rbtree_test.c

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#include <linux/module.h>
#include <linux/rbtree_augmented.h>
#include <linux/random.h>
#include <asm/timex.h>

#define NODES       100
#define PERF_LOOPS  100000
#define CHECK_LOOPS 100

struct test_node {
    struct rb_node rb;
    u32 key;

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

static struct rb_root root = RB_ROOT;
static struct test_node nodes[NODES];

static struct rnd_state rnd;

static void insert(struct test_node *node, struct rb_root *root)
{
    struct rb_node **new = &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);
}

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

static inline u32 augment_recompute(struct test_node *node)
{
    u32 max = node->val, child_augmented;
    if (node->rb.rb_left) {
        child_augmented = rb_entry(node->rb.rb_left, struct test_node,
                       rb)->augmented;
        if (max < child_augmented)
            max = child_augmented;
    }
    if (node->rb.rb_right) {
        child_augmented = rb_entry(node->rb.rb_right, struct test_node,
                       rb)->augmented;
        if (max < child_augmented)
            max = child_augmented;
    }
    return max;
}

RB_DECLARE_CALLBACKS(static, augment_callbacks, struct test_node, rb,
             u32, augmented, augment_recompute)

static void insert_augmented(struct test_node *node, struct rb_root *root)
{
    struct rb_node **new = &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, &augment_callbacks);
}

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

static void init(void)
{
    int i;
    for (i = 0; i < NODES; i++) {
        nodes[i].key = prandom32(&rnd);
        nodes[i].val = prandom32(&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(int nr_nodes)
{
    struct rb_node *rb;
    int count = 0;
    int blacks;
    u32 prev_key = 0;

    for (rb = rb_first(&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);
}

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

    check(nr_nodes);
    for (rb = rb_first(&root); rb; rb = rb_next(rb)) {
        struct test_node *node = rb_entry(rb, struct test_node, rb);
        WARN_ON_ONCE(node->augmented != augment_recompute(node));
    }
}

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

    printk(KERN_ALERT "rbtree testing");

    prandom32_seed(&rnd, 3141592653589793238ULL);
    init();

    time1 = get_cycles();

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

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

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

    for (i = 0; i < CHECK_LOOPS; i++) {
        init();
        for (j = 0; j < NODES; j++) {
            check(j);
            insert(nodes + j, &root);
        }
        for (j = 0; j < NODES; j++) {
            check(NODES - j);
            erase(nodes + j, &root);
        }
        check(0);
    }

    printk(KERN_ALERT "augmented rbtree testing");

    init();

    time1 = get_cycles();

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

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

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

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

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

static void 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");