Merge branch 'ps/object-source-loose' into seen

A part of code paths that deals with loose objects has been cleaned
up.

* ps/object-source-loose:
  object-file: refactor writing objects via a stream
  object-file: rename `write_object_file()`
  object-file: refactor freshening of objects
  object-file: rename `has_loose_object()`
  object-file: read objects via the loose object source
  object-file: move loose object map into loose source
  object-file: hide internals when we need to reprepare loose sources
  object-file: move loose object cache into loose source
  object-file: introduce `struct odb_loose_source`
  object-file: move `fetch_if_missing`
  odb: adjust naming to free object sources
  odb: introduce `odb_source_new()`
  odb: fix subtle logic to check whether an alternate is usable

Author: gitster

builtin/pack-objects.c

@@ -1715,7 +1715,7 @@ static int want_object_in_pack_mtime(const struct object_id *oid,
 		 */
 		struct odb_source *source = the_repository->objects->sources->next;
 		for (; source; source = source->next)
-			if (has_loose_object(source, oid))
+			if (odb_loose_source_has_object(source, oid))
 				return 0;
 	}
 
@@ -3976,7 +3976,7 @@ static void add_cruft_object_entry(const struct object_id *oid, enum object_type
 			int found = 0;
 
 			for (; !found && source; source = source->next)
-				if (has_loose_object(source, oid))
+				if (odb_loose_source_has_object(source, oid))
 					found = 1;
 
 			/*

builtin/unpack-objects.c

@@ -363,7 +363,7 @@ struct input_zstream_data {
 	int status;
 };
 
-static const void *feed_input_zstream(struct input_stream *in_stream,
+static const void *feed_input_zstream(struct odb_write_stream *in_stream,
 				      unsigned long *readlen)
 {
 	struct input_zstream_data *data = in_stream->data;
@@ -393,7 +393,7 @@ static void stream_blob(unsigned long size, unsigned nr)
 {
 	git_zstream zstream = { 0 };
 	struct input_zstream_data data = { 0 };
-	struct input_stream in_stream = {
+	struct odb_write_stream in_stream = {
 		.read = feed_input_zstream,
 		.data = &data,
 	};
@@ -402,8 +402,7 @@ static void stream_blob(unsigned long size, unsigned nr)
 	data.zstream = &zstream;
 	git_inflate_init(&zstream);
 
-	if (stream_loose_object(the_repository->objects->sources,
-				&in_stream, size, &info->oid))
+	if (odb_write_object_stream(the_repository->objects, &in_stream, size, &info->oid))
 		die(_("failed to write object in stream"));
 
 	if (data.status != Z_STREAM_END)

loose.c

@@ -1,6 +1,7 @@
 #include "git-compat-util.h"
 #include "hash.h"
 #include "path.h"
+#include "object-file.h"
 #include "odb.h"
 #include "hex.h"
 #include "repository.h"
@@ -48,13 +49,13 @@ static int insert_loose_map(struct odb_source *source,
 			    const struct object_id *oid,
 			    const struct object_id *compat_oid)
 {
-	struct loose_object_map *map = source->loose_map;
+	struct loose_object_map *map = source->loose->map;
 	int inserted = 0;
 
 	inserted |= insert_oid_pair(map->to_compat, oid, compat_oid);
 	inserted |= insert_oid_pair(map->to_storage, compat_oid, oid);
 	if (inserted)
-		oidtree_insert(source->loose_objects_cache, compat_oid);
+		oidtree_insert(source->loose->cache, compat_oid);
 
 	return inserted;
 }
@@ -64,11 +65,11 @@ static int load_one_loose_object_map(struct repository *repo, struct odb_source
 	struct strbuf buf = STRBUF_INIT, path = STRBUF_INIT;
 	FILE *fp;
 
-	if (!source->loose_map)
-		loose_object_map_init(&source->loose_map);
-	if (!source->loose_objects_cache) {
-		ALLOC_ARRAY(source->loose_objects_cache, 1);
-		oidtree_init(source->loose_objects_cache);
+	if (!source->loose->map)
+		loose_object_map_init(&source->loose->map);
+	if (!source->loose->cache) {
+		ALLOC_ARRAY(source->loose->cache, 1);
+		oidtree_init(source->loose->cache);
 	}
 
 	insert_loose_map(source, repo->hash_algo->empty_tree, repo->compat_hash_algo->empty_tree);
@@ -124,7 +125,7 @@ int repo_read_loose_object_map(struct repository *repo)
 
 int repo_write_loose_object_map(struct repository *repo)
 {
-	kh_oid_map_t *map = repo->objects->sources->loose_map->to_compat;
+	kh_oid_map_t *map = repo->objects->sources->loose->map->to_compat;
 	struct lock_file lock;
 	int fd;
 	khiter_t iter;
@@ -230,7 +231,7 @@ int repo_loose_object_map_oid(struct repository *repo,
 	khiter_t pos;
 
 	for (source = repo->objects->sources; source; source = source->next) {
-		struct loose_object_map *loose_map = source->loose_map;
+		struct loose_object_map *loose_map = source->loose->map;
 		if (!loose_map)
 			continue;
 		map = (to == repo->compat_hash_algo) ?