[PATCH v5] fetch-pack.c: use oidset to check existence of loose object
- From
- Takuto Ikuta <tikuta@chromium.org>
- Date
- Mar 10, 2018, 12:46 UTC
- Message-ID
- <20180310124643.82666-1-tikuta@chromium.org>
- In-Reply-To
- <20180310123445.79609-1-tikuta@chromium.org>
In repository having large number of remote refs, because to check existence of each refs in local repository to packed and loose objects, 'git fetch' ends up doing a lot of lstat(2) to non-existing loose form, which makes it slow.
Instead of making as many lstat(2) calls as the refs the remote side advertised to see if these objects exist in the loose form, first enumerate all the existing loose objects in hashmap beforehand and use it to check existence of them if the number of refs is larger than the number of loose objects.
With this patch, the number of lstat(2) calls in `git fetch` is reduced from 411412 to 13794 for chromium repository, it has more than 480000 remote refs.
I took time stat of `git fetch` when fetch-pack happens for chromium repository 3 times on linux with SSD. * with this patch 8.105s 8.309s 7.640s avg: 8.018s
* master 12.287s 11.175s 12.227s avg: 11.896s
On my MacBook Air which has slower lstat(2). * with this patch 14.501s
* master 1m16.027s
`git fetch` on slow disk will be improved largely.
Signed-off-by: Takuto Ikuta <tikuta@chromium.org> --- cache.h | 2 ++ fetch-pack.c | 45 ++++++++++++++++++++++++++++++++++++++++++--- sha1_file.c | 3 +++ 3 files changed, 47 insertions(+), 3 deletions(-)
diff --git a/cache.h b/cache.h index d06932ed0..6a72f54d7 100644 --- a/cache.h +++ b/cache.h @@ -1773,6 +1773,8 @@ struct object_info { #define OBJECT_INFO_SKIP_CACHED 4 /* Do not retry packed storage after checking packed and loose storage */ #define OBJECT_INFO_QUICK 8 +/* Do not check loose object */ +#define OBJECT_INFO_IGNORE_LOOSE 16 extern int sha1_object_info_extended(const unsigned char *, struct object_info *, unsigned flags); /* diff --git a/fetch-pack.c b/fetch-pack.c index d97461296..92b9bb4d9 100644 --- a/fetch-pack.c +++ b/fetch-pack.c @@ -711,6 +711,28 @@ static void mark_alternate_complete(struct object *obj) mark_complete(&obj->oid); } +struct loose_object_iter { + struct oidset *loose_object_set; + struct ref *refs; +}; + +/* + * If the number of refs is not larger than the number of loose objects, + * this function stops inserting and returns false. + */ +static int add_loose_objects_to_set(const struct object_id *oid, + const char *path, + void *data) +{ + struct loose_object_iter *iter = data; + oidset_insert(iter->loose_object_set, oid); + if (iter->refs == NULL) + return 1; + + iter->refs = iter->refs->next; + return 0; +} + static int everything_local(struct fetch_pack_args *args, struct ref **refs, struct ref **sought, int nr_sought) @@ -719,16 +741,31 @@ static int everything_local(struct fetch_pack_args *args, int retval; int old_save_commit_buffer = save_commit_buffer; timestamp_t cutoff = 0; + struct oidset loose_oid_set = OIDSET_INIT; + int use_oidset = 0; + struct loose_object_iter iter = {&loose_oid_set, *refs}; + + /* Enumerate all loose objects or know refs are not so many. */ + use_oidset = !for_each_loose_object(add_loose_objects_to_set, + &iter, 0); save_commit_buffer = 0; for (ref = *refs; ref; ref = ref->next) { struct object *o; + unsigned int flags = OBJECT_INFO_QUICK; - if (!has_object_file_with_flags(&ref->old_oid, - OBJECT_INFO_QUICK)) - continue; + if (use_oidset && + !oidset_contains(&loose_oid_set, &ref->old_oid)) { + /* + * I know this does not exist in the loose form, + * so check if it exists in a non-loose form. + */ + flags |= OBJECT_INFO_IGNORE_LOOSE; + } + if (!has_object_file_with_flags(&ref->old_oid, flags)) + continue; o = parse_object(&ref->old_oid); if (!o) continue; @@ -744,6 +781,8 @@ static int everything_local(struct fetch_pack_args *args, } } + oidset_clear(&loose_oid_set); + if (!args->no_dependents) { if (!args->deepen) { for_each_ref(mark_complete_oid, NULL); diff --git a/sha1_file.c b/sha1_file.c index 1b94f39c4..c0a197947 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -1262,6 +1262,9 @@ int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi, if (find_pack_entry(real, &e)) break; + if (flags & OBJECT_INFO_IGNORE_LOOSE) + return -1; + /* Most likely it's a loose object. */ if (!sha1_loose_object_info(real, oi, flags)) return 0;
-- 2.16.2