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restore_wizard.py
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restore_wizard.py
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# Copyright 2019 The FastEstimator 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.
# ==============================================================================
import os
import shutil
from typing import List, Union
import fastestimator as fe
from fastestimator.trace.trace import Trace
from fastestimator.util.data import Data
from fastestimator.util.traceability_util import traceable
from fastestimator.util.base_util import to_list
@traceable()
class RestoreWizard(Trace):
"""A trace that can backup and load your entire training status.
Args:
directory: Directory to save and load the training status.
frequency: Saving frequency in epoch(s).
"""
def __init__(self, directory: str, frequency: int = 1) -> None:
super().__init__(inputs="*", mode="train") # inputs to cause this trace to sort to the end of the list
self.directory = os.path.abspath(os.path.normpath(directory))
self.frequency = frequency
# For robust saving, we need to create 2 different directories and have a key file to switch between them
self.dirs = [os.path.join(self.directory, 'A'), os.path.join(self.directory, 'B')]
self.key_path = os.path.join(self.directory, 'key.txt')
self.dir_idx = 0
def on_begin(self, data: Data) -> None:
if fe.fe_deterministic_seed is not None:
raise RuntimeError("You cannot use RestoreWizard while in deterministic training mode since a restored" +
" training can't guarantee that all prngs will be reset to exactly the same position")
if not self.should_restore():
self._cleanup(self.dirs) # Remove any partially completed checkpoints
print("FastEstimator-RestoreWizard: Backing up to {}".format(self.directory))
else:
self._load_key()
directory = self.dirs[self.dir_idx]
self.system.load_state(directory)
data.write_with_log("epoch", self.system.epoch_idx)
print("FastEstimator-RestoreWizard: Restoring from {}, resume training".format(directory))
self.dir_idx = int(not self.dir_idx) # Flip the idx so that next save goes to other dir
self._cleanup(self.dirs[self.dir_idx]) # Clean out the other dir in case it had a partial save
def on_epoch_end(self, data: Data) -> None:
if self.system.epoch_idx % self.frequency == 0:
directory = self.dirs[self.dir_idx]
self.system.save_state(directory)
self._write_key()
# Everything after this is free to die without causing problems with restore
self.dir_idx = int(not self.dir_idx)
self._cleanup(self.dirs[self.dir_idx])
print("FastEstimator-RestoreWizard: Saved milestones to {}".format(directory))
def should_restore(self) -> bool:
"""Whether a restore will be performed.
Returns:
True iff the wizard will perform a restore.
"""
return os.path.exists(self.directory) and os.path.exists(self.key_path)
def _load_key(self) -> None:
"""Set the dir_idx based on the key last saved by the restore wizard.
Raises:
ValueError: If the key file has been modified.
"""
with open(self.key_path, 'r') as key_file:
key = key_file.readline()
if key not in ('A', 'B'):
raise ValueError("RestoreWizard encountered an invalid key file at {}. Either delete it to restart, or undo"
" whatever manual changes were made to the file.".format(self.key_path))
self.dir_idx = 0 if key == 'A' else 1
def _write_key(self) -> None:
"""Generate a new key file and then atomically replace the old key file.
"""
sub_dir = self.dirs[self.dir_idx]
new_key_path = os.path.join(sub_dir, 'key.txt')
with open(new_key_path, 'w') as new_key_file:
new_key_file.write("B" if self.dir_idx else "A")
os.replace(new_key_path, self.key_path) # This operation is atomic per POSIX requirements
@staticmethod
def _cleanup(paths: Union[str, List[str]]) -> None:
"""Delete stale directories if they exist.
Args:
paths: Which directories to delete.
"""
paths = to_list(paths)
for path in paths:
if os.path.exists(path):
shutil.rmtree(path)