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/*-
* Public Domain 2014-2017 MongoDB, Inc.
* Public Domain 2008-2014 WiredTiger, Inc.
*
* This is free and unencumbered software released into the public domain.
*
* Anyone is free to copy, modify, publish, use, compile, sell, or
* distribute this software, either in source code form or as a compiled
* binary, for any purpose, commercial or non-commercial, and by any
* means.
*
* In jurisdictions that recognize copyright laws, the author or authors
* of this software dedicate any and all copyright interest in the
* software to the public domain. We make this dedication for the benefit
* of the public at large and to the detriment of our heirs and
* successors. We intend this dedication to be an overt act of
* relinquishment in perpetuity of all present and future rights to this
* software under copyright law.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include "wt_internal.h"
/*
* __time_check_monotonic --
* Check and prevent time running backward. If we detect that it has, we
* set the time structure to the previous values, making time stand still
* until we see a time in the future of the highest value seen so far.
*/
static void
__time_check_monotonic(WT_SESSION_IMPL *session, struct timespec *tsp)
{
/*
* Detect time going backward. If so, use the last
* saved timestamp.
*/
if (session == NULL)
return;
if (tsp->tv_sec < session->last_epoch.tv_sec ||
(tsp->tv_sec == session->last_epoch.tv_sec &&
tsp->tv_nsec < session->last_epoch.tv_nsec)) {
WT_STAT_CONN_INCR(session, time_travel);
*tsp = session->last_epoch;
} else
session->last_epoch = *tsp;
}
/*
* __wt_epoch --
* Return the time since the Epoch, adjusted so it never appears to go
* backwards.
*/
void
__wt_epoch(WT_SESSION_IMPL *session, struct timespec *tsp)
WT_GCC_FUNC_ATTRIBUTE((visibility("default")))
{
struct timespec tmp;
/*
* Read into a local variable so that we're comparing the correct
* value when we check for monotonic increasing time. There are
* many places we read into an unlocked global variable.
*/
__wt_epoch_raw(session, &tmp);
__time_check_monotonic(session, &tmp);
*tsp = tmp;
}
/*
* __wt_seconds --
* Return the seconds since the Epoch.
*/
void
__wt_seconds(WT_SESSION_IMPL *session, time_t *timep)
{
struct timespec t;
__wt_epoch(session, &t);
*timep = t.tv_sec;
}
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