[HiCache] Add an env var to control transfer engine reuse (#19867)

python/sglang/srt/environ.py

@@ -289,6 +289,7 @@ class Envs:
 
     # Mooncake Store
     SGLANG_HICACHE_MOONCAKE_CONFIG_PATH = EnvStr(None)
+    SGLANG_HICACHE_MOONCAKE_REUSE_TE = EnvBool(True)
     MOONCAKE_MASTER = EnvStr(None)
     MOONCAKE_CLIENT = EnvStr(None)
     MOONCAKE_LOCAL_HOSTNAME = EnvStr("localhost")

python/sglang/srt/model_executor/model_runner.py

@@ -868,6 +868,7 @@ class ModelRunner(ModelRunnerKVCacheMixin):
             or (
                 self.server_args.enable_hierarchical_cache
                 and self.server_args.hicache_storage_backend == "mooncake"
+                and envs.SGLANG_HICACHE_MOONCAKE_REUSE_TE.get()
             )
             or (
                 self.server_args.encoder_only