[RUNTIME] Fix cache dir (#2196)

---------

Co-authored-by: Keren Zhou <[email protected]>

python/triton/runtime/cache.py

@@ -40,18 +40,20 @@ def __init__(self, key):
         self.key = key
         self.lock_path = None
         # create cache directory if it doesn't exist
-        self.cache_dir = os.environ.get('TRITON_CACHE_DIR', default_cache_dir())
+        self.cache_dir = os.getenv('TRITON_CACHE_DIR', "").strip() or default_cache_dir()
         if self.cache_dir:
             self.cache_dir = os.path.join(self.cache_dir, self.key)
             self.lock_path = os.path.join(self.cache_dir, "lock")
             os.makedirs(self.cache_dir, exist_ok=True)
+        else:
+            raise RuntimeError("Could not create or locate cache dir")
 
     def _make_path(self, filename) -> str:
         return os.path.join(self.cache_dir, filename)
 
-    def has_file(self, filename):
+    def has_file(self, filename) -> bool:
         if not self.cache_dir:
-            return False
+            raise RuntimeError("Could not create or locate cache dir")
         return os.path.exists(self._make_path(filename))
 
     def get_file(self, filename) -> Optional[str]:
@@ -80,16 +82,16 @@ def get_group(self, filename: str) -> Optional[Dict[str, str]]:
         return result
 
     # Note a group of pushed files as being part of a group
-    def put_group(self, filename: str, group: Dict[str, str]):
+    def put_group(self, filename: str, group: Dict[str, str]) -> str:
         if not self.cache_dir:
-            return
+            raise RuntimeError("Could not create or locate cache dir")
         grp_contents = json.dumps({"child_paths": sorted(list(group.keys()))})
         grp_filename = f"__grp__{filename}"
         return self.put(grp_contents, grp_filename, binary=False)
 
     def put(self, data, filename, binary=True) -> str:
         if not self.cache_dir:
-            return
+            raise RuntimeError("Could not create or locate cache dir")
         binary = isinstance(data, bytes)
         if not binary:
             data = str(data)