odb: add odb_source_files_try() for heterogeneous source iteration

Makefile

@@ -1544,6 +1544,7 @@ CLAR_TEST_SUITES += u-strvec
 CLAR_TEST_SUITES += u-trailer
 CLAR_TEST_SUITES += u-urlmatch-normalization
 CLAR_TEST_SUITES += u-utf8-width
+CLAR_TEST_SUITES += u-odb-source
 CLAR_TEST_PROG = $(UNIT_TEST_BIN)/unit-tests$(X)
 CLAR_TEST_OBJS = $(patsubst %,$(UNIT_TEST_DIR)/%.o,$(CLAR_TEST_SUITES))
 CLAR_TEST_OBJS += $(UNIT_TEST_DIR)/clar/clar.o

builtin/cat-file.c

@@ -882,9 +882,12 @@ static void batch_each_object(struct batch_options *opt,
 		struct object_info oi = { 0 };
 
 		for (source = the_repository->objects->sources; source; source = source->next) {
-			struct odb_source_files *files = odb_source_files_downcast(source);
-			int ret = packfile_store_for_each_object(files->packed, &oi,
-								 batch_one_object_oi, &payload, flags);
+			struct odb_source_files *files = odb_source_files_try(source);
+			int ret;
+			if (!files)
+				continue;
+			ret = packfile_store_for_each_object(files->packed, &oi,
+							     batch_one_object_oi, &payload, flags);
 			if (ret)
 				break;
 		}

builtin/fast-import.c

@@ -982,7 +982,9 @@ static int store_object(
 	}
 
 	for (source = the_repository->objects->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct odb_source_files *files = odb_source_files_try(source);
+		if (!files)
+			continue;
 
 		if (!packfile_list_find_oid(packfile_store_get_packs(files->packed), &oid))
 			continue;
@@ -1189,7 +1191,9 @@ static void stream_blob(uintmax_t len, struct object_id *oidout, uintmax_t mark)
 	}
 
 	for (source = the_repository->objects->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct odb_source_files *files = odb_source_files_try(source);
+		if (!files)
+			continue;
 
 		if (!packfile_list_find_oid(packfile_store_get_packs(files->packed), &oid))
 			continue;

builtin/grep.c

@@ -1219,7 +1219,9 @@ int cmd_grep(int argc,
 
 			odb_prepare_alternates(the_repository->objects);
 			for (source = the_repository->objects->sources; source; source = source->next) {
-				struct odb_source_files *files = odb_source_files_downcast(source);
+				struct odb_source_files *files = odb_source_files_try(source);
+				if (!files)
+					continue;
 				packfile_store_prepare(files->packed);
 			}
 		}

builtin/pack-objects.c

@@ -1531,8 +1531,11 @@ static int want_cruft_object_mtime(struct repository *r,
 	struct odb_source *source;
 
 	for (source = r->objects->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
-		struct packed_git **cache = packfile_store_get_kept_pack_cache(files->packed, flags);
+		struct odb_source_files *files = odb_source_files_try(source);
+		struct packed_git **cache;
+		if (!files)
+			continue;
+		cache = packfile_store_get_kept_pack_cache(files->packed, flags);
 
 		for (; *cache; cache++) {
 			struct packed_git *p = *cache;
@@ -1754,7 +1757,9 @@ static int want_object_in_pack_mtime(const struct object_id *oid,
 	}
 
 	for (source = the_repository->objects->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct odb_source_files *files = odb_source_files_try(source);
+		if (!files)
+			continue;
 
 		for (e = files->packed->packs.head; e; e = e->next) {
 			struct packed_git *p = e->pack;
@@ -4350,7 +4355,9 @@ static void add_objects_in_unpacked_packs(void)
 
 	odb_prepare_alternates(to_pack.repo->objects);
 	for (source = to_pack.repo->objects->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct odb_source_files *files = odb_source_files_try(source);
+		if (!files)
+			continue;
 
 		if (!source->local)
 			continue;

commit-graph.c

@@ -1981,7 +1981,9 @@ static void fill_oids_from_all_packs(struct write_commit_graph_context *ctx)
 
 	odb_prepare_alternates(ctx->r->objects);
 	for (source = ctx->r->objects->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct odb_source_files *files = odb_source_files_try(source);
+		if (!files)
+			continue;
 		packfile_store_for_each_object(files->packed, &oi, add_packed_commits_oi,
 					       ctx, ODB_FOR_EACH_OBJECT_PACK_ORDER);
 	}

loose.c

@@ -64,10 +64,13 @@ static int insert_loose_map(struct odb_source *source,
 
 static int load_one_loose_object_map(struct repository *repo, struct odb_source *source)
 {
-	struct odb_source_files *files = odb_source_files_downcast(source);
+	struct odb_source_files *files = odb_source_files_try(source);
 	struct strbuf buf = STRBUF_INIT, path = STRBUF_INIT;
 	FILE *fp;
 
+	if (!files)
+		return 0;
+
 	if (!files->loose->map)
 		loose_object_map_init(&files->loose->map);
 	if (!files->loose->cache) {
@@ -235,8 +238,11 @@ int repo_loose_object_map_oid(struct repository *repo,
 	khiter_t pos;
 
 	for (source = repo->objects->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
-		struct loose_object_map *loose_map = files->loose->map;
+		struct odb_source_files *files = odb_source_files_try(source);
+		struct loose_object_map *loose_map;
+		if (!files)
+			continue;
+		loose_map = files->loose->map;
 		if (!loose_map)
 			continue;
 		map = (to == repo->compat_hash_algo) ?

midx.c

@@ -95,7 +95,9 @@ static int midx_read_object_offsets(const unsigned char *chunk_start,
 
 struct multi_pack_index *get_multi_pack_index(struct odb_source *source)
 {
-	struct odb_source_files *files = odb_source_files_downcast(source);
+	struct odb_source_files *files = odb_source_files_try(source);
+	if (!files)
+		return NULL;
 	packfile_store_prepare(files->packed);
 	return files->packed->midx;
 }
@@ -806,7 +808,9 @@ void clear_midx_file(struct repository *r)
 		struct odb_source *source;
 
 		for (source = r->objects->sources; source; source = source->next) {
-			struct odb_source_files *files = odb_source_files_downcast(source);
+			struct odb_source_files *files = odb_source_files_try(source);
+			if (!files)
+				continue;
 			if (files->packed->midx)
 				close_midx(files->packed->midx);
 			files->packed->midx = NULL;

object-file.c

@@ -1879,14 +1879,20 @@ static int append_loose_object(const struct object_id *oid,
 struct oidtree *odb_source_loose_cache(struct odb_source *source,
 				       const struct object_id *oid)
 {
-	struct odb_source_files *files = odb_source_files_downcast(source);
-	int subdir_nr = oid->hash[0];
+	struct odb_source_files *files = odb_source_files_try(source);
+	int subdir_nr;
 	struct strbuf buf = STRBUF_INIT;
-	size_t word_bits = bitsizeof(files->loose->subdir_seen[0]);
-	size_t word_index = subdir_nr / word_bits;
-	size_t mask = (size_t)1u << (subdir_nr % word_bits);
+	size_t word_bits, word_index, mask;
 	uint32_t *bitmap;
 
+	if (!files)
+		return NULL;
+
+	subdir_nr = oid->hash[0];
+	word_bits = bitsizeof(files->loose->subdir_seen[0]);
+	word_index = subdir_nr / word_bits;
+	mask = (size_t)1u << (subdir_nr % word_bits);
+
 	if (subdir_nr < 0 ||
 	    (size_t) subdir_nr >= bitsizeof(files->loose->subdir_seen))
 		BUG("subdir_nr out of range");
@@ -1919,7 +1925,9 @@ static void odb_source_loose_clear_cache(struct odb_source_loose *loose)
 
 void odb_source_loose_reprepare(struct odb_source *source)
 {
-	struct odb_source_files *files = odb_source_files_downcast(source);
+	struct odb_source_files *files = odb_source_files_try(source);
+	if (!files)
+		return;
 	odb_source_loose_clear_cache(files->loose);
 }
 

object-name.c

@@ -115,9 +115,11 @@ static void find_short_object_filename(struct disambiguate_state *ds)
 {
 	struct odb_source *source;
 
-	for (source = ds->repo->objects->sources; source && !ds->ambiguous; source = source->next)
-		oidtree_each(odb_source_loose_cache(source, &ds->bin_pfx),
-				&ds->bin_pfx, ds->len, match_prefix, ds);
+	for (source = ds->repo->objects->sources; source && !ds->ambiguous; source = source->next) {
+		struct oidtree *tree = odb_source_loose_cache(source, &ds->bin_pfx);
+		if (tree)
+			oidtree_each(tree, &ds->bin_pfx, ds->len, match_prefix, ds);
+	}
 }
 
 static int match_hash(unsigned len, const unsigned char *a, const unsigned char *b)

odb/source-files.h

@@ -32,4 +32,18 @@ static inline struct odb_source_files *odb_source_files_downcast(struct odb_sour
 	return container_of(source, struct odb_source_files, base);
 }
 
+/*
+ * Try to cast the given source to the files backend. Returns NULL if
+ * the source uses a different backend. Use this in loops that iterate
+ * over heterogeneous source chains (e.g. when alternates may include
+ * non-files backends). Use odb_source_files_downcast() when the source
+ * is known to be a files backend.
+ */
+static inline struct odb_source_files *odb_source_files_try(struct odb_source *source)
+{
+	if (source->type != ODB_SOURCE_FILES)
+		return NULL;
+	return container_of(source, struct odb_source_files, base);
+}
+
 #endif

packfile.c

@@ -363,7 +363,9 @@ static int unuse_one_window(struct object_database *odb)
 	struct pack_window *lru_w = NULL, *lru_l = NULL;
 
 	for (source = odb->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct odb_source_files *files = odb_source_files_try(source);
+		if (!files)
+			continue;
 		for (e = files->packed->packs.head; e; e = e->next)
 			scan_windows(e->pack, &lru_p, &lru_w, &lru_l);
 	}
@@ -539,7 +541,9 @@ static int close_one_pack(struct repository *r)
 	int accept_windows_inuse = 1;
 
 	for (source = r->objects->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct odb_source_files *files = odb_source_files_try(source);
+		if (!files)
+			continue;
 		for (e = files->packed->packs.head; e; e = e->next) {
 			if (e->pack->pack_fd == -1)
 				continue;
@@ -1251,8 +1255,10 @@ const struct packed_git *has_packed_and_bad(struct repository *r,
 	struct odb_source *source;
 
 	for (source = r->objects->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct odb_source_files *files = odb_source_files_try(source);
 		struct packfile_list_entry *e;
+		if (!files)
+			continue;
 
 		for (e = files->packed->packs.head; e; e = e->next)
 			if (oidset_contains(&e->pack->bad_objects, oid))
@@ -2268,8 +2274,11 @@ int has_object_pack(struct repository *r, const struct object_id *oid)
 
 	odb_prepare_alternates(r->objects);
 	for (source = r->objects->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
-		int ret = find_pack_entry(files->packed, oid, &e);
+		struct odb_source_files *files = odb_source_files_try(source);
+		int ret;
+		if (!files)
+			continue;
+		ret = find_pack_entry(files->packed, oid, &e);
 		if (ret)
 			return ret;
 	}
@@ -2284,8 +2293,10 @@ int has_object_kept_pack(struct repository *r, const struct object_id *oid,
 	struct pack_entry e;
 
 	for (source = r->objects->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
+		struct odb_source_files *files = odb_source_files_try(source);
 		struct packed_git **cache;
+		if (!files)
+			continue;
 
 		cache = packfile_store_get_kept_pack_cache(files->packed, flags);
 

packfile.h

@@ -193,8 +193,11 @@ static inline struct repo_for_each_pack_data repo_for_eack_pack_data_init(struct
 	odb_prepare_alternates(repo->objects);
 
 	for (struct odb_source *source = repo->objects->sources; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
-		struct packfile_list_entry *entry = packfile_store_get_packs(files->packed);
+		struct odb_source_files *files = odb_source_files_try(source);
+		struct packfile_list_entry *entry;
+		if (!files)
+			continue;
+		entry = packfile_store_get_packs(files->packed);
 		if (!entry)
 			continue;
 		data.source = source;
@@ -214,8 +217,11 @@ static inline void repo_for_each_pack_data_next(struct repo_for_each_pack_data *
 		return;
 
 	for (source = data->source->next; source; source = source->next) {
-		struct odb_source_files *files = odb_source_files_downcast(source);
-		struct packfile_list_entry *entry = packfile_store_get_packs(files->packed);
+		struct odb_source_files *files = odb_source_files_try(source);
+		struct packfile_list_entry *entry;
+		if (!files)
+			continue;
+		entry = packfile_store_get_packs(files->packed);
 		if (!entry)
 			continue;
 		data->source = source;

t/meson.build

@@ -6,6 +6,7 @@ clar_test_suites = [
   'unit-tests/u-hashmap.c',
   'unit-tests/u-list-objects-filter-options.c',
   'unit-tests/u-mem-pool.c',
+  'unit-tests/u-odb-source.c',
   'unit-tests/u-oid-array.c',
   'unit-tests/u-oidmap.c',
   'unit-tests/u-oidtree.c',

t/unit-tests/u-odb-source.c

@@ -0,0 +1,25 @@
+#include "unit-test.h"
+#include "odb/source.h"
+#include "odb/source-files.h"
+
+/*
+ * Verify that odb_source_files_try() returns the files backend
+ * for ODB_SOURCE_FILES and NULL for other source types.
+ */
+void test_odb_source__try_returns_files_for_files_type(void)
+{
+	struct odb_source_files files_src;
+	memset(&files_src, 0, sizeof(files_src));
+	files_src.base.type = ODB_SOURCE_FILES;
+
+	cl_assert(odb_source_files_try(&files_src.base) == &files_src);
+}
+
+void test_odb_source__try_returns_null_for_unknown_type(void)
+{
+	struct odb_source other_src;
+	memset(&other_src, 0, sizeof(other_src));
+	other_src.type = ODB_SOURCE_UNKNOWN;
+
+	cl_assert(odb_source_files_try(&other_src) == NULL);
+}