This program is free software; you can redistribute it and/or modify
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* Redistributions of source code must retain this COPYING
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COPYRIGHT NOTICE:
TokuDB, Tokutek Fractal Tree Indexing Library.
Copyright (C) 2007-2013 Tokutek, Inc.
DISCLAIMER:
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.
UNIVERSITY PATENT NOTICE:
The technology is licensed by the Massachusetts Institute of
Technology, Rutgers State University of New Jersey, and the Research
Foundation of State University of New York at Stony Brook under
United States of America Serial No. 11/760379 and to the patents
and/or patent applications resulting from it.
PATENT MARKING NOTICE:
This software is covered by US Patent No. 8,185,551.
This software is covered by US Patent No. 8,489,638.
PATENT RIGHTS GRANT:
"THIS IMPLEMENTATION" means the copyrightable works distributed by
Tokutek as part of the Fractal Tree project.
"PATENT CLAIMS" means the claims of patents that are owned or
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the absence of this license would be infringed by THIS
IMPLEMENTATION or by using or running THIS IMPLEMENTATION.
"PATENT CHALLENGE" shall mean a challenge to the validity,
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Tokutek hereby grants to you, for the term and geographical scope of
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*/
#ident "Copyright (c) 2007-2013 Tokutek Inc. All rights reserved."
#ident "The technology is licensed by the Massachusetts Institute of Technology, Rutgers State University of New Jersey, and the Research Foundation of State University of New York at Stony Brook under United States of America Serial No. 11/760379 and to the patents and/or patent applications resulting from it."
#include "toku_pthread.h"
#include <portability/toku_atomic.h>
// Fair readers/writer locks. These are fair (meaning first-come first-served. No reader starvation, and no writer starvation). And they are
// probably faster than the linux readers/writer locks (pthread_rwlock_t).
structtoku_fair_rwlock_waiter_state;// this structure is used internally.
typedefstructtoku_fair_rwlock_s{
// Try to put enough state into STATE so that in many cases, a compare-and-swap will work.
// The 64-bit state bits are as follows:
// bit 0: 1 iff someone has exclusive ownership of the entire state. (This is a spin lock).
// bit 1: 1 iff someone holds a write lock.
// bit 2: 1 iff the queue is not empty (if the queue is not empty, then you cannot use the fast path.)
// bits 3--31 how many read locks are held.
uint64_tvolatilestate;
// The waiters each provide a condition variable. This is the mutex they are all using.
// If anyone holds this mutex, they must set the RWS_MUTEXED bit first. Then they grab the mutex. Then they clear the bit indicating that they don't have the mutex. No one else can change anything while the RWS_MUTEXED bit is set.
