Re: [PATCH v2 8/9] rbtree: faster augmented rbtree manipulation

[Peter Zijlstra]

On Mon, 2012-08-06 at 16:17 +0200, Peter Zijlstra wrote:

> Why would every user need to replicate the propagate and rotate
> boilerplate?

So I don't have a tree near that any of this applies to (hence no actual
patch), but why can't we have something like:

struct rb_augment_callback {
        const bool (*update)(struct rb_node *node);
        const int offset;
        const int size;
};

#define RB_AUGMENT_CALLBACK(_update, _type, _rb_member, _aug_member)    \
(struct rb_augment_callback){                                           \
        .update = _update,                                              \
        .offset = offsetof(_type, _aug_member) -                        \
                  offsetof(_type, _rb_member),                          \
        .size   = sizeof(((_type *)NULL)->_aug_member),                 \
}

static __always_inline void 
augment_copy(struct rb_node *dst, struct rb_node *src,
             const rb_augment_callback *ac)
{
        memcpy((void *)dst + ac->offset,
               (void *)src + ac->offset,
               ac->size);
} 

static __always_inline void 
augment_propagate(struct rb_node *rb, struct rb_node *stop,
                  const struct rb_augment_callback *ac)
{
        while (rb != stop) {
                if (!ac->update(rb))
                        break;
                rb = rb_parent(rb);
        }
}

static __always_inline void
augment_rotate(struct rb_node *old, struct rb_node *new.
               const struct rb_augment_callback *ac)
{
        augment_copy(new, old, ac);
        (void)ac->update(old);
}


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