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+/*****************************************************************************
+
+Copyright (c) 2012, 2015, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 2017, 2019, MariaDB Corporation.
+
+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; version 2 of the License.
+
+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 GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA
+
+*****************************************************************************/
+
+/**************************************************//**
+@file include/ut0counter.h
+
+Counter utility class
+
+Created 2012/04/12 by Sunny Bains
+*******************************************************/
+
+#ifndef ut0counter_h
+#define ut0counter_h
+
+#include "os0thread.h"
+#include "my_rdtsc.h"
+
+/** CPU cache line size */
+#ifdef CPU_LEVEL1_DCACHE_LINESIZE
+# define CACHE_LINE_SIZE	CPU_LEVEL1_DCACHE_LINESIZE
+#else
+# error CPU_LEVEL1_DCACHE_LINESIZE is undefined
+#endif /* CPU_LEVEL1_DCACHE_LINESIZE */
+
+/** Default number of slots to use in ib_counter_t */
+#define IB_N_SLOTS		64
+
+/** Use the result of my_timer_cycles(), which mainly uses RDTSC for cycles
+as a random value. See the comments for my_timer_cycles() */
+/** @return result from RDTSC or similar functions. */
+static inline size_t
+get_rnd_value()
+{
+	size_t c = static_cast<size_t>(my_timer_cycles());
+
+	if (c != 0) {
+		return c;
+	}
+
+	/* We may go here if my_timer_cycles() returns 0,
+	so we have to have the plan B for the counter. */
+#if !defined(_WIN32)
+	return (size_t)os_thread_get_curr_id();
+#else
+	LARGE_INTEGER cnt;
+	QueryPerformanceCounter(&cnt);
+
+	return static_cast<size_t>(cnt.QuadPart);
+#endif /* !_WIN32 */
+}
+
+/** Class for using fuzzy counters. The counter is multi-instance relaxed atomic
+so the results are not guaranteed to be 100% accurate but close
+enough. Creates an array of counters and separates each element by the
+CACHE_LINE_SIZE bytes */
+template <typename Type, int N = IB_N_SLOTS>
+struct ib_counter_t {
+	/** Increment the counter by 1. */
+	void inc() { add(1); }
+
+	/** Increment the counter by 1.
+	@param[in]	index	a reasonably thread-unique identifier */
+	void inc(size_t index) { add(index, 1); }
+
+	/** Add to the counter.
+	@param[in]	n	amount to be added */
+	void add(Type n) { add(get_rnd_value(), n); }
+
+	/** Add to the counter.
+	@param[in]	index	a reasonably thread-unique identifier
+	@param[in]	n	amount to be added */
+	void add(size_t index, Type n) {
+		index = index % N;
+
+		ut_ad(index < UT_ARR_SIZE(m_counter));
+
+		m_counter[index].value.fetch_add(n, std::memory_order_relaxed);
+	}
+
+	/* @return total value - not 100% accurate, since it is relaxed atomic*/
+	operator Type() const {
+		Type	total = 0;
+
+		for (const auto &counter : m_counter) {
+			total += counter.value.load(std::memory_order_relaxed);
+		}
+
+		return(total);
+	}
+
+private:
+	/** Atomic which occupies whole CPU cache line.
+	Note: We rely on the default constructor of std::atomic and
+	do not explicitly initialize the contents. This works for us,
+	because ib_counter_t is only intended for usage with global
+	memory that is allocated from the .bss and thus guaranteed to
+	be zero-initialized by the run-time environment.
+	@see srv_stats
+	@see rw_lock_stats */
+	struct ib_counter_element_t {
+		MY_ALIGNED(CACHE_LINE_SIZE) std::atomic<Type> value;
+	};
+	static_assert(sizeof(ib_counter_element_t) == CACHE_LINE_SIZE, "");
+
+	/** Array of counter elements */
+	MY_ALIGNED(CACHE_LINE_SIZE) ib_counter_element_t m_counter[N];
+};
+
+#endif /* ut0counter_h */