Merge branch 'ds/reachable' into pu

The code for computing history reachability has been shuffled,
obtained a bunch of new tests to cover them, and then being
improved.

* ds/reachable:
  commit-reach: use can_all_from_reach
  commit-reach: make can_all_from_reach... linear
  commit-reach: replace ref_newer logic
  test-reach: test commit_contains
  test-reach: test can_all_from_reach_with_flags
  test-reach: test reduce_heads
  test-reach: test get_merge_bases_many
  test-reach: test is_descendant_of
  test-reach: test in_merge_bases
  test-reach: create new test tool for ref_newer
  commit-reach: move can_all_from_reach_with_flags
  upload-pack: generalize commit date cutoff
  upload-pack: refactor ok_to_give_up()
  upload-pack: make reachable() more generic
  commit-reach: move commit_contains from ref-filter
  commit-reach: move ref_newer from remote.c
  commit.h: remove method declarations
  commit-reach: move walk methods from commit.c

Author: gitster

Makefile

@@ -723,6 +723,7 @@ TEST_BUILTINS_OBJS += test-mktemp.o
 TEST_BUILTINS_OBJS += test-online-cpus.o
 TEST_BUILTINS_OBJS += test-path-utils.o
 TEST_BUILTINS_OBJS += test-prio-queue.o
+TEST_BUILTINS_OBJS += test-reach.o
 TEST_BUILTINS_OBJS += test-read-cache.o
 TEST_BUILTINS_OBJS += test-read-midx.o
 TEST_BUILTINS_OBJS += test-ref-store.o
@@ -837,6 +838,7 @@ LIB_OBJS += column.o
 LIB_OBJS += combine-diff.o
 LIB_OBJS += commit.o
 LIB_OBJS += commit-graph.o
+LIB_OBJS += commit-reach.o
 LIB_OBJS += compat/obstack.o
 LIB_OBJS += compat/terminal.o
 LIB_OBJS += config.o

bisect.c

@@ -13,6 +13,7 @@
 #include "sha1-array.h"
 #include "argv-array.h"
 #include "commit-slab.h"
+#include "commit-reach.h"
 
 static struct oid_array good_revs;
 static struct oid_array skipped_revs;

builtin/branch.c

@@ -23,6 +23,7 @@
 #include "ref-filter.h"
 #include "worktree.h"
 #include "help.h"
+#include "commit-reach.h"
 
 static const char * const builtin_branch_usage[] = {
 	N_("git branch [<options>] [-r | -a] [--merged | --no-merged]"),

builtin/commit.c

@@ -33,6 +33,7 @@
 #include "sequencer.h"
 #include "mailmap.h"
 #include "help.h"
+#include "commit-reach.h"
 
 static const char * const builtin_commit_usage[] = {
 	N_("git commit [<options>] [--] <pathspec>..."),

builtin/fetch.c

@@ -23,6 +23,7 @@
 #include "packfile.h"
 #include "list-objects-filter-options.h"
 #include "remote-odb.h"
+#include "commit-reach.h"
 
 static const char * const builtin_fetch_usage[] = {
 	N_("git fetch [<options>] [<repository> [<refspec>...]]"),

builtin/fmt-merge-msg.c

@@ -12,6 +12,7 @@
 #include "fmt-merge-msg.h"
 #include "gpg-interface.h"
 #include "repository.h"
+#include "commit-reach.h"
 
 static const char * const fmt_merge_msg_usage[] = {
 	N_("git fmt-merge-msg [-m <message>] [--log[=<n>] | --no-log] [--file <file>]"),

builtin/log.c

@@ -31,6 +31,7 @@
 #include "progress.h"
 #include "commit-slab.h"
 #include "repository.h"
+#include "commit-reach.h"
 
 #define MAIL_DEFAULT_WRAP 72
 

builtin/merge-base.c

@@ -7,6 +7,7 @@
 #include "revision.h"
 #include "parse-options.h"
 #include "repository.h"
+#include "commit-reach.h"
 
 static int show_merge_base(struct commit **rev, int rev_nr, int show_all)
 {

builtin/merge.c

@@ -36,6 +36,7 @@
 #include "packfile.h"
 #include "tag.h"
 #include "alias.h"
+#include "commit-reach.h"
 
 #define DEFAULT_TWOHEAD (1<<0)
 #define DEFAULT_OCTOPUS (1<<1)

builtin/pull.c

@@ -22,6 +22,7 @@
 #include "tempfile.h"
 #include "lockfile.h"
 #include "wt-status.h"
+#include "commit-reach.h"
 
 enum rebase_type {
 	REBASE_INVALID = -1,

builtin/receive-pack.c

@@ -27,6 +27,7 @@
 #include "packfile.h"
 #include "object-store.h"
 #include "protocol.h"
+#include "commit-reach.h"
 
 static const char * const receive_pack_usage[] = {
 	N_("git receive-pack <git-dir>"),

builtin/remote.c

@@ -10,6 +10,7 @@
 #include "refspec.h"
 #include "object-store.h"
 #include "argv-array.h"
+#include "commit-reach.h"
 
 static const char * const builtin_remote_usage[] = {
 	N_("git remote [-v | --verbose]"),

builtin/rev-parse.c

@@ -14,6 +14,7 @@
 #include "revision.h"
 #include "split-index.h"
 #include "submodule.h"
+#include "commit-reach.h"
 
 #define DO_REVS		1
 #define DO_NOREV	2

commit-graph.c

@@ -256,6 +256,24 @@ static int prepare_commit_graph(struct repository *r)
 	return !!r->objects->commit_graph;
 }
 
+int generation_numbers_enabled(struct repository *r)
+{
+	uint32_t first_generation;
+	struct commit_graph *g;
+	if (!prepare_commit_graph(r))
+	       return 0;
+
+	g = r->objects->commit_graph;
+
+	if (!g->num_commits)
+		return 0;
+
+	first_generation = get_be32(g->chunk_commit_data +
+				    g->hash_len + 8) >> 2;
+
+	return !!first_generation;
+}
+
 void close_commit_graph(struct repository *r)
 {
 	free_commit_graph(r->objects->commit_graph);

commit-graph.h

@@ -51,6 +51,12 @@ struct commit_graph {
 
 struct commit_graph *load_commit_graph_one(const char *graph_file);
 
+/*
+ * Return 1 if and only if the repository has a commit-graph
+ * file and generation numbers are computed in that file.
+ */
+int generation_numbers_enabled(struct repository *r);
+
 void write_commit_graph_reachable(const char *obj_dir, int append);
 void write_commit_graph(const char *obj_dir,
 			struct string_list *pack_indexes,