| Message ID | 20241003211317.GE11328@coredump.intra.peff.net (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 1164e270b5af80516625b628945ec7365d992055 |
| Headers | show |
| Series | diff output_prefix cleanups | expand |
Jeff King <peff@peff.net> writes: > Since we only need the strbuf when we are formatting graph padding, we > can give ownership of the strbuf to the git_graph struct, letting us > free it when that struct is no longer in use. > > static const char *diff_output_prefix_callback(struct diff_options *opt, void *data) > { > struct git_graph *graph = data; > - static struct strbuf msgbuf = STRBUF_INIT; > > assert(opt); > > if (!graph) > return opt->line_prefix; > > - strbuf_reset(&msgbuf); Oooh, I love this change. The fewer file scope statics (or global states in general) we have, the better ;-).
On Thu, Oct 03, 2024 at 04:43:40PM -0700, Junio C Hamano wrote: > Jeff King <peff@peff.net> writes: > > > Since we only need the strbuf when we are formatting graph padding, we > > can give ownership of the strbuf to the git_graph struct, letting us > > free it when that struct is no longer in use. > > > > static const char *diff_output_prefix_callback(struct diff_options *opt, void *data) > > { > > struct git_graph *graph = data; > > - static struct strbuf msgbuf = STRBUF_INIT; > > > > assert(opt); > > > > if (!graph) > > return opt->line_prefix; > > > > - strbuf_reset(&msgbuf); > > Oooh, I love this change. The fewer file scope statics (or global > states in general) we have, the better ;-). True, thanks for going the extra mile here! The other patches look good to me, as well. Patrick
diff --git a/graph.c b/graph.c index 0d200ca77f..bf000fdbe1 100644 --- a/graph.c +++ b/graph.c @@ -309,24 +309,28 @@ struct git_graph { * stored as an index into the array column_colors. */ unsigned short default_column_color; + + /* + * Scratch buffer for generating prefixes to be used with + * diff_output_prefix_callback(). + */ + struct strbuf prefix_buf; }; static const char *diff_output_prefix_callback(struct diff_options *opt, void *data) { struct git_graph *graph = data; - static struct strbuf msgbuf = STRBUF_INIT; assert(opt); if (!graph) return opt->line_prefix; - strbuf_reset(&msgbuf); + strbuf_reset(&graph->prefix_buf); if (opt->line_prefix) - strbuf_addstr(&msgbuf, opt->line_prefix); - if (graph) - graph_padding_line(graph, &msgbuf); - return msgbuf.buf; + strbuf_addstr(&graph->prefix_buf, opt->line_prefix); + graph_padding_line(graph, &graph->prefix_buf); + return graph->prefix_buf.buf; } static const struct diff_options *default_diffopt; @@ -396,6 +400,7 @@ struct git_graph *graph_init(struct rev_info *opt) * The diff output prefix callback, with this we can make * all the diff output to align with the graph lines. */ + strbuf_init(&graph->prefix_buf, 0); opt->diffopt.output_prefix = diff_output_prefix_callback; opt->diffopt.output_prefix_data = graph; @@ -411,6 +416,7 @@ void graph_clear(struct git_graph *graph) free(graph->new_columns); free(graph->mapping); free(graph->old_mapping); + strbuf_release(&graph->prefix_buf); free(graph); }
The diffopt output_prefix interface makes it the callback's job to handle ownership of the memory it returns, keeping it valid while callers are using it and then eventually freeing it when we are done diffing. In diff_output_prefix_callback() we handle this with a static strbuf, effectively "leaking" it when the diff is done (but not triggering any leak detectors because it's technically still reachable). This has not been a big problem in practice, but it is a problem for libification: two diffs running in the same process could stomp on each other's prefix buffers. Since we only need the strbuf when we are formatting graph padding, we can give ownership of the strbuf to the git_graph struct, letting us free it when that struct is no longer in use. Signed-off-by: Jeff King <peff@peff.net> --- graph.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)