/*
* To remove a leaf_node:
* Search to the tree location appropriate for the given leaf_node's key:
* - If location does not hold a matching entry, abort and do nothing.
* - Replace the matching leaf_node with a NULL entry (and free the leaf_node).
* - Consolidate int_nodes repeatedly, while walking up the tree towards root.
*/
static void note_tree_remove(struct notes_tree *t, struct int_node *tree,
unsigned char n, struct leaf_node *entry)
{
struct leaf_node *l;
struct int_node *parent_stack[20];
unsigned char i, j;
void **p = note_tree_search(t, &tree, &n, entry->key_sha1);
assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
if (GET_PTR_TYPE(*p) != PTR_TYPE_NOTE)
return; /* type mismatch, nothing to remove */
l = (struct leaf_node *) CLR_PTR_TYPE(*p);
if (hashcmp(l->key_sha1, entry->key_sha1))
return; /* key mismatch, nothing to remove */
/* we have found a matching entry */
free(l);
*p = SET_PTR_TYPE(NULL, PTR_TYPE_NULL);
/* consolidate this tree level, and parent levels, if possible */
if (!n)
return; /* cannot consolidate top level */
/* first, build stack of ancestors between root and current node */
parent_stack[0] = t->root;
for (i = 0; i < n; i++) {
j = GET_NIBBLE(i, entry->key_sha1);
parent_stack[i + 1] = CLR_PTR_TYPE(parent_stack[i]->a[j]);
}
assert(i == n && parent_stack[i] == tree);
/* next, unwind stack until note_tree_consolidate() is done */
while (i > 0 &&
!note_tree_consolidate(parent_stack[i], parent_stack[i - 1],
GET_NIBBLE(i - 1, entry->key_sha1)))
i--;
}
/*
* To find a leaf_node:
* Search to the tree location appropriate for the given key:
* If a note entry with matching key, return the note entry, else return NULL.
*/
static struct leaf_node *note_tree_find(struct notes_tree *t,
struct int_node *tree, unsigned char n,
const unsigned char *key_sha1)
{
void **p = note_tree_search(t, &tree, &n, key_sha1);
if (GET_PTR_TYPE(*p) == PTR_TYPE_NOTE) {
struct leaf_node *l = (struct leaf_node *) CLR_PTR_TYPE(*p);
if (hasheq(key_sha1, l->key_oid.hash))
return l;
}
return NULL;
}
/*
* To insert a leaf_node:
* Search to the tree location appropriate for the given leaf_node's key:
* - If location is unused (NULL), store the tweaked pointer directly there
* - If location holds a note entry that matches the note-to-be-inserted, then
* combine the two notes (by calling the given combine_notes function).
* - If location holds a note entry that matches the subtree-to-be-inserted,
* then unpack the subtree-to-be-inserted into the location.
* - If location holds a matching subtree entry, unpack the subtree at that
* location, and restart the insert operation from that level.
* - Else, create a new int_node, holding both the node-at-location and the
* node-to-be-inserted, and store the new int_node into the location.
*/
static int note_tree_insert(struct notes_tree *t, struct int_node *tree,
unsigned char n, struct leaf_node *entry, unsigned char type,
combine_notes_fn combine_notes)
{
struct int_node *new_node;
struct leaf_node *l;
void **p = note_tree_search(t, &tree, &n, entry->key_oid.hash);
int ret = 0;
assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
l = (struct leaf_node *) CLR_PTR_TYPE(*p);
switch (GET_PTR_TYPE(*p)) {
case PTR_TYPE_NULL:
assert(!*p);
if (is_null_oid(&entry->val_oid))
free(entry);
else
*p = SET_PTR_TYPE(entry, type);
return 0;
case PTR_TYPE_NOTE:
switch (type) {
case PTR_TYPE_NOTE:
if (oideq(&l->key_oid, &entry->key_oid)) {
/* skip concatenation if l == entry */
if (oideq(&l->val_oid, &entry->val_oid))
return 0;
ret = combine_notes(&l->val_oid,
&entry->val_oid);
if (!ret && is_null_oid(&l->val_oid))
note_tree_remove(t, tree, n, entry);
free(entry);
return ret;
}
break;
case PTR_TYPE_SUBTREE:
if (!SUBTREE_SHA1_PREFIXCMP(l->key_oid.hash,
entry->key_oid.hash)) {
/* unpack 'entry' */
load_subtree(t, entry, tree, n);
free(entry);
return 0;
}
break;
}
break;
case PTR_TYPE_SUBTREE:
if (!SUBTREE_SHA1_PREFIXCMP(entry->key_oid.hash, l->key_oid.hash)) {
/* unpack 'l' and restart insert */
*p = NULL;
load_subtree(t, l, tree, n);
free(l);
return note_tree_insert(t, tree, n, entry, type,
combine_notes);
}
break;
}
/* non-matching leaf_node */
assert(GET_PTR_TYPE(*p) == PTR_TYPE_NOTE ||
GET_PTR_TYPE(*p) == PTR_TYPE_SUBTREE);
if (is_null_oid(&entry->val_oid)) { /* skip insertion of empty note */
free(entry);
return 0;
}
new_node = (struct int_node *) xcalloc(1, sizeof(struct int_node));
ret = note_tree_insert(t, new_node, n + 1, l, GET_PTR_TYPE(*p),
combine_notes);
if (ret)
return ret;
*p = SET_PTR_TYPE(new_node, PTR_TYPE_INTERNAL);
return note_tree_insert(t, new_node, n + 1, entry, type, combine_notes);
}
/*
* To insert a leaf_node:
* Search to the tree location appropriate for the given leaf_node's key:
* - If location is unused (NULL), store the tweaked pointer directly there
* - If location holds a note entry that matches the note-to-be-inserted, then
* combine the two notes (by calling the given combine_notes function).
* - If location holds a note entry that matches the subtree-to-be-inserted,
* then unpack the subtree-to-be-inserted into the location.
* - If location holds a matching subtree entry, unpack the subtree at that
* location, and restart the insert operation from that level.
* - Else, create a new int_node, holding both the node-at-location and the
* node-to-be-inserted, and store the new int_node into the location.
*/
static void note_tree_insert(struct notes_tree *t, struct int_node *tree,
unsigned char n, struct leaf_node *entry, unsigned char type,
combine_notes_fn combine_notes)
{
struct int_node *new_node;
struct leaf_node *l;
void **p = note_tree_search(t, &tree, &n, entry->key_sha1);
assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
l = (struct leaf_node *) CLR_PTR_TYPE(*p);
switch (GET_PTR_TYPE(*p)) {
case PTR_TYPE_NULL:
assert(!*p);
*p = SET_PTR_TYPE(entry, type);
return;
case PTR_TYPE_NOTE:
switch (type) {
case PTR_TYPE_NOTE:
if (!hashcmp(l->key_sha1, entry->key_sha1)) {
/* skip concatenation if l == entry */
if (!hashcmp(l->val_sha1, entry->val_sha1))
return;
if (combine_notes(l->val_sha1, entry->val_sha1))
die("failed to combine notes %s and %s"
" for object %s",
sha1_to_hex(l->val_sha1),
sha1_to_hex(entry->val_sha1),
sha1_to_hex(l->key_sha1));
free(entry);
return;
}
break;
case PTR_TYPE_SUBTREE:
if (!SUBTREE_SHA1_PREFIXCMP(l->key_sha1,
entry->key_sha1)) {
/* unpack 'entry' */
load_subtree(t, entry, tree, n);
free(entry);
return;
}
break;
}
break;
case PTR_TYPE_SUBTREE:
if (!SUBTREE_SHA1_PREFIXCMP(entry->key_sha1, l->key_sha1)) {
/* unpack 'l' and restart insert */
*p = NULL;
load_subtree(t, l, tree, n);
free(l);
note_tree_insert(t, tree, n, entry, type,
combine_notes);
return;
}
break;
}
/* non-matching leaf_node */
assert(GET_PTR_TYPE(*p) == PTR_TYPE_NOTE ||
GET_PTR_TYPE(*p) == PTR_TYPE_SUBTREE);
new_node = (struct int_node *) xcalloc(sizeof(struct int_node), 1);
note_tree_insert(t, new_node, n + 1, l, GET_PTR_TYPE(*p),
combine_notes);
*p = SET_PTR_TYPE(new_node, PTR_TYPE_INTERNAL);
note_tree_insert(t, new_node, n + 1, entry, type, combine_notes);
}