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https://github.com/git-for-windows/git.git
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ee610b535c
The oidtree data structure is currently only used to store object IDs, without any associated data. So consequently, it can only really be used to track which object IDs exist, and we can use the tree structure to efficiently operate on OID prefixes. But there are valid use cases where we want to both: - Store object IDs in a sorted order. - Associated arbitrary data with them. Refactor the oidtree interface so that it allows us to store arbitrary payloads within the respective nodes. This will be used in the next commit. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
133 lines
3.1 KiB
C
133 lines
3.1 KiB
C
/*
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* A wrapper around cbtree which stores oids
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* May be used to replace oid-array for prefix (abbreviation) matches
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*/
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#include "git-compat-util.h"
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#include "oidtree.h"
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#include "hash.h"
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struct oidtree_node {
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struct cb_node base;
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struct object_id key;
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void *data;
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};
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void oidtree_init(struct oidtree *ot)
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{
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cb_init(&ot->tree, offsetof(struct oidtree_node, key));
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mem_pool_init(&ot->mem_pool, 0);
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}
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void oidtree_clear(struct oidtree *ot)
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{
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if (ot) {
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mem_pool_discard(&ot->mem_pool, 0);
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oidtree_init(ot);
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}
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}
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struct oidtree_data {
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struct object_id oid;
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};
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void oidtree_insert(struct oidtree *ot, const struct object_id *oid,
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void *data)
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{
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struct oidtree_node *on;
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struct cb_node *node;
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if (!oid->algo)
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BUG("oidtree_insert requires oid->algo");
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on = mem_pool_alloc(&ot->mem_pool, sizeof(*on));
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oidcpy(&on->key, oid);
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on->data = data;
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/*
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* n.b. Current callers won't get us duplicates, here. If a
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* future caller causes duplicates, there'll be a small leak
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* that won't be freed until oidtree_clear. Currently it's not
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* worth maintaining a free list
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*/
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node = cb_insert(&ot->tree, &on->base, sizeof(*oid));
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if (node) {
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struct oidtree_node *preexisting = container_of(node, struct oidtree_node, base);
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preexisting->data = data;
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}
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}
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static struct oidtree_node *oidtree_lookup(struct oidtree *ot,
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const struct object_id *oid)
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{
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struct object_id k;
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size_t klen = sizeof(k);
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struct cb_node *node;
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oidcpy(&k, oid);
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if (oid->algo == GIT_HASH_UNKNOWN)
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klen -= sizeof(oid->algo);
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/* cb_lookup relies on memcmp on the struct, so order matters: */
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klen += BUILD_ASSERT_OR_ZERO(offsetof(struct object_id, hash) <
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offsetof(struct object_id, algo));
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node = cb_lookup(&ot->tree, (const uint8_t *)&k, klen);
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return node ? container_of(node, struct oidtree_node, base) : NULL;
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}
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bool oidtree_contains(struct oidtree *ot, const struct object_id *oid)
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{
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struct oidtree_node *node = oidtree_lookup(ot, oid);
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return node ? 1 : 0;
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}
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void *oidtree_get(struct oidtree *ot, const struct object_id *oid)
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{
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struct oidtree_node *node = oidtree_lookup(ot, oid);
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return node ? node->data : NULL;
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}
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struct oidtree_each_data {
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oidtree_each_cb cb;
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void *cb_data;
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size_t *last_nibble_at;
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uint32_t algo;
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uint8_t last_byte;
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};
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static int iter(struct cb_node *n, void *cb_data)
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{
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struct oidtree_node *node = container_of(n, struct oidtree_node, base);
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struct oidtree_each_data *data = cb_data;
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if (data->algo != GIT_HASH_UNKNOWN && data->algo != node->key.algo)
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return 0;
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if (data->last_nibble_at) {
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if ((node->key.hash[*data->last_nibble_at] ^ data->last_byte) & 0xf0)
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return 0;
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}
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return data->cb(&node->key, node->data, data->cb_data);
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}
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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,
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.cb_data = cb_data,
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.algo = prefix->algo,
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};
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size_t klen = prefix_hex_len / 2;
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assert(prefix_hex_len <= GIT_MAX_HEXSZ);
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if (prefix_hex_len & 1) {
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data.last_byte = prefix->hash[klen];
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data.last_nibble_at = &klen;
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}
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return cb_each(&ot->tree, prefix->hash, klen, iter, &data);
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}
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