| // workqueue-threads.cc -- the threaded workqueue for gold |
| |
| // Copyright (C) 2007-2021 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. |
| |
| // This file holds the workqueue implementation which may be used when |
| // using threads. |
| |
| #include "gold.h" |
| |
| #ifdef ENABLE_THREADS |
| |
| #include <cstring> |
| #include <pthread.h> |
| |
| #include "debug.h" |
| #include "gold-threads.h" |
| #include "workqueue.h" |
| #include "workqueue-internal.h" |
| |
| namespace gold |
| { |
| |
| // Class Workqueue_thread represents a single thread. Creating an |
| // instance of this spawns a new thread. |
| |
| class Workqueue_thread |
| { |
| public: |
| Workqueue_thread(Workqueue_threader_threadpool*, int thread_number); |
| |
| ~Workqueue_thread(); |
| |
| private: |
| // This class can not be copied. |
| Workqueue_thread(const Workqueue_thread&); |
| Workqueue_thread& operator=(const Workqueue_thread&); |
| |
| // Check for error from a pthread function. |
| void |
| check(const char* function, int err) const; |
| |
| // A function to pass to pthread_create. This is called with a |
| // pointer to an instance of this object. |
| static void* |
| thread_body(void*); |
| |
| // A pointer to the threadpool that this thread is part of. |
| Workqueue_threader_threadpool* threadpool_; |
| // The thread number. |
| int thread_number_; |
| // The thread ID. |
| pthread_t tid_; |
| }; |
| |
| // Create the thread in the constructor. |
| |
| Workqueue_thread::Workqueue_thread(Workqueue_threader_threadpool* threadpool, |
| int thread_number) |
| : threadpool_(threadpool), thread_number_(thread_number) |
| { |
| pthread_attr_t attr; |
| int err = pthread_attr_init(&attr); |
| this->check("pthread_attr_init", err); |
| |
| err = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); |
| this->check("pthread_attr_setdetachstate", err); |
| |
| err = pthread_create(&this->tid_, &attr, &Workqueue_thread::thread_body, |
| reinterpret_cast<void*>(this)); |
| this->check("pthread_create", err); |
| |
| err = pthread_attr_destroy(&attr); |
| this->check("pthread_attr_destroy", err); |
| } |
| |
| // The destructor will be called when the thread is exiting. |
| |
| Workqueue_thread::~Workqueue_thread() |
| { |
| } |
| |
| // Check for an error. |
| |
| void |
| Workqueue_thread::check(const char* function, int err) const |
| { |
| if (err != 0) |
| gold_fatal(_("%s failed: %s"), function, strerror(err)); |
| } |
| |
| // Passed to pthread_create. |
| |
| extern "C" |
| void* |
| Workqueue_thread::thread_body(void* arg) |
| { |
| Workqueue_thread* pwt = reinterpret_cast<Workqueue_thread*>(arg); |
| |
| pwt->threadpool_->process(pwt->thread_number_); |
| |
| // Delete the thread object as we exit. |
| delete pwt; |
| |
| return NULL; |
| } |
| |
| // Class Workqueue_threader_threadpool. |
| |
| // Constructor. |
| |
| Workqueue_threader_threadpool::Workqueue_threader_threadpool( |
| Workqueue* workqueue) |
| : Workqueue_threader(workqueue), |
| check_thread_count_(0), |
| lock_(), |
| desired_thread_count_(1), |
| threads_(1) |
| { |
| } |
| |
| // Destructor. |
| |
| Workqueue_threader_threadpool::~Workqueue_threader_threadpool() |
| { |
| // Tell the threads to exit. |
| this->get_workqueue()->set_thread_count(0); |
| } |
| |
| // Set the thread count. |
| |
| void |
| Workqueue_threader_threadpool::set_thread_count(int thread_count) |
| { |
| int create; |
| { |
| Hold_lock hl(this->lock_); |
| |
| this->desired_thread_count_ = thread_count; |
| create = this->desired_thread_count_ - this->threads_; |
| if (create < 0) |
| this->check_thread_count_ = 1; |
| } |
| |
| if (create > 0) |
| { |
| for (int i = 0; i < create; ++i) |
| { |
| // Note that threads delete themselves when they exit, so we |
| // don't keep pointers to them. |
| new Workqueue_thread(this, this->threads_); |
| ++this->threads_; |
| } |
| } |
| } |
| |
| // Return whether the current thread should be cancelled. |
| |
| bool |
| Workqueue_threader_threadpool::should_cancel_thread(int thread_number) |
| { |
| // Fast exit without taking a lock. |
| if (!this->check_thread_count_) |
| return false; |
| |
| { |
| Hold_lock hl(this->lock_); |
| if (thread_number > this->desired_thread_count_) |
| { |
| --this->threads_; |
| if (this->threads_ <= this->desired_thread_count_) |
| this->check_thread_count_ = 0; |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| } // End namespace gold. |
| |
| #endif // defined(ENABLE_THREADS) |