When the input rev_info has UNINTERESTING starting points, we want to be
sure that the UNINTERESTING flag is passed appropriately through the
objects. To match how this is done in places such as 'git pack-objects', we
use the mark_edges_uninteresting() method.
This method has an option for using the "sparse" walk, which is similar in
spirit to the path-walk API's walk. To be sure to keep it independent, add a
new 'prune_all_uninteresting' option to the path_walk_info struct.
To check how the UNINTERSTING flag is spread through our objects, extend the
'test-tool path-walk' command to output whether or not an object has that
flag. This changes our tests significantly, including the removal of some
objects that were previously visited due to the incomplete implementation.
Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The rev_info that is specified for a path-walk traversal may specify
visiting tag refs (both lightweight and annotated) and also may specify
indexed objects (blobs and trees). Update the path-walk API to walk
these objects as well.
When walking tags, we need to peel the annotated objects until reaching
a non-tag object. If we reach a commit, then we can add it to the
pending objects to make sure we visit in the commit walk portion. If we
reach a tree, then we will assume that it is a root tree. If we reach a
blob, then we have no good path name and so add it to a new list of
"tagged blobs".
When the rev_info includes the "--indexed-objects" flag, then the
pending set includes blobs and trees found in the cache entries and
cache-tree. The cache entries are usually blobs, though they could be
trees in the case of a sparse index. The cache-tree stores
previously-hashed tree objects but these are cleared out when staging
objects below those paths. We add tests that demonstrate this.
The indexed objects come with a non-NULL 'path' value in the pending
item. This allows us to prepopulate the 'path_to_lists' strmap with
lists for these paths.
The tricky thing about this walk is that we will want to combine the
indexed objects walk with the commit walk, especially in the future case
of walking objects during a command like 'git repack'.
Whenever possible, we want the objects from the index to be grouped with
similar objects in history. We don't want to miss any paths that appear
only in the index and not in the commit history.
Thus, we need to be careful to let the path stack be populated initially
with only the root tree path (and possibly tags and tagged blobs) and go
through the normal depth-first search. Afterwards, if there are other
paths that are remaining in the paths_to_lists strmap, we should then
iterate through the stack and visit those objects recursively.
Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We add the ability to filter the object types in the path-walk API so
the callback function is called fewer times.
This adds the ability to ask for the commits in a list, as well. We
re-use the empty string for this set of objects because these are passed
directly to the callback function instead of being part of the
'path_stack'.
Future changes will add the ability to visit annotated tags.
Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In anticipation of a few planned applications, introduce the most basic form
of a path-walk API. It currently assumes that there are no UNINTERESTING
objects, and does not include any complicated filters. It calls a function
pointer on groups of tree and blob objects as grouped by path. This only
includes objects the first time they are discovered, so an object that
appears at multiple paths will not be included in two batches.
These batches are collected in 'struct type_and_oid_list' objects, which
store an object type and an oid_array of objects.
The data structures are documented in 'struct path_walk_context', but in
summary the most important are:
* 'paths_to_lists' is a strmap that connects a path to a
type_and_oid_list for that path. To avoid conflicts in path names,
we make sure that tree paths end in "/" (except the root path with
is an empty string) and blob paths do not end in "/".
* 'path_stack' is a string list that is added to in an append-only
way. This stores the stack of our depth-first search on the heap
instead of using recursion.
* 'path_stack_pushed' is a strmap that stores path names that were
already added to 'path_stack', to avoid repeating paths in the
stack. Mostly, this saves us from quadratic lookups from doing
unsorted checks into the string_list.
The coupling of 'path_stack' and 'path_stack_pushed' is protected by the
push_to_stack() method. Call this instead of inserting into these
structures directly.
The walk_objects_by_path() method initializes these structures and
starts walking commits from the given rev_info struct. The commits are
used to find the list of root trees which populate the start of our
depth-first search.
The core of our depth-first search is in a while loop that continues
while we have not indicated an early exit and our 'path_stack' still has
entries in it. The loop body pops a path off of the stack and "visits"
the path via the walk_path() method.
The walk_path() method gets the list of OIDs from the 'path_to_lists'
strmap and executes the callback method on that list with the given path
and type. If the OIDs correspond to tree objects, then iterate over all
trees in the list and run add_children() to add the child objects to
their own lists, adding new entries to the stack if necessary.
In testing, this depth-first search approach was the one that used the
least memory while iterating over the object lists. There is still a
chance that repositories with too-wide path patterns could cause memory
pressure issues. Limiting the stack size could be done in the future by
limiting how many objects are being considered in-progress, or by
visiting blob paths earlier than trees.
There are many future adaptations that could be made, but they are left for
future updates when consumers are ready to take advantage of those features.
Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
