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/*********************************************************
* Copyright (C) 2008 VMware, Inc. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation version 2.1 and no later version.
*
* 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 Lesser GNU General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
*********************************************************/
/**
* @file monotonicTimer.c
*
* A GSource that implements a timer backed by a monotonic time source.
*/
#include <limits.h>
#include "vmware.h"
#include "system.h"
#include "vmware/tools/utils.h"
typedef struct MTimerSource {
GSource src;
gint timeout;
uint64 last;
} MTimerSource;
/*
*******************************************************************************
* MTimerSourcePrepare -- */ /**
*
* Callback for the "prepare()" event source function. Sets the timeout to
* the number of milliseconds this timer expects to sleep for. If the timeout
* has already expired, update the internal state tracking the last time the
* timer was fired.
*
* @param[in] src The source.
* @param[out] timeout Where to store the timeout.
*
* @return TRUE if timeout has already expired.
*
*******************************************************************************
*/
static gboolean
MTimerSourcePrepare(GSource *src,
gint *timeout)
{
MTimerSource *timer = (MTimerSource *) src;
if (timer->timeout == 0) {
*timeout = 0;
return TRUE;
} else {
uint64 now = System_GetTimeMonotonic() * 10;
uint64 diff;
ASSERT(now >= timer->last);
diff = now - timer->last;
if (diff >= timer->timeout) {
timer->last = now;
*timeout = 0;
return TRUE;
}
*timeout = MIN(INT_MAX, timer->timeout - diff);
return FALSE;
}
}
/*
*******************************************************************************
* MTimerSourceCheck -- */ /**
*
* Checks whether the timeout has expired.
*
* @param[in] src The source.
*
* @return Whether the timeout has expired.
*
*******************************************************************************
*/
static gboolean
MTimerSourceCheck(GSource *src)
{
gint unused;
return MTimerSourcePrepare(src, &unused);
}
/*
*******************************************************************************
* MTimerSourceDispatch -- */ /**
*
* Calls the callback associated with the timer, if any.
*
* @param[in] src Unused.
* @param[in] callback The callback to be called.
* @param[in] data User-supplied data.
*
* @return The return value of the callback, or FALSE if the callback is NULL.
*
*******************************************************************************
*/
static gboolean
MTimerSourceDispatch(GSource *src,
GSourceFunc callback,
gpointer data)
{
return (callback != NULL) ? callback(data) : FALSE;
}
/*
*******************************************************************************
* MTimerSourceFinalize -- */ /**
*
* Does nothing. The main glib code already does all the cleanup needed.
*
* @param[in] src The source.
*
*******************************************************************************
*/
static void
MTimerSourceFinalize(GSource *src)
{
}
/**
*
* @addtogroup vmtools_utils
* @{
*/
/*
*******************************************************************************
* VMTools_CreateTimer -- */ /**
*
* @brief Create a timer based on a monotonic clock source.
*
* This timer differs from the glib timeout source, which uses the system time.
* It is recommended for code that needs more reliable time tracking, using a
* clock that is not affected by changes in the system time (which can happen
* when using NTP or the Tools time synchronization feature).
*
* @param[in] timeout The timeout for the timer, must be >= 0.
*
* @return The new source.
*
*******************************************************************************
*/
GSource *
VMTools_CreateTimer(gint timeout)
{
static GSourceFuncs srcFuncs = {
MTimerSourcePrepare,
MTimerSourceCheck,
MTimerSourceDispatch,
MTimerSourceFinalize,
NULL,
NULL
};
MTimerSource *ret;
ASSERT(timeout >= 0);
ret = (MTimerSource *) g_source_new(&srcFuncs, sizeof *ret);
ret->last = System_GetTimeMonotonic() * 10;
ret->timeout = timeout;
return &ret->src;
}
/** @} */
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