// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/rbtree_augmented.h>
#include <linux/prandom.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 rb-tree");
__param(int, perf_loops, 1000, "Number of iterations modifying the rb-tree");
__param(int, check_loops, 100, "Number of iterations modifying and verifying the rb-tree");
__param(ullong, seed, 3141592653589793238ULL, "Random seed");

struct test_node {
        u32 key;
        struct rb_node rb;

        /* following fields used for testing augmented rbtree functionality */
        u32 val;
        u32 augmented;
};

static struct rb_root_cached root = RB_ROOT_CACHED;
static struct test_node *nodes = NULL;

static struct rnd_state rnd;

static void insert(struct test_node *node, struct rb_root_cached *root)
{
        struct rb_node **new = &root->rb_root.rb_node, *parent = NULL;
        u32 key = node->key;

        while (*new) {
                parent = *new;
                if (key < rb_entry(parent, struct test_node, rb)->key)
                        new = &parent->rb_left;
                else
                        new = &parent->rb_right;
        }

        rb_link_node(&node->rb, parent, new);
        rb_insert_color(&node->rb, &root->rb_root);
}

static void insert_cached(struct test_node *node, struct rb_root_cached *root)
{
        struct rb_node **new = &root->rb_root.rb_node, *parent = NULL;
        u32 key = node->key;
        bool leftmost = true;

        while (*new) {
                parent = *new;
                if (key < rb_entry(parent, struct test_node, rb)->key)
                        new = &parent->rb_left;
                else {
                        new = &parent->rb_right;
                        leftmost = false;
                }
        }

        rb_link_node(&node->rb, parent, new);
        rb_insert_color_cached(&node->rb, root, leftmost);
}

static inline void erase(struct test_node *node, struct rb_root_cached *root)
{
        rb_erase(&node->rb, &root->rb_root);
}

static inline void erase_cached(struct test_node *node, struct rb_root_cached *root)
{
        rb_erase_cached(&node->rb, root);
}


#define NODE_VAL(node) ((node)->val)

RB_DECLARE_CALLBACKS_MAX(static, augment_callbacks,
                         struct test_node, rb, u32, augmented, NODE_VAL)

static void insert_augmented(struct test_node *node,
                             struct rb_root_cached *root)
{
        struct rb_node **new = &root->rb_root.rb_node, *rb_parent = NULL;
        u32 key = node->key;
        u32 val = node->val;
        struct test_node *parent;

        while (*new) {
                rb_parent = *new;
                parent = rb_entry(rb_parent, struct test_node, rb);
                if (parent->augmented < val)
                        parent->augmented = val;
                if (key < parent->key)
                        new = &parent->rb.rb_left;
                else
                        new = &parent->rb.rb_right;
        }

        node->augmented = val;
        rb_link_node(&node->rb, rb_parent, new);
        rb_insert_augmented(&node->rb, &root->rb_root, &augment_callbacks);
}

static void insert_augmented_cached(struct test_node *node,
                                    struct rb_root_cached *root)
{
        struct rb_node **new = &root->rb_root.rb_node, *rb_parent = NULL;
        u32 key = node->key;
        u32 val = node->val;
        struct test_node *parent;
        bool leftmost = true;

        while (*new) {
                rb_parent = *new;
                parent = rb_entry(rb_parent, struct test_node, rb);
                if (parent->augmented < val)
                        parent->augmented = val;
                if (key < parent->key)
                        new = &parent->rb.rb_left;
                else {
                        new = &parent->rb.rb_right;
                        leftmost = false;
                }
        }

        node->augmented = val;
        rb_link_node(&node->rb, rb_parent, new);
        rb_insert_augmented_cached(&node->rb, root,
                                   leftmost, &augment_callbacks);
}


static void erase_augmented(struct test_node *node, struct rb_root_cached *root)
{
        rb_erase_augmented(&node->rb, &root->rb_root, &augment_callbacks);
}

static void erase_augmented_cached(struct test_node *node,
                                   struct rb_root_cached *root)
{
        rb_erase_augmented_cached(&node->rb, root, &augment_callbacks);
}

static void init(void)
{
        int i;
        for (i = 0; i < nnodes; i++) {
                nodes[i].key = prandom_u32_state(&rnd);
                nodes[i].val = prandom_u32_state(&rnd);
        }
}

static bool is_red(struct rb_node *rb)
{
        return !(rb->__rb_parent_color & 1);
}

static int black_path_count(struct rb_node *rb)
{
        int count;
        for (count = 0; rb; rb = rb_parent(rb))
                count += !is_red(rb);
        return count;
}

static void check_postorder_foreach(int nr_nodes)
{
        struct test_node *cur, *n;
        int count = 0;
        rbtree_postorder_for_each_entry_safe(cur, n, &root.rb_root, rb)
                count++;

        WARN_ON_ONCE(count != nr_nodes);
}

static void check_postorder(int nr_nodes)
{
        struct rb_node *rb;
        int count = 0;
        for (rb = rb_first_postorder(&root.rb_root); rb; rb = rb_next_postorder(rb))
                count++;

        WARN_ON_ONCE(count != nr_nodes);
}

static void check(int nr_nodes)
{
        struct rb_node *rb;
        int count = 0, blacks = 0;
        u32 prev_key = 0;

        for (rb = rb_first(&root.rb_root); rb; rb = rb_next(rb)) {
                struct test_node *node = rb_entry(rb, struct test_node, rb);
                WARN_ON_ONCE(node->key < prev_key);
                WARN_ON_ONCE(is_red(rb) &&
                             (!rb_parent(rb) || is_red(rb_parent(rb))));
                if (!count)
                        blacks = black_path_count(rb);
                else
                        WARN_ON_ONCE((!rb->rb_left || !rb->rb_right) &&
                                     blacks != black_path_count(rb));
                prev_key = node->key;
                count++;
        }

        WARN_ON_ONCE(count != nr_nodes);
        WARN_ON_ONCE(count < (1 << black_path_count(rb_last(&root.rb_root))) - 1);

        check_postorder(nr_nodes);
        check_postorder_foreach(nr_nodes);
}

static void check_augmented(int nr_nodes)
{
        struct rb_node *rb;

        check(nr_nodes);
        for (rb = rb_first(&root.rb_root); rb; rb = rb_next(rb)) {
                struct test_node *node = rb_entry(rb, struct test_node, rb);
                u32 subtree, max = node->val;
                if (node->rb.rb_left) {
                        subtree = rb_entry(node->rb.rb_left, struct test_node,
                                           rb)->augmented;
                        if (max < subtree)
                                max = subtree;
                }
                if (node->rb.rb_right) {
                        subtree = rb_entry(node->rb.rb_right, struct test_node,
                                           rb)->augmented;
                        if (max < subtree)
                                max = subtree;
                }
                WARN_ON_ONCE(node->augmented != max);
        }
}

static int basic_check(void)
{
        int i, j;
        cycles_t time1, time2, time;
        struct rb_node *node;

        printk(KERN_ALERT "rbtree testing");

        init();

        time1 = get_cycles();

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

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

        time = div_u64(time, perf_loops);
        printk(" -> test 1 (latency of nnodes insert+delete): %llu cycles\n",
               (unsigned long long)time);

        time1 = get_cycles();

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

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

        time = div_u64(time, perf_loops);
        printk(" -> test 2 (latency of nnodes cached insert+delete): %llu cycles\n",
               (unsigned long long)time);

        for (i = 0; i < nnodes; i++)
                insert(nodes + i, &root);

        time1 = get_cycles();

        for (i = 0; i < perf_loops; i++) {
                for (node = rb_first(&root.rb_root); node; node = rb_next(node))
                        ;
        }

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

        time = div_u64(time, perf_loops);
        printk(" -> test 3 (latency of inorder traversal): %llu cycles\n",
               (unsigned long long)time);

        time1 = get_cycles();

        for (i = 0; i < perf_loops; i++)
                node = rb_first(&root.rb_root);

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

        time = div_u64(time, perf_loops);
        printk(" -> test 4 (latency to fetch first node)\n");
        printk("        non-cached: %llu cycles\n", (unsigned long long)time);

        time1 = get_cycles();

        for (i = 0; i < perf_loops; i++)
                node = rb_first_cached(&root);

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

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

        for (i = 0; i < nnodes; i++)
                erase(nodes + i, &root);

        /* run checks */
        for (i = 0; i < check_loops; i++) {
                init();
                for (j = 0; j < nnodes; j++) {
                        check(j);
                        insert(nodes + j, &root);
                }
                for (j = 0; j < nnodes; j++) {
                        check(nnodes - j);
                        erase(nodes + j, &root);
                }
                check(0);
        }

        return 0;
}

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

        printk(KERN_ALERT "augmented rbtree testing");

        init();

        time1 = get_cycles();

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

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

        time = div_u64(time, perf_loops);
        printk(" -> test 1 (latency of nnodes insert+delete): %llu cycles\n", (unsigned long long)time);

        time1 = get_cycles();

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

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

        time = div_u64(time, perf_loops);
        printk(" -> test 2 (latency of nnodes cached insert+delete): %llu cycles\n", (unsigned long long)time);

        for (i = 0; i < check_loops; i++) {
                init();
                for (j = 0; j < nnodes; j++) {
                        check_augmented(j);
                        insert_augmented(nodes + j, &root);
                }
                for (j = 0; j < nnodes; j++) {
                        check_augmented(nnodes - j);
                        erase_augmented(nodes + j, &root);
                }
                check_augmented(0);
        }

        return 0;
}

static int __init rbtree_test_init(void)
{
        nodes = kmalloc_objs(*nodes, nnodes);
        if (!nodes)
                return -ENOMEM;

        prandom_seed_state(&rnd, seed);

        basic_check();
        augmented_check();

        kfree(nodes);

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

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

module_init(rbtree_test_init)
module_exit(rbtree_test_exit)

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