Re: [PATCH v3 2/4] commit-graph: introduce commit_graph_data_slab
From: SZEDER Gábor <hidden>
Date: 2020-06-13 06:53:48
On Sat, Jun 13, 2020 at 12:10:12AM +0530, Abhishek Kumar wrote:
quoted hunk ↗ jump to hunk
diff --git a/commit-graph.c b/commit-graph.c index 2ff042fbf4..91120ba3d3 100644 --- a/commit-graph.c +++ b/commit-graph.c@@ -87,6 +87,55 @@ static int commit_pos_cmp(const void *va, const void *vb) commit_pos_at(&commit_pos, b); } +define_commit_slab(commit_graph_data_slab, struct commit_graph_data); +static struct commit_graph_data_slab commit_graph_data_slab = + COMMIT_SLAB_INIT(1, commit_graph_data_slab); + +uint32_t commit_graph_position(const struct commit *c) +{ + struct commit_graph_data *data = + commit_graph_data_slab_peek(&commit_graph_data_slab, c); + + return data ? data->graph_pos : COMMIT_NOT_FROM_GRAPH; +} + +uint32_t commit_graph_generation(const struct commit *c) +{ + struct commit_graph_data *data = + commit_graph_data_slab_peek(&commit_graph_data_slab, c); + + if (!data) + return GENERATION_NUMBER_INFINITY; + else if (data->graph_pos == COMMIT_NOT_FROM_GRAPH) + return GENERATION_NUMBER_INFINITY; + + return data->generation; +} + +static struct commit_graph_data *commit_graph_data_at(const struct commit *c)
commit-graph.c: At top level:
commit-graph.c:115:34: error: ‘commit_graph_data_at’ defined but not used [-Werror=unused-function]
static struct commit_graph_data *commit_graph_data_at(const struct commit *c)
^
Please make sure that each and every commit of your series can be
built with DEVELOPER=1 and passes the test suite.
+{
+ uint32_t i = commit_graph_data_slab.slab_count, j;
+ uint32_t slab_size = commit_graph_data_slab.slab_size;
+ struct commit_graph_data *data =
+ commit_graph_data_slab_at(&commit_graph_data_slab, c);
+
+ /*
+ * commit-slab initializes elements with zero, overwrite this with
+ * COMMIT_NOT_FROM_GRAPH for graph_pos.
+ *
+ * We avoid initializing generation with checking if graph position
+ * is not COMMIT_NOT_FROM_GRAPH.
+ */
+ for (; i < commit_graph_data_slab.slab_count; i++) {
+ for (j = 0; j < slab_size; j++) {
+ commit_graph_data_slab[i][j].graph_pos =
commit-graph.c: In function ‘commit_graph_data_at’:
commit-graph.c:131:26: error: subscripted value is neither array nor pointer nor vector
commit_graph_data_slab[i][j].graph_pos =
^
Once the next patch is applied Git can be built again, but then:
$ ~/src/git/git -C webkit.git commit-graph write
Finding commits for commit graph among packed objects: 100% (3984415/3984415), done.
Expanding reachable commits in commit graph: 219420, done.
Segmentation fault
Looking at it with a debugger:
Program received signal SIGSEGV, Segmentation fault.
0x00000000005079b2 in commit_graph_data_at (c=0x1ad9aa0) at commit-graph.c:131
131 commit_graph_data_slab.slab[i][j].graph_pos =
(gdb) bt
#0 0x00000000005079b2 in commit_graph_data_at (c=0x1ad9aa0)
at commit-graph.c:131
#1 0x000000000050a6a7 in compute_generation_numbers (ctx=0x9d61a0)
at commit-graph.c:1304
#2 0x000000000050d37d in write_commit_graph (odb=0x9d3d80, pack_indexes=0x0,
commits=0x0, flags=COMMIT_GRAPH_WRITE_PROGRESS,
split_opts=0x98e730 <split_opts>) at commit-graph.c:2178
#3 0x000000000042bb7e in graph_write (argc=0, argv=0x7fffffffe2f0)
at builtin/commit-graph.c:242
#4 0x000000000042bc8d in cmd_commit_graph (argc=1, argv=0x7fffffffe2f0,
prefix=0x0) at builtin/commit-graph.c:278
#5 0x00000000004061d1 in run_builtin (p=0x97b950 <commands+528>, argc=2,
argv=0x7fffffffe2f0) at git.c:448
#6 0x0000000000406521 in handle_builtin (argc=2, argv=0x7fffffffe2f0)
at git.c:673
#7 0x00000000004067c9 in run_argv (argcp=0x7fffffffe18c, argv=0x7fffffffe180)
at git.c:740
#8 0x0000000000406c3a in cmd_main (argc=2, argv=0x7fffffffe2f0) at git.c:871
#9 0x00000000004cfbda in main (argc=5, argv=0x7fffffffe2d8)
at common-main.c:52
(gdb) p commit_graph_data_slab
$1 = {
slab_size = 65532,
stride = 1,
slab_count = 4,
slab = 0x4f68690
}
(gdb) p i
$2 = 0
(gdb) p commit_graph_data_slab.slab[i]
$3 = (struct commit_graph_data *) 0x0
(gdb) p c->index
$4 = 213506
(gdb) up
#1 0x000000000050a6a7 in compute_generation_numbers (ctx=0x9d61a0)
at commit-graph.c:1304
1304 uint32_t generation = commit_graph_data_at(ctx->commits.list[i])->generation;
(gdb) p i
$5 = 0
The way the loop variable 'i' is initialized and is used in the loop
header suggests that you assume that all slabs with an index
<slab_count are allocated. That's not the case, only those slabs are
allocated that contain data associated with a commit that has already
been looked at.
quoted hunk ↗ jump to hunk
+ COMMIT_NOT_FROM_GRAPH; + } + } + + return data; +} + static int commit_gen_cmp(const void *va, const void *vb) { const struct commit *a = *(const struct commit **)va;diff --git a/commit-graph.h b/commit-graph.h index 3ba0da1e5f..cc76757007 100644 --- a/commit-graph.h +++ b/commit-graph.h@@ -135,4 +135,14 @@ void free_commit_graph(struct commit_graph *); */ void disable_commit_graph(struct repository *r); +struct commit_graph_data { + uint32_t graph_pos; + uint32_t generation; +}; + +/*
This line adds a trailing space which is then removed in next patch. Please don't add it in the first place.
+ * Commits should be parsed before accessing generation, graph positions. + */ +uint32_t commit_graph_generation(const struct commit *); +uint32_t commit_graph_position(const struct commit *); #endif -- 2.27.0