Merge branch 'nd/unpack-trees-with-cache-tree'

The unpack_trees() API used in checking out a branch and merging
walks one or more trees along with the index.  When the cache-tree
in the index tells us that we are walking a tree whose flattened
contents is known (i.e. matches a span in the index), as linearly
scanning a span in the index is much more efficient than having to
open tree objects recursively and listing their entries, the walk
can be optimized, which is done in this topic.

* nd/unpack-trees-with-cache-tree:
  Document update for nd/unpack-trees-with-cache-tree
  cache-tree: verify valid cache-tree in the test suite
  unpack-trees: add missing cache invalidation
  unpack-trees: reuse (still valid) cache-tree from src_index
  unpack-trees: reduce malloc in cache-tree walk
  unpack-trees: optimize walking same trees with cache-tree
  unpack-trees: add performance tracing
  trace.h: support nested performance tracing

1 files changed, 80 insertions, 0 deletions

diff --git a/cache-tree.c b/cache-tree.c
index 16ea022c46..490a25adf0 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -4,6 +4,7 @@
 #include "tree-walk.h"
 #include "cache-tree.h"
 #include "object-store.h"
+#include "replace-object.h"
 
 #ifndef DEBUG
 #define DEBUG 0
@@ -433,7 +434,9 @@ int cache_tree_update(struct index_state *istate, int flags)
 
 	if (i)
 		return i;
+	trace_performance_enter();
 	i = update_one(it, cache, entries, "", 0, &skip, flags);
+	trace_performance_leave("cache_tree_update");
 	if (i < 0)
 		return i;
 	istate->cache_changed |= CACHE_TREE_CHANGED;
@@ -718,3 +721,80 @@ int cache_tree_matches_traversal(struct cache_tree *root,
 		return it->entry_count;
 	return 0;
 }
+
+static void verify_one(struct index_state *istate,
+		       struct cache_tree *it,
+		       struct strbuf *path)
+{
+	int i, pos, len = path->len;
+	struct strbuf tree_buf = STRBUF_INIT;
+	struct object_id new_oid;
+
+	for (i = 0; i < it->subtree_nr; i++) {
+		strbuf_addf(path, "%s/", it->down[i]->name);
+		verify_one(istate, it->down[i]->cache_tree, path);
+		strbuf_setlen(path, len);
+	}
+
+	if (it->entry_count < 0 ||
+	    /* no verification on tests (t7003) that replace trees */
+	    lookup_replace_object(the_repository, &it->oid) != &it->oid)
+		return;
+
+	if (path->len) {
+		pos = index_name_pos(istate, path->buf, path->len);
+		pos = -pos - 1;
+	} else {
+		pos = 0;
+	}
+
+	i = 0;
+	while (i < it->entry_count) {
+		struct cache_entry *ce = istate->cache[pos + i];
+		const char *slash;
+		struct cache_tree_sub *sub = NULL;
+		const struct object_id *oid;
+		const char *name;
+		unsigned mode;
+		int entlen;
+
+		if (ce->ce_flags & (CE_STAGEMASK | CE_INTENT_TO_ADD | CE_REMOVE))
+			BUG("%s with flags 0x%x should not be in cache-tree",
+			    ce->name, ce->ce_flags);
+		name = ce->name + path->len;
+		slash = strchr(name, '/');
+		if (slash) {
+			entlen = slash - name;
+			sub = find_subtree(it, ce->name + path->len, entlen, 0);
+			if (!sub || sub->cache_tree->entry_count < 0)
+				BUG("bad subtree '%.*s'", entlen, name);
+			oid = &sub->cache_tree->oid;
+			mode = S_IFDIR;
+			i += sub->cache_tree->entry_count;
+		} else {
+			oid = &ce->oid;
+			mode = ce->ce_mode;
+			entlen = ce_namelen(ce) - path->len;
+			i++;
+		}
+		strbuf_addf(&tree_buf, "%o %.*s%c", mode, entlen, name, '\0');
+		strbuf_add(&tree_buf, oid->hash, the_hash_algo->rawsz);
+	}
+	hash_object_file(tree_buf.buf, tree_buf.len, tree_type, &new_oid);
+	if (oidcmp(&new_oid, &it->oid))
+		BUG("cache-tree for path %.*s does not match. "
+		    "Expected %s got %s", len, path->buf,
+		    oid_to_hex(&new_oid), oid_to_hex(&it->oid));
+	strbuf_setlen(path, len);
+	strbuf_release(&tree_buf);
+}
+
+void cache_tree_verify(struct index_state *istate)
+{
+	struct strbuf path = STRBUF_INIT;
+
+	if (!istate->cache_tree)
+		return;
+	verify_one(istate, istate->cache_tree, &path);
+	strbuf_release(&path);
+}