// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/interval_tree.h>
#include <linux/prandom.h>
#include <linux/slab.h>
#include <asm/timex.h>
#include <linux/bitmap.h>
#include <linux/maple_tree.h>

#define __param(type, name, init, msg)		\
	static type name = init;		\
	module_param(name, type, 0444);		\
	MODULE_PARM_DESC(name, msg);

__param(int, nnodes, 100, "Number of nodes in the interval tree");
__param(int, perf_loops, 1000, "Number of iterations modifying the tree");

__param(int, nsearches, 100, "Number of searches to the interval tree");
__param(int, search_loops, 1000, "Number of iterations searching the tree");
__param(bool, search_all, false, "Searches will iterate all nodes in the tree");

__param(uint, max_endpoint, ~0, "Largest value for the interval's endpoint");
__param(ullong, seed, 3141592653589793238ULL, "Random seed");

static struct rb_root_cached root = RB_ROOT_CACHED;
static struct interval_tree_node *nodes = NULL;
static u32 *queries = NULL;

static struct rnd_state rnd;

static inline unsigned long
search(struct rb_root_cached *root, unsigned long start, unsigned long last)
{
	struct interval_tree_node *node;
	unsigned long results = 0;

	for (node = interval_tree_iter_first(root, start, last); node;
	     node = interval_tree_iter_next(node, start, last))
		results++;
	return results;
}

static void init(void)
{
	int i;

	for (i = 0; i < nnodes; i++) {
		u32 b = (prandom_u32_state(&rnd) >> 4) % max_endpoint;
		u32 a = (prandom_u32_state(&rnd) >> 4) % b;

		nodes[i].start = a;
		nodes[i].last = b;
	}

	/*
	 * Limit the search scope to what the user defined.
	 * Otherwise we are merely measuring empty walks,
	 * which is pointless.
	 */
	for (i = 0; i < nsearches; i++)
		queries[i] = (prandom_u32_state(&rnd) >> 4) % max_endpoint;
}

static int basic_check(void)
{
	int i, j;
	cycles_t time1, time2, time;

	printk(KERN_ALERT "interval tree insert/remove");

	init();

	time1 = get_cycles();

	for (i = 0; i < perf_loops; i++) {
		for (j = 0; j < nnodes; j++)
			interval_tree_insert(nodes + j, &root);
		for (j = 0; j < nnodes; j++)
			interval_tree_remove(nodes + j, &root);
	}

	time2 = get_cycles();
	time = time2 - time1;

	time = div_u64(time, perf_loops);
	printk(" -> %llu cycles\n", (unsigned long long)time);

	return 0;
}

static int search_check(void)
{
	int i, j;
	unsigned long results;
	cycles_t time1, time2, time;

	printk(KERN_ALERT "interval tree search");

	init();

	for (j = 0; j < nnodes; j++)
		interval_tree_insert(nodes + j, &root);

	time1 = get_cycles();

	results = 0;
	for (i = 0; i < search_loops; i++)
		for (j = 0; j < nsearches; j++) {
			unsigned long start = search_all ? 0 : queries[j];
			unsigned long last = search_all ? max_endpoint : queries[j];

			results += search(&root, start, last);
		}

	time2 = get_cycles();
	time = time2 - time1;

	time = div_u64(time, search_loops);
	results = div_u64(results, search_loops);
	printk(" -> %llu cycles (%lu results)\n",
	       (unsigned long long)time, results);

	for (j = 0; j < nnodes; j++)
		interval_tree_remove(nodes + j, &root);

	return 0;
}

static int intersection_range_check(void)
{
	int i, j, k;
	unsigned long start, last;
	struct interval_tree_node *node;
	unsigned long *intxn1;
	unsigned long *intxn2;

	printk(KERN_ALERT "interval tree iteration\n");

	intxn1 = bitmap_alloc(nnodes, GFP_KERNEL);
	if (!intxn1) {
		WARN_ON_ONCE("Failed to allocate intxn1\n");
		return -ENOMEM;
	}

	intxn2 = bitmap_alloc(nnodes, GFP_KERNEL);
	if (!intxn2) {
		WARN_ON_ONCE("Failed to allocate intxn2\n");
		bitmap_free(intxn1);
		return -ENOMEM;
	}

	for (i = 0; i < search_loops; i++) {
		/* Initialize interval tree for each round */
		init();
		for (j = 0; j < nnodes; j++)
			interval_tree_insert(nodes + j, &root);

		/* Let's try nsearches different ranges */
		for (k = 0; k < nsearches; k++) {
			/* Try whole range once */
			if (!k) {
				start = 0UL;
				last = ULONG_MAX;
			} else {
				last = (prandom_u32_state(&rnd) >> 4) % max_endpoint;
				start = (prandom_u32_state(&rnd) >> 4) % last;
			}

			/* Walk nodes to mark intersection nodes */
			bitmap_zero(intxn1, nnodes);
			for (j = 0; j < nnodes; j++) {
				node = nodes + j;

				if (start <= node->last && last >= node->start)
					bitmap_set(intxn1, j, 1);
			}

			/* Iterate tree to clear intersection nodes */
			bitmap_zero(intxn2, nnodes);
			for (node = interval_tree_iter_first(&root, start, last); node;
			     node = interval_tree_iter_next(node, start, last))
				bitmap_set(intxn2, node - nodes, 1);

			WARN_ON_ONCE(!bitmap_equal(intxn1, intxn2, nnodes));
		}

		for (j = 0; j < nnodes; j++)
			interval_tree_remove(nodes + j, &root);
	}

	bitmap_free(intxn1);
	bitmap_free(intxn2);
	return 0;
}

#ifdef CONFIG_INTERVAL_TREE_SPAN_ITER
/*
 * Helper function to get span of current position from maple tree point of
 * view.
 */
static void mas_cur_span(struct ma_state *mas, struct interval_tree_span_iter *state)
{
	unsigned long cur_start;
	unsigned long cur_last;
	int is_hole;

	if (mas->status == ma_overflow)
		return;

	/* walk to current position */
	state->is_hole = mas_walk(mas) ? 0 : 1;

	cur_start = mas->index < state->first_index ?
			state->first_index : mas->index;

	/* whether we have followers */
	do {

		cur_last = mas->last > state->last_index ?
				state->last_index : mas->last;

		is_hole = mas_next_range(mas, state->last_index) ? 0 : 1;

	} while (mas->status != ma_overflow && is_hole == state->is_hole);

	if (state->is_hole) {
		state->start_hole = cur_start;
		state->last_hole = cur_last;
	} else {
		state->start_used = cur_start;
		state->last_used = cur_last;
	}

	/* advance position for next round */
	if (mas->status != ma_overflow)
		mas_set(mas, cur_last + 1);
}

static int span_iteration_check(void)
{
	int i, j, k;
	unsigned long start, last;
	struct interval_tree_span_iter span, mas_span;

	DEFINE_MTREE(tree);

	MA_STATE(mas, &tree, 0, 0);

	printk(KERN_ALERT "interval tree span iteration\n");

	for (i = 0; i < search_loops; i++) {
		/* Initialize interval tree for each round */
		init();
		for (j = 0; j < nnodes; j++)
			interval_tree_insert(nodes + j, &root);

		/* Put all the range into maple tree */
		mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE);
		mt_set_in_rcu(&tree);

		for (j = 0; j < nnodes; j++)
			WARN_ON_ONCE(mtree_store_range(&tree, nodes[j].start,
					nodes[j].last, nodes + j, GFP_KERNEL));

		/* Let's try nsearches different ranges */
		for (k = 0; k < nsearches; k++) {
			/* Try whole range once */
			if (!k) {
				start = 0UL;
				last = ULONG_MAX;
			} else {
				last = (prandom_u32_state(&rnd) >> 4) % max_endpoint;
				start = (prandom_u32_state(&rnd) >> 4) % last;
			}

			mas_span.first_index = start;
			mas_span.last_index = last;
			mas_span.is_hole = -1;
			mas_set(&mas, start);

			interval_tree_for_each_span(&span, &root, start, last) {
				mas_cur_span(&mas, &mas_span);

				WARN_ON_ONCE(span.is_hole != mas_span.is_hole);

				if (span.is_hole) {
					WARN_ON_ONCE(span.start_hole != mas_span.start_hole);
					WARN_ON_ONCE(span.last_hole != mas_span.last_hole);
				} else {
					WARN_ON_ONCE(span.start_used != mas_span.start_used);
					WARN_ON_ONCE(span.last_used != mas_span.last_used);
				}
			}

		}

		WARN_ON_ONCE(mas.status != ma_overflow);

		/* Cleanup maple tree for each round */
		mtree_destroy(&tree);
		/* Cleanup interval tree for each round */
		for (j = 0; j < nnodes; j++)
			interval_tree_remove(nodes + j, &root);
	}
	return 0;
}
#else
static inline int span_iteration_check(void) {return 0; }
#endif

static int interval_tree_test_init(void)
{
	nodes = kmalloc_array(nnodes, sizeof(struct interval_tree_node),
			      GFP_KERNEL);
	if (!nodes)
		return -ENOMEM;

	queries = kmalloc_array(nsearches, sizeof(int), GFP_KERNEL);
	if (!queries) {
		kfree(nodes);
		return -ENOMEM;
	}

	prandom_seed_state(&rnd, seed);

	basic_check();
	search_check();
	intersection_range_check();
	span_iteration_check();

	kfree(queries);
	kfree(nodes);

	return -EAGAIN; /* Fail will directly unload the module */
}

static void interval_tree_test_exit(void)
{
	printk(KERN_ALERT "test exit\n");
}

module_init(interval_tree_test_init)
module_exit(interval_tree_test_exit)

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Michel Lespinasse");
MODULE_DESCRIPTION("Interval Tree test");