[REFACTOR] Rename MLC_LLM_READONLY_WEIGHT_CACHES (#2423)

This PR renames MLC_LLM_READONLY_WEIGHT_CACHES=>MLC_LLM_READONLY_WEIGHT_CACHE
to be consistent with rest of env var convention

Author: tqchen

python/mlc_llm/support/constants.py

@@ -67,8 +67,8 @@ def _get_test_model_path() -> List[Path]:
 
 
 def _get_read_only_weight_caches() -> List[Path]:
-    if "MLC_LLM_READONLY_WEIGHT_CACHES" in os.environ:
-        return [Path(p) for p in os.environ["MLC_LLM_READONLY_WEIGHT_CACHES"].split(os.pathsep)]
+    if "MLC_LLM_READONLY_WEIGHT_CACHE" in os.environ:
+        return [Path(p) for p in os.environ["MLC_LLM_READONLY_WEIGHT_CACHE"].split(os.pathsep)]
     return []
 
 
@@ -80,6 +80,6 @@ def _get_read_only_weight_caches() -> List[Path]:
 
 MLC_DOWNLOAD_POLICY = os.environ.get("MLC_DOWNLOAD_POLICY", "ON")
 MLC_LLM_HOME: Path = _get_cache_dir()
-MLC_LLM_READONLY_WEIGHT_CACHES = _get_read_only_weight_caches()
+MLC_LLM_READONLY_WEIGHT_CACHE = _get_read_only_weight_caches()
 
 _check()

python/mlc_llm/support/download.py

@@ -16,7 +16,7 @@
 from .constants import (
     MLC_DOWNLOAD_POLICY,
     MLC_LLM_HOME,
-    MLC_LLM_READONLY_WEIGHT_CACHES,
+    MLC_LLM_READONLY_WEIGHT_CACHE,
     MLC_TEMP_DIR,
 )
 from .style import bold
@@ -147,7 +147,7 @@ def download_and_cache_mlc_weights(  # pylint: disable=too-many-locals
     domain = "hf"
 
     readonly_cache_dirs = []
-    for base in MLC_LLM_READONLY_WEIGHT_CACHES:
+    for base in MLC_LLM_READONLY_WEIGHT_CACHE:
         cache_dir = base / domain / user / repo
         readonly_cache_dirs.append(str(cache_dir))
         if (cache_dir / "mlc-chat-config.json").is_file():
@@ -170,7 +170,7 @@ def download_and_cache_mlc_weights(  # pylint: disable=too-many-locals
         raise RuntimeError(
             f"Cannot find cache for {model_url}, "
             "cannot proceed to download as MLC_DOWNLOAD_POLICY=READONLY, "
-            "please check settings MLC_LLM_READONLY_WEIGHT_CACHES, "
+            "please check settings MLC_LLM_READONLY_WEIGHT_CACHE, "
             f"local path candidates: {readonly_cache_dirs}"
         )