ACE/apps/JAWS/clients/Caching/ID_Generator.h

   1 /* -*- C++ -*- */
   2
   3
   4 //=============================================================================
   5 /**
   6  *  @file    ID_Generator.h
   7  *
   8  *  @author Nanbor Wang
   9  */
  10 //=============================================================================
  11
  12
  13 #ifndef ACE_ID_GENERATOR_H
  14 #define ACE_ID_GENERATOR_h
  15
  16 #include "ace/config-all.h"
  17
  18 #if !defined (ACE_LACKS_PRAGMA_ONCE)
  19 # pragma once
  20 #endif /* ACE_LACKS_PRAGMA_ONCE */
  21
  22 #define ACE_OFFER_ID_LENGTH 21
  23
  24 /**
  25  * @class ACE_ID_Generator
  26  *
  27  * @brief An unique ID generator.
  28  */
  29 class ACE_ID_Generator
  30
  31   //     Generate an offer ID according to current time and avoid
  32   //     duplicate ID.  It guarantees ID uniqueness within a process,
  33   //     i.e. no two threads may get the same ID string.  Using a
  34   //     similar method like the backery algorithm.
  35 {
  36 public:
  37   /// allocate a new ID string and point <id> to it.
  38   static char *get_new_id (char *id);
  39
  40 private:
  41   /// Atomically get info required to generate an offer ID.
  42   static void get_serial_id (time_t &t, size_t &s);
  43
  44   /// Get the lock instance.
  45   static ACE_SYNCH_MUTEX *get_lock ();
  46
  47   /// Record the time last offer ID generated.
  48   static time_t last_time_;
  49
  50   /// Record serial number of last offer ID with same
  51   /// generation time.
  52   static size_t last_number_;
  53
  54   /// mutex to access private member.
  55   static ACE_SYNCH_MUTEX *lock_;
  56 };
  57
  58 #endif /* ACE_ID_GENERATOR_H */