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https://sourceware.org/git/binutils-gdb.git
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451 lines
9.0 KiB
C++
451 lines
9.0 KiB
C++
// gold-threads.cc -- thread support for gold
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// Copyright (C) 2006-2014 Free Software Foundation, Inc.
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// Written by Ian Lance Taylor <iant@google.com>.
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// This file is part of gold.
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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#include "gold.h"
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#include <cstring>
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#ifdef ENABLE_THREADS
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#include <pthread.h>
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#endif
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#include "options.h"
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#include "parameters.h"
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#include "gold-threads.h"
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namespace gold
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{
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class Condvar_impl_nothreads;
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// The non-threaded version of Lock_impl.
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class Lock_impl_nothreads : public Lock_impl
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{
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public:
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Lock_impl_nothreads()
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: acquired_(false)
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{ }
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~Lock_impl_nothreads()
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{ gold_assert(!this->acquired_); }
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void
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acquire()
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{
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gold_assert(!this->acquired_);
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this->acquired_ = true;
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}
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void
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release()
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{
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gold_assert(this->acquired_);
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this->acquired_ = false;
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}
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private:
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friend class Condvar_impl_nothreads;
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bool acquired_;
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};
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#ifdef ENABLE_THREADS
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class Condvar_impl_threads;
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// The threaded version of Lock_impl.
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class Lock_impl_threads : public Lock_impl
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{
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public:
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Lock_impl_threads();
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~Lock_impl_threads();
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void acquire();
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void release();
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private:
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// This class can not be copied.
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Lock_impl_threads(const Lock_impl_threads&);
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Lock_impl_threads& operator=(const Lock_impl_threads&);
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friend class Condvar_impl_threads;
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pthread_mutex_t mutex_;
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};
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Lock_impl_threads::Lock_impl_threads()
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{
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pthread_mutexattr_t attr;
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int err = pthread_mutexattr_init(&attr);
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if (err != 0)
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gold_fatal(_("pthead_mutextattr_init failed: %s"), strerror(err));
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#ifdef PTHREAD_MUTEX_ADAPTIVE_NP
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err = pthread_mutextattr_settype(&attr, PTHREAD_MUTEX_ADAPTIVE_NP);
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if (err != 0)
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gold_fatal(_("pthread_mutextattr_settype failed: %s"), strerror(err));
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#endif
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err = pthread_mutex_init(&this->mutex_, &attr);
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if (err != 0)
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gold_fatal(_("pthread_mutex_init failed: %s"), strerror(err));
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err = pthread_mutexattr_destroy(&attr);
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if (err != 0)
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gold_fatal(_("pthread_mutexattr_destroy failed: %s"), strerror(err));
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}
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Lock_impl_threads::~Lock_impl_threads()
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{
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int err = pthread_mutex_destroy(&this->mutex_);
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if (err != 0)
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gold_fatal(_("pthread_mutex_destroy failed: %s"), strerror(err));
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}
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void
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Lock_impl_threads::acquire()
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{
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int err = pthread_mutex_lock(&this->mutex_);
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if (err != 0)
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gold_fatal(_("pthread_mutex_lock failed: %s"), strerror(err));
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}
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void
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Lock_impl_threads::release()
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{
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int err = pthread_mutex_unlock(&this->mutex_);
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if (err != 0)
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gold_fatal(_("pthread_mutex_unlock failed: %s"), strerror(err));
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}
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#endif // defined(ENABLE_THREADS)
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// Class Lock.
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Lock::Lock()
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{
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if (!parameters->options().threads())
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this->lock_ = new Lock_impl_nothreads;
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else
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{
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#ifdef ENABLE_THREADS
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this->lock_ = new Lock_impl_threads;
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#else
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gold_unreachable();
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#endif
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}
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}
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Lock::~Lock()
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{
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delete this->lock_;
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}
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// The non-threaded version of Condvar_impl.
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class Condvar_impl_nothreads : public Condvar_impl
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{
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public:
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Condvar_impl_nothreads()
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{ }
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~Condvar_impl_nothreads()
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{ }
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void
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wait(Lock_impl* li)
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{ gold_assert(static_cast<Lock_impl_nothreads*>(li)->acquired_); }
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void
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signal()
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{ }
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void
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broadcast()
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{ }
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};
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#ifdef ENABLE_THREADS
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// The threaded version of Condvar_impl.
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class Condvar_impl_threads : public Condvar_impl
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{
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public:
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Condvar_impl_threads();
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~Condvar_impl_threads();
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void
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wait(Lock_impl*);
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void
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signal();
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void
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broadcast();
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private:
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// This class can not be copied.
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Condvar_impl_threads(const Condvar_impl_threads&);
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Condvar_impl_threads& operator=(const Condvar_impl_threads&);
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pthread_cond_t cond_;
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};
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Condvar_impl_threads::Condvar_impl_threads()
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{
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int err = pthread_cond_init(&this->cond_, NULL);
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if (err != 0)
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gold_fatal(_("pthread_cond_init failed: %s"), strerror(err));
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}
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Condvar_impl_threads::~Condvar_impl_threads()
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{
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int err = pthread_cond_destroy(&this->cond_);
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if (err != 0)
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gold_fatal(_("pthread_cond_destroy failed: %s"), strerror(err));
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}
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void
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Condvar_impl_threads::wait(Lock_impl* li)
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{
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Lock_impl_threads* lit = static_cast<Lock_impl_threads*>(li);
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int err = pthread_cond_wait(&this->cond_, &lit->mutex_);
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if (err != 0)
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gold_fatal(_("pthread_cond_wait failed: %s"), strerror(err));
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}
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void
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Condvar_impl_threads::signal()
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{
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int err = pthread_cond_signal(&this->cond_);
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if (err != 0)
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gold_fatal(_("pthread_cond_signal failed: %s"), strerror(err));
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}
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void
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Condvar_impl_threads::broadcast()
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{
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int err = pthread_cond_broadcast(&this->cond_);
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if (err != 0)
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gold_fatal(_("pthread_cond_broadcast failed: %s"), strerror(err));
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}
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#endif // defined(ENABLE_THREADS)
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// Methods for Condvar class.
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Condvar::Condvar(Lock& lock)
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: lock_(lock)
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{
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if (!parameters->options().threads())
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this->condvar_ = new Condvar_impl_nothreads;
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else
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{
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#ifdef ENABLE_THREADS
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this->condvar_ = new Condvar_impl_threads;
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#else
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gold_unreachable();
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#endif
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}
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}
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Condvar::~Condvar()
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{
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delete this->condvar_;
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}
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#ifdef ENABLE_THREADS
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// Class Once_initialize. This exists to hold a pthread_once_t
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// structure for Once.
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class Once_initialize
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{
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public:
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Once_initialize()
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: once_(PTHREAD_ONCE_INIT)
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{ }
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// Return a pointer to the pthread_once_t variable.
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pthread_once_t*
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once_control()
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{ return &this->once_; }
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private:
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pthread_once_t once_;
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};
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#endif // defined(ENABLE_THREADS)
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#ifdef ENABLE_THREADS
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// A single lock which controls access to once_pointer. This is used
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// because we can't pass parameters to functions passed to
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// pthread_once.
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static pthread_mutex_t once_pointer_control = PTHREAD_MUTEX_INITIALIZER;
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// A pointer to Once structure we want to run. Access to this is
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// controlled by once_pointer_control.
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static Once* once_pointer;
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// The argument to pass to the Once structure. Access to this is
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// controlled by once_pointer_control.
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static void* once_arg;
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// A routine passed to pthread_once which runs the Once pointer.
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extern "C"
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{
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static void
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c_run_once(void)
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{
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once_pointer->internal_run(once_arg);
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}
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}
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#endif // defined(ENABLE_THREADS)
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// Class Once.
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Once::Once()
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: was_run_(false)
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#if defined(ENABLE_THREADS) && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
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, was_run_lock_(0)
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#endif
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{
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#ifndef ENABLE_THREADS
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this->once_ = NULL;
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#else
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this->once_ = new Once_initialize();
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#endif
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}
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// Run the function once.
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void
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Once::run_once(void* arg)
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{
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#ifndef ENABLE_THREADS
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// If there is no threads support, we don't need to use pthread_once.
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if (!this->was_run_)
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this->internal_run(arg);
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#else // defined(ENABLE_THREADS)
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if (parameters->options_valid() && !parameters->options().threads())
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{
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// If we are not using threads, we don't need to lock.
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if (!this->was_run_)
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this->internal_run(arg);
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return;
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}
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// If we have the sync builtins, use them to skip the lock if the
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// value has already been initialized.
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#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
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while (true)
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{
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if (__sync_bool_compare_and_swap(&this->was_run_lock_, 0, 1))
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break;
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}
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bool was_run = this->was_run_;
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while (true)
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{
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if (__sync_bool_compare_and_swap(&this->was_run_lock_, 1, 0))
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break;
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}
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if (was_run)
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return;
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#endif
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// Since we can't pass parameters to routines called by
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// pthread_once, we use a static variable: once_pointer. This in
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// turns means that we need to use a mutex to control access to
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// once_pointer.
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int err = pthread_mutex_lock(&once_pointer_control);
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if (err != 0)
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gold_fatal(_("pthread_mutex_lock failed: %s"), strerror(err));
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once_pointer = this;
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once_arg = arg;
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err = pthread_once(this->once_->once_control(), c_run_once);
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if (err != 0)
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gold_fatal(_("pthread_once failed: %s"), strerror(err));
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once_pointer = NULL;
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once_arg = NULL;
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err = pthread_mutex_unlock(&once_pointer_control);
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if (err != 0)
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gold_fatal(_("pthread_mutex_unlock failed: %s"), strerror(err));
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#endif // defined(ENABLE_THREADS)
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}
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// Actually run the function in the child class. This function will
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// be run only once.
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void
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Once::internal_run(void* arg)
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{
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this->do_run_once(arg);
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this->was_run_ = true;
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}
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// Class Initialize_lock.
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// Initialize the lock.
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bool
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Initialize_lock::initialize()
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{
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// We can't initialize the lock until we have read the options.
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if (!parameters->options_valid())
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return false;
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else
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{
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this->run_once(NULL);
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return true;
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}
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}
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// Initialize the lock exactly once.
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void
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Initialize_lock::do_run_once(void*)
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{
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*this->pplock_ = new Lock();
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}
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} // End namespace gold.
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