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