plomlompom.com Git - misc/blob - plomlib.py

   1 import os
   2 from http.server import BaseHTTPRequestHandler
   3
   4
   5 class PlomException(Exception):
   6     pass
   7
   8
   9 class PlomDB:
  10
  11     def __init__(self, db_name):
  12         self.db_file = db_name
  13         self.lock_file = db_name+ '.lock'
  14         if os.path.exists(self.db_file):
  15             with open(self.db_file, 'r') as f:
  16                 self.read_db_file(f)
  17
  18     def lock(self):
  19         if os.path.exists(self.lock_file):
  20             raise PlomException('Sorry, lock file!')
  21         f = open(self.lock_file, 'w+')
  22         f.close()
  23
  24     def unlock(self):
  25         os.remove(self.lock_file)
  26
  27     def backup(self):
  28         import shutil
  29         from datetime import datetime, timedelta
  30         if not os.path.exists(self.db_file):
  31             return
  32
  33         # collect modification times of numbered .bak files
  34         bak_prefix = f'{self.db_file}.bak.'
  35         backup_dates = []
  36         i = 0
  37         bak_as = f'{bak_prefix}{i}'
  38         while os.path.exists(bak_as):
  39             mod_time = os.path.getmtime(bak_as)
  40             backup_dates += [str(datetime.fromtimestamp(mod_time))]
  41             i += 1
  42             bak_as = f'{bak_prefix}{i}'
  43
  44         # collect what numbered .bak files to save: the older, the fewer; for each
  45         # timedelta, keep the newest file that's older
  46         ages_to_keep = [timedelta(minutes=4**i) for i in range(0, 8)]
  47         now = datetime.now()
  48         to_save = []
  49         for age in ages_to_keep:
  50             limit = now - age
  51             for i, date in enumerate(reversed(backup_dates)):
  52                 if datetime.strptime(date, '%Y-%m-%d %H:%M:%S.%f') < limit:
  53                     unreversed_i = len(backup_dates) - i - 1
  54                     if unreversed_i not in to_save:
  55                         to_save += [unreversed_i]
  56                     break
  57
  58         # remove redundant backup files
  59         j = 0
  60         for i in to_save:
  61             if i != j:
  62                 source = f'{bak_prefix}{i}'
  63                 target = f'{bak_prefix}{j}'
  64                 shutil.move(source, target)
  65             j += 1
  66         for i in range(j, len(backup_dates)):
  67             try:
  68                 os.remove(f'{bak_prefix}{i}')
  69             except FileNotFoundError:
  70                 pass
  71
  72         # put copy of current state at end of bak list
  73         shutil.copy(self.db_file, f'{bak_prefix}{j}')
  74
  75     def write_text_to_db(self, text, mode='w'):
  76         self.lock()
  77         self.backup()
  78         with open(self.db_file, mode) as f:
  79             f.write(text);
  80         self.unlock()
  81
  82
  83 class PlomHandler(BaseHTTPRequestHandler):
  84     homepage = '/'
  85     html_head = '<!DOCTYPE html>\n<html>\n<meta charset="UTF-8">'
  86     html_foot = '</body>\n</html>'
  87
  88     def fail_400(self, e):
  89         self.send_HTML(f'ERROR: {e}', 400)
  90
  91     def send_HTML(self, html, code=200):
  92         self.send_code_and_headers(code, [('Content-type', 'text/html')])
  93         self.wfile.write(bytes(f'{self.html_head}\n{html}\n{self.html_foot}', 'utf-8'))
  94
  95     def send_code_and_headers(self, code, headers=[]):
  96         self.send_response(code)
  97         for fieldname, content in headers:
  98             self.send_header(fieldname, content)
  99         self.end_headers()
 100
 101     def redirect(self, url='/'):
 102         self.send_code_and_headers(302, [('Location', url)])
 103
 104     def try_do(self, do_method):
 105         try:
 106             do_method()
 107         except PlomException as e:
 108             self.fail_400(e)
 109
 110
 111
 112 def run_server(port, handler_class):
 113     from http.server import HTTPServer
 114     webServer = HTTPServer(('localhost', port), handler_class)
 115     print(f"Server started http://localhost:{port}")
 116     try:
 117         webServer.serve_forever()
 118     except KeyboardInterrupt:
 119         pass
 120     webServer.server_close()
 121     print("Server stopped.")