From da76459dc21b5af2449af2d36eb95226cb186ce2 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sun, 28 Apr 2024 11:35:11 +0200
Subject: Adding upstream version 2.6.12.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 src/freq_ctr.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 src/freq_ctr.c

(limited to 'src/freq_ctr.c')

diff --git a/src/freq_ctr.c b/src/freq_ctr.c
new file mode 100644
index 0000000..54aa78f
--- /dev/null
+++ b/src/freq_ctr.c
@@ -0,0 +1,104 @@
+/*
+ * Event rate calculation functions.
+ *
+ * Copyright 2000-2010 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 <haproxy/api.h>
+#include <haproxy/freq_ctr.h>
+#include <haproxy/tools.h>
+
+/* Returns the total number of events over the current + last period, including
+ * a number of already pending events <pend>. The average frequency will be
+ * obtained by dividing the output by <period>. This is essentially made to
+ * ease implementation of higher-level read functions.
+ *
+ * As a special case, if pend < 0, it's assumed there are no pending
+ * events and a flapping correction must be applied at the end. This is used by
+ * read_freq_ctr_period() to avoid reporting ups and downs on low-frequency
+ * events when the past value is <= 1.
+ */
+ullong freq_ctr_total(const struct freq_ctr *ctr, uint period, int pend)
+{
+	ullong curr, past, old_curr, old_past;
+	uint tick, old_tick;
+	int remain;
+
+	tick = HA_ATOMIC_LOAD(&ctr->curr_tick);
+	curr = HA_ATOMIC_LOAD(&ctr->curr_ctr);
+	past = HA_ATOMIC_LOAD(&ctr->prev_ctr);
+
+	while (1) {
+		if (tick & 0x1) // change in progress
+			goto redo0;
+
+		old_tick = tick;
+		old_curr = curr;
+		old_past = past;
+
+		/* now let's load the values a second time and make sure they
+		 * did not change, which will indicate it was a stable reading.
+		 */
+
+		tick = HA_ATOMIC_LOAD(&ctr->curr_tick);
+		if (tick & 0x1) // change in progress
+			goto redo0;
+
+		if (tick != old_tick)
+			goto redo1;
+
+		curr = HA_ATOMIC_LOAD(&ctr->curr_ctr);
+		if (curr != old_curr)
+			goto redo2;
+
+		past = HA_ATOMIC_LOAD(&ctr->prev_ctr);
+		if (past != old_past)
+			goto redo3;
+
+		/* all values match between two loads, they're stable, let's
+		 * quit now.
+		 */
+		break;
+	redo0:
+		tick = HA_ATOMIC_LOAD(&ctr->curr_tick);
+	redo1:
+		curr = HA_ATOMIC_LOAD(&ctr->curr_ctr);
+	redo2:
+		past = HA_ATOMIC_LOAD(&ctr->prev_ctr);
+	redo3:
+		__ha_cpu_relax();
+	};
+
+	remain = tick + period - HA_ATOMIC_LOAD(&global_now_ms);
+	if (unlikely(remain < 0)) {
+		/* We're past the first period, check if we can still report a
+		 * part of last period or if we're too far away.
+		 */
+		remain += period;
+		past = (remain >= 0) ? curr : 0;
+		curr = 0;
+	}
+
+	if (pend < 0) {
+		/* enable flapping correction at very low rates */
+		pend = 0;
+		if (!curr && past <= 1)
+			return past * period;
+	}
+
+	/* compute the total number of confirmed events over the period */
+	return past * remain + (curr + pend) * period;
+}
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ */
-- 
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