oidtree: extend iteration to allow for arbitrary return codes
The interface `cb_each()` iterates through a crit-bit tree and calls a specific callback function for each of the contained items. The callback function is expected to return either: - `CB_CONTINUE` in case iteration shall continue. - `CB_BREAK` to abort iteration. This is needlessly restrictive though, as callers may want to return arbitrary values and have them be bubbled up to the `cb_each()` call site. In fact, this is a rather common pattern we have: whenever such a callback function returns a non-zero error code, we abort iteration and bubble up the code as-is. Refactor both the crit-bit tree and oidtree subsystems to behave accordingly. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Patrick Steinhardt committed
Mar 20, 2026 at 08:07 UTC
fe446b01aeaab307adcbfb39d4aaa72c37afbcda
6 files changed
+43
-33
cbtree.c
+12
-9
@@ -96,26 +96,28 @@ struct cb_node *cb_lookup(struct cb_tree *t, const uint8_t *k, size_t klen)
96
return p && !memcmp(p->k, k, klen) ? p : NULL;
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}
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-static enum cb_next cb_descend(struct cb_node *p, cb_iter fn, void *arg)
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+static int cb_descend(struct cb_node *p, cb_iter fn, void *arg)
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{
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if (1 & (uintptr_t)p) {
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struct cb_node *q = cb_node_of(p);
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- enum cb_next n = cb_descend(q->child[0], fn, arg);
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-
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- return n == CB_BREAK ? n : cb_descend(q->child[1], fn, arg);
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+ int ret = cb_descend(q->child[0], fn, arg);
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+ if (ret)
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+ return ret;
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+ return cb_descend(q->child[1], fn, arg);
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} else {
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return fn(p, arg);
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}
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}
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-void cb_each(struct cb_tree *t, const uint8_t *kpfx, size_t klen,
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- cb_iter fn, void *arg)
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+int cb_each(struct cb_tree *t, const uint8_t *kpfx, size_t klen,
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+ cb_iter fn, void *arg)
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{
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struct cb_node *p = t->root;
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struct cb_node *top = p;
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size_t i = 0;
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- if (!p) return; /* empty tree */
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+ if (!p)
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+ return 0; /* empty tree */
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/* Walk tree, maintaining top pointer */
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while (1 & (uintptr_t)p) {
@@ -130,7 +132,8 @@ void cb_each(struct cb_tree *t, const uint8_t *kpfx, size_t klen,
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for (i = 0; i < klen; i++) {
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if (p->k[i] != kpfx[i])
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- return; /* "best" match failed */
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+ return 0; /* "best" match failed */
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}
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- cb_descend(top, fn, arg);
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+
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+ return cb_descend(top, fn, arg);
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}
cbtree.h
+9
-8
@@ -30,11 +30,6 @@ struct cb_tree {
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struct cb_node *root;
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};
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-enum cb_next {
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- CB_CONTINUE = 0,
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- CB_BREAK = 1
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-};
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-
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#define CBTREE_INIT { 0 }
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static inline void cb_init(struct cb_tree *t)
@@ -46,9 +41,15 @@ static inline void cb_init(struct cb_tree *t)
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struct cb_node *cb_lookup(struct cb_tree *, const uint8_t *k, size_t klen);
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struct cb_node *cb_insert(struct cb_tree *, struct cb_node *, size_t klen);
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-typedef enum cb_next (*cb_iter)(struct cb_node *, void *arg);
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+/*
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+ * Callback invoked by `cb_each()` for each node in the critbit tree. A return
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+ * value of 0 will cause the iteration to continue, a non-zero return code will
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+ * cause iteration to abort. The error code will be relayed back from
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+ * `cb_each()` in that case.
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+ */
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+typedef int (*cb_iter)(struct cb_node *, void *arg);
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-void cb_each(struct cb_tree *, const uint8_t *kpfx, size_t klen,
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- cb_iter, void *arg);
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+int cb_each(struct cb_tree *, const uint8_t *kpfx, size_t klen,
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+ cb_iter, void *arg);
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#endif /* CBTREE_H */
object-name.c
+2
-2
@@ -103,12 +103,12 @@ static void update_candidates(struct disambiguate_state *ds, const struct object
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static int match_hash(unsigned, const unsigned char *, const unsigned char *);
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-static enum cb_next match_prefix(const struct object_id *oid, void *arg)
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+static int match_prefix(const struct object_id *oid, void *arg)
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{
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struct disambiguate_state *ds = arg;
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/* no need to call match_hash, oidtree_each did prefix match */
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update_candidates(ds, oid);
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- return ds->ambiguous ? CB_BREAK : CB_CONTINUE;
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+ return ds->ambiguous;
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}
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static void find_short_object_filename(struct disambiguate_state *ds)
oidtree.c
+6
-6
@@ -71,7 +71,7 @@ struct oidtree_each_data {
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uint8_t last_byte;
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};
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-static enum cb_next iter(struct cb_node *n, void *cb_data)
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+static int iter(struct cb_node *n, void *cb_data)
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{
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struct oidtree_each_data *data = cb_data;
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struct object_id k;
@@ -80,18 +80,18 @@ static enum cb_next iter(struct cb_node *n, void *cb_data)
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memcpy(&k, n->k, sizeof(k));
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if (data->algo != GIT_HASH_UNKNOWN && data->algo != k.algo)
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- return CB_CONTINUE;
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+ return 0;
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if (data->last_nibble_at) {
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if ((k.hash[*data->last_nibble_at] ^ data->last_byte) & 0xf0)
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- return CB_CONTINUE;
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+ return 0;
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}
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return data->cb(&k, data->cb_data);
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}
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-void oidtree_each(struct oidtree *ot, const struct object_id *prefix,
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- size_t prefix_hex_len, oidtree_each_cb cb, void *cb_data)
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+int oidtree_each(struct oidtree *ot, const struct object_id *prefix,
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+ size_t prefix_hex_len, oidtree_each_cb cb, void *cb_data)
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{
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struct oidtree_each_data data = {
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.cb = cb,
@@ -106,5 +106,5 @@ void oidtree_each(struct oidtree *ot, const struct object_id *prefix,
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data.last_nibble_at = &klen;
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}
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- cb_each(&ot->tree, prefix->hash, klen, iter, &data);
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+ return cb_each(&ot->tree, prefix->hash, klen, iter, &data);
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}
oidtree.h
+12
-6
@@ -35,16 +35,22 @@ void oidtree_insert(struct oidtree *ot, const struct object_id *oid);
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/* Check whether the tree contains the given object ID. */
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bool oidtree_contains(struct oidtree *ot, const struct object_id *oid);
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-/* Callback function used for `oidtree_each()`. */
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-typedef enum cb_next (*oidtree_each_cb)(const struct object_id *oid,
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- void *cb_data);
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+/*
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+ * Callback function used for `oidtree_each()`. Returning a non-zero exit code
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+ * will cause iteration to stop. The exit code will be propagated to the caller
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+ * of `oidtree_each()`.
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+ */
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+typedef int (*oidtree_each_cb)(const struct object_id *oid,
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+ void *cb_data);
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/*
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* Iterate through all object IDs in the tree whose prefix matches the given
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* object ID prefix and invoke the callback function on each of them.
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+ *
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+ * Returns any non-zero exit code from the provided callback function.
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*/
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-void oidtree_each(struct oidtree *ot,
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- const struct object_id *prefix, size_t prefix_hex_len,
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- oidtree_each_cb cb, void *cb_data);
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+int oidtree_each(struct oidtree *ot,
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+ const struct object_id *prefix, size_t prefix_hex_len,
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+ oidtree_each_cb cb, void *cb_data);
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#endif /* OIDTREE_H */
t/unit-tests/u-oidtree.c
+2
-2
@@ -38,7 +38,7 @@ struct expected_hex_iter {
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const char *query;
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};
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-static enum cb_next check_each_cb(const struct object_id *oid, void *data)
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+static int check_each_cb(const struct object_id *oid, void *data)
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{
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struct expected_hex_iter *hex_iter = data;
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struct object_id expected;
@@ -49,7 +49,7 @@ static enum cb_next check_each_cb(const struct object_id *oid, void *data)
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&expected);
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cl_assert_equal_s(oid_to_hex(oid), oid_to_hex(&expected));
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hex_iter->i += 1;
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- return CB_CONTINUE;
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+ return 0;
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}
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LAST_ARG_MUST_BE_NULL