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46 lines
1.4 KiB
C
46 lines
1.4 KiB
C
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/*
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* Event rate calculation functions.
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*
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* Copyright 2000-2009 Willy Tarreau <w@1wt.eu>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <common/config.h>
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#include <common/standard.h>
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#include <common/time.h>
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#include <proto/freq_ctr.h>
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/* Read a frequency counter taking history into account for missing time in
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* current period. Current second is sub-divided in 1000 chunks of one ms,
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* and the missing ones are read proportionally from previous value. The
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* return value has the same precision as one input data sample, so low rates
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* will be inaccurate still appropriate for max checking. One trick we use for
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* low values is to specially handle the case where the rate is between 0 and 1
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* in order to avoid flapping while waiting for the next event.
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*/
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unsigned int read_freq_ctr(struct freq_ctr *ctr)
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{
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unsigned int cur;
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if (unlikely(ctr->curr_sec != now.tv_sec))
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rotate_freq_ctr(ctr);
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cur = ctr->curr_ctr;
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if (ctr->prev_ctr <= 1 && !ctr->curr_ctr)
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return ctr->prev_ctr; /* very low rate, avoid flapping */
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return cur + mul32hi(ctr->prev_ctr, ~curr_sec_ms_scaled);
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}
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/*
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* Local variables:
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* c-indent-level: 8
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* c-basic-offset: 8
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* End:
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*/
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