From: Junio C Hamano Date: Tue, 25 Sep 2018 20:25:04 +0000 (-0700) Subject: fetch: replace string-list used as a look-up table with a hashmap X-Git-Tag: v2.20.0-rc0~43^2 X-Git-Url: http://git.ipfire.org/?p=thirdparty%2Fgit.git;a=commitdiff_plain;h=e198b3a740409fabe5ba774c5f1255b55fdd21c1 fetch: replace string-list used as a look-up table with a hashmap 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). Similarly, get_ref_map() uses another string-list as a look-up table for existing refs. Replace it with a hashmap. Signed-off-by: Junio C Hamano --- diff --git a/builtin/fetch.c b/builtin/fetch.c index 0696abfc2a..aee1d9bf21 100644 --- a/builtin/fetch.c +++ b/builtin/fetch.c @@ -223,18 +223,6 @@ static void add_merge_config(struct ref **head, } } -static int add_existing(const char *refname, const struct object_id *oid, - int flag, void *cbdata) -{ - struct string_list *list = (struct string_list *)cbdata; - struct string_list_item *item = string_list_insert(list, refname); - struct object_id *old_oid = xmalloc(sizeof(*old_oid)); - - oidcpy(old_oid, oid); - item->util = old_oid; - return 0; -} - static int will_fetch(struct ref **head, const unsigned char *sha1) { struct ref *rm = *head; @@ -246,16 +234,72 @@ 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 void *e1_, + const void *e2_, + const void *keydata) +{ + const struct refname_hash_entry *e1 = e1_; + const struct refname_hash_entry *e2 = e2_; + + 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, strhash(refname)); + 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, refname_hash_entry_cmp, NULL, 0); +} + +static int refname_hash_exists(struct hashmap *map, const char *refname) +{ + return !!hashmap_get_from_hash(map, strhash(refname), 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; + + refname_hash_init(&existing_refs); + refname_hash_init(&remote_refs); - for_each_ref(add_existing, &existing_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 +315,10 @@ 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; } @@ -286,48 +330,53 @@ 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; + + item = hashmap_get_from_hash(&remote_refs, strhash(refname), refname); + if (!item) + BUG("unseen remote ref?"); + /* 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; } } - - string_list_clear(&remote_refs, 0); + hashmap_free(&remote_refs, 1); + string_list_clear(&remote_refs_list, 0); } static struct ref *get_ref_map(struct remote *remote, @@ -343,7 +392,7 @@ static struct ref *get_ref_map(struct remote *remote, /* opportunistically-updated references: */ struct ref *orefs = NULL, **oref_tail = &orefs; - struct string_list existing_refs = STRING_LIST_INIT_DUP; + struct hashmap existing_refs; if (rs->nr) { struct refspec *fetch_refspec; @@ -437,19 +486,24 @@ static struct ref *get_ref_map(struct remote *remote, ref_map = ref_remove_duplicates(ref_map); - for_each_ref(add_existing, &existing_refs); + refname_hash_init(&existing_refs); + for_each_ref(add_one_refname, &existing_refs); + for (rm = ref_map; rm; rm = rm->next) { if (rm->peer_ref) { - struct string_list_item *peer_item = - string_list_lookup(&existing_refs, - rm->peer_ref->name); + const char *refname = rm->peer_ref->name; + struct refname_hash_entry *peer_item; + + peer_item = hashmap_get_from_hash(&existing_refs, + strhash(refname), + refname); if (peer_item) { - struct object_id *old_oid = peer_item->util; + struct object_id *old_oid = &peer_item->oid; oidcpy(&rm->peer_ref->old_oid, old_oid); } } } - string_list_clear(&existing_refs, 1); + hashmap_free(&existing_refs, 1); return ref_map; }