[GSoC PATCH v5 0/3] reftable: return proper error codes from block_writer_add

This patch series attempts to avoid making an assumption regarding error codes returned by block_writer_add().

Changes since v4:
    - update commit message.
    - add documentation comment.

Meet Soni (3):
  reftable: propagate specific error codes in block_writer_add()
  reftable: adapt writer_add_record() to propagate block_writer_add()
    errors
  reftable: adapt write_object_record() to propagate block_writer_add()
    errors

 reftable/block.c  | 13 ++++++------
 reftable/block.h  |  2 +-
 reftable/record.c | 53 +++++++++++++++++++++--------------------------
 reftable/writer.c | 34 +++++++++++++++++++++---------
 4 files changed, 56 insertions(+), 46 deletions(-)

Range-diff against v4:
1:  6ab35d569c = 1:  6ab35d569c reftable: propagate specific error codes in block_writer_add()
2:  7f0bdc27e1 ! 2:  873a991a2c reftable: adapt writer_add_record() to propagate block_writer_add() errors
    @@ Metadata
      ## Commit message ##
         reftable: adapt writer_add_record() to propagate block_writer_add() errors
     
    -        Previously, writer_add_record() would flush the current block and
    -        retry appending the record whenever block_writer_add() returned any
    -        nonzero error. This forced an assumption that every failure meant
    -        the block was full, even when errors such as memory allocation or I/O
    -        failures occurred.
    +    Previously, writer_add_record() would flush the current block and retry
    +    appending the record whenever block_writer_add() returned any nonzero
    +    error. This forced an assumption that every failure meant the block was
    +    full, even when errors such as memory allocation or I/O failures occurred.
     
    -        Update the writer_add_record() to inspect the error code returned by
    -        block_writer_add() and only flush and reinitialize the writer when the
    -        error is REFTABLE_ENTRY_TOO_BIG_ERROR. For any other error, immediately
    -        propagate it.
    +    Update the writer_add_record() to inspect the error code returned by
    +    block_writer_add() and only flush and reinitialize the writer when the
    +    error is REFTABLE_ENTRY_TOO_BIG_ERROR. For any other error, immediately
    +    propagate it.
     
         Signed-off-by: Meet Soni <meetsoni3017@gmail.com>
     
3:  480ac27797 ! 3:  1e2f7ff83f reftable: adapt write_object_record() to propagate block_writer_add() errors
    @@ Metadata
      ## Commit message ##
         reftable: adapt write_object_record() to propagate block_writer_add() errors
     
    -        Previously, write_object_record() would flush the current block and
    -        retry appending the record whenever block_writer_add() returned any
    -        nonzero error. This forced an assumption that every failure meant the
    -        block was full, even when errors such as memory allocation or I/O
    -        failures occurred.
    +    Previously, write_object_record() would flush the current block and retry
    +    appending the record whenever block_writer_add() returned any nonzero
    +    error. This forced an assumption that every failure meant the block was
    +    full, even when errors such as memory allocation or I/O failures occurred.
     
    -        Update the write_object_record() to inspect the error code returned by
    -        block_writer_add() and only flush and reinitialize the writer when the
    -        error is REFTABLE_ENTRY_TOO_BIG_ERROR. For any other error, immediately
    -        propagate it.
    +    Update the write_object_record() to inspect the error code returned by
    +    block_writer_add() and flush and reinitialize the writer iff the
    +    error is REFTABLE_ENTRY_TOO_BIG_ERROR. For any other error, immediately
    +    propagate it.
     
    -        All call sites now handle various error codes returned by
    -        block_writer_add().
    +    If the flush and reinitialization still fail with
    +    REFTABLE_ENTRY_TOO_BIG_ERROR, reset the record's offset length to zero
    +    before a final attempt.
    +
    +    All call sites now handle various error codes returned by
    +    block_writer_add().
     
         Signed-off-by: Meet Soni <meetsoni3017@gmail.com>
     
    @@ reftable/writer.c: static void write_object_record(void *void_arg, void *key)
      	arg->err = writer_flush_block(arg->w);
      	if (arg->err < 0)
      		goto done;
    +@@ reftable/writer.c: static void write_object_record(void *void_arg, void *key)
    + 	if (arg->err < 0)
    + 		goto done;
    + 
    ++	/*
    ++	 * If this still fails then we may need to reset record's offset
    ++	 * length to reduce the data size to be written.
    ++	 */
    + 	arg->err = block_writer_add(arg->w->block_writer, &rec);
    + 	if (arg->err == 0)
    + 		goto done;
    + 
    ++	if (arg->err != REFTABLE_ENTRY_TOO_BIG_ERROR)
    ++		goto done;
    ++
    + 	rec.u.obj.offset_len = 0;
    + 	arg->err = block_writer_add(arg->w->block_writer, &rec);
    +