This includes adding internal functions for maintaining a healthy notes tree
structure after removing individual notes.
Signed-off-by: Johan Herland <johan@xxxxxxxxxxx>
---
notes.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
notes.h | 3 ++
2 files changed, 87 insertions(+), 1 deletions(-)
diff --git a/notes.c b/notes.c
index 2c0d14e..2e82d71 100644
--- a/notes.c
+++ b/notes.c
@@ -44,7 +44,7 @@ struct leaf_node {
#define CLR_PTR_TYPE(ptr) ((void *) ((uintptr_t) (ptr) & ~3))
#define SET_PTR_TYPE(ptr, type) ((void *) ((uintptr_t) (ptr) | (type)))
-#define GET_NIBBLE(n, sha1) (((sha1[n >> 1]) >> ((~n & 0x01) << 2)) & 0x0f)
+#define GET_NIBBLE(n, sha1) (((sha1[(n) >> 1]) >> ((~(n) & 0x01) << 2)) & 0x0f)
#define SUBTREE_SHA1_PREFIXCMP(key_sha1, subtree_sha1) \
(memcmp(key_sha1, subtree_sha1, subtree_sha1[19]))
@@ -249,6 +249,79 @@ static void note_tree_insert(struct int_node *tree, unsigned char n,
note_tree_insert(new_node, n + 1, entry, type);
}
+/*
+ * How to consolidate an int_node:
+ * If there are > 1 non-NULL entries, give up and return non-zero.
+ * Otherwise replace the int_node at the given index in the given parent node
+ * with the only entry (or a NULL entry if no entries) from the given tree,
+ * and return 0.
+ */
+static int note_tree_consolidate(struct int_node *tree,
+ struct int_node *parent, unsigned char index)
+{
+ unsigned int i;
+ void *p = NULL;
+
+ assert(tree && parent);
+ assert(CLR_PTR_TYPE(parent->a[index]) == tree);
+
+ for (i = 0; i < 16; i++) {
+ if (GET_PTR_TYPE(tree->a[i]) != PTR_TYPE_NULL) {
+ if (p) /* more than one entry */
+ return -2;
+ p = tree->a[i];
+ }
+ }
+
+ /* replace tree with p in parent[index] */
+ parent->a[index] = p;
+ free(tree);
+ return 0;
+}
+
+/*
+ * 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 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(&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] = &root_node;
+ 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--;
+}
+
/* Free the entire notes data contained in the given tree */
static void note_tree_free(struct int_node *tree)
{
@@ -379,6 +452,16 @@ void add_note(const unsigned char *object_sha1, const unsigned char *note_sha1)
note_tree_insert(&root_node, 0, l, PTR_TYPE_NOTE);
}
+void remove_note(const unsigned char *object_sha1)
+{
+ struct leaf_node l;
+
+ assert(initialized);
+ hashcpy(l.key_sha1, object_sha1);
+ hashclr(l.val_sha1);
+ return note_tree_remove(&root_node, 0, &l);
+}
+
static unsigned char *lookup_notes(const unsigned char *object_sha1)
{
struct leaf_node *found = note_tree_find(&root_node, 0, object_sha1);
diff --git a/notes.h b/notes.h
index 5f22852..9e66855 100644
--- a/notes.h
+++ b/notes.h
@@ -25,6 +25,9 @@ void init_notes(const char *notes_ref, int flags);
void add_note(const unsigned char *object_sha1,
const unsigned char *note_sha1);
+/* Remove the given note object from the internal notes tree structure */
+void remove_note(const unsigned char *object_sha1);
+
/* Free (and de-initialize) the internal notes tree structure */
void free_notes(void);
--
1.6.6.405.g80ed6
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