| /* |
| * Copyright (C) 2015 The Android Open Source Project |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
| * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
| * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| */ |
| #include<pthread.h> |
| |
| #include"private/bionic_lock.h" |
| |
| // User-level spinlocks can be hazardous to battery life on Android. |
| // We implement a simple compromise that behaves mostly like a spinlock, |
| // but prevents excessively long spinning. |
| |
| structpthread_spinlock_internal_t{ |
| Lock lock; |
| }; |
| |
| static_assert(sizeof(pthread_spinlock_t)==sizeof(pthread_spinlock_internal_t), |
| "pthread_spinlock_t should actually be pthread_spinlock_internal_t."); |
| |
| static_assert(alignof(pthread_spinlock_t)>=4, |
| "pthread_spinlock_t should fulfill the alignment of pthread_spinlock_internal_t."); |
| |
| staticinlinepthread_spinlock_internal_t* __get_internal_spinlock(pthread_spinlock_t* lock){ |
| returnreinterpret_cast<pthread_spinlock_internal_t*>(lock); |
| } |
| |
| int pthread_spin_init(pthread_spinlock_t* lock_interface,int pshared){ |
| pthread_spinlock_internal_t* lock= __get_internal_spinlock(lock_interface); |
| lock->lock.init(pshared); |
| return0; |
| } |
| |
| int pthread_spin_destroy(pthread_spinlock_t* lock_interface){ |
| pthread_spinlock_internal_t* lock= __get_internal_spinlock(lock_interface); |
| return lock->lock.trylock()?0: EBUSY; |
| } |
| |
| int pthread_spin_trylock(pthread_spinlock_t* lock_interface){ |
| pthread_spinlock_internal_t* lock= __get_internal_spinlock(lock_interface); |
| return lock->lock.trylock()?0: EBUSY; |
| } |
| |
| int pthread_spin_lock(pthread_spinlock_t* lock_interface){ |
| pthread_spinlock_internal_t* lock= __get_internal_spinlock(lock_interface); |
| for(int i=0; i<10000;++i){ |
| if(lock->lock.trylock()){ |
| return0; |
| } |
| } |
| lock->lock.lock(); |
| return0; |
| } |
| |
| int pthread_spin_unlock(pthread_spinlock_t* lock_interface){ |
| pthread_spinlock_internal_t* lock= __get_internal_spinlock(lock_interface); |
| lock->lock.unlock(); |
| return0; |
| } |
