[tune] logger refactor part 3: Add ExperimentLogger class (#11749)

python/ray/tune/utils/util.py

@@ -6,6 +6,7 @@ import os
 import inspect
 import threading
 import time
+import uuid
 from collections import defaultdict, deque, Mapping, Sequence
 from datetime import datetime
 from threading import Thread
@@ -540,6 +541,30 @@ def detect_config_single(func):
     return use_config_single
 
 
+def create_logdir(dirname: str, local_dir: str):
+    """Create an empty logdir with name `dirname` in `local_dir`.
+
+    If `local_dir`/`dirname` already exists, a unique string is appended
+    to the dirname.
+
+    Args:
+        dirname (str): Dirname to create in `local_dir`
+        local_dir (str): Root directory for the log dir
+
+    Returns: full path to the newly created logdir.
+    """
+    local_dir = os.path.expanduser(local_dir)
+    logdir = os.path.join(local_dir, dirname)
+    if os.path.exists(logdir):
+        old_dirname = dirname
+        dirname += "_" + uuid.uuid4().hex[:4]
+        logger.info(f"Creating a new dirname {dirname} because "
+                    f"trial dirname '{old_dirname}' already exists.")
+        logdir = os.path.join(local_dir, dirname)
+    os.makedirs(logdir, exist_ok=True)
+    return logdir
+
+
 class SafeFallbackEncoder(json.JSONEncoder):
     def __init__(self, nan_str="null", **kwargs):
         super(SafeFallbackEncoder, self).__init__(**kwargs)