Centralize logging (#6434)

* Logging

* Style

* hf_logging > utils.logging

* Address @thomwolf's comments

* Update test

* Update src/transformers/benchmark/benchmark_utils.py

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* Revert bad change

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

src/transformers/utils/logging.py

@@ -0,0 +1,165 @@
+# coding=utf-8
+# Copyright 2020 Optuna, Hugging Face
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+""" Logging utilities. """
+
+import logging
+import threading
+from logging import CRITICAL  # NOQA
+from logging import DEBUG  # NOQA
+from logging import ERROR  # NOQA
+from logging import FATAL  # NOQA
+from logging import INFO  # NOQA
+from logging import NOTSET  # NOQA
+from logging import WARN  # NOQA
+from logging import WARNING  # NOQA
+from typing import Optional
+
+
+_lock = threading.Lock()
+_default_handler: Optional[logging.Handler] = None
+
+
+def _get_library_name() -> str:
+
+    return __name__.split(".")[0]
+
+
+def _get_library_root_logger() -> logging.Logger:
+
+    return logging.getLogger(_get_library_name())
+
+
+def _configure_library_root_logger() -> None:
+
+    global _default_handler
+
+    with _lock:
+        if _default_handler:
+            # This library has already configured the library root logger.
+            return
+        _default_handler = logging.StreamHandler()  # Set sys.stderr as stream.
+
+        # Apply our default configuration to the library root logger.
+        library_root_logger = _get_library_root_logger()
+        library_root_logger.addHandler(_default_handler)
+        library_root_logger.setLevel(logging.INFO)
+        library_root_logger.propagate = False
+
+
+def _reset_library_root_logger() -> None:
+
+    global _default_handler
+
+    with _lock:
+        if not _default_handler:
+            return
+
+        library_root_logger = _get_library_root_logger()
+        library_root_logger.removeHandler(_default_handler)
+        library_root_logger.setLevel(logging.NOTSET)
+        _default_handler = None
+
+
+def get_logger(name: Optional[str] = None) -> logging.Logger:
+    """Return a logger with the specified name.
+    This function is not supposed to be directly accessed by library users.
+    """
+
+    if name is None:
+        name = _get_library_name()
+
+    _configure_library_root_logger()
+    return logging.getLogger(name)
+
+
+def get_verbosity() -> int:
+    """Return the current level for the HuggingFace Transformers's root logger.
+    Returns:
+        Logging level, e.g., ``transformers.logging.DEBUG`` and ``transformers.logging.INFO``.
+    .. note::
+        HuggingFace Transformers has following logging levels:
+        - ``transformers.logging.CRITICAL``, ``transformers.logging.FATAL``
+        - ``transformers.logging.ERROR``
+        - ``transformers.logging.WARNING``, ``transformers.logging.WARN``
+        - ``transformers.logging.INFO``
+        - ``transformers.logging.DEBUG``
+    """
+
+    _configure_library_root_logger()
+    return _get_library_root_logger().getEffectiveLevel()
+
+
+def set_verbosity(verbosity: int) -> None:
+    """Set the level for the HuggingFace Transformers's root logger.
+    Args:
+        verbosity:
+            Logging level, e.g., ``transformers.logging.DEBUG`` and ``transformers.logging.INFO``.
+    """
+
+    _configure_library_root_logger()
+    _get_library_root_logger().setLevel(verbosity)
+
+
+def set_verbosity_info():
+    return set_verbosity(INFO)
+
+
+def set_verbosity_warning():
+    return set_verbosity(WARNING)
+
+
+def set_verbosity_debug():
+    return set_verbosity(DEBUG)
+
+
+def set_verbosity_error():
+    return set_verbosity(ERROR)
+
+
+def disable_default_handler() -> None:
+    """Disable the default handler of the HuggingFace Transformers's root logger."""
+
+    _configure_library_root_logger()
+
+    assert _default_handler is not None
+    _get_library_root_logger().removeHandler(_default_handler)
+
+
+def enable_default_handler() -> None:
+    """Enable the default handler of the HuggingFace Transformers's root logger."""
+
+    _configure_library_root_logger()
+
+    assert _default_handler is not None
+    _get_library_root_logger().addHandler(_default_handler)
+
+
+def disable_propagation() -> None:
+    """Disable propagation of the library log outputs.
+    Note that log propagation is disabled by default.
+    """
+
+    _configure_library_root_logger()
+    _get_library_root_logger().propagate = False
+
+
+def enable_propagation() -> None:
+    """Enable propagation of the library log outputs.
+    Please disable the HuggingFace Transformers's default handler to prevent double logging if the root logger has
+    been configured.
+    """
+
+    _configure_library_root_logger()
+    _get_library_root_logger().propagate = True