mirror of https://github.com/schoebel/mars
56 lines
2.0 KiB
C
56 lines
2.0 KiB
C
/*
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* MARS Long Distance Replication Software
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*
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* This file is part of MARS project: http://schoebel.github.io/mars/
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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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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef LAMPORT_H
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#define LAMPORT_H
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#include <linux/time.h>
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/*
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* We always get both the local real time and the Lamport time in parallel,
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* consistently.
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*
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* The implementation ensures that the distributed Lamport timestamp can
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* never fall behind the local real time.
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*
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* When not interested in real time, you can simply leave real_now at NULL.
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*/
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extern void get_lamport(struct timespec *real_now, struct timespec *lamport_now);
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/* This ensures _strict_ monotonicity of the Lamport clock */
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extern void set_lamport(struct timespec *lamport_old);
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/* Non-strict version.
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* Use this for better performance when strictness is not needed.
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*/
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extern void set_lamport_nonstrict(struct timespec *lamport_old);
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/* After strictly advancing the Lamport time, re-get the new values.
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* This is almost equivalent to a sequence of set_lamport() ; get_lamport()
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* but (1) atomic and (2) more efficient
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* because the internal lock is taken only once.
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*/
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extern void set_get_lamport(struct timespec *lamport_old, struct timespec *real_now, struct timespec *lamport_now);
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#endif
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