import cPickle as pickle
 
 class HashCache(object):
     def __init__(self):
         self.inodes = dict()

     def add(self, dev, inode, mtime, size, md5):
         if dev not in self.inodes:
             self.inodes[dev] = dict()
         if inode not in self.inodes[dev]:
             self.inodes[dev][inode] = dict()
         self.inodes[dev][inode][mtime] = dict(md5=md5, size=size)
 
     def md5(self, dev, inode, mtime, size):
         try:
             d = self.inodes[dev][inode][mtime]
             if d['size'] != size:
                 return None
         except:
             return None
         return d['md5']
 
     def mark_all_for_purge(self):
         for d in self.inodes.keys():
             for i in self.inodes[d].keys():
                 for c in self.inodes[d][i].keys():
                     self.inodes[d][i][c]['purge'] = True
 
     def unmark_for_purge(self, dev, inode, mtime, size):
         d = self.inodes[dev][inode][mtime]
         if d['size'] == size and 'purge' in d:
             del self.inodes[dev][inode][mtime]['purge']
 
     def purge(self):
         for d in self.inodes.keys():
             for i in self.inodes[d].keys():
                 for m in self.inodes[d][i].keys():
                     if 'purge' in self.inodes[d][i][m]:
                         del self.inodes[d][i]

                         break

     def save(self, f):
         d = dict(inodes=self.inodes, version=1)
         f = open(f, 'w')
         p = pickle.dump(d, f)
         f.close()
 
     def load(self, f):
         f = open(f, 'r')
         d = pickle.load(f)
         f.close()
         if d.get('version') == 1 and 'inodes' in d:
             self.inodes = d['inodes']