60 lines
1.7 KiB
C
60 lines
1.7 KiB
C
#ifndef _SPINLOCK_H
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#define _SPINLOCK_H
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/*
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* This file is distributed as part of the SkySQL Gateway. It is free
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* software: you can redistribute it and/or modify it under the terms of the
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* GNU General Public License as published by the Free Software Foundation,
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* version 2.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 51
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* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Copyright SkySQL Ab 2013
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*/
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/**
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* @file spinlock.h
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*
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* Spinlock implementation for ther gateway.
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*
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* Spinlocks are cheap locks that can be used to protect short code blocks, they are
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* generally wasteful as any blocked threads will spin, consuming CPU cycles, waiting
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* for the lock to be released. However they are useful in that they do not involve
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* system calls and are light weight when the expected wait time for a lock is low.
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*/
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#include <thread.h>
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typedef struct spinlock {
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int lock;
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#if DEBUG
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int spins;
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int acquired;
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THREAD owner;
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#endif
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} SPINLOCK;
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#ifndef TRUE
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#define TRUE (1 == 1)
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#endif
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#ifndef FALSE
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#define FALSE (1 == 0)
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#endif
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#if DEBUG
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#define SPINLOCK_INIT { 0, 0, 0, NULL }
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#else
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#define SPINLOCK_INIT { 0 }
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#endif
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extern void spinlock_init(SPINLOCK *lock);
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extern void spinlock_acquire(SPINLOCK *lock);
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extern int spinlock_acquire_nowait(SPINLOCK *lock);
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extern void spinlock_release(SPINLOCK *lock);
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#endif
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