# Copyright (c) 2022, NVIDIA CORPORATION. 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 json
import os
from nvflare.apis.event_type import EventType
from nvflare.apis.fl_constant import FLContextKey
from nvflare.apis.fl_context import FLContext
from nvflare.app_common.abstract.model import ModelLearnable, ModelLearnableKey, make_model_learnable
from nvflare.app_common.abstract.model_persistor import ModelPersistor
from nvflare.app_common.app_constant import AppConstants
[docs]class XGBModelPersistor(ModelPersistor):
def __init__(self, save_name="xgboost_model.json", load_as_dict=True):
super().__init__()
self.save_name = save_name
self.load_as_dict = load_as_dict
def _initialize(self, fl_ctx: FLContext):
# get save path from FLContext
app_root = fl_ctx.get_prop(FLContextKey.APP_ROOT)
self.log_dir = app_root
self.save_path = os.path.join(self.log_dir, self.save_name)
if not os.path.exists(self.log_dir):
os.makedirs(self.log_dir)
fl_ctx.sync_sticky()
[docs] def load_model(self, fl_ctx: FLContext) -> ModelLearnable:
"""Initialize and load the Model.
Args:
fl_ctx: FLContext
Returns:
ModelLearnable object
"""
model = None
if os.path.exists(self.save_path):
self.logger.info("Loading server model")
with open(self.save_path, "r") as json_file:
model = json.load(json_file)
if not self.load_as_dict:
model = bytearray(json.dumps(model), "utf-8")
else:
self.logger.info("Initializing server model as None")
model_learnable = make_model_learnable(weights=model, meta_props=dict())
return model_learnable
[docs] def handle_event(self, event: str, fl_ctx: FLContext):
if event == EventType.START_RUN:
self._initialize(fl_ctx)
[docs] def save_model(self, model_learnable: ModelLearnable, fl_ctx: FLContext):
"""Persists the Model object.
Args:
model_learnable: ModelLearnable object
fl_ctx: FLContext
"""
if model_learnable:
if fl_ctx.get_prop(AppConstants.CURRENT_ROUND) == fl_ctx.get_prop(AppConstants.NUM_ROUNDS) - 1:
self.logger.info(f"Saving received model to {os.path.abspath(self.save_path)}")
# save 'weights' which is actual model, loadable by xgboost library
model = model_learnable[ModelLearnableKey.WEIGHTS]
with open(self.save_path, "w") as f:
if isinstance(model, dict):
json.dump(model, f)
elif isinstance(model, bytes) or isinstance(model, bytearray) or isinstance(model, str):
# should already be json, but double check by loading and dumping at some extra cost
json.dump(json.loads(model), f)
else:
self.logger.error("unknown model format")
self.system_panic(reason="No global base model!", fl_ctx=fl_ctx)