Merge branch 'close-graph-everywhere'

This topic branch is a backport of
https://github.com/gitgitgadget/git/pull/208, which avoids a lock
contention in `git gc --auto` where the `git gc` process holds a read
lock to the `commit-graph` file (if `core.commitgraph=true`) and the
spawned `git commit-graph write` (if `gc.writecommitgraph=true`) tries
to overwrite it.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

builtin/am.c

@@ -1803,7 +1803,7 @@ next:
 	 */
 	if (!state->rebasing) {
 		am_destroy(state);
-		close_all_packs(the_repository->objects);
+		close_object_store(the_repository->objects);
 		run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 	}
 }

builtin/clone.c

@@ -1247,7 +1247,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	transport_disconnect(transport);
 
 	if (option_dissociate) {
-		close_all_packs(the_repository->objects);
+		close_object_store(the_repository->objects);
 		dissociate_from_references();
 	}
 

builtin/fetch.c

@@ -1672,7 +1672,7 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
 
 	string_list_clear(&list, 0);
 
-	close_all_packs(the_repository->objects);
+	close_object_store(the_repository->objects);
 
 	argv_array_pushl(&argv_gc_auto, "gc", "--auto", NULL);
 	if (verbosity < 0)

builtin/gc.c

@@ -653,7 +653,7 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	gc_before_repack();
 
 	if (!repository_format_precious_objects) {
-		close_all_packs(the_repository->objects);
+		close_object_store(the_repository->objects);
 		if (run_command_v_opt(repack.argv, RUN_GIT_CMD))
 			die(FAILED_RUN, repack.argv[0]);
 
@@ -681,7 +681,7 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	report_garbage = report_pack_garbage;
 	reprepare_packed_git(the_repository);
 	if (pack_garbage.nr > 0) {
-		close_all_packs(the_repository->objects);
+		close_object_store(the_repository->objects);
 		clean_pack_garbage();
 	}
 

builtin/merge.c

@@ -457,7 +457,7 @@ static void finish(struct commit *head_commit,
 			 * We ignore errors in 'gc --auto', since the
 			 * user should see them.
 			 */
-			close_all_packs(the_repository->objects);
+			close_object_store(the_repository->objects);
 			run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 		}
 	}

builtin/rebase.c

@@ -741,7 +741,7 @@ static int finish_rebase(struct rebase_options *opts)
 
 	delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
 	apply_autostash(opts);
-	close_all_packs(the_repository->objects);
+	close_object_store(the_repository->objects);
 	/*
 	 * We ignore errors in 'gc --auto', since the
 	 * user should see them.

builtin/receive-pack.c

@@ -2043,7 +2043,7 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
 			proc.git_cmd = 1;
 			proc.argv = argv_gc_auto;
 
-			close_all_packs(the_repository->objects);
+			close_object_store(the_repository->objects);
 			if (!start_command(&proc)) {
 				if (use_sideband)
 					copy_to_sideband(proc.err, -1, NULL);

builtin/repack.c

@@ -422,7 +422,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	if (!names.nr && !po_args.quiet)
 		printf_ln(_("Nothing new to pack."));
 
-	close_all_packs(the_repository->objects);
+	close_object_store(the_repository->objects);
 
 	/*
 	 * Ok we have prepared all new packfiles.

commit-graph.c

@@ -361,10 +361,10 @@ int generation_numbers_enabled(struct repository *r)
 	return !!first_generation;
 }
 
-void close_commit_graph(struct repository *r)
+void close_commit_graph(struct raw_object_store *o)
 {
-	free_commit_graph(r->objects->commit_graph);
-	r->objects->commit_graph = NULL;
+	free_commit_graph(o->commit_graph);
+	o->commit_graph = NULL;
 }
 
 static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
@@ -1110,7 +1110,7 @@ void write_commit_graph(const char *obj_dir,
 	stop_progress(&progress);
 	strbuf_release(&progress_title);
 
-	close_commit_graph(the_repository);
+	close_commit_graph(the_repository->objects);
 	finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
 	commit_lock_file(&lk);
 

commit-graph.h

@@ -74,7 +74,7 @@ void write_commit_graph(const char *obj_dir,
 
 int verify_commit_graph(struct repository *r, struct commit_graph *g);
 
-void close_commit_graph(struct repository *);
+void close_commit_graph(struct raw_object_store *);
 void free_commit_graph(struct commit_graph *);
 
 #endif

object.c

@@ -517,7 +517,7 @@ void raw_object_store_clear(struct raw_object_store *o)
 	o->loaded_alternates = 0;
 
 	INIT_LIST_HEAD(&o->packed_git_mru);
-	close_all_packs(o);
+	close_object_store(o);
 	o->packed_git = NULL;
 }
 

packfile.c

@@ -16,6 +16,7 @@
 #include "tree.h"
 #include "object-store.h"
 #include "midx.h"
+#include "commit-graph.h"
 
 char *odb_pack_name(struct strbuf *buf,
 		    const unsigned char *sha1,
@@ -336,7 +337,7 @@ void close_pack(struct packed_git *p)
 	close_pack_index(p);
 }
 
-void close_all_packs(struct raw_object_store *o)
+void close_object_store(struct raw_object_store *o)
 {
 	struct packed_git *p;
 
@@ -350,6 +351,8 @@ void close_all_packs(struct raw_object_store *o)
 		close_midx(o->multi_pack_index);
 		o->multi_pack_index = NULL;
 	}
+
+	close_commit_graph(o);
 }
 
 /*

packfile.h

@@ -90,7 +90,7 @@ uint32_t get_pack_fanout(struct packed_git *p, uint32_t value);
 unsigned char *use_pack(struct packed_git *, struct pack_window **, off_t, unsigned long *);
 void close_pack_windows(struct packed_git *);
 void close_pack(struct packed_git *);
-void close_all_packs(struct raw_object_store *o);
+void close_object_store(struct raw_object_store *o);
 void unuse_pack(struct pack_window **);
 void clear_delta_base_cache(void);
 struct packed_git *add_packed_git(const char *path, size_t path_len, int local);

upload-pack.c

@@ -722,7 +722,7 @@ static void deepen_by_rev_list(struct packet_writer *writer, int ac,
 {
 	struct commit_list *result;
 
-	close_commit_graph(the_repository);
+	close_commit_graph(the_repository->objects);
 	result = get_shallow_commits_by_rev_list(ac, av, SHALLOW, NOT_SHALLOW);
 	send_shallow(writer, result);
 	free_commit_list(result);