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[binutils/dougsmingw.git] / gold / gold-threads.cc
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1 // gold-threads.cc -- thread support for gold
3 // Copyright 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
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.
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.
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.
23 #include "gold.h"
25 #include <cstring>
27 #ifdef ENABLE_THREADS
28 #include <pthread.h>
29 #endif
31 #include "options.h"
32 #include "parameters.h"
33 #include "gold-threads.h"
35 namespace gold
38 class Condvar_impl_nothreads;
40 // The non-threaded version of Lock_impl.
42 class Lock_impl_nothreads : public Lock_impl
44 public:
45 Lock_impl_nothreads()
46 : acquired_(false)
47 { }
49 ~Lock_impl_nothreads()
50 { gold_assert(!this->acquired_); }
52 void
53 acquire()
55 gold_assert(!this->acquired_);
56 this->acquired_ = true;
59 void
60 release()
62 gold_assert(this->acquired_);
63 this->acquired_ = false;
66 private:
67 friend class Condvar_impl_nothreads;
69 bool acquired_;
72 #ifdef ENABLE_THREADS
74 class Condvar_impl_threads;
76 // The threaded version of Lock_impl.
78 class Lock_impl_threads : public Lock_impl
80 public:
81 Lock_impl_threads();
82 ~Lock_impl_threads();
84 void acquire();
86 void release();
88 private:
89 // This class can not be copied.
90 Lock_impl_threads(const Lock_impl_threads&);
91 Lock_impl_threads& operator=(const Lock_impl_threads&);
93 friend class Condvar_impl_threads;
95 pthread_mutex_t mutex_;
98 Lock_impl_threads::Lock_impl_threads()
100 pthread_mutexattr_t attr;
101 int err = pthread_mutexattr_init(&attr);
102 if (err != 0)
103 gold_fatal(_("pthead_mutextattr_init failed: %s"), strerror(err));
104 #ifdef PTHREAD_MUTEXT_ADAPTIVE_NP
105 err = pthread_mutextattr_settype(&attr, PTHREAD_MUTEX_ADAPTIVE_NP);
106 if (err != 0)
107 gold_fatal(_("pthread_mutextattr_settype failed: %s"), strerror(err));
108 #endif
110 err = pthread_mutex_init (&this->mutex_, &attr);
111 if (err != 0)
112 gold_fatal(_("pthread_mutex_init failed: %s"), strerror(err));
114 err = pthread_mutexattr_destroy(&attr);
115 if (err != 0)
116 gold_fatal(_("pthread_mutexattr_destroy failed: %s"), strerror(err));
119 Lock_impl_threads::~Lock_impl_threads()
121 int err = pthread_mutex_destroy(&this->mutex_);
122 if (err != 0)
123 gold_fatal(_("pthread_mutex_destroy failed: %s"), strerror(err));
126 void
127 Lock_impl_threads::acquire()
129 int err = pthread_mutex_lock(&this->mutex_);
130 if (err != 0)
131 gold_fatal(_("pthread_mutex_lock failed: %s"), strerror(err));
134 void
135 Lock_impl_threads::release()
137 int err = pthread_mutex_unlock(&this->mutex_);
138 if (err != 0)
139 gold_fatal(_("pthread_mutex_unlock failed: %s"), strerror(err));
142 #endif // defined(ENABLE_THREADS)
144 // Class Lock.
146 Lock::Lock()
148 if (!parameters->options().threads())
149 this->lock_ = new Lock_impl_nothreads;
150 else
152 #ifdef ENABLE_THREADS
153 this->lock_ = new Lock_impl_threads;
154 #else
155 gold_unreachable();
156 #endif
160 Lock::~Lock()
162 delete this->lock_;
165 // The non-threaded version of Condvar_impl.
167 class Condvar_impl_nothreads : public Condvar_impl
169 public:
170 Condvar_impl_nothreads()
173 ~Condvar_impl_nothreads()
176 void
177 wait(Lock_impl* li)
178 { gold_assert(static_cast<Lock_impl_nothreads*>(li)->acquired_); }
180 void
181 signal()
184 void
185 broadcast()
189 #ifdef ENABLE_THREADS
191 // The threaded version of Condvar_impl.
193 class Condvar_impl_threads : public Condvar_impl
195 public:
196 Condvar_impl_threads();
197 ~Condvar_impl_threads();
199 void
200 wait(Lock_impl*);
202 void
203 signal();
205 void
206 broadcast();
208 private:
209 // This class can not be copied.
210 Condvar_impl_threads(const Condvar_impl_threads&);
211 Condvar_impl_threads& operator=(const Condvar_impl_threads&);
213 pthread_cond_t cond_;
216 Condvar_impl_threads::Condvar_impl_threads()
218 int err = pthread_cond_init(&this->cond_, NULL);
219 if (err != 0)
220 gold_fatal(_("pthread_cond_init failed: %s"), strerror(err));
223 Condvar_impl_threads::~Condvar_impl_threads()
225 int err = pthread_cond_destroy(&this->cond_);
226 if (err != 0)
227 gold_fatal(_("pthread_cond_destroy failed: %s"), strerror(err));
230 void
231 Condvar_impl_threads::wait(Lock_impl* li)
233 Lock_impl_threads* lit = static_cast<Lock_impl_threads*>(li);
234 int err = pthread_cond_wait(&this->cond_, &lit->mutex_);
235 if (err != 0)
236 gold_fatal(_("pthread_cond_wait failed: %s"), strerror(err));
239 void
240 Condvar_impl_threads::signal()
242 int err = pthread_cond_signal(&this->cond_);
243 if (err != 0)
244 gold_fatal(_("pthread_cond_signal failed: %s"), strerror(err));
247 void
248 Condvar_impl_threads::broadcast()
250 int err = pthread_cond_broadcast(&this->cond_);
251 if (err != 0)
252 gold_fatal(_("pthread_cond_broadcast failed: %s"), strerror(err));
255 #endif // defined(ENABLE_THREADS)
257 // Methods for Condvar class.
259 Condvar::Condvar(Lock& lock)
260 : lock_(lock)
262 if (!parameters->options().threads())
263 this->condvar_ = new Condvar_impl_nothreads;
264 else
266 #ifdef ENABLE_THREADS
267 this->condvar_ = new Condvar_impl_threads;
268 #else
269 gold_unreachable();
270 #endif
274 Condvar::~Condvar()
276 delete this->condvar_;
279 #ifdef ENABLE_THREADS
281 // Class Once_initialize. This exists to hold a pthread_once_t
282 // structure for Once.
284 class Once_initialize
286 public:
287 Once_initialize()
288 : once_(PTHREAD_ONCE_INIT)
291 // Return a pointer to the pthread_once_t variable.
292 pthread_once_t*
293 once_control()
294 { return &this->once_; }
296 private:
297 pthread_once_t once_;
300 #endif // defined(ENABLE_THREADS)
302 #ifdef ENABLE_THREADS
304 // A single lock which controls access to once_pointer. This is used
305 // because we can't pass parameters to functions passed to
306 // pthread_once.
308 static pthread_mutex_t once_pointer_control = PTHREAD_MUTEX_INITIALIZER;
310 // A pointer to Once structure we want to run. Access to this is
311 // controlled by once_pointer_control.
313 static Once* once_pointer;
315 // The argument to pass to the Once structure. Access to this is
316 // controlled by once_pointer_control.
318 static void* once_arg;
320 // A routine passed to pthread_once which runs the Once pointer.
322 extern "C"
325 static void
326 c_run_once(void)
328 once_pointer->internal_run(once_arg);
333 #endif // defined(ENABLE_THREADS)
335 // Class Once.
337 Once::Once()
338 : was_run_(false), was_run_lock_(0)
340 #ifndef ENABLE_THREADS
341 this->once_ = NULL;
342 #else
343 this->once_ = new Once_initialize();
344 #endif
347 // Run the function once.
349 void
350 Once::run_once(void* arg)
352 #ifndef ENABLE_THREADS
354 // If there is no threads support, we don't need to use pthread_once.
355 if (!this->was_run_)
356 this->internal_run(arg);
358 #else // defined(ENABLE_THREADS)
360 if (parameters->options_valid() && !parameters->options().threads())
362 // If we are not using threads, we don't need to lock.
363 if (!this->was_run_)
364 this->internal_run(arg);
365 return;
368 // If we have the sync builtins, use them to skip the lock if the
369 // value has already been initialized.
370 #ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
371 while (true)
373 if (__sync_bool_compare_and_swap(&this->was_run_lock_, 0, 1))
374 break;
376 bool was_run = this->was_run_;
377 while (true)
379 if (__sync_bool_compare_and_swap(&this->was_run_lock_, 1, 0))
380 break;
382 if (was_run)
383 return;
384 #endif
386 // Since we can't pass parameters to routines called by
387 // pthread_once, we use a static variable: once_pointer. This in
388 // turns means that we need to use a mutex to control access to
389 // once_pointer.
391 int err = pthread_mutex_lock(&once_pointer_control);
392 if (err != 0)
393 gold_fatal(_("pthread_mutex_lock failed: %s"), strerror(err));
395 once_pointer = this;
396 once_arg = arg;
398 err = pthread_once(this->once_->once_control(), c_run_once);
399 if (err != 0)
400 gold_fatal(_("pthread_once failed: %s"), strerror(err));
402 once_pointer = NULL;
403 once_arg = NULL;
405 err = pthread_mutex_unlock(&once_pointer_control);
406 if (err != 0)
407 gold_fatal(_("pthread_mutex_unlock falied: %s"), strerror(err));
409 #endif // defined(ENABLE_THREADS)
412 // Actually run the function in the child class. This function will
413 // be run only once.
415 void
416 Once::internal_run(void* arg)
418 this->do_run_once(arg);
419 this->was_run_ = true;
422 // Class Initialize_lock.
424 // Initialize the lock.
426 bool
427 Initialize_lock::initialize()
429 // We can't initialize the lock until we have read the options.
430 if (!parameters->options_valid())
431 return false;
432 else
434 this->run_once(NULL);
435 return true;
439 // Initialize the lock exactly once.
441 void
442 Initialize_lock::do_run_once(void*)
444 *this->pplock_ = new Lock();
447 } // End namespace gold.