errval_t
mdb_remove(struct cte *target)
{
MDB_TRACE_ENTER(mdb_root, "%p", target);
errval_t err = mdb_subtree_remove(target, &mdb_root, NULL);
MDB_TRACE_LEAVE_SUB_RET("%"PRIuPTR, err, mdb_root);
}
errval_t
mdb_remove(struct cte *target)
{
MDB_TRACE_ENTER(mdb_root, "%p", target);
CHECK_INVARIANTS(mdb_root, target, true);
#ifdef IN_KERNEL
#ifdef MDB_TRACE_NO_RECURSIVE
char prefix[50];
snprintf(prefix, 50, "mdb_remove.%d: ", my_core_id);
print_cte(target, prefix);
#endif
#endif
errval_t err = mdb_subtree_remove(target, &mdb_root, NULL);
CHECK_INVARIANTS(mdb_root, target, false);
MDB_TRACE_LEAVE_SUB_RET("%"PRIuPTR, err, mdb_root);
}
static errval_t
mdb_subtree_remove(struct cte *target, struct cte **current, struct cte *parent)
{
assert(current);
MDB_TRACE_ENTER(*current, "%p, %p (*%p), %p", target, *current, current, parent);
errval_t err;
struct cte *current_ = *current;
if (!current_) {
err = CAPS_ERR_MDB_ENTRY_NOTFOUND;
MDB_TRACE_LEAVE_SUB_RET("%"PRIuPTR, err, current_);
}
int compare = compare_caps(C(target), C(current_), true);
if (compare > 0) {
err = mdb_subtree_remove(target, &N(current_)->right, current_);
if (err != SYS_ERR_OK) {
MDB_TRACE_LEAVE_SUB_RET("%"PRIuPTR, err, current_);
return err;
}
}
else if (compare < 0) {
err = mdb_subtree_remove(target, &N(current_)->left, current_);
if (err != SYS_ERR_OK) {
MDB_TRACE_LEAVE_SUB_RET("%"PRIuPTR, err, current_);
}
}
else {
assert(current_ == target);
if (!N(current_)->left && !N(current_)->right) {
// target is leaf, just remove
*current = NULL;
err = SYS_ERR_OK;
MDB_TRACE_LEAVE_SUB_RET("%"PRIuPTR, err, NULL);
}
else if (!N(current_)->left) {
// move to right child then go left (dir=-1)
// curr, new_right = xchg_rm(elem, parent, current.right, current, -1)
struct cte *new_current = NULL;
struct cte *new_right = N(current_)->right;
mdb_exchange_remove(target, parent, &new_right, current_, -1,
&new_current);
assert(new_current);
current_ = new_current;
N(current_)->right = new_right;
assert(!mdb_is_reachable(mdb_root, target));
}
else {
// move to left child then go right (dir=1)
// curr, new_left = xchg_rm(elem, parent, current.left, current, 1)
struct cte *new_current = NULL;
struct cte *new_left = N(current_)->left;
mdb_exchange_remove(target, parent, &new_left, current_, 1,
&new_current);
assert(new_current);
current_ = new_current;
N(current_)->left = new_left;
assert(!mdb_is_reachable(mdb_root, target));
}
}
// rebalance after remove from subtree
current_ = mdb_rebalance(current_);
*current = current_;
assert(C(target)->type != 0);
assert(!*current || C(*current)->type != 0);
err = SYS_ERR_OK;
MDB_TRACE_LEAVE_SUB_RET("%"PRIuPTR, err, current_);
}
