#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/interval_tree.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <asm/timex.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, 100000, "Number of iterations modifying the tree");

__param(int, nsearches, 100, "Number of searches to the interval tree");
__param(int, search_loops, 10000, "Number of iterations searching the tree");


static struct rb_root root = RB_ROOT;
static struct interval_tree_node *nodes = NULL;
static u32 *queries = NULL;

static struct rnd_state rnd;

static inline unsigned long
search(unsigned long query, struct rb_root *root)
{
	struct interval_tree_node *node;
	unsigned long results = 0;

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

static void init(void)
{
	int i;

	for (i = 0; i < nnodes; i++) {
		u32 a = prandom_u32_state(&rnd);
		u32 b = prandom_u32_state(&rnd);
		if (a <= b) {
			nodes[i].start = a;
			nodes[i].last = b;
		} else {
			nodes[i].start = b;
			nodes[i].last = a;
		}
	}
	for (i = 0; i < nsearches; i++)
		queries[i] = prandom_u32_state(&rnd);
}

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

	nodes = kmalloc(nnodes * sizeof(struct interval_tree_node), GFP_KERNEL);
	if (!nodes)
		return -ENOMEM;

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

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

	prandom_seed_state(&rnd, 3141592653589793238ULL);
	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);

	printk(KERN_ALERT "interval tree search");

	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++)
			results += search(queries[j], &root);

	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);

	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");