EAGLE cache fix for SWARadixCache (#11231)

Co-authored-by: Hanming Lu <69857889+hanming-lu@users.noreply.github.com>

python/sglang/srt/managers/scheduler.py

@@ -777,6 +777,7 @@ class Scheduler(
                     sliding_window_size=self.sliding_window_size,
                     page_size=self.page_size,
                     disable=server_args.disable_radix_cache,
+                    is_eagle=self.spec_algorithm.is_eagle(),
                 )
             elif server_args.enable_lmcache:
                 from sglang.srt.mem_cache.storage.lmcache.lmc_radix_cache import (

python/sglang/srt/mem_cache/allocator.py

@@ -274,10 +274,15 @@ class SWATokenToKVPoolAllocator(BaseTokenToKVPoolAllocator):
         self.full_to_swa_index_mapping[free_index] = 0
 
     def backup_state(self):
-        raise NotImplementedError
+        return [
+            self.full_attn_allocator.backup_state(),
+            self.swa_attn_allocator.backup_state(),
+        ]
 
     def restore_state(self, state):
-        raise NotImplementedError
+        assert len(state) == 2
+        self.full_attn_allocator.restore_state(state[0])
+        self.swa_attn_allocator.restore_state(state[1])
 
     def clear(self):
         self.swa_attn_allocator.clear()

python/sglang/srt/mem_cache/memory_pool.py

@@ -749,6 +749,7 @@ class SWAKVPool(KVCache):
         self,
         size: int,
         size_swa: int,
+        dtype: torch.dtype,
         swa_attention_layer_ids: List[int],
         full_attention_layer_ids: List[int],
         enable_kvcache_transpose: bool,
@@ -757,6 +758,7 @@ class SWAKVPool(KVCache):
     ):
         self.size = size
         self.size_swa = size_swa
+        self.dtype = dtype
         self.swa_layer_nums = len(swa_attention_layer_ids)
         self.full_layer_nums = len(full_attention_layer_ids)
         kwargs["page_size"] = 1
@@ -766,11 +768,13 @@ class SWAKVPool(KVCache):
 
         self.swa_kv_pool = token_to_kv_pool_class(
             size=size_swa,
+            dtype=dtype,
             layer_num=self.swa_layer_nums,
             **kwargs,
         )
         self.full_kv_pool = token_to_kv_pool_class(
             size=size,
+            dtype=dtype,
             layer_num=self.full_layer_nums,
             **kwargs,
         )

python/sglang/srt/mem_cache/radix_cache.py

@@ -326,6 +326,8 @@ class RadixCache(BasePrefixCache):
 
         token_ids = (req.origin_input_ids + req.output_ids)[:-1]
         all_token_len = len(token_ids)
+        # For EAGLE radix cache, we will convert the key to bigram key, e.g. [1,2,3,4] -> [(1,2), (2,3), (3,4)], the length will -1. ((len([(1,2), (2,3), (3,4)]) = len([1,2,3,4]) - 1))
+        # So for the corresponding kv length should also -1. Then we get the actual_kv_len, and use it to do later calculation and slicing.
         actual_kv_len = all_token_len - 1 if self.is_eagle else all_token_len
         kv_indices = self.req_to_token_pool.req_to_token[
             req.req_pool_idx, :all_token_len
@@ -349,7 +351,8 @@ class RadixCache(BasePrefixCache):
 
         old_prefix_len = len(req.prefix_indices)
         if self.is_eagle and old_prefix_len > req.last_matched_prefix_len:
-            # prefix_indices attached partial part (for page_size > 1) and one unmatched token (for EAGLE)
+            # In EAGLE chunked prefill case, the prefix_indices included one unmatched token (kv_indices[actual_kv_len:])
+            # Here we -1 to make sure the kv of the unmatched token can be freed correctly to avoid memory leak
             old_prefix_len -= 1
 
         # Radix Cache takes one ref in memory pool
@@ -370,7 +373,8 @@ class RadixCache(BasePrefixCache):
 
         token_ids = req.fill_ids
         all_token_len = len(token_ids)
-        # The actual kv len for EAGLE is len(token_ids), since EAGLE uses bigram key
+        # For EAGLE radix cache, we will convert the key to bigram key, e.g. [1,2,3,4] -> [(1,2), (2,3), (3,4)], the length will -1. ((len([(1,2), (2,3), (3,4)]) = len([1,2,3,4]) - 1))
+        # So for the corresponding kv length should also -1. Then we get the actual_kv_len, and use it to do later calculation and slicing.
         actual_kv_len = all_token_len - 1 if self.is_eagle else all_token_len
         kv_indices = self.req_to_token_pool.req_to_token[
             req.req_pool_idx, :all_token_len
@@ -393,7 +397,8 @@ class RadixCache(BasePrefixCache):
 
         old_prefix_len = len(req.prefix_indices)
         if self.is_eagle and old_prefix_len > req.last_matched_prefix_len:
-            # prefix_indices attached partial part (for page_size > 1) and one unmatched token (for EAGLE)
+            # In EAGLE chunked prefill case, the prefix_indices included one unmatched token (kv_indices[actual_kv_len:])
+            # Here we -1 to make sure the kv of the unmatched token can be freed correctly to avoid memory leak
             old_prefix_len -= 1
 
         # Radix Cache takes one ref in memory pool

python/sglang/srt/mem_cache/swa_radix_cache.py

@@ -32,6 +32,7 @@ from sglang.srt.mem_cache.base_prefix_cache import BasePrefixCache, MatchResult
 from sglang.srt.mem_cache.memory_pool import ReqToTokenPool
 from sglang.srt.mem_cache.radix_cache import (
     RadixKey,
+    _convert_to_bigram_key,
     _key_match_page_size1,
     _key_match_paged,
     get_child_key,
@@ -327,12 +328,14 @@ class SWARadixCache(BasePrefixCache):
         sliding_window_size: int,
         page_size: int,
         disable: bool = False,
+        is_eagle: bool = False,
     ):
         assert isinstance(token_to_kv_pool_allocator, SWATokenToKVPoolAllocator)
         self.req_to_token_pool = req_to_token_pool
         self.token_to_kv_pool_allocator = token_to_kv_pool_allocator
         self.page_size = page_size
         self.disable = disable
+        self.is_eagle = is_eagle
 
         if self.token_to_kv_pool_allocator:
             self.device = self.token_to_kv_pool_allocator.device
@@ -346,6 +349,11 @@ class SWARadixCache(BasePrefixCache):
             self.key_match_fn = partial(_key_match_paged, page_size=page_size)
             self.get_child_key_fn = partial(get_child_key, page_size=page_size)
 
+        if is_eagle:
+            self.key_convert_fn = _convert_to_bigram_key
+        else:
+            self.key_convert_fn = lambda key: key
+
         self.sliding_window_size = sliding_window_size
         self.reset()
 
@@ -376,6 +384,8 @@ class SWARadixCache(BasePrefixCache):
             The last node create a new child if the prefix is shorter
             than the last node's value.
         """
+        key.token_ids = self.key_convert_fn(key.token_ids)
+
         if self.disable or len(key) == 0:
             return MatchResult(
                 device_indices=torch.empty(
@@ -406,8 +416,15 @@ class SWARadixCache(BasePrefixCache):
         if self.disable:
             return 0
 
+        key.token_ids = self.key_convert_fn(key.token_ids)
+
         if value is None:
             value = torch.tensor([x for x in key.token_ids], dtype=torch.int64)
+
+        if self.is_eagle:
+            # Make sure the value len equal to the EAGLE bigram key len
+            value = value[: len(key)]
+
         return self._insert_helper(self.root_node, key, value, prev_prefix_len)
 
     def cache_finished_req(self, req: Req) -> None:
@@ -422,25 +439,41 @@ class SWARadixCache(BasePrefixCache):
             return
 
         token_ids = (req.origin_input_ids + req.output_ids)[:-1]
+        all_token_len = len(token_ids)
+        # For EAGLE radix cache, we will convert the key to bigram key, e.g. [1,2,3,4] -> [(1,2), (2,3), (3,4)], the length will -1. ((len([(1,2), (2,3), (3,4)]) = len([1,2,3,4]) - 1))
+        # So for the corresponding kv length should also -1. Then we get the actual_kv_len, and use it to do later calculation and slicing.
+        actual_kv_len = all_token_len - 1 if self.is_eagle else all_token_len
         kv_indices = self.req_to_token_pool.req_to_token[
-            req.req_pool_idx, : len(token_ids)
+            req.req_pool_idx, :all_token_len
         ]
 
         if self.page_size != 1:
-            page_aligned_len = len(kv_indices) // self.page_size * self.page_size
+            page_aligned_len = actual_kv_len // self.page_size * self.page_size
             page_aligned_kv_indices = kv_indices[:page_aligned_len].clone()
             self.token_to_kv_pool_allocator.free(kv_indices[page_aligned_len:])
         else:
-            page_aligned_len = len(kv_indices)
+            page_aligned_len = actual_kv_len
             page_aligned_kv_indices = kv_indices.clone()
+            if self.is_eagle:
+                self.token_to_kv_pool_allocator.free(kv_indices[page_aligned_len:])
+
+        page_aligned_token_len = (
+            page_aligned_len + 1 if self.is_eagle else page_aligned_len
+        )
+
+        old_prefix_len = len(req.prefix_indices)
+        if self.is_eagle and old_prefix_len > req.last_matched_prefix_len:
+            # In EAGLE chunked prefill case, the prefix_indices included one unmatched token (kv_indices[actual_kv_len:])
+            # Here we -1 to make sure the kv of the unmatched token can be freed correctly to avoid memory leak
+            old_prefix_len -= 1
 
         # Radix Cache takes one ref in memory pool
         # insert the token_ids and kv_indices into the radix tree
         # Note: the insert function already frees the overlapped kv_indices
         new_prefix_len = self.insert(
-            RadixKey(token_ids[:page_aligned_len], req.extra_key),
+            RadixKey(token_ids[:page_aligned_token_len], req.extra_key),
             page_aligned_kv_indices,
-            len(req.prefix_indices),
+            old_prefix_len,
         )
 
         # Remove req slot release the cache lock
@@ -459,39 +492,56 @@ class SWARadixCache(BasePrefixCache):
             return
 
         token_ids = req.fill_ids
+        all_token_len = len(token_ids)
+        # For EAGLE radix cache, we will convert the key to bigram key, e.g. [1,2,3,4] -> [(1,2), (2,3), (3,4)], the length will -1. ((len([(1,2), (2,3), (3,4)]) = len([1,2,3,4]) - 1))
+        # So for the corresponding kv length should also -1. Then we get the actual_kv_len, and use it to do later calculation and slicing.
+        actual_kv_len = all_token_len - 1 if self.is_eagle else all_token_len
         kv_indices = self.req_to_token_pool.req_to_token[
-            req.req_pool_idx, : len(token_ids)
+            req.req_pool_idx, :all_token_len
         ]
 
         if self.page_size != 1:
-            page_aligned_len = len(kv_indices) // self.page_size * self.page_size
+            page_aligned_len = actual_kv_len // self.page_size * self.page_size
             page_aligned_kv_indices = kv_indices[:page_aligned_len].clone()
         else:
-            page_aligned_len = len(kv_indices)
+            page_aligned_len = actual_kv_len
             page_aligned_kv_indices = kv_indices.clone()
-        page_aligned_token_ids = token_ids[:page_aligned_len]
+
+        # For EAGLE, the page_aligned_len is for the bigram key, the normal key len should +1
+        page_aligned_token_len = (
+            page_aligned_len + 1 if self.is_eagle else page_aligned_len
+        )
+        page_aligned_token_ids = token_ids[:page_aligned_token_len]
+
+        old_prefix_len = len(req.prefix_indices)
+        if self.is_eagle and old_prefix_len > req.last_matched_prefix_len:
+            # In EAGLE chunked prefill case, the prefix_indices included one unmatched token (kv_indices[actual_kv_len:])
+            # Here we -1 to make sure the kv of the unmatched token can be freed correctly to avoid memory leak
+            old_prefix_len -= 1
 
         # Radix Cache takes one ref in memory pool
         # Note: the insert function already frees the overlapped kv_indices
         new_prefix_len = self.insert(
             RadixKey(page_aligned_token_ids, req.extra_key),
             page_aligned_kv_indices,
-            len(req.prefix_indices),
+            old_prefix_len,
         )
 
         # The prefix indices could be updated, reuse it
         new_indices, new_last_node, _, _ = self.match_prefix(
             RadixKey(page_aligned_token_ids, req.extra_key)
         )
-        assert len(req.prefix_indices) <= len(
+        assert old_prefix_len <= len(
             new_indices
         ), f"{req.prefix_indices=}, {new_indices=}"
         assert new_prefix_len <= len(new_indices), f"{new_prefix_len=}, {new_indices=}"
         self.req_to_token_pool.write(
-            (req.req_pool_idx, slice(len(req.prefix_indices), len(new_indices))),
-            new_indices[len(req.prefix_indices) :],
+            (req.req_pool_idx, slice(old_prefix_len, len(new_indices))),
+            new_indices[old_prefix_len:],
         )
 
+        req.last_matched_prefix_len = len(new_indices)
+
         self.dec_lock_ref(req.last_node, req.swa_uuid_for_lock)
         swa_uuid_for_lock = self.inc_lock_ref(new_last_node)
 
@@ -501,7 +551,13 @@ class SWARadixCache(BasePrefixCache):
                 [new_indices, kv_indices[len(new_indices) :]]
             )
         else:
-            req.prefix_indices = new_indices
+            if self.is_eagle:
+                # Attach the kv index of the last token for EAGLE, it can be used in chunked prefill
+                req.prefix_indices = torch.cat(
+                    [new_indices, kv_indices[actual_kv_len:]]
+                )
+            else:
+                req.prefix_indices = new_indices
         req.last_node = new_last_node
         req.swa_uuid_for_lock = swa_uuid_for_lock
 

python/sglang/srt/models/utils.py

@@ -27,7 +27,11 @@ if _is_cuda:
 
 def enable_fused_set_kv_buffer(forward_batch: ForwardBatch):
     """Enable fused set_kv_buffer only on CUDA with bfloat16 KV cache."""
-    return _is_cuda and forward_batch.token_to_kv_pool.dtype == torch.bfloat16
+    return (
+        _is_cuda
+        and hasattr(forward_batch.token_to_kv_pool, "dtype")
+        and forward_batch.token_to_kv_pool.dtype == torch.bfloat16
+    )
 
 
 def create_fused_set_kv_buffer_arg(

test/srt/run_suite.py

@@ -113,6 +113,7 @@ suites = {
         TestFile("test_srt_engine.py", 261),
         TestFile("test_srt_endpoint.py", 130),
         TestFile("test_start_profile.py", 60),
+        TestFile("test_swa_unittest.py", 1),
         TestFile("test_torch_compile.py", 76),
         TestFile("test_torch_compile_moe.py", 172),
         TestFile("test_torch_native_attention_backend.py", 123),

test/srt/test_swa_unittest.py

@@ -50,9 +50,14 @@ class TestSWA(unittest.TestCase):
             kvcache=pool,
             need_sort=False,
         )
-        assert alloc.available_size() == size + size_swa
+        self.assertEqual(
+            alloc.full_available_size() + alloc.swa_available_size(), size + size_swa
+        )
         index = alloc.alloc(1)
-        assert alloc.available_size() == size_swa + size_swa - 2
+        self.assertEqual(
+            alloc.full_available_size() + alloc.swa_available_size(),
+            size_swa + size_swa - 2,
+        )
         alloc.free_swa(index)
         result = alloc.translate_loc_from_full_to_swa(index)
         print(result)
@@ -117,38 +122,174 @@ class TestSWA(unittest.TestCase):
             f"[Start] allocator swa available size: {allocator.swa_available_size()}, full available size: {allocator.full_available_size()}"
         )
         req1_token_ids, req1_kv_indices = [1, 2, 3], allocator.alloc(3)
-        assert len(req1_token_ids) == len(req1_kv_indices)
+        self.assertEqual(len(req1_token_ids), len(req1_kv_indices))
+        print(
+            f"req1: inserting, req1_token_ids: {req1_token_ids}, req1_kv_indices: {req1_kv_indices}"
+        )
+        prefix_len = tree.insert(RadixKey(req1_token_ids), req1_kv_indices)
+        print(
+            f"req1: prefix_len: {prefix_len}, allocator swa available size: {allocator.swa_available_size()}, full available size: {allocator.full_available_size()}"
+        )
+        req2_token_ids, req2_kv_indices = [1, 2, 3, 4, 5, 6, 7], allocator.alloc(7)
+        self.assertEqual(len(req2_token_ids), len(req2_kv_indices))
+        print(
+            f"req2: inserting, req2_token_ids: {req2_token_ids}, req2_kv_indices: {req2_kv_indices}"
+        )
+        prefix_len = tree.insert(RadixKey(req2_token_ids), req2_kv_indices)
+        print(
+            f"req2: prefix_len: {prefix_len}, allocator swa available size: {allocator.swa_available_size()}, full available size: {allocator.full_available_size()}"
+        )
+        req3_token_ids, req3_kv_indices = [10, 11, 12], allocator.alloc(3)
+        self.assertEqual(len(req3_token_ids), len(req3_kv_indices))
+        print(
+            f"req3: inserting, req3_token_ids: {req3_token_ids}, req3_kv_indices: {req3_kv_indices}"
+        )
+        prefix_len = tree.insert(RadixKey(req3_token_ids), req3_kv_indices)
+        print(
+            f"req3: prefix_len: {prefix_len}, allocator swa available size: {allocator.swa_available_size()}, full available size: {allocator.full_available_size()}"
+        )
+        req4_token_ids, req4_kv_indices = [1, 2, 3, 4, 5, 60, 70], allocator.alloc(7)
+        self.assertEqual(len(req4_token_ids), len(req4_kv_indices))
+        print(
+            f"req4: inserting, req4_token_ids: {req4_token_ids}, req4_kv_indices: {req4_kv_indices}"
+        )
+        prefix_len = tree.insert(RadixKey(req4_token_ids), req4_kv_indices)
+        print(
+            f"req4: prefix_len: {prefix_len}, allocator swa available size: {allocator.swa_available_size()}, full available size: {allocator.full_available_size()}"
+        )
+
+        tree.pretty_print()
+        full_num_tokens, swa_num_tokens = 1, 0
+        print(f"evicting {full_num_tokens} full token and {swa_num_tokens} swa token")
+        tree.evict(full_num_tokens=full_num_tokens, swa_num_tokens=swa_num_tokens)
+        tree.pretty_print()
+
+        full_num_tokens, swa_num_tokens = 0, 1
+        print(f"evicting {full_num_tokens} full token and {swa_num_tokens} swa token")
+        tree.evict(full_num_tokens=full_num_tokens, swa_num_tokens=swa_num_tokens)
+        tree.pretty_print()
+
+        full_num_tokens, swa_num_tokens = 1, 2
+        print(f"evicting {full_num_tokens} full token and {swa_num_tokens} swa token")
+        tree.evict(full_num_tokens=full_num_tokens, swa_num_tokens=swa_num_tokens)
+        tree.pretty_print()
+
+        req5_token_ids = [1, 2, 3, 4, 5]
+        result = tree.match_prefix(RadixKey(req5_token_ids))
+        kv_indices, last_node = result.device_indices, result.last_device_node
+        print(
+            f"req5: token_ids: {req5_token_ids}, matched kv_indices: {kv_indices}, last_node.key: {last_node.key}"
+        )
+        self.assertEqual(len(kv_indices), 0)
+
+        req6_token_ids = [1, 2, 3, 4, 5, 60, 70]
+        result = tree.match_prefix(RadixKey(req6_token_ids))
+        kv_indices, last_node = result.device_indices, result.last_device_node
+        print(
+            f"req6: token_ids: {req6_token_ids}, matched kv_indices: {kv_indices}, last_node.key: {last_node.key}"
+        )
+        self.assertEqual(len(kv_indices), 7)
+        self.assertEqual(len(last_node.key), 2)
+        self.assertEqual(last_node.key.token_ids[0], 60)
+        self.assertEqual(last_node.key.token_ids[1], 70)
+
+    def test_swa_radix_cache_eagle(self):
+        # args
+        req_size = 10
+        max_context_len = 128
+        kv_size = 128
+        kv_size_swa = 64
+        sliding_window_size = 4
+        head_num = 8
+        head_dim = 128
+        num_layers = 48
+        global_interval = 4
+        dtype = torch.bfloat16
+        device = "cuda"
+        full_attention_layer_ids = [i for i in range(0, num_layers, global_interval)]
+        full_attention_layer_ids_set = set(full_attention_layer_ids)
+        swa_attention_layer_ids = [
+            i for i in range(num_layers) if i not in full_attention_layer_ids_set
+        ]
+        # setup req to token pool
+        req_to_token_pool = ReqToTokenPool(
+            size=req_size,
+            max_context_len=max_context_len,
+            device=device,
+            enable_memory_saver=False,
+        )
+        # setup kv pool
+        kv_pool = SWAKVPool(
+            size=kv_size,
+            size_swa=kv_size_swa,
+            dtype=dtype,
+            head_num=head_num,
+            head_dim=head_dim,
+            swa_attention_layer_ids=swa_attention_layer_ids,
+            full_attention_layer_ids=full_attention_layer_ids,
+            enable_kvcache_transpose=False,
+            device=device,
+        )
+        # setup token to kv pool allocator
+        allocator = SWATokenToKVPoolAllocator(
+            size=kv_size,
+            size_swa=kv_size_swa,
+            dtype=dtype,
+            device=device,
+            kvcache=kv_pool,
+            need_sort=False,
+        )
+        # setup radix cache
+        tree = SWARadixCache(
+            req_to_token_pool=req_to_token_pool,
+            token_to_kv_pool_allocator=allocator,
+            sliding_window_size=sliding_window_size,
+            page_size=1,
+            disable=False,
+            is_eagle=True,
+        )
+
+        # test
+        print(
+            f"[Start] allocator swa available size: {allocator.swa_available_size()}, full available size: {allocator.full_available_size()}"
+        )
+        req1_token_ids, req1_kv_indices = [1, 2, 3], allocator.alloc(3)
+        self.assertEqual(len(req1_token_ids), len(req1_kv_indices))
         print(
             f"req1: inserting, req1_token_ids: {req1_token_ids}, req1_kv_indices: {req1_kv_indices}"
         )
         prefix_len = tree.insert(RadixKey(req1_token_ids), req1_kv_indices)
+        self.assertEqual(prefix_len, 0)
         print(
             f"req1: prefix_len: {prefix_len}, allocator swa available size: {allocator.swa_available_size()}, full available size: {allocator.full_available_size()}"
         )
         req2_token_ids, req2_kv_indices = [1, 2, 3, 4, 5, 6, 7], allocator.alloc(7)
-        assert len(req2_token_ids) == len(req2_kv_indices)
+        self.assertEqual(len(req2_token_ids), len(req2_kv_indices))
         print(
             f"req2: inserting, req2_token_ids: {req2_token_ids}, req2_kv_indices: {req2_kv_indices}"
         )
         prefix_len = tree.insert(RadixKey(req2_token_ids), req2_kv_indices)
+        self.assertEqual(prefix_len, 2)
         print(
             f"req2: prefix_len: {prefix_len}, allocator swa available size: {allocator.swa_available_size()}, full available size: {allocator.full_available_size()}"
         )
         req3_token_ids, req3_kv_indices = [10, 11, 12], allocator.alloc(3)
-        assert len(req3_token_ids) == len(req3_kv_indices)
+        self.assertEqual(len(req3_token_ids), len(req3_kv_indices))
         print(
             f"req3: inserting, req3_token_ids: {req3_token_ids}, req3_kv_indices: {req3_kv_indices}"
         )
         prefix_len = tree.insert(RadixKey(req3_token_ids), req3_kv_indices)
+        self.assertEqual(prefix_len, 0)
         print(
             f"req3: prefix_len: {prefix_len}, allocator swa available size: {allocator.swa_available_size()}, full available size: {allocator.full_available_size()}"
         )
         req4_token_ids, req4_kv_indices = [1, 2, 3, 4, 5, 60, 70], allocator.alloc(7)
-        assert len(req4_token_ids) == len(req4_kv_indices)
+        self.assertEqual(len(req4_token_ids), len(req4_kv_indices))
         print(
             f"req4: inserting, req4_token_ids: {req4_token_ids}, req4_kv_indices: {req4_kv_indices}"
         )
         prefix_len = tree.insert(RadixKey(req4_token_ids), req4_kv_indices)
+        self.assertEqual(prefix_len, 4)
         print(
             f"req4: prefix_len: {prefix_len}, allocator swa available size: {allocator.swa_available_size()}, full available size: {allocator.full_available_size()}"
         )
@@ -175,7 +316,7 @@ class TestSWA(unittest.TestCase):
         print(
             f"req5: token_ids: {req5_token_ids}, matched kv_indices: {kv_indices}, last_node.key: {last_node.key}"
         )
-        assert len(kv_indices) == 0
+        self.assertEqual(len(kv_indices), 0)  # no swa prefix matched
 
         req6_token_ids = [1, 2, 3, 4, 5, 60, 70]
         result = tree.match_prefix(RadixKey(req6_token_ids))
@@ -183,10 +324,10 @@ class TestSWA(unittest.TestCase):
         print(
             f"req6: token_ids: {req6_token_ids}, matched kv_indices: {kv_indices}, last_node.key: {last_node.key}"
         )
-        assert len(kv_indices) == 7
-        assert len(last_node.key) == 2
-        assert last_node.key.token_ids[0] == 60
-        assert last_node.key.token_ids[1] == 70
+        self.assertEqual(len(kv_indices), 6)
+        self.assertEqual(len(last_node.key), 2)
+        self.assertEqual(last_node.key.token_ids[0], (5, 60))
+        self.assertEqual(last_node.key.token_ids[1], (60, 70))
 
 
 if __name__ == "__main__":