reftable: honor core.fsync

While the reffiles backend honors configured fsync settings, the
reftable backend does not. Address this by fsyncing reftable files using
the write-or-die api's fsync_component() in two places: when we
add additional entries into the table, and when we close the reftable
writer.

This commits adds a flush function pointer as a new member of
reftable_writer because we are not sure that the first argument to the
*write function pointer always contains a file descriptor. In the case of
strbuf_add_void, the first argument is a buffer. This way, we can pass
in a corresponding flush function that knows how to flush depending on
which writer is being used.

This patch does not contain tests as they will need to wait for another
patch to start to exercise the reftable backend. At that point, the
tests will be added to observe that fsyncs are happening when the
reftable is in use.

Signed-off-by: John Cai <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 12 insertions, 12 deletions

diff --git a/reftable/readwrite_test.c b/reftable/readwrite_test.c
index b8a3224016..6b99daeaf2 100644
--- a/reftable/readwrite_test.c
+++ b/reftable/readwrite_test.c
@@ -51,7 +51,7 @@ static void write_table(char ***names, struct strbuf *buf, int N,
 		.hash_id = hash_id,
 	};
 	struct reftable_writer *w =
-		reftable_new_writer(&strbuf_add_void, buf, &opts);
+		reftable_new_writer(&strbuf_add_void, &noop_flush, buf, &opts);
 	struct reftable_ref_record ref = { NULL };
 	int i = 0, n;
 	struct reftable_log_record log = { NULL };
@@ -130,7 +130,7 @@ static void test_log_buffer_size(void)
 					   .message = "commit: 9\n",
 				   } } };
 	struct reftable_writer *w =
-		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+		reftable_new_writer(&strbuf_add_void, &noop_flush, &buf, &opts);
 
 	/* This tests buffer extension for log compression. Must use a random
 	   hash, to ensure that the compressed part is larger than the original.
@@ -171,7 +171,7 @@ static void test_log_overflow(void)
 					   .message = msg,
 				   } } };
 	struct reftable_writer *w =
-		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+		reftable_new_writer(&strbuf_add_void, &noop_flush, &buf, &opts);
 
 	uint8_t hash1[GIT_SHA1_RAWSZ]  = {1}, hash2[GIT_SHA1_RAWSZ] = { 2 };
 
@@ -202,7 +202,7 @@ static void test_log_write_read(void)
 	struct reftable_block_source source = { NULL };
 	struct strbuf buf = STRBUF_INIT;
 	struct reftable_writer *w =
-		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+		reftable_new_writer(&strbuf_add_void, &noop_flush, &buf, &opts);
 	const struct reftable_stats *stats = NULL;
 	reftable_writer_set_limits(w, 0, N);
 	for (i = 0; i < N; i++) {
@@ -294,7 +294,7 @@ static void test_log_zlib_corruption(void)
 	struct reftable_block_source source = { 0 };
 	struct strbuf buf = STRBUF_INIT;
 	struct reftable_writer *w =
-		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+		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 };
@@ -535,7 +535,7 @@ static void test_table_refs_for(int indexed)
 
 	struct strbuf buf = STRBUF_INIT;
 	struct reftable_writer *w =
-		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+		reftable_new_writer(&strbuf_add_void, &noop_flush, &buf, &opts);
 
 	struct reftable_iterator it = { NULL };
 	int j;
@@ -628,7 +628,7 @@ static void test_write_empty_table(void)
 	struct reftable_write_options opts = { 0 };
 	struct strbuf buf = STRBUF_INIT;
 	struct reftable_writer *w =
-		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+		reftable_new_writer(&strbuf_add_void, &noop_flush, &buf, &opts);
 	struct reftable_block_source source = { NULL };
 	struct reftable_reader *rd = NULL;
 	struct reftable_ref_record rec = { NULL };
@@ -666,7 +666,7 @@ static void test_write_object_id_min_length(void)
 	};
 	struct strbuf buf = STRBUF_INIT;
 	struct reftable_writer *w =
-		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+		reftable_new_writer(&strbuf_add_void, &noop_flush, &buf, &opts);
 	struct reftable_ref_record ref = {
 		.update_index = 1,
 		.value_type = REFTABLE_REF_VAL1,
@@ -701,7 +701,7 @@ static void test_write_object_id_length(void)
 	};
 	struct strbuf buf = STRBUF_INIT;
 	struct reftable_writer *w =
-		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+		reftable_new_writer(&strbuf_add_void, &noop_flush, &buf, &opts);
 	struct reftable_ref_record ref = {
 		.update_index = 1,
 		.value_type = REFTABLE_REF_VAL1,
@@ -735,7 +735,7 @@ static void test_write_empty_key(void)
 	struct reftable_write_options opts = { 0 };
 	struct strbuf buf = STRBUF_INIT;
 	struct reftable_writer *w =
-		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+		reftable_new_writer(&strbuf_add_void, &noop_flush, &buf, &opts);
 	struct reftable_ref_record ref = {
 		.refname = "",
 		.update_index = 1,
@@ -758,7 +758,7 @@ static void test_write_key_order(void)
 	struct reftable_write_options opts = { 0 };
 	struct strbuf buf = STRBUF_INIT;
 	struct reftable_writer *w =
-		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+		reftable_new_writer(&strbuf_add_void, &noop_flush, &buf, &opts);
 	struct reftable_ref_record refs[2] = {
 		{
 			.refname = "b",
@@ -801,7 +801,7 @@ static void test_write_multiple_indices(void)
 	struct reftable_reader *reader;
 	int err, i;
 
-	writer = reftable_new_writer(&strbuf_add_void, &writer_buf, &opts);
+	writer = reftable_new_writer(&strbuf_add_void, &noop_flush, &writer_buf, &opts);
 	reftable_writer_set_limits(writer, 1, 1);
 	for (i = 0; i < 100; i++) {
 		struct reftable_ref_record ref = {