In find_non_local_tags() helper function (used to implement the "follow tags"), we use string_list_has_string() on two string lists as a way to see if a refname has already been processed, etc.
All this code predates more modern in-core lookup API like hashmap; replace them with two hashmaps and one string list---the hashmaps are used for look-ups and the string list is to keep the order of items in the returned result stable (which is the only single thing hashmap does worse than lookups on string-list). Signed-off-by: Junio C Hamano <[email protected]> --- * Just to remind ourselves that we talked about getting rid of string-list used as look-up tables by replacing them with hashmap but haven't seen much effort expended on it. I think this is my first semi-serious use of hashmap, and the code is expected to be full of newbie mistakes, inefficiencies and ignorance of idioms; pointing out any of which is much appreciated. builtin/fetch.c | 116 +++++++++++++++++++++++++++++++++++++----------- 1 file changed, 90 insertions(+), 26 deletions(-) diff --git a/builtin/fetch.c b/builtin/fetch.c index 0696abfc2a..5d1fd8dd49 100644 --- a/builtin/fetch.c +++ b/builtin/fetch.c @@ -246,16 +246,73 @@ static int will_fetch(struct ref **head, const unsigned char *sha1) return 0; } +struct refname_hash_entry { + struct hashmap_entry ent; /* must be the first member */ + struct object_id oid; + char refname[FLEX_ARRAY]; +}; + +static int refname_hash_entry_cmp(const void *hashmap_cmp_fn_data, + const struct refname_hash_entry *e1, + const struct refname_hash_entry *e2, + const void *keydata) +{ + return strcmp(e1->refname, keydata ? keydata : e2->refname); +} + +static struct refname_hash_entry *refname_hash_add(struct hashmap *map, + const char *refname, + const struct object_id *oid) +{ + struct refname_hash_entry *ent; + size_t len = strlen(refname); + + FLEX_ALLOC_MEM(ent, refname, refname, len); + hashmap_entry_init(ent, memhash(refname, len)); + oidcpy(&ent->oid, oid); + hashmap_add(map, ent); + return ent; +} + +static int add_one_refname(const char *refname, + const struct object_id *oid, + int flag, void *cbdata) +{ + struct hashmap *refname_map = cbdata; + + (void) refname_hash_add(refname_map, refname, oid); + return 0; +} + +static void refname_hash_init(struct hashmap *map) +{ + hashmap_init(map, (hashmap_cmp_fn)refname_hash_entry_cmp, NULL, 0); +} + +static int refname_hash_exists(struct hashmap *map, const char *refname) +{ + struct hashmap_entry key; + size_t len = strlen(refname); + hashmap_entry_init(&key, memhash(refname, len)); + + return !!hashmap_get(map, &key, refname); +} + static void find_non_local_tags(const struct ref *refs, struct ref **head, struct ref ***tail) { - struct string_list existing_refs = STRING_LIST_INIT_DUP; - struct string_list remote_refs = STRING_LIST_INIT_NODUP; + struct hashmap existing_refs; + struct hashmap remote_refs; + struct string_list remote_refs_list = STRING_LIST_INIT_NODUP; + struct string_list_item *remote_ref_item; const struct ref *ref; - struct string_list_item *item = NULL; + struct refname_hash_entry *item = NULL; - for_each_ref(add_existing, &existing_refs); + refname_hash_init(&existing_refs); + refname_hash_init(&remote_refs); + + for_each_ref(add_one_refname, &existing_refs); for (ref = refs; ref; ref = ref->next) { if (!starts_with(ref->name, "refs/tags/")) continue; @@ -271,10 +328,10 @@ static void find_non_local_tags(const struct ref *refs, !has_object_file_with_flags(&ref->old_oid, OBJECT_INFO_QUICK) && !will_fetch(head, ref->old_oid.hash) && - !has_sha1_file_with_flags(item->util, + !has_sha1_file_with_flags(item->oid.hash, OBJECT_INFO_QUICK) && - !will_fetch(head, item->util)) - item->util = NULL; + !will_fetch(head, item->oid.hash)) + oidclr(&item->oid); item = NULL; continue; } @@ -286,47 +343,54 @@ static void find_non_local_tags(const struct ref *refs, * fetch. */ if (item && - !has_sha1_file_with_flags(item->util, OBJECT_INFO_QUICK) && - !will_fetch(head, item->util)) - item->util = NULL; + !has_sha1_file_with_flags(item->oid.hash, OBJECT_INFO_QUICK) && + !will_fetch(head, item->oid.hash)) + oidclr(&item->oid); item = NULL; /* skip duplicates and refs that we already have */ - if (string_list_has_string(&remote_refs, ref->name) || - string_list_has_string(&existing_refs, ref->name)) + if (refname_hash_exists(&remote_refs, ref->name) || + refname_hash_exists(&existing_refs, ref->name)) continue; - item = string_list_insert(&remote_refs, ref->name); - item->util = (void *)&ref->old_oid; + item = refname_hash_add(&remote_refs, ref->name, &ref->old_oid); + string_list_insert(&remote_refs_list, ref->name); } - string_list_clear(&existing_refs, 1); + hashmap_free(&existing_refs, 1); /* * We may have a final lightweight tag that needs to be * checked to see if it needs fetching. */ if (item && - !has_sha1_file_with_flags(item->util, OBJECT_INFO_QUICK) && - !will_fetch(head, item->util)) - item->util = NULL; + !has_sha1_file_with_flags(item->oid.hash, OBJECT_INFO_QUICK) && + !will_fetch(head, item->oid.hash)) + oidclr(&item->oid); /* - * For all the tags in the remote_refs string list, + * For all the tags in the remote_refs_list, * add them to the list of refs to be fetched */ - for_each_string_list_item(item, &remote_refs) { + for_each_string_list_item(remote_ref_item, &remote_refs_list) { + const char *refname = remote_ref_item->string; + struct hashmap_entry key; + + hashmap_entry_init(&key, memhash(refname, strlen(refname))); + item = hashmap_get(&remote_refs, &key, refname); + if (!item) + continue; /* can this happen??? */ + /* Unless we have already decided to ignore this item... */ - if (item->util) - { - struct ref *rm = alloc_ref(item->string); - rm->peer_ref = alloc_ref(item->string); - oidcpy(&rm->old_oid, item->util); + if (!is_null_oid(&item->oid)) { + struct ref *rm = alloc_ref(item->refname); + rm->peer_ref = alloc_ref(item->refname); + oidcpy(&rm->old_oid, &item->oid); **tail = rm; *tail = &rm->next; } } - + hashmap_free(&remote_refs, 1); string_list_clear(&remote_refs, 0); } -- 2.19.0-271-gfe8321ec05
