_cache.value),
             logits_soft_cap=softcap,
             sm_scale=softmax_scale,
-            window_left=window_size_left,
             k_scale=kv_scales.key_scale_cpu if can_scale else 1.0,
             v_scale=kv_scales.value_scale_cpu if can_scale else 1.0,
         )

server/text_generation_server/layers/attention/flashinfer.py

@@ -84,7 +84,7 @@ def use_prefill_with_paged_kv_state(
 
     token = prefill_with_paged_kv_state.set(state)
     try:
-        state.begin_forward(
+        state.plan(
             qo_indptr=cu_seqlens,
             paged_kv_indptr=indptr,
             paged_kv_indices=block_tables,
@@ -99,7 +99,6 @@ def use_prefill_with_paged_kv_state(
         )
         yield
     finally:
-        state.end_forward()
         if token is not None:
             prefill_with_paged_kv_state.reset(token)
 
@@ -200,7 +199,7 @@ def use_decode_state(
     token = decode_state.set(state)
 
     try:
-        state.begin_forward(
+        state.plan(
             indptr=indptr,
             indices=block_tables,
             last_page_len=last_page_len,
@@ -214,6 +213,5 @@ def use_decode_state(
         )
         yield
     finally:
-        state.end_forward()
         if token is not None:
             decode_state.reset(token)