gold/gold-threads.h

   1 // gold-threads.h -- thread support for gold  -*- C++ -*-
   2
   3 // Copyright 2006, 2007 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 // gold can be configured to support threads.  If threads are
  24 // supported, the user can specify at runtime whether or not to
  25 // support them.  This provides an interface to manage locking
  26 // accordingly.
  27
  28 // Lock
  29 //   A simple lock class.
  30
  31 #ifndef GOLD_THREADS_H
  32 #define GOLD_THREADS_H
  33
  34 namespace gold
  35 {
  36
  37 class Lock_impl;
  38 class Condvar;
  39
  40 // A simple lock class.
  41
  42 class Lock
  43 {
  44  public:
  45   Lock();
  46   ~Lock();
  47
  48   // Acquire the lock.
  49   void
  50   acquire();
  51
  52   // Release the lock.
  53   void
  54   release();
  55
  56  private:
  57   // This class can not be copied.
  58   Lock(const Lock&);
  59   Lock& operator=(const Lock&);
  60
  61   friend class Condvar;
  62   Lock_impl*
  63   get_impl() const
  64   { return this->lock_; }
  65
  66   Lock_impl* lock_;
  67 };
  68
  69 // RAII for Lock.
  70
  71 class Hold_lock
  72 {
  73  public:
  74   Hold_lock(Lock& lock)
  75     : lock_(lock)
  76   { this->lock_.acquire(); }
  77
  78   ~Hold_lock()
  79   { this->lock_.release(); }
  80
  81  private:
  82   // This class can not be copied.
  83   Hold_lock(const Hold_lock&);
  84   Hold_lock& operator=(const Hold_lock&);
  85
  86   Lock& lock_;
  87 };
  88
  89 class Condvar_impl;
  90
  91 // A simple condition variable class.  It is always associated with a
  92 // specific lock.
  93
  94 class Condvar
  95 {
  96  public:
  97   Condvar(Lock& lock);
  98   ~Condvar();
  99
 100   // Wait for the condition variable to be signalled.  This should
 101   // only be called when the lock is held.
 102   void
 103   wait();
 104
 105   // Signal the condition variable.  This should only be called when
 106   // the lock is held.
 107   void
 108   signal();
 109
 110  private:
 111   // This class can not be copied.
 112   Condvar(const Condvar&);
 113   Condvar& operator=(const Condvar&);
 114
 115   Lock& lock_;
 116   Condvar_impl* condvar_;
 117 };
 118
 119 } // End namespace gold.
 120
 121 #endif // !defined(GOLD_THREADS_H)