feat: improve the synced enforcer like Go casbin #130

	# Copyright 2021 The casbin 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.

	name: Memcheck

	on: [push, pull_request]

	jobs:
	linux:
	name: "Linux Ubuntu 20.04 (GNU 9.3.0)"
	runs-on: ubuntu-20.04
	steps:
	- name: Checkout
	id: checkout
	uses: actions/checkout@v2
	- name: Install requirement
	id: install-requirements
	run: \|
	sudo apt-get update
	sudo apt-get install valgrind
	- name: Configuring CMake files
	id: building-files
	run: \|
	mkdir build && cd build && cmake .. -DCMAKE_BUILD_TYPE=Release
	- name: Building library
	id: building-lib
	run: \|
	cd build && cmake --build . --config Release --target all -j 10 --
	- name: Memcheck
	id: memcheck
	run: \|
	cd build
	ctest -j10 -C Release -T MemCheck --output-on-failure
	- name: Cleanup
	id: clean-up
	run: \|
	rm -r build

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