mirror of https://github.com/schoebel/mars
62 lines
1.5 KiB
C
62 lines
1.5 KiB
C
/*
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* MARS Long Distance Replication Software
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*
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* Copyright (C) 2010-2014 Thomas Schoebel-Theuer
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* Copyright (C) 2011-2014 1&1 Internet AG
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*
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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 2 of the License, or
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* (at your option) any later version.
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*
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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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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/semaphore.h>
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#include "lamport.h"
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/* TODO: replace with spinlock if possible (first check) */
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struct semaphore lamport_sem = __SEMAPHORE_INITIALIZER(lamport_sem, 1);
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struct timespec lamport_now = {};
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void get_lamport(struct timespec *now)
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{
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int diff;
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down(&lamport_sem);
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*now = CURRENT_TIME;
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diff = timespec_compare(now, &lamport_now);
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if (diff >= 0) {
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timespec_add_ns(now, 1);
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memcpy(&lamport_now, now, sizeof(lamport_now));
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timespec_add_ns(&lamport_now, 1);
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} else {
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timespec_add_ns(&lamport_now, 1);
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memcpy(now, &lamport_now, sizeof(*now));
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}
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up(&lamport_sem);
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}
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void set_lamport(struct timespec *old)
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{
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int diff;
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down(&lamport_sem);
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diff = timespec_compare(old, &lamport_now);
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if (diff >= 0) {
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memcpy(&lamport_now, old, sizeof(lamport_now));
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timespec_add_ns(&lamport_now, 1);
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}
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up(&lamport_sem);
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}
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