binutils-gdb/gold/gold-threads.cc

404 lines
8.5 KiB
C++

// gold-threads.cc -- thread support for gold
// 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.
#include "gold.h"
#include <cstring>
#ifdef ENABLE_THREADS
#include <pthread.h>
#endif
#include "options.h"
#include "parameters.h"
#include "gold-threads.h"
namespace gold
{
class Condvar_impl_nothreads;
// The non-threaded version of Lock_impl.
class Lock_impl_nothreads : public Lock_impl
{
public:
Lock_impl_nothreads()
: acquired_(false)
{ }
~Lock_impl_nothreads()
{ gold_assert(!this->acquired_); }
void
acquire()
{
gold_assert(!this->acquired_);
this->acquired_ = true;
}
void
release()
{
gold_assert(this->acquired_);
this->acquired_ = false;
}
private:
friend class Condvar_impl_nothreads;
bool acquired_;
};
#ifdef ENABLE_THREADS
class Condvar_impl_threads;
// The threaded version of Lock_impl.
class Lock_impl_threads : public Lock_impl
{
public:
Lock_impl_threads();
~Lock_impl_threads();
void acquire();
void release();
private:
// This class can not be copied.
Lock_impl_threads(const Lock_impl_threads&);
Lock_impl_threads& operator=(const Lock_impl_threads&);
friend class Condvar_impl_threads;
pthread_mutex_t mutex_;
};
Lock_impl_threads::Lock_impl_threads()
{
pthread_mutexattr_t attr;
int err = pthread_mutexattr_init(&attr);
if (err != 0)
gold_fatal(_("pthead_mutextattr_init failed: %s"), strerror(err));
#ifdef PTHREAD_MUTEXT_ADAPTIVE_NP
err = pthread_mutextattr_settype(&attr, PTHREAD_MUTEX_ADAPTIVE_NP);
if (err != 0)
gold_fatal(_("pthread_mutextattr_settype failed: %s"), strerror(err));
#endif
err = pthread_mutex_init (&this->mutex_, &attr);
if (err != 0)
gold_fatal(_("pthread_mutex_init failed: %s"), strerror(err));
err = pthread_mutexattr_destroy(&attr);
if (err != 0)
gold_fatal(_("pthread_mutexattr_destroy failed: %s"), strerror(err));
}
Lock_impl_threads::~Lock_impl_threads()
{
int err = pthread_mutex_destroy(&this->mutex_);
if (err != 0)
gold_fatal(_("pthread_mutex_destroy failed: %s"), strerror(err));
}
void
Lock_impl_threads::acquire()
{
int err = pthread_mutex_lock(&this->mutex_);
if (err != 0)
gold_fatal(_("pthread_mutex_lock failed: %s"), strerror(err));
}
void
Lock_impl_threads::release()
{
int err = pthread_mutex_unlock(&this->mutex_);
if (err != 0)
gold_fatal(_("pthread_mutex_unlock failed: %s"), strerror(err));
}
#endif // defined(ENABLE_THREADS)
// Class Lock.
Lock::Lock()
{
if (!parameters->options().threads())
this->lock_ = new Lock_impl_nothreads;
else
{
#ifdef ENABLE_THREADS
this->lock_ = new Lock_impl_threads;
#else
gold_unreachable();
#endif
}
}
Lock::~Lock()
{
delete this->lock_;
}
// The non-threaded version of Condvar_impl.
class Condvar_impl_nothreads : public Condvar_impl
{
public:
Condvar_impl_nothreads()
{ }
~Condvar_impl_nothreads()
{ }
void
wait(Lock_impl* li)
{ gold_assert(static_cast<Lock_impl_nothreads*>(li)->acquired_); }
void
signal()
{ }
void
broadcast()
{ }
};
#ifdef ENABLE_THREADS
// The threaded version of Condvar_impl.
class Condvar_impl_threads : public Condvar_impl
{
public:
Condvar_impl_threads();
~Condvar_impl_threads();
void
wait(Lock_impl*);
void
signal();
void
broadcast();
private:
// This class can not be copied.
Condvar_impl_threads(const Condvar_impl_threads&);
Condvar_impl_threads& operator=(const Condvar_impl_threads&);
pthread_cond_t cond_;
};
Condvar_impl_threads::Condvar_impl_threads()
{
int err = pthread_cond_init(&this->cond_, NULL);
if (err != 0)
gold_fatal(_("pthread_cond_init failed: %s"), strerror(err));
}
Condvar_impl_threads::~Condvar_impl_threads()
{
int err = pthread_cond_destroy(&this->cond_);
if (err != 0)
gold_fatal(_("pthread_cond_destroy failed: %s"), strerror(err));
}
void
Condvar_impl_threads::wait(Lock_impl* li)
{
Lock_impl_threads* lit = static_cast<Lock_impl_threads*>(li);
int err = pthread_cond_wait(&this->cond_, &lit->mutex_);
if (err != 0)
gold_fatal(_("pthread_cond_wait failed: %s"), strerror(err));
}
void
Condvar_impl_threads::signal()
{
int err = pthread_cond_signal(&this->cond_);
if (err != 0)
gold_fatal(_("pthread_cond_signal failed: %s"), strerror(err));
}
void
Condvar_impl_threads::broadcast()
{
int err = pthread_cond_broadcast(&this->cond_);
if (err != 0)
gold_fatal(_("pthread_cond_broadcast failed: %s"), strerror(err));
}
#endif // defined(ENABLE_THREADS)
// Methods for Condvar class.
Condvar::Condvar(Lock& lock)
: lock_(lock)
{
if (!parameters->options().threads())
this->condvar_ = new Condvar_impl_nothreads;
else
{
#ifdef ENABLE_THREADS
this->condvar_ = new Condvar_impl_threads;
#else
gold_unreachable();
#endif
}
}
Condvar::~Condvar()
{
delete this->condvar_;
}
#ifdef ENABLE_THREADS
// Class Initialize_lock_once. This exists to hold a pthread_once_t
// structure for Initialize_lock.
class Initialize_lock_once
{
public:
Initialize_lock_once()
: once_(PTHREAD_ONCE_INIT)
{ }
// Return a pointer to the pthread_once_t variable.
pthread_once_t*
once_control()
{ return &this->once_; }
private:
pthread_once_t once_;
};
#endif // !defined(ENABLE_THREADS)
#ifdef ENABLE_THREADS
// A single lock which controls access to initialize_lock_pointer.
// This is used because we can't pass parameters to functions passed
// to pthread_once.
static pthread_mutex_t initialize_lock_control = PTHREAD_MUTEX_INITIALIZER;
// A pointer to a pointer to the lock which we need to initialize
// once. Access to this is controlled by initialize_lock_control.
static Lock** initialize_lock_pointer;
// A routine passed to pthread_once which initializes the lock which
// initialize_lock_pointer points to.
extern "C"
{
static void
initialize_lock_once()
{
*initialize_lock_pointer = new Lock();
}
}
#endif // !defined(ENABLE_THREADS)
// Class Initialize_lock.
Initialize_lock::Initialize_lock(Lock** pplock)
: pplock_(pplock)
{
#ifndef ENABLE_THREADS
this->once_ = NULL;
#else
this->once_ = new Initialize_lock_once();
#endif
}
// Initialize the lock.
bool
Initialize_lock::initialize()
{
// If the lock has already been initialized, we don't need to do
// anything. Note that this assumes that the pointer value will be
// set completely or not at all. I hope this is always safe. We
// want to do this for efficiency.
if (*this->pplock_ != NULL)
return true;
// We can't initialize the lock until we have read the options.
if (!parameters->options_valid())
return false;
// If the user did not use --threads, then we can initialize
// directly.
if (!parameters->options().threads())
{
*this->pplock_ = new Lock();
return true;
}
#ifndef ENABLE_THREADS
// If there is no threads support, we don't need to use
// pthread_once.
*this->pplock_ = new Lock();
#else // !defined(ENABLE_THREADS)
// Since we can't pass parameters to routines called by
// pthread_once, we use a static variable: initialize_lock_pointer.
// That in turns means that we need to use a mutex to control access
// to initialize_lock_pointer.
int err = pthread_mutex_lock(&initialize_lock_control);
if (err != 0)
gold_fatal(_("pthread_mutex_lock failed: %s"), strerror(err));
initialize_lock_pointer = this->pplock_;
err = pthread_once(this->once_->once_control(), initialize_lock_once);
if (err != 0)
gold_fatal(_("pthread_once failed: %s"), strerror(err));
initialize_lock_pointer = NULL;
err = pthread_mutex_unlock(&initialize_lock_control);
if (err != 0)
gold_fatal(_("pthread_mutex_unlock failed: %s"), strerror(err));
gold_assert(*this->pplock_ != NULL);
#endif // !defined(ENABLE_THREADS)
return true;
}
} // End namespace gold.