cache-tree: integrate with sparse directory entries

The cache-tree extension was previously disabled with sparse indexes.
However, the cache-tree is an important performance feature for commands
like 'git status' and 'git add'. Integrate it with sparse directory
entries.

When writing a sparse index, completely clear and recalculate the cache
tree. By starting from scratch, the only integration necessary is to
check if we hit a sparse directory entry and create a leaf of the
cache-tree that has an entry_count of one and no subtrees.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/cache-tree.c b/cache-tree.c
index 5f07a39e501e63bff07f8c33bdf536bbd24c8446..950a9615db8fcd53b146a65d552c7a709fcfbeb0 100644 (file)
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -256,6 +256,24 @@ static int update_one(struct cache_tree *it,
 
        *skip_count = 0;
 
+       /*
+        * If the first entry of this region is a sparse directory
+        * entry corresponding exactly to 'base', then this cache_tree
+        * struct is a "leaf" in the data structure, pointing to the
+        * tree OID specified in the entry.
+        */
+       if (entries > 0) {
+               const struct cache_entry *ce = cache[0];
+
+               if (S_ISSPARSEDIR(ce->ce_mode) &&
+                   ce->ce_namelen == baselen &&
+                   !strncmp(ce->name, base, baselen)) {
+                       it->entry_count = 1;
+                       oidcpy(&it->oid, &ce->oid);
+                       return 1;
+               }
+       }
+
        if (0 <= it->entry_count && has_object_file(&it->oid))
                return it->entry_count;
 

diff --git a/sparse-index.c b/sparse-index.c
index 4c73772c6d6c8f25a5b3c89d47b47b4da4b78a80..95ea17174da3b8f7356b9f969d3b31eb82be775b 100644 (file)
--- a/sparse-index.c
+++ b/sparse-index.c
@@ -172,7 +172,11 @@ int convert_to_sparse(struct index_state *istate)
        istate->cache_nr = convert_to_sparse_rec(istate,
                                                 0, 0, istate->cache_nr,
                                                 "", 0, istate->cache_tree);
-       istate->drop_cache_tree = 1;
+
+       /* Clear and recompute the cache-tree */
+       cache_tree_free(&istate->cache_tree);
+       cache_tree_update(istate, 0);
+
        istate->sparse_index = 1;
        trace2_region_leave("index", "convert_to_sparse", istate->repo);
        return 0;
@@ -273,5 +277,9 @@ void ensure_full_index(struct index_state *istate)
        strbuf_release(&base);
        free(full);
 
+       /* Clear and recompute the cache-tree */
+       cache_tree_free(&istate->cache_tree);
+       cache_tree_update(istate, 0);
+
        trace2_region_leave("index", "ensure_full_index", istate->repo);
 }