git/packfile.h, branch v2.20.2

fuzz: add fuzz testing for packfile indices.

2018-10-15T05:29:03Z

Breaks the majority of check_packed_git_idx() into a separate function, load_idx(). The latter function operates on arbitrary buffers, which makes it suitable as a fuzzing test target. Signed-off-by: Josh Steadmon Signed-off-by: Junio C Hamano

packfile: add all_packs list

2018-08-20T22:31:40Z

If a repo contains a multi-pack-index, then the packed_git list does not contain the packfiles that are covered by the multi-pack-index. This is important for doing object lookups, abbreviations, and approximating object count. However, there are many operations that really want to iterate over all packfiles. Create a new 'all_packs' linked list that contains this list, starting with the packfiles in the multi-pack-index and then continuing along the packed_git linked list. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano

Sync 'ds/multi-pack-index' to v2.19.0-rc0

2018-08-20T22:29:54Z

* ds/multi-pack-index: (23 commits) midx: clear midx on repack packfile: skip loading index if in multi-pack-index midx: prevent duplicate packfile loads midx: use midx in approximate_object_count midx: use existing midx when writing new one midx: use midx in abbreviation calculations midx: read objects from multi-pack-index config: create core.multiPackIndex setting midx: write object offsets midx: write object id fanout chunk midx: write object ids in a chunk midx: sort and deduplicate objects from packfiles midx: read pack names into array multi-pack-index: write pack names in chunk multi-pack-index: read packfile list packfile: generalize pack directory list t5319: expand test data multi-pack-index: load into memory midx: write header information to lockfile multi-pack-index: add 'write' verb ...

Merge branch 'jk/for-each-object-iteration'

2018-08-20T18:33:52Z

The API to iterate over all objects learned to optionally list objects in the order they appear in packfiles, which helps locality of access if the caller accesses these objects while as objects are enumerated. * jk/for-each-object-iteration: for_each_*_object: move declarations to object-store.h cat-file: use a single strbuf for all output cat-file: split batch "buf" into two variables cat-file: use oidset check-and-insert cat-file: support "unordered" output for --batch-all-objects cat-file: rename batch_{loose,packed}_object callbacks t1006: test cat-file --batch-all-objects with duplicates for_each_packed_object: support iterating in pack-order for_each_*_object: give more comprehensive docstrings for_each_*_object: take flag arguments as enum for_each_*_object: store flag definitions in a single location

for_each_*_object: move declarations to object-store.h

2018-08-14T19:29:57Z

The for_each_loose_object() and for_each_packed_object() functions are meant to be part of a unified interface: they use the same set of for_each_object_flags, and it's not inconceivable that we might one day add a single for_each_object() wrapper around them. Let's put them together in a single file, so we can avoid awkwardness like saying "the flags for this function are over in cache.h". Moving the loose functions to packfile.h is silly. Moving the packed functions to cache.h works, but makes the "cache.h is a kitchen sink" problem worse. The best place is the recently-created object-store.h, since these are quite obviously related to object storage. The for_each_*_in_objdir() functions do not use the same flags, but they are logically part of the same interface as for_each_loose_object(), and share callback signatures. So we'll move those, as well, as they also make sense in object-store.h. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

for_each_packed_object: support iterating in pack-order

2018-08-13T20:48:28Z

We currently iterate over objects within a pack in .idx order, which uses the object hashes. That means that it is effectively random with respect to the location of the object within the pack. If you're going to access the actual object data, there are two reasons to move linearly through the pack itself: 1. It improves the locality of access in the packfile. In the cold-cache case, this may mean fewer disk seeks, or better usage of disk cache. 2. We store related deltas together in the packfile. Which means that the delta base cache can operate much more efficiently if we visit all of those related deltas in sequence, as the earlier items are likely to still be in the cache. Whereas if we visit the objects in random order, our cache entries are much more likely to have been evicted by unrelated deltas in the meantime. So in general, if you're going to access the object contents pack order is generally going to end up more efficient. But if you're simply generating a list of object names, or if you're going to end up sorting the result anyway, you're better off just using the .idx order, as finding the pack order means generating the in-memory pack-revindex. According to the numbers in 8b8dfd5132 (pack-revindex: radix-sort the revindex, 2013-07-11), that takes about 200ms for linux.git, and 20ms for git.git (those numbers are a few years old but are still a good ballpark). That makes it a good optimization for some cases (we can save tens of seconds in git.git by having good locality of delta access, for a 20ms cost), but a bad one for others (e.g., right now "cat-file --batch-all-objects --batch-check="%(objectname)" is 170ms in git.git, so adding 20ms to that is noticeable). Hence this patch makes it an optional flag. You can't actually do any interesting timings yet, as it's not plumbed through to any user-facing tools like cat-file. That will come in a later patch. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

for_each_*_object: give more comprehensive docstrings

2018-08-13T20:48:26Z

We already mention the local/alternate behavior of these functions, but we can help clarify a few other behaviors: - there's no need to mention LOCAL_ONLY specifically, since we already reference the flags by type (and as we add more flags, we don't want to have to mention each) - clarify that reachability doesn't matter here; this is all accessible objects - what ordering/uniqueness guarantees we give - how pack-specific flags are handled for the loose case Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

for_each_*_object: take flag arguments as enum

2018-08-13T20:48:25Z

It's not wrong to pass our flags in an "unsigned", as we know it will be at least as large as the enum. However, using the enum in the declaration makes it more obvious where to find the list of flags. While we're here, let's also drop the "extern" noise-words from the declarations, per our modern coding style. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

for_each_*_object: store flag definitions in a single location

2018-08-13T20:47:50Z

These flags were split between cache.h and packfile.h, because some of the flags apply only to packs. However, they share a single numeric namespace, since both are respected for the packed variant. Let's make sure they're defined together so that nobody accidentally adds a new flag in one location that duplicates the other. While we're here, let's also put them in an enum (which helps debugger visibility) and use "(1< Signed-off-by: Junio C Hamano

packfile: ensure that enum object_type is defined

2018-07-26T17:36:26Z

When compiling under Apple LLVM version 9.1.0 (clang-902.0.39.2) with "make DEVELOPER=1 DEVOPTS=pedantic", the compiler says error: redeclaration of already-defined enum 'object_type' is a GNU extension [-Werror,-Wgnu-redeclared-enum] According to https://en.cppreference.com/w/c/language/declarations (section "Redeclaration"), a repeated declaration after the definition is only legal for structs and unions, but not for enums. Drop the belated declaration of enum object_type and include cache.h instead to make sure the enum is defined. Helped-by: Jonathan Nieder Signed-off-by: Beat Bolli Reviewed-by: Jonathan Nieder Signed-off-by: Junio C Hamano