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[PATCH 2/6] commit-graph.h: store object directory in 'struct commit_graph'

From
Taylor Blau <me@ttaylorr.com>
Date
Jan 30, 2020, 23:00 UTC
Message-ID
<890e0e7136204f5ca47f0703f32b4adb99ad8d7e.1580424766.git.me@ttaylorr.com>
In-Reply-To
<cover.1580424766.git.me@ttaylorr.com>

There are lots of places in 'commit-graph.h' where a function either has (or almost has) a full 'struct object_directory *', accesses '->path', and then throws away the rest of the struct.

This can cause headaches when comparing the locations of object directories across alternates (e.g., in the case of deciding if two commit-graph layers can be merged). These paths are normalized with 'normalize_path_copy()' which mitigates some comparison issues, but not all [1].

Instead of getting rid of the 'struct object_directory *', store that insead of a 'char *odb' in 'struct commit_graph'. Once the 'struct write_commit_graph_context' has an object_directory pointer, too, this will allow calling code to replace these error-prone path comparisons with raw pointer comparisons, thereby circumventing any normalization-related errors. This will be introduced in a subsequent patch.

[1]: In my testing, for example, I can get one side of the commit-graph code to fill object_dir with "./objects" and the other with just "objects".

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 builtin/commit-graph.c | 13 +++++++---
 builtin/commit.c       |  1 +
 commit-graph.c         | 59 ++++++++++++++++++++++++++++++------------
 commit-graph.h         |  8 ++++--
 4 files changed, 58 insertions(+), 23 deletions(-)
diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index e0c6fc4bbf..3edac318e8 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c
@@ -76,8 +76,11 @@ static int graph_verify(int argc, const char **argv)
 
 	if (open_ok)
 		graph = load_commit_graph_one_fd_st(fd, &st);
-	 else
-		graph = read_commit_graph_one(the_repository, opts.obj_dir);
+	else {
+		struct object_directory *odb;
+		if ((odb = find_odb(the_repository, opts.obj_dir)))
+			graph = read_commit_graph_one(the_repository, odb);
+	}
 
 	/* Return failure if open_ok predicted success */
 	if (!graph)
@@ -97,6 +100,7 @@ static int graph_write(int argc, const char **argv)
 	struct string_list lines;
 	int result = 0;
 	enum commit_graph_write_flags flags = 0;
+	struct object_directory *odb = NULL;
 
 	static struct option builtin_commit_graph_write_options[] = {
 		OPT_STRING(0, "object-dir", &opts.obj_dir,
@@ -145,9 +149,10 @@ static int graph_write(int argc, const char **argv)
 		flags |= COMMIT_GRAPH_WRITE_PROGRESS;
 
 	read_replace_refs = 0;
+	odb = find_odb(the_repository, opts.obj_dir);
 
 	if (opts.reachable) {
-		if (write_commit_graph_reachable(opts.obj_dir, flags, &split_opts))
+		if (write_commit_graph_reachable(odb->path, flags, &split_opts))
 			return 1;
 		return 0;
 	}
@@ -169,7 +174,7 @@ static int graph_write(int argc, const char **argv)
 		UNLEAK(buf);
 	}
 
-	if (write_commit_graph(opts.obj_dir,
+	if (write_commit_graph(odb->path,
 			       pack_indexes,
 			       commit_hex,
 			       flags,
diff --git a/builtin/commit.c b/builtin/commit.c
index aa1332308a..bd071169d7 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -36,6 +36,7 @@
 #include "help.h"
 #include "commit-reach.h"
 #include "commit-graph.h"
+#include "object-store.h"
 
 static const char * const builtin_commit_usage[] = {
 	N_("git commit [<options>] [--] <pathspec>..."),
diff --git a/commit-graph.c b/commit-graph.c
index b205e65ed1..2c06876b26 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -75,6 +75,26 @@ static uint8_t oid_version(void)
 	return 1;
 }
 
+struct object_directory *find_odb(struct repository *r, const char *obj_dir)
+{
+	struct object_directory *odb;
+	char *obj_dir_real = real_pathdup(obj_dir, 1);
+	int cmp = -1;
+
+	prepare_alt_odb(r);
+	for (odb = r->objects->odb; odb; odb = odb->next) {
+		cmp = strcmp(obj_dir_real, real_path(odb->path));
+		if (!cmp)
+			break;
+	}
+
+	free(obj_dir_real);
+
+	if (cmp)
+		odb = NULL;
+	return odb;
+}
+
 static struct commit_graph *alloc_commit_graph(void)
 {
 	struct commit_graph *g = xcalloc(1, sizeof(*g));
@@ -327,14 +347,15 @@ static struct commit_graph *load_commit_graph_one(const char *graph_file)
 	return g;
 }
 
-static struct commit_graph *load_commit_graph_v1(struct repository *r, const char *obj_dir)
+static struct commit_graph *load_commit_graph_v1(struct repository *r,
+						 struct object_directory *odb)
 {
-	char *graph_name = get_commit_graph_filename(obj_dir);
+	char *graph_name = get_commit_graph_filename(odb->path);
 	struct commit_graph *g = load_commit_graph_one(graph_name);
 	free(graph_name);
 
 	if (g)
-		g->obj_dir = obj_dir;
+		g->odb = odb;
 
 	return g;
 }
@@ -372,14 +393,15 @@ static int add_graph_to_chain(struct commit_graph *g,
 	return 1;
 }
 
-static struct commit_graph *load_commit_graph_chain(struct repository *r, const char *obj_dir)
+static struct commit_graph *load_commit_graph_chain(struct repository *r,
+						    struct object_directory *odb)
 {
 	struct commit_graph *graph_chain = NULL;
 	struct strbuf line = STRBUF_INIT;
 	struct stat st;
 	struct object_id *oids;
 	int i = 0, valid = 1, count;
-	char *chain_name = get_chain_filename(obj_dir);
+	char *chain_name = get_chain_filename(odb->path);
 	FILE *fp;
 	int stat_res;
 
@@ -418,7 +440,7 @@ static struct commit_graph *load_commit_graph_chain(struct repository *r, const
 			free(graph_name);
 
 			if (g) {
-				g->obj_dir = odb->path;
+				g->odb = odb;
 
 				if (add_graph_to_chain(g, graph_chain, oids, i)) {
 					graph_chain = g;
@@ -442,23 +464,25 @@ static struct commit_graph *load_commit_graph_chain(struct repository *r, const
 	return graph_chain;
 }
 
-struct commit_graph *read_commit_graph_one(struct repository *r, const char *obj_dir)
+struct commit_graph *read_commit_graph_one(struct repository *r,
+					   struct object_directory *odb)
 {
-	struct commit_graph *g = load_commit_graph_v1(r, obj_dir);
+	struct commit_graph *g = load_commit_graph_v1(r, odb);
 
 	if (!g)
-		g = load_commit_graph_chain(r, obj_dir);
+		g = load_commit_graph_chain(r, odb);
 
 	return g;
 }
 
-static void prepare_commit_graph_one(struct repository *r, const char *obj_dir)
+static void prepare_commit_graph_one(struct repository *r,
+				     struct object_directory *odb)
 {
 
 	if (r->objects->commit_graph)
 		return;
 
-	r->objects->commit_graph = read_commit_graph_one(r, obj_dir);
+	r->objects->commit_graph = read_commit_graph_one(r, odb);
 }
 
 /*
@@ -505,7 +529,7 @@ static int prepare_commit_graph(struct repository *r)
 	for (odb = r->objects->odb;
 	     !r->objects->commit_graph && odb;
 	     odb = odb->next)
-		prepare_commit_graph_one(r, odb->path);
+		prepare_commit_graph_one(r, odb);
 	return !!r->objects->commit_graph;
 }
 
@@ -1470,7 +1494,7 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
 
 	if (ctx->split && ctx->base_graph_name && ctx->num_commit_graphs_after > 1) {
 		char *new_base_hash = xstrdup(oid_to_hex(&ctx->new_base_graph->oid));
-		char *new_base_name = get_split_graph_filename(ctx->new_base_graph->obj_dir, new_base_hash);
+		char *new_base_name = get_split_graph_filename(ctx->new_base_graph->odb->path, new_base_hash);
 
 		free(ctx->commit_graph_filenames_after[ctx->num_commit_graphs_after - 2]);
 		free(ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 2]);
@@ -1553,7 +1577,7 @@ static void split_graph_merge_strategy(struct write_commit_graph_context *ctx)
 
 	while (g && (g->num_commits <= size_mult * num_commits ||
 		    (max_commits && num_commits > max_commits))) {
-		if (strcmp(g->obj_dir, ctx->obj_dir))
+		if (strcmp(g->odb->path, ctx->obj_dir))
 			break;
 
 		num_commits += g->num_commits;
@@ -1565,10 +1589,10 @@ static void split_graph_merge_strategy(struct write_commit_graph_context *ctx)
 	ctx->new_base_graph = g;
 
 	if (ctx->num_commit_graphs_after == 2) {
-		char *old_graph_name = get_commit_graph_filename(g->obj_dir);
+		char *old_graph_name = get_commit_graph_filename(g->odb->path);
 
 		if (!strcmp(g->filename, old_graph_name) &&
-		    strcmp(g->obj_dir, ctx->obj_dir)) {
+		    strcmp(g->odb->path, ctx->obj_dir)) {
 			ctx->num_commit_graphs_after = 1;
 			ctx->new_base_graph = NULL;
 		}
@@ -1824,7 +1848,8 @@ int write_commit_graph(const char *obj_dir,
 		ctx->oids.alloc = split_opts->max_commits;
 
 	if (ctx->append) {
-		prepare_commit_graph_one(ctx->r, ctx->obj_dir);
+		struct object_directory *odb = find_odb(ctx->r, ctx->obj_dir);
+		prepare_commit_graph_one(ctx->r, odb);
 		if (ctx->r->objects->commit_graph)
 			ctx->oids.alloc += ctx->r->objects->commit_graph->num_commits;
 	}
diff --git a/commit-graph.h b/commit-graph.h
index 7f5c933fa2..9700a6c7c2 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -5,6 +5,7 @@
 #include "repository.h"
 #include "string-list.h"
 #include "cache.h"
+#include "object-store.h"
 
 #define GIT_TEST_COMMIT_GRAPH "GIT_TEST_COMMIT_GRAPH"
 #define GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD "GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD"
@@ -14,6 +15,8 @@ struct commit;
 char *get_commit_graph_filename(const char *obj_dir);
 int open_commit_graph(const char *graph_file, int *fd, struct stat *st);
 
+struct object_directory *find_odb(struct repository *r, const char *obj_dir);
+
 /*
  * Given a commit struct, try to fill the commit struct info, including:
  *  1. tree object
@@ -48,7 +51,7 @@ struct commit_graph {
 	uint32_t num_commits;
 	struct object_id oid;
 	char *filename;
-	const char *obj_dir;
+	struct object_directory *odb;
 
 	uint32_t num_commits_in_base;
 	struct commit_graph *base_graph;
@@ -61,7 +64,8 @@ struct commit_graph {
 };
 
 struct commit_graph *load_commit_graph_one_fd_st(int fd, struct stat *st);
-struct commit_graph *read_commit_graph_one(struct repository *r, const char *obj_dir);
+struct commit_graph *read_commit_graph_one(struct repository *r,
+					   struct object_directory *odb);
 struct commit_graph *parse_commit_graph(void *graph_map, int fd,
 					size_t graph_size);
 

-- 
2.25.0.dirty
Previous: Taylor BlauNext: Martin Ågren
Message 5 of 28 in “commit-graph: use 'struct object_directory *' everywhere”
  1. 0/6 commit-graph: use 'struct object_directory *' everywhereTaylor Blau, Jan 30, 2020
  2. 1/6 t5318: don't pass non-object directory to '--object-dir'Taylor Blau, Jan 30, 2020
  3. 5/6 commit-graph.c: remove path normalization, comparisonTaylor Blau, Jan 30, 2020
  4. 6/6 commit-graph.h: use odb in 'load_commit_graph_one_fd_st'Taylor Blau, Jan 30, 2020
  5. 2/6 commit-graph.h: store object directory in 'struct commit_graph'Taylor Blau, Jan 30, 2020
  6. Martin ÅgrenJan 31, 2020
  7. Jeff KingJan 31, 2020
  8. Martin ÅgrenJan 31, 2020
  9. Taylor BlauFeb 3, 2020
  10. Jeff KingFeb 3, 2020
  11. Junio C HamanoJan 31, 2020
  12. Taylor BlauFeb 3, 2020
  13. 4/6 commit-graph.h: store an odb in 'struct write_commit_graph_context'Taylor Blau, Jan 30, 2020
  14. 3/6 builtin/commit-graph.c: die() with unknown '--object-dir'Taylor Blau, Jan 30, 2020
  15. Jeff KingJan 31, 2020
  16. Derrick StoleeJan 31, 2020
  17. Taylor BlauFeb 3, 2020
  18. 0/5 commit-graph: use 'struct object_directory *' everywhereTaylor Blau, Feb 3, 2020
  19. 1/5 t5318: don't pass non-object directory to '--object-dir'Taylor Blau, Feb 3, 2020
  20. 2/5 commit-graph.h: store an odb in 'struct write_commit_graph_context'Taylor Blau, Feb 3, 2020
  21. 2/5 commit-graph.h: store an odb in 'struct write_commit_graph_context'Taylor Blau, Feb 4, 2020
  22. Junio C HamanoFeb 4, 2020
  23. Taylor BlauFeb 4, 2020
  24. Junio C HamanoFeb 4, 2020
  25. 5/5 commit-graph.h: use odb in 'load_commit_graph_one_fd_st'Taylor Blau, Feb 3, 2020
  26. 4/5 commit-graph.c: remove path normalization, comparisonTaylor Blau, Feb 3, 2020
  27. 3/5 commit-graph.h: store object directory in 'struct commit_graph'Taylor Blau, Feb 3, 2020
  28. Jeff KingFeb 5, 2020

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