/*
 * Resizable, Scalable, Concurrent Hash Table
 *
 * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>
 * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

/**************************************************************************
 * Self Test
 **************************************************************************/

#include <linux/init.h>
#include <linux/jhash.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/rcupdate.h>
#include <linux/rhashtable.h>
#include <linux/slab.h>


#define MAX_ENTRIES	1000000

static int entries = 50000;
module_param(entries, int, 0);
MODULE_PARM_DESC(entries, "Number of entries to add (default: 50000)");

static int runs = 4;
module_param(runs, int, 0);
MODULE_PARM_DESC(runs, "Number of test runs per variant (default: 4)");

static int max_size = 65536;
module_param(max_size, int, 0);
MODULE_PARM_DESC(runs, "Maximum table size (default: 65536)");

static bool shrinking = false;
module_param(shrinking, bool, 0);
MODULE_PARM_DESC(shrinking, "Enable automatic shrinking (default: off)");

static int size = 8;
module_param(size, int, 0);
MODULE_PARM_DESC(size, "Initial size hint of table (default: 8)");

struct test_obj {
	int			value;
	struct rhash_head	node;
};

static struct test_obj array[MAX_ENTRIES];

static struct rhashtable_params test_rht_params = {
	.head_offset = offsetof(struct test_obj, node),
	.key_offset = offsetof(struct test_obj, value),
	.key_len = sizeof(int),
	.hashfn = jhash,
	.nulls_base = (3U << RHT_BASE_SHIFT),
};

static int __init test_rht_lookup(struct rhashtable *ht)
{
	unsigned int i;

	for (i = 0; i < entries * 2; i++) {
		struct test_obj *obj;
		bool expected = !(i % 2);
		u32 key = i;

		obj = rhashtable_lookup_fast(ht, &key, test_rht_params);

		if (expected && !obj) {
			pr_warn("Test failed: Could not find key %u\n", key);
			return -ENOENT;
		} else if (!expected && obj) {
			pr_warn("Test failed: Unexpected entry found for key %u\n",
				key);
			return -EEXIST;
		} else if (expected && obj) {
			if (obj->value != i) {
				pr_warn("Test failed: Lookup value mismatch %u!=%u\n",
					obj->value, i);
				return -EINVAL;
			}
		}
	}

	return 0;
}

static void test_bucket_stats(struct rhashtable *ht, bool quiet)
{
	unsigned int cnt, rcu_cnt, i, total = 0;
	struct rhash_head *pos;
	struct test_obj *obj;
	struct bucket_table *tbl;

	tbl = rht_dereference_rcu(ht->tbl, ht);
	for (i = 0; i < tbl->size; i++) {
		rcu_cnt = cnt = 0;

		if (!quiet)
			pr_info(" [%#4x/%u]", i, tbl->size);

		rht_for_each_entry_rcu(obj, pos, tbl, i, node) {
			cnt++;
			total++;
			if (!quiet)
				pr_cont(" [%p],", obj);
		}

		rht_for_each_entry_rcu(obj, pos, tbl, i, node)
			rcu_cnt++;

		if (rcu_cnt != cnt)
			pr_warn("Test failed: Chain count mismach %d != %d",
				cnt, rcu_cnt);

		if (!quiet)
			pr_cont("\n  [%#x] first element: %p, chain length: %u\n",
				i, tbl->buckets[i], cnt);
	}

	pr_info("  Traversal complete: counted=%u, nelems=%u, entries=%d\n",
		total, atomic_read(&ht->nelems), entries);

	if (total != atomic_read(&ht->nelems) || total != entries)
		pr_warn("Test failed: Total count mismatch ^^^");
}

static s64 __init test_rhashtable(struct rhashtable *ht)
{
	struct test_obj *obj;
	int err;
	unsigned int i;
	s64 start, end;

	/*
	 * Insertion Test:
	 * Insert entries into table with all keys even numbers
	 */
	pr_info("  Adding %d keys\n", entries);
	start = ktime_get_ns();
	for (i = 0; i < entries; i++) {
		struct test_obj *obj = &array[i];

		obj->value = i * 2;

		err = rhashtable_insert_fast(ht, &obj->node, test_rht_params);
		if (err)
			return err;
	}

	rcu_read_lock();
	test_bucket_stats(ht, true);
	test_rht_lookup(ht);
	rcu_read_unlock();

	rcu_read_lock();
	test_bucket_stats(ht, true);
	rcu_read_unlock();

	pr_info("  Deleting %d keys\n", entries);
	for (i = 0; i < entries; i++) {
		u32 key = i * 2;

		obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
		BUG_ON(!obj);

		rhashtable_remove_fast(ht, &obj->node, test_rht_params);
	}

	end = ktime_get_ns();
	pr_info("  Duration of test: %lld ns\n", end - start);

	return end - start;
}

static struct rhashtable ht;

static int __init test_rht_init(void)
{
	int i, err;
	u64 total_time = 0;

	entries = min(entries, MAX_ENTRIES);

	test_rht_params.automatic_shrinking = shrinking;
	test_rht_params.max_size = max_size;
	test_rht_params.nelem_hint = size;

	pr_info("Running rhashtable test nelem=%d, max_size=%d, shrinking=%d\n",
		size, max_size, shrinking);

	for (i = 0; i < runs; i++) {
		s64 time;

		pr_info("Test %02d:\n", i);
		memset(&array, 0, sizeof(array));
		err = rhashtable_init(&ht, &test_rht_params);
		if (err < 0) {
			pr_warn("Test failed: Unable to initialize hashtable: %d\n",
				err);
			continue;
		}

		time = test_rhashtable(&ht);
		rhashtable_destroy(&ht);
		if (time < 0) {
			pr_warn("Test failed: return code %lld\n", time);
			return -EINVAL;
		}

		total_time += time;
	}

	pr_info("Average test time: %llu\n", total_time / runs);

	return 0;
}

static void __exit test_rht_exit(void)
{
}

module_init(test_rht_init);
module_exit(test_rht_exit);

MODULE_LICENSE("GPL v2");