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// gold-threads.h -- thread support for gold -*- C++ -*-
// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
// gold can be configured to support threads. If threads are
// supported, the user can specify at runtime whether or not to
// support them. This provides an interface to manage locking
// accordingly.
// Lock
// A simple lock class.
#ifndef GOLD_THREADS_H
#define GOLD_THREADS_H
namespace gold
{
class Condvar;
// The interface for the implementation of a Lock.
class Lock_impl
{
public:
Lock_impl()
{ }
virtual
~Lock_impl()
{ }
virtual void
acquire() = 0;
virtual void
release() = 0;
};
// A simple lock class.
class Lock
{
public:
Lock();
~Lock();
// Acquire the lock.
void
acquire()
{ this->lock_->acquire(); }
// Release the lock.
void
release()
{ this->lock_->release(); }
private:
// This class can not be copied.
Lock(const Lock&);
Lock& operator=(const Lock&);
friend class Condvar;
Lock_impl*
get_impl() const
{ return this->lock_; }
Lock_impl* lock_;
};
// RAII for Lock.
class Hold_lock
{
public:
Hold_lock(Lock& lock)
: lock_(lock)
{ this->lock_.acquire(); }
~Hold_lock()
{ this->lock_.release(); }
private:
// This class can not be copied.
Hold_lock(const Hold_lock&);
Hold_lock& operator=(const Hold_lock&);
Lock& lock_;
};
class Hold_optional_lock
{
public:
Hold_optional_lock(Lock* lock)
: lock_(lock)
{
if (this->lock_ != NULL)
this->lock_->acquire();
}
~Hold_optional_lock()
{
if (this->lock_ != NULL)
this->lock_->release();
}
private:
Hold_optional_lock(const Hold_optional_lock&);
Hold_optional_lock& operator=(const Hold_optional_lock&);
Lock* lock_;
};
// The interface for the implementation of a condition variable.
class Condvar_impl
{
public:
Condvar_impl()
{ }
virtual
~Condvar_impl()
{ }
virtual void
wait(Lock_impl*) = 0;
virtual void
signal() = 0;
virtual void
broadcast() = 0;
};
// A simple condition variable class. It is always associated with a
// specific lock.
class Condvar
{
public:
Condvar(Lock& lock);
~Condvar();
// Wait for the condition variable to be signalled. This should
// only be called when the lock is held.
void
wait()
{ this->condvar_->wait(this->lock_.get_impl()); }
// Signal the condition variable--wake up at least one thread
// waiting on the condition variable. This should only be called
// when the lock is held.
void
signal()
{ this->condvar_->signal(); }
// Broadcast the condition variable--wake up all threads waiting on
// the condition variable. This should only be called when the lock
// is held.
void
broadcast()
{ this->condvar_->broadcast(); }
private:
// This class can not be copied.
Condvar(const Condvar&);
Condvar& operator=(const Condvar&);
Lock& lock_;
Condvar_impl* condvar_;
};
} // End namespace gold.
#endif // !defined(GOLD_THREADS_H)
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