optimize radix cache. (#968)

Co-authored-by: Weichao Luo <luoweichao@sensetime.com>

Author: kingder

lightllm/server/router/dynamic_prompt/radix_cache.py

@@ -82,13 +82,20 @@ def is_leaf(self):
         return len(self.children) == 0
 
 
-def match(key, seq):
-    i = 0
-    for k, w in zip(key, seq):
-        if k != w:
-            break
-        i += 1
-    return i
+def match(t1: torch.Tensor, t2: torch.Tensor) -> int:
+    # Ensure same shape for comparison: flatten and get min length
+    t1_flat = t1.flatten()
+    t2_flat = t2.flatten()
+    min_len = min(t1_flat.size(0), t2_flat.size(0))
+
+    # Compare elements and find first mismatch
+    diff = t1_flat[:min_len] != t2_flat[:min_len]
+    mismatch_indices = torch.nonzero(diff)
+
+    if mismatch_indices.numel() == 0:
+        return min_len  # All matched up to min_len
+    else:
+        return mismatch_indices[0].item()
 
 
 class RadixCache: