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/*
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)queue.h 8.5 (Berkeley) 8/20/94
* $FreeBSD: src/sys/sys/queue.h,v 1.54 2002/08/05 05:18:43 alfred Exp $
*/
#ifndef _DB_QUEUE_H_
#define _DB_QUEUE_H_
#if defined(__cplusplus)
extern "C" {
#endif
/*
* WiredTiger only uses the TAILQ macros (we've gotten into trouble in the past
* by trying to use simpler queues and subsequently discovering a list we didn't
* think would ever get to be large could, under some workloads, become large,
* and the linear performance for removal of elements from simpler macros proved
* to be more trouble than the memory savings were worth.
*
* Additionally, we've altered the TAILQ_INSERT_XXX functions to include a write
* barrier, in order to ensure we never insert a partially built structure onto
* a list (this is required because the spinlocks we use don't necessarily imply
* a write barrier).
*
* We #undef all of the macros because there are incompatible versions of this
* file and these macros on various systems. What makes the problem worse is
* they are included and/or defined by system include files which we may have
* already loaded into Berkeley DB before getting here. For example, FreeBSD's
* <rpc/rpc.h> includes its system <sys/queue.h>, and VxWorks UnixLib.h defines
* several of the LIST_XXX macros. Visual C.NET 7.0 also defines some of these
* same macros in Vc7\PlatformSDK\Include\WinNT.h. Make sure we use ours.
*/
#undef TAILQ_CONCAT
#undef TAILQ_EMPTY
#undef TAILQ_ENTRY
#undef TAILQ_FIRST
#undef TAILQ_FOREACH
#undef TAILQ_FOREACH_REVERSE
#undef TAILQ_HEAD
#undef TAILQ_HEAD_INITIALIZER
#undef TAILQ_INIT
#undef TAILQ_INSERT_AFTER
#undef TAILQ_INSERT_BEFORE
#undef TAILQ_INSERT_HEAD
#undef TAILQ_INSERT_TAIL
#undef TAILQ_LAST
#undef TAILQ_NEXT
#undef TAILQ_PREV
#undef TAILQ_REMOVE
#undef TRACEBUF
#undef TRASHIT
#define QUEUE_MACRO_DEBUG 0
#if QUEUE_MACRO_DEBUG
/* Store the last 2 places the queue element or head was altered */
struct qm_trace {
char * lastfile;
int lastline;
char * prevfile;
int prevline;
};
#define TRACEBUF struct qm_trace trace;
#define TRASHIT(x) do {(x) = (void *)-1;} while (0)
#define QMD_TRACE_HEAD(head) do { \
(head)->trace.prevline = (head)->trace.lastline; \
(head)->trace.prevfile = (head)->trace.lastfile; \
(head)->trace.lastline = __LINE__; \
(head)->trace.lastfile = __FILE__; \
} while (0)
#define QMD_TRACE_ELEM(elem) do { \
(elem)->trace.prevline = (elem)->trace.lastline; \
(elem)->trace.prevfile = (elem)->trace.lastfile; \
(elem)->trace.lastline = __LINE__; \
(elem)->trace.lastfile = __FILE__; \
} while (0)
#else
#define QMD_TRACE_ELEM(elem)
#define QMD_TRACE_HEAD(head)
#define TRACEBUF
#define TRASHIT(x)
#endif /* QUEUE_MACRO_DEBUG */
/*
* Tail queue declarations.
*/
#define TAILQ_HEAD(name, type) \
struct name { \
struct type *tqh_first; /* first element */ \
struct type **tqh_last; /* addr of last next element */ \
TRACEBUF \
}
#define TAILQ_HEAD_INITIALIZER(head) \
{ NULL, &(head).tqh_first }
#define TAILQ_ENTRY(type) \
struct { \
struct type *tqe_next; /* next element */ \
struct type **tqe_prev; /* address of previous next element */ \
TRACEBUF \
}
/*
* Tail queue functions.
*/
#define TAILQ_CONCAT(head1, head2, field) do { \
if (!TAILQ_EMPTY(head2)) { \
*(head1)->tqh_last = (head2)->tqh_first; \
(head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
(head1)->tqh_last = (head2)->tqh_last; \
TAILQ_INIT((head2)); \
QMD_TRACE_HEAD(head); \
QMD_TRACE_HEAD(head2); \
} \
} while (0)
#define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
#define TAILQ_FIRST(head) ((head)->tqh_first)
#define TAILQ_FOREACH(var, head, field) \
for ((var) = TAILQ_FIRST((head)); \
(var); \
(var) = TAILQ_NEXT((var), field))
#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
for ((var) = TAILQ_LAST((head), headname); \
(var); \
(var) = TAILQ_PREV((var), headname, field))
#define TAILQ_INIT(head) do { \
TAILQ_FIRST((head)) = NULL; \
(head)->tqh_last = &TAILQ_FIRST((head)); \
QMD_TRACE_HEAD(head); \
} while (0)
#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
WT_WRITE_BARRIER(); \
if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
TAILQ_NEXT((elm), field)->field.tqe_prev = \
&TAILQ_NEXT((elm), field); \
else { \
(head)->tqh_last = &TAILQ_NEXT((elm), field); \
QMD_TRACE_HEAD(head); \
} \
TAILQ_NEXT((listelm), field) = (elm); \
(elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
QMD_TRACE_ELEM(&(elm)->field); \
QMD_TRACE_ELEM(&listelm->field); \
} while (0)
#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
WT_WRITE_BARRIER(); \
(elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
TAILQ_NEXT((elm), field) = (listelm); \
*(listelm)->field.tqe_prev = (elm); \
(listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
QMD_TRACE_ELEM(&(elm)->field); \
QMD_TRACE_ELEM(&listelm->field); \
} while (0)
#define TAILQ_INSERT_HEAD(head, elm, field) do { \
WT_WRITE_BARRIER(); \
if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
TAILQ_FIRST((head))->field.tqe_prev = \
&TAILQ_NEXT((elm), field); \
else \
(head)->tqh_last = &TAILQ_NEXT((elm), field); \
TAILQ_FIRST((head)) = (elm); \
(elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
QMD_TRACE_HEAD(head); \
QMD_TRACE_ELEM(&(elm)->field); \
} while (0)
#define TAILQ_INSERT_TAIL(head, elm, field) do { \
WT_WRITE_BARRIER(); \
TAILQ_NEXT((elm), field) = NULL; \
(elm)->field.tqe_prev = (head)->tqh_last; \
*(head)->tqh_last = (elm); \
(head)->tqh_last = &TAILQ_NEXT((elm), field); \
QMD_TRACE_HEAD(head); \
QMD_TRACE_ELEM(&(elm)->field); \
} while (0)
#define TAILQ_LAST(head, headname) \
(*(((struct headname *)((head)->tqh_last))->tqh_last))
#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
#define TAILQ_PREV(elm, headname, field) \
(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
#define TAILQ_REMOVE(head, elm, field) do { \
if ((TAILQ_NEXT((elm), field)) != NULL) \
TAILQ_NEXT((elm), field)->field.tqe_prev = \
(elm)->field.tqe_prev; \
else { \
(head)->tqh_last = (elm)->field.tqe_prev; \
QMD_TRACE_HEAD(head); \
} \
*(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
TRASHIT((elm)->field.tqe_next); \
TRASHIT((elm)->field.tqe_prev); \
QMD_TRACE_ELEM(&(elm)->field); \
} while (0)
#if defined(__cplusplus)
}
#endif
#endif /* !_DB_QUEUE_H_ */
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