Patrick Steinhardt <ps@xxxxxx> writes:
> @@ -139,39 +143,60 @@ int block_writer_finish(struct block_writer *w)
> w->next += 2;
> put_be24(w->buf + 1 + w->header_off, w->next);
>
> + /*
> + * Log records are stored zlib-compressed. Note that the compression
> + * also spans over the restart points we have just written.
> + */
> if (block_writer_type(w) == BLOCK_TYPE_LOG) {
> int block_header_skip = 4 + w->header_off;
> + uLongf src_len = w->next - block_header_skip, compressed_len;
> + unsigned char *compressed;
> + int ret;
> +
> + ret = deflateReset(w->zstream);
> + if (ret != Z_OK)
> + return REFTABLE_ZLIB_ERROR;
> +
> + /*
> + * Precompute the upper bound of how many bytes the compressed
> + * data may end up with. Combined with `Z_FINISH`, `deflate()`
> + * is guaranteed to return `Z_STREAM_END`.
> + */
> + compressed_len = deflateBound(w->zstream, src_len);
> + REFTABLE_ALLOC_ARRAY(compressed, compressed_len);
OK.
> + w->zstream->next_out = compressed;
> + w->zstream->avail_out = compressed_len;
> + w->zstream->next_in = w->buf + block_header_skip;
> + w->zstream->avail_in = src_len;
> +
> + /*
> + * We want to perform all decompression in a single
> + * step, which is why we can pass Z_FINISH here. Note
> + * that both `Z_OK` and `Z_BUF_ERROR` indicate that we
> + * need to retry according to documentation.
> + *
> + * If the call fails we retry with a bigger output
> + * buffer.
> + */
I am not sure where the retry is happening, though.
block_writer_finish() is called by writer_flush_nonempty_block()
which returns a negative return to its caller, which is
writer_flush_block(). writer_flush_block() in turn returns a
negative return to its callers from writer_add_record(),
write_finish_section(), and write_object_record(). Nobody seems to
react to REFTABLE_ZLIB_ERROR (other than the reftable/error.c that
stringifies the error for messages).
But we have asked deflateBound() so if we did not get Z_STREAM_END,
wouldn't it mean some data corruption that retrying would not help?
> + ret = deflate(w->zstream, Z_FINISH);
> + if (ret != Z_STREAM_END) {
> reftable_free(compressed);
> - break;
> + return REFTABLE_ZLIB_ERROR;
> }
> +
> + /*
> + * Overwrite the uncompressed data we have already written and
> + * adjust the `next` pointer to point right after the
> + * compressed data.
> + */
> + memcpy(w->buf + block_header_skip, compressed,
> + w->zstream->total_out);
> + w->next = w->zstream->total_out + block_header_skip;
> +
> + reftable_free(compressed);
> }
> +
> return w->next;
> }
OK.
> @@ -425,6 +450,8 @@ int block_reader_seek(struct block_reader *br, struct block_iter *it,
>
> void block_writer_release(struct block_writer *bw)
> {
> + deflateEnd(bw->zstream);
> + FREE_AND_NULL(bw->zstream);
> FREE_AND_NULL(bw->restarts);
> strbuf_release(&bw->last_key);
> /* the block is not owned. */
> diff --git a/reftable/block.h b/reftable/block.h
> index 47acc62c0a..1375957fc8 100644
> --- a/reftable/block.h
> +++ b/reftable/block.h
> @@ -18,6 +18,7 @@ license that can be found in the LICENSE file or at
> * allocation overhead.
> */
> struct block_writer {
> + z_stream *zstream;
> uint8_t *buf;
> uint32_t block_size;
>
> diff --git a/reftable/writer.c b/reftable/writer.c
> index d347ec4cc6..51e663bb19 100644
> --- a/reftable/writer.c
> +++ b/reftable/writer.c
> @@ -153,6 +153,10 @@ void reftable_writer_free(struct reftable_writer *w)
> {
> if (!w)
> return;
> + if (w->block_writer) {
> + block_writer_release(w->block_writer);
> + w->block_writer = NULL;
> + }
This smells like an orthogonal fix to an unrelated resource leakage?
> reftable_free(w->block);
> reftable_free(w);
> }
Thanks.
