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# Copyright 2023 The TensorFlow Authors. All Rights Reserved.
#
# 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.
"""Utilities to save models."""
import os
import typing
from absl import logging
import tensorflow as tf, tf_keras
def export_bert_model(model_export_path: typing.Text,
model: tf_keras.Model,
checkpoint_dir: typing.Optional[typing.Text] = None,
restore_model_using_load_weights: bool = False) -> None:
"""Export BERT model for serving which does not include the optimizer.
Args:
model_export_path: Path to which exported model will be saved.
model: Keras model object to export.
checkpoint_dir: Path from which model weights will be loaded, if
specified.
restore_model_using_load_weights: Whether to use checkpoint.restore() API
for custom checkpoint or to use model.load_weights() API. There are 2
different ways to save checkpoints. One is using tf.train.Checkpoint and
another is using Keras model.save_weights(). Custom training loop
implementation uses tf.train.Checkpoint API and Keras ModelCheckpoint
callback internally uses model.save_weights() API. Since these two API's
cannot be used toghether, model loading logic must be take into account
how model checkpoint was saved.
Raises:
ValueError when either model_export_path or model is not specified.
"""
if not model_export_path:
raise ValueError('model_export_path must be specified.')
if not isinstance(model, tf_keras.Model):
raise ValueError('model must be a tf_keras.Model object.')
if checkpoint_dir:
if restore_model_using_load_weights:
model_weight_path = os.path.join(checkpoint_dir, 'checkpoint')
assert tf.io.gfile.exists(model_weight_path)
model.load_weights(model_weight_path)
else:
checkpoint = tf.train.Checkpoint(model=model)
# Restores the model from latest checkpoint.
latest_checkpoint_file = tf.train.latest_checkpoint(checkpoint_dir)
assert latest_checkpoint_file
logging.info('Checkpoint file %s found and restoring from '
'checkpoint', latest_checkpoint_file)
checkpoint.restore(
latest_checkpoint_file).assert_existing_objects_matched()
model.save(model_export_path, include_optimizer=False, save_format='tf')