Source Code for Module arvados.cache

 1  # Copyright (C) The Arvados Authors. All rights reserved. 
 2  # 
 3  # SPDX-License-Identifier: Apache-2.0 
 4   
 5  from builtins import object 
 6  import errno 
 7  import hashlib 
 8  import os 
 9  import tempfile 
10  import time 
11   
12 -class SafeHTTPCache(object): 
13      """Thread-safe replacement for httplib2.FileCache""" 
14   
15 -    def __init__(self, path=None, max_age=None): 
16          self._dir = path 
17          if max_age is not None: 
18              try: 
19                  self._clean(threshold=time.time() - max_age) 
20              except: 
21                  pass 
22   
23 -    def _clean(self, threshold=0): 
24          for ent in os.listdir(self._dir): 
25              fnm = os.path.join(self._dir, ent) 
26              if os.path.isdir(fnm) or not fnm.endswith('.tmp'): 
27                  continue 
28              stat = os.lstat(fnm) 
29              if stat.st_mtime < threshold: 
30                  try: 
31                      os.unlink(fnm) 
32                  except OSError as err: 
33                      if err.errno != errno.ENOENT: 
34                          raise 
35   
36 -    def __str__(self): 
37          return self._dir 
38   
39 -    def _filename(self, url): 
40          return os.path.join(self._dir, hashlib.md5(url.encode('utf-8')).hexdigest()+'.tmp') 
41   
42 -    def get(self, url): 
43          filename = self._filename(url) 
44          try: 
45              with open(filename, 'rb') as f: 
46                  return f.read() 
47          except (IOError, OSError): 
48              return None 
49   
50 -    def set(self, url, content): 
51          try: 
52              fd, tempname = tempfile.mkstemp(dir=self._dir) 
53          except: 
54              return None 
55          try: 
56              try: 
57                  f = os.fdopen(fd, 'wb') 
58              except: 
59                  os.close(fd) 
60                  raise 
61              try: 
62                  f.write(content) 
63              finally: 
64                  f.close() 
65              os.rename(tempname, self._filename(url)) 
66              tempname = None 
67          finally: 
68              if tempname: 
69                  os.unlink(tempname) 
70   
71 -    def delete(self, url): 
72          try: 
73              os.unlink(self._filename(url)) 
74          except OSError as err: 
75              if err.errno != errno.ENOENT: 
76                  raise 
77