Improved tree iterator internals

This updates the tree iterator internals to be more efficient.

The tree_iterator_entry objects are now kept as pointers that are
allocated from a git_pool, so that we may use git__tsort_r for
sorting (which is better than qsort, given that the tree is
likely mostly ordered already).

Those tree_iterator_entry objects now keep direct pointers to the
data they refer to instead of keeping indirect index values.  This
simplifies a lot of the data structure traversal code.

This also adds bsearch to find the start item position for range-
limited tree iterators, and is more explicit about using
git_path_cmp instead of reimplementing it.  The git_path_cmp
changed a bit to make it easier for tree_iterators to use it (but
it was barely being used previously, so not a big deal).

This adds a git_pool_free_array function that efficiently frees a
list of pool allocated pointers (which the tree_iterator keeps).
Also, added new tests for the git_pool free list functionality
that was not previously being tested (or used).

1 files changed, 7 insertions, 0 deletions

diff --git a/src/pool.h b/src/pool.h
index 2b262a588..5ac9b764f 100644
--- a/src/pool.h
+++ b/src/pool.h
@@ -126,6 +126,13 @@ extern char *git_pool_strcat(git_pool *pool, const char *a, const char *b);
  */
 extern void git_pool_free(git_pool *pool, void *ptr);
 
+/**
+ * Push an array of pool allocated blocks efficiently onto the free list.
+ *
+ * This has the same constraints as `git_pool_free()` above.
+ */
+extern void git_pool_free_array(git_pool *pool, size_t count, void **ptrs);
+
 /*
  * Misc utilities
  */