[PATCH 13/15] [GSOC] cat-file: reuse err buf in batch_object_write()

["ZheNing Hu via GitGitGadget" <gitgitgadget@gmail.com>]

From: ZheNing Hu <adlternative@gmail.com>

Reuse the `err` buffer in batch_object_write(), as the
buffer `scratch` does. This will reduce the overhead
of multiple allocations of memory of the err buffer.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Hariom Verma <hariom18599@gmail.com>
Signed-off-by: ZheNing Hu <adlternative@gmail.com>
---
 builtin/cat-file.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index 5b163551fc6..dc604a9879d 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -212,35 +212,36 @@ static void batch_write(struct batch_options *opt, const void *data, int len)
 
 static void batch_object_write(const char *obj_name,
 			       struct strbuf *scratch,
+			       struct strbuf *err,
 			       struct batch_options *opt,
 			       struct expand_data *data)
 {
 	int ret;
-	struct strbuf err = STRBUF_INIT;
 	struct ref_array_item item = { data->oid, data->rest };
 
 	strbuf_reset(scratch);
+	strbuf_reset(err);
 
-	ret = format_ref_array_item(&item, &opt->format, scratch, &err);
+	ret = format_ref_array_item(&item, &opt->format, scratch, err);
 	if (ret < 0)
-		die("%s\n", err.buf);
+		die("%s\n", err->buf);
 	if (ret) {
 		/* ret > 0 means when the object corresponding to oid
 		 * cannot be found in format_ref_array_item(), we only print
 		 * the error message.
 		 */
-		printf("%s\n", err.buf);
+		printf("%s\n", err->buf);
 		fflush(stdout);
 	} else {
 		strbuf_addch(scratch, '\n');
 		batch_write(opt, scratch->buf, scratch->len);
 	}
 	free_ref_array_item_value(&item);
-	strbuf_release(&err);
 }
 
 static void batch_one_object(const char *obj_name,
 			     struct strbuf *scratch,
+			     struct strbuf *err,
 			     struct batch_options *opt,
 			     struct expand_data *data)
 {
@@ -294,7 +295,7 @@ static void batch_one_object(const char *obj_name,
 		return;
 	}
 
-	batch_object_write(obj_name, scratch, opt, data);
+	batch_object_write(obj_name, scratch, err, opt, data);
 }
 
 struct object_cb_data {
@@ -302,13 +303,14 @@ struct object_cb_data {
 	struct expand_data *expand;
 	struct oidset *seen;
 	struct strbuf *scratch;
+	struct strbuf *err;
 };
 
 static int batch_object_cb(const struct object_id *oid, void *vdata)
 {
 	struct object_cb_data *data = vdata;
 	oidcpy(&data->expand->oid, oid);
-	batch_object_write(NULL, data->scratch, data->opt, data->expand);
+	batch_object_write(NULL, data->scratch, data->err, data->opt, data->expand);
 	return 0;
 }
 
@@ -364,6 +366,7 @@ static int batch_objects(struct batch_options *batch, const struct option *optio
 {
 	struct strbuf input = STRBUF_INIT;
 	struct strbuf output = STRBUF_INIT;
+	struct strbuf err = STRBUF_INIT;
 	struct strbuf format = STRBUF_INIT;
 	struct expand_data data;
 	int save_warning;
@@ -392,6 +395,7 @@ static int batch_objects(struct batch_options *batch, const struct option *optio
 		cb.opt = batch;
 		cb.expand = &data;
 		cb.scratch = &output;
+		cb.err = &err;
 
 		if (batch->unordered) {
 			struct oidset seen = OIDSET_INIT;
@@ -416,6 +420,7 @@ static int batch_objects(struct batch_options *batch, const struct option *optio
 
 		strbuf_release(&format);
 		strbuf_release(&output);
+		strbuf_release(&err);
 		return 0;
 	}
 
@@ -444,12 +449,13 @@ static int batch_objects(struct batch_options *batch, const struct option *optio
 			data.rest = p;
 		}
 
-		batch_one_object(input.buf, &output, batch, &data);
+		batch_one_object(input.buf, &output, &err, batch, &data);
 	}
 
 	strbuf_release(&format);
 	strbuf_release(&input);
 	strbuf_release(&output);
+	strbuf_release(&err);
 	warn_on_object_refname_ambiguity = save_warning;
 	return retval;
 }
-- 
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