gold/gold-threads.h

   1 // gold-threads.h -- thread support for gold  -*- C++ -*-
   2
   3 // gold can be configured to support threads.  If threads are
   4 // supported, the user can specify at runtime whether or not to
   5 // support them.  This provides an interface to manage locking
   6 // accordingly.
   7
   8 // Lock
   9 //   A simple lock class.
  10
  11 #ifndef GOLD_THREADS_H
  12 #define GOLD_THREADS_H
  13
  14 namespace gold
  15 {
  16
  17 class Lock_impl;
  18 class Condvar;
  19
  20 // A simple lock class.
  21
  22 class Lock
  23 {
  24  public:
  25   Lock();
  26   ~Lock();
  27
  28   // Acquire the lock.
  29   void
  30   acquire();
  31
  32   // Release the lock.
  33   void
  34   release();
  35
  36  private:
  37   // This class can not be copied.
  38   Lock(const Lock&);
  39   Lock& operator=(const Lock&);
  40
  41   friend class Condvar;
  42   Lock_impl*
  43   get_impl() const
  44   { return this->lock_; }
  45
  46   Lock_impl* lock_;
  47 };
  48
  49 // RAII for Lock.
  50
  51 class Hold_lock
  52 {
  53  public:
  54   Hold_lock(Lock& lock)
  55     : lock_(lock)
  56   { this->lock_.acquire(); }
  57
  58   ~Hold_lock()
  59   { this->lock_.release(); }
  60
  61  private:
  62   // This class can not be copied.
  63   Hold_lock(const Hold_lock&);
  64   Hold_lock& operator=(const Hold_lock&);
  65
  66   Lock& lock_;
  67 };
  68
  69 class Condvar_impl;
  70
  71 // A simple condition variable class.  It is always associated with a
  72 // specific lock.
  73
  74 class Condvar
  75 {
  76  public:
  77   Condvar(Lock& lock);
  78   ~Condvar();
  79
  80   // Wait for the condition variable to be signalled.  This should
  81   // only be called when the lock is held.
  82   void
  83   wait();
  84
  85   // Signal the condition variable.  This should only be called when
  86   // the lock is held.
  87   void
  88   signal();
  89
  90  private:
  91   // This class can not be copied.
  92   Condvar(const Condvar&);
  93   Condvar& operator=(const Condvar&);
  94
  95   Lock& lock_;
  96   Condvar_impl* condvar_;
  97 };
  98
  99 } // End namespace gold.
 100
 101 #endif // !defined(GOLD_THREADS_H)