reftable/record: convert old and new object IDs to arrays

In 7af607c58d (reftable/record: store "val1" hashes as static arrays,
2024-01-03) and b31e3cc620 (reftable/record: store "val2" hashes as
static arrays, 2024-01-03) we have converted ref records to store their
object IDs in a static array. Convert log records to do the same so that
their old and new object IDs are arrays, too.

This change results in two allocations less per log record that we're
iterating over. Before:

    HEAP SUMMARY:
        in use at exit: 13,473 bytes in 122 blocks
      total heap usage: 8,068,495 allocs, 8,068,373 frees, 401,011,862 bytes allocated

After:

    HEAP SUMMARY:
        in use at exit: 13,473 bytes in 122 blocks
      total heap usage: 6,068,489 allocs, 6,068,367 frees, 361,011,822 bytes allocated

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 25 insertions, 37 deletions

diff --git a/reftable/readwrite_test.c b/reftable/readwrite_test.c
index 363fe0f998..a6dbd214c5 100644
--- a/reftable/readwrite_test.c
+++ b/reftable/readwrite_test.c
@@ -77,18 +77,15 @@ static void write_table(char ***names, struct strbuf *buf, int N,
 	}
 
 	for (i = 0; i < N; i++) {
-		uint8_t hash[GIT_SHA256_RAWSZ] = { 0 };
 		char name[100];
 		int n;
 
-		set_test_hash(hash, i);
-
 		snprintf(name, sizeof(name), "refs/heads/branch%02d", i);
 
 		log.refname = name;
 		log.update_index = update_index;
 		log.value_type = REFTABLE_LOG_UPDATE;
-		log.value.update.new_hash = hash;
+		set_test_hash(log.value.update.new_hash, i);
 		log.value.update.message = "message";
 
 		n = reftable_writer_add_log(w, &log);
@@ -137,13 +134,10 @@ static void test_log_buffer_size(void)
 	/* This tests buffer extension for log compression. Must use a random
 	   hash, to ensure that the compressed part is larger than the original.
 	*/
-	uint8_t hash1[GIT_SHA1_RAWSZ], hash2[GIT_SHA1_RAWSZ];
 	for (i = 0; i < GIT_SHA1_RAWSZ; i++) {
-		hash1[i] = (uint8_t)(git_rand() % 256);
-		hash2[i] = (uint8_t)(git_rand() % 256);
+		log.value.update.old_hash[i] = (uint8_t)(git_rand() % 256);
+		log.value.update.new_hash[i] = (uint8_t)(git_rand() % 256);
 	}
-	log.value.update.old_hash = hash1;
-	log.value.update.new_hash = hash2;
 	reftable_writer_set_limits(w, update_index, update_index);
 	err = reftable_writer_add_log(w, &log);
 	EXPECT_ERR(err);
@@ -161,25 +155,26 @@ static void test_log_overflow(void)
 		.block_size = ARRAY_SIZE(msg),
 	};
 	int err;
-	struct reftable_log_record
-		log = { .refname = "refs/heads/master",
-			.update_index = 0xa,
-			.value_type = REFTABLE_LOG_UPDATE,
-			.value = { .update = {
-					   .name = "Han-Wen Nienhuys",
-					   .email = "hanwen@google.com",
-					   .tz_offset = 100,
-					   .time = 0x5e430672,
-					   .message = msg,
-				   } } };
+	struct reftable_log_record log = {
+		.refname = "refs/heads/master",
+		.update_index = 0xa,
+		.value_type = REFTABLE_LOG_UPDATE,
+		.value = {
+			.update = {
+				.old_hash = { 1 },
+				.new_hash = { 2 },
+				.name = "Han-Wen Nienhuys",
+				.email = "hanwen@google.com",
+				.tz_offset = 100,
+				.time = 0x5e430672,
+				.message = msg,
+			},
+		},
+	};
 	struct reftable_writer *w =
 		reftable_new_writer(&strbuf_add_void, &noop_flush, &buf, &opts);
 
-	uint8_t hash1[GIT_SHA1_RAWSZ]  = {1}, hash2[GIT_SHA1_RAWSZ] = { 2 };
-
 	memset(msg, 'x', sizeof(msg) - 1);
-	log.value.update.old_hash = hash1;
-	log.value.update.new_hash = hash2;
 	reftable_writer_set_limits(w, update_index, update_index);
 	err = reftable_writer_add_log(w, &log);
 	EXPECT(err == REFTABLE_ENTRY_TOO_BIG_ERROR);
@@ -219,16 +214,13 @@ static void test_log_write_read(void)
 		EXPECT_ERR(err);
 	}
 	for (i = 0; i < N; i++) {
-		uint8_t hash1[GIT_SHA1_RAWSZ], hash2[GIT_SHA1_RAWSZ];
 		struct reftable_log_record log = { NULL };
-		set_test_hash(hash1, i);
-		set_test_hash(hash2, i + 1);
 
 		log.refname = names[i];
 		log.update_index = i;
 		log.value_type = REFTABLE_LOG_UPDATE;
-		log.value.update.old_hash = hash1;
-		log.value.update.new_hash = hash2;
+		set_test_hash(log.value.update.old_hash, i);
+		set_test_hash(log.value.update.new_hash, i + 1);
 
 		err = reftable_writer_add_log(w, &log);
 		EXPECT_ERR(err);
@@ -298,18 +290,15 @@ static void test_log_zlib_corruption(void)
 	struct reftable_writer *w =
 		reftable_new_writer(&strbuf_add_void, &noop_flush, &buf, &opts);
 	const struct reftable_stats *stats = NULL;
-	uint8_t hash1[GIT_SHA1_RAWSZ] = { 1 };
-	uint8_t hash2[GIT_SHA1_RAWSZ] = { 2 };
 	char message[100] = { 0 };
 	int err, i, n;
-
 	struct reftable_log_record log = {
 		.refname = "refname",
 		.value_type = REFTABLE_LOG_UPDATE,
 		.value = {
 			.update = {
-				.new_hash = hash1,
-				.old_hash = hash2,
+				.new_hash = { 1 },
+				.old_hash = { 2 },
 				.name = "My Name",
 				.email = "myname@invalid",
 				.message = message,
@@ -821,13 +810,12 @@ static void test_write_multiple_indices(void)
 	}
 
 	for (i = 0; i < 100; i++) {
-		unsigned char hash[GIT_SHA1_RAWSZ] = {i};
 		struct reftable_log_record log = {
 			.update_index = 1,
 			.value_type = REFTABLE_LOG_UPDATE,
 			.value.update = {
-				.old_hash = hash,
-				.new_hash = hash,
+				.old_hash = { i },
+				.new_hash = { i },
 			},
 		};