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FileHandler for Sessions

Specification

Summary

The FileHandler will provide Handler-interface to file storage. It will store pickled data, session id & client’s IP address in specified directory as files. Also retreiving & removing requested data by id will be implemented. On request the FileHandler will perform a generall clean up -> delete old session files.

Implementation details

FileHandler is a derivate of Handler. All files will be created in the directory web.config.handler_parameters.file_dir with prefix web.config.handler_parameters.file_prefix.

Public methods

  • store() - it will store the session data (& pickle them before that); if the argument _old_id is set, it will look for an already storaged session data, it will create locks on both old & new session files, it will try to retreive time of the old session creation; after the pickle data is stored, the lock will be released; it will call _acquire_lock(), _release_lock() and _session_file()
  • retreive() - it will retreive storaged data unpickled in a Storage object ( id, ip, time, data), if there aren’t any for given id, it will return empty Storage object; all necessary lock procedures will be used; it will call _acquire_lock(), _release_lock() and _session_file()
  • remove() - it will remove storaged data for given id; all necessary lock procedures will be used, it will simply unlink the session file (ignoring if it’s not existing); it will call _acquire_lock(), _release_lock() and _session_file()
  • clean() - it will remove all session data, which been updated longer then before given timeout; all necessary lock procedures will be used (however not blocking); it will call _acquire_lock() and _release_lock()

Private methods

  • _session_file() - it will return the full name of the session storage file
  • _lock_file() - it will return the full name of the session storage lock file; ; it will call _session_file()
  • _acquire_lock() - it will create a lock file; if the lock file is already present, it will check, that the lock file is not older than 60s, in that case the old lock file will be erased; if blocking is set False, it will not wait; it will call _lock_file()
  • _release_lock() - it will simply unlink the session lock file (ignoring if it’s not existing); it will call _lock_file()

Requirements

FileHandler will need a storage directory (web.config.handler_parameters.file_dir) on the filesystem with write (& read) permission.

Sessions specs