[RFC PATCH 1/2] reftable: remove the "return_block" abstraction

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

This abstraction added in 1214aa841bc (reftable: add blocksource, an
abstraction for random access reads, 2021-10-07) has the caller
provide a "blockp->data", so there's not point in having the vtable
have a custom free() function.

In addition this had what looked like a poor man's SANITIZE=address
doing a memset() to 0xff just before the data was free'd.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 reftable/block.c                |  4 +---
 reftable/blocksource.c          | 28 +---------------------------
 reftable/reftable-blocksource.h |  2 --
 3 files changed, 2 insertions(+), 32 deletions(-)

diff --git a/reftable/block.c b/reftable/block.c
index 34d4d073692..bb17cc32372 100644
--- a/reftable/block.c
+++ b/reftable/block.c
@@ -442,9 +442,7 @@ void block_writer_release(struct block_writer *bw)
 
 void reftable_block_done(struct reftable_block *blockp)
 {
-	struct reftable_block_source source = blockp->source;
-	if (blockp && source.ops)
-		source.ops->return_block(source.arg, blockp);
+	FREE_AND_NULL(blockp->data);
 	blockp->data = NULL;
 	blockp->len = 0;
 	blockp->source.ops = NULL;
diff --git a/reftable/blocksource.c b/reftable/blocksource.c
index 2605371c28d..d9e47cc316b 100644
--- a/reftable/blocksource.c
+++ b/reftable/blocksource.c
@@ -13,12 +13,6 @@ license that can be found in the LICENSE file or at
 #include "reftable-blocksource.h"
 #include "reftable-error.h"
 
-static void strbuf_return_block(void *b, struct reftable_block *dest)
-{
-	memset(dest->data, 0xff, dest->len);
-	reftable_free(dest->data);
-}
-
 static void strbuf_close(void *b)
 {
 }
@@ -42,7 +36,6 @@ static uint64_t strbuf_size(void *b)
 static struct reftable_block_source_vtable strbuf_vtable = {
 	.size = &strbuf_size,
 	.read_block = &strbuf_read_block,
-	.return_block = &strbuf_return_block,
 	.close = &strbuf_close,
 };
 
@@ -54,19 +47,7 @@ void block_source_from_strbuf(struct reftable_block_source *bs,
 	bs->arg = buf;
 }
 
-static void malloc_return_block(void *b, struct reftable_block *dest)
-{
-	memset(dest->data, 0xff, dest->len);
-	reftable_free(dest->data);
-}
-
-static struct reftable_block_source_vtable malloc_vtable = {
-	.return_block = &malloc_return_block,
-};
-
-static struct reftable_block_source malloc_block_source_instance = {
-	.ops = &malloc_vtable,
-};
+static struct reftable_block_source malloc_block_source_instance = { 0 };
 
 struct reftable_block_source malloc_block_source(void)
 {
@@ -83,12 +64,6 @@ static uint64_t file_size(void *b)
 	return ((struct file_block_source *)b)->size;
 }
 
-static void file_return_block(void *b, struct reftable_block *dest)
-{
-	memset(dest->data, 0xff, dest->len);
-	reftable_free(dest->data);
-}
-
 static void file_close(void *b)
 {
 	int fd = ((struct file_block_source *)b)->fd;
@@ -115,7 +90,6 @@ static int file_read_block(void *v, struct reftable_block *dest, uint64_t off,
 static struct reftable_block_source_vtable file_vtable = {
 	.size = &file_size,
 	.read_block = &file_read_block,
-	.return_block = &file_return_block,
 	.close = &file_close,
 };
 
diff --git a/reftable/reftable-blocksource.h b/reftable/reftable-blocksource.h
index 5aa3990a573..7b7cb280b73 100644
--- a/reftable/reftable-blocksource.h
+++ b/reftable/reftable-blocksource.h
@@ -35,8 +35,6 @@ struct reftable_block_source_vtable {
 	   beyond the end of the block */
 	int (*read_block)(void *source, struct reftable_block *dest,
 			  uint64_t off, uint32_t size);
-	/* mark the block as read; may return the data back to malloc */
-	void (*return_block)(void *source, struct reftable_block *blockp);
 
 	/* release all resources associated with the block source */
 	void (*close)(void *source);
-- 
2.36.0.rc2.863.gfc2c14e3b91