import os
import shutil
import datetime
import threading
import time
import inspect
import ctypes
import hashlib

PATH_DIR = "./"

# 求字符串的md5码
def md5_str(org_str):
    md5obj = hashlib.md5()
    md5obj.update(str(org_str).encode("utf8"))
    _hash = md5obj.hexdigest()
    return str(_hash).upper()

# 求一个文件的md5码
def get_file_md5(file_path):
    """
    获取文件md5值
    :param file_path: 文件路径名
    :return: 文件md5值
    """
    with open(file_path, 'rb') as f:
        return md5_str(f.read())

# 求一个文件夹下所有文件MD5码总和的MD5码
def get_path_files(files_path):
    md5_total = ""
    for parent, dirnames, filenames in os.walk(files_path,  followlinks=True):
            for filename in filenames:
                file_path = os.path.join(parent, filename)
                md5_total += get_file_md5(file_path)
    return md5_str(md5_total)

def _async_raise(tid, exctype):
   """raises the exception, performs cleanup if needed"""
   tid = ctypes.c_long(tid)
   if not inspect.isclass(exctype):
      exctype = type(exctype)
   res = ctypes.pythonapi.PyThreadState_SetAsyncExc(tid, ctypes.py_object(exctype))
   if res == 0:
      raise ValueError("invalid thread id")
   elif res != 1:
      # """if it returns a number greater than one, you're in trouble,
      # and you should call it again with exc=NULL to revert the effect"""
      ctypes.pythonapi.PyThreadState_SetAsyncExc(tid, None)
      raise SystemError("PyThreadState_SetAsyncExc failed")

# 配合上个_async_raise函数，优雅关闭线程
def stop_thread(thread):
   _async_raise(thread.ident, SystemExit)

# 示例线程
class TestThread(threading.Thread):
   def run(self):
      print("begin")
      time.sleep(0.1)
      print('end')

# 先启动线程，并进行文件夹内所有文件的MD5码求值
t = TestThread()
t.start()
t.join()
files_md5 = get_path_files(PATH_DIR)

while True:
    # 每隔sleep时间，作一次文件夹MD5码求值，如果发生了变化，说明文件更新，则关闭线程，然后重启线程，实现服务的热加载。
    new_files_md5 = get_path_files(PATH_DIR)
    print(new_files_md5)
    if new_files_md5 == files_md5:
        pass
    else:
        files_md5 = new_files_md5
        print("stop thread")
        try:
            stop_thread(t)
        except ValueError as e:
            print(e)
        except SystemError as e:
            print(e)

        finally:
            print("start thread")
            t = TestThread()
            t.start()
            t.join()
    time.sleep(5)