From: Junio C Hamano <gitster@pobox.com>
To: Patrick Steinhardt <ps@pks.im>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 7/9] reftable/block: reuse zstream when writing log blocks
Date: Wed, 03 Apr 2024 12:35:22 -0700 [thread overview]
Message-ID: <xmqqplv65jet.fsf@gitster.g> (raw)
In-Reply-To: <86dab54dfe4501dfa5e50e5a01513c890b62bb4d.1712078736.git.ps@pks.im> (Patrick Steinhardt's message of "Tue, 2 Apr 2024 19:30:16 +0200")
Patrick Steinhardt <ps@pks.im> 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.
next prev parent reply other threads:[~2024-04-03 19:35 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-02 17:29 [PATCH 0/9] reftable: optimize write performance Patrick Steinhardt
2024-04-02 17:29 ` [PATCH 1/9] refs/reftable: fix D/F conflict error message on ref copy Patrick Steinhardt
2024-04-03 18:28 ` Junio C Hamano
2024-04-02 17:29 ` [PATCH 2/9] refs/reftable: perform explicit D/F check when writing symrefs Patrick Steinhardt
2024-04-02 17:30 ` [PATCH 3/9] refs/reftable: skip duplicate name checks Patrick Steinhardt
2024-04-02 17:30 ` [PATCH 4/9] refs/reftable: don't recompute committer ident Patrick Steinhardt
2024-04-03 18:58 ` Junio C Hamano
2024-04-04 5:36 ` Patrick Steinhardt
2024-04-02 17:30 ` [PATCH 5/9] reftable/writer: refactorings for `writer_add_record()` Patrick Steinhardt
2024-04-02 17:30 ` [PATCH 6/9] reftable/writer: refactorings for `writer_flush_nonempty_block()` Patrick Steinhardt
2024-04-02 17:30 ` [PATCH 7/9] reftable/block: reuse zstream when writing log blocks Patrick Steinhardt
2024-04-03 19:35 ` Junio C Hamano [this message]
2024-04-04 5:36 ` Patrick Steinhardt
2024-04-02 17:30 ` [PATCH 8/9] reftable/block: reuse compressed array Patrick Steinhardt
2024-04-02 17:30 ` [PATCH 9/9] reftable/writer: reset `last_key` instead of releasing it Patrick Steinhardt
2024-04-04 5:48 ` [PATCH v2 00/11] reftable: optimize write performance Patrick Steinhardt
2024-04-04 5:48 ` [PATCH v2 01/11] refs/reftable: fix D/F conflict error message on ref copy Patrick Steinhardt
2024-04-04 5:48 ` [PATCH v2 02/11] refs/reftable: perform explicit D/F check when writing symrefs Patrick Steinhardt
2024-04-04 5:48 ` [PATCH v2 03/11] refs/reftable: skip duplicate name checks Patrick Steinhardt
2024-04-04 5:48 ` [PATCH v2 04/11] reftable: remove " Patrick Steinhardt
2024-04-04 5:48 ` [PATCH v2 05/11] refs/reftable: don't recompute committer ident Patrick Steinhardt
2024-04-04 5:48 ` [PATCH v2 06/11] reftable/writer: refactorings for `writer_add_record()` Patrick Steinhardt
2024-04-04 6:58 ` Han-Wen Nienhuys
2024-04-04 7:32 ` Patrick Steinhardt
2024-04-04 5:48 ` [PATCH v2 07/11] reftable/writer: refactorings for `writer_flush_nonempty_block()` Patrick Steinhardt
2024-04-04 5:48 ` [PATCH v2 08/11] reftable/writer: unify releasing memory Patrick Steinhardt
2024-04-04 7:08 ` Han-Wen Nienhuys
2024-04-04 7:32 ` Patrick Steinhardt
2024-04-04 9:00 ` Han-Wen Nienhuys
2024-04-04 11:43 ` Patrick Steinhardt
2024-04-04 5:48 ` [PATCH v2 09/11] reftable/writer: reset `last_key` instead of releasing it Patrick Steinhardt
2024-04-04 5:48 ` [PATCH v2 10/11] reftable/block: reuse zstream when writing log blocks Patrick Steinhardt
2024-04-04 5:48 ` [PATCH v2 11/11] reftable/block: reuse compressed array Patrick Steinhardt
2024-04-04 7:09 ` [PATCH v2 00/11] reftable: optimize write performance Han-Wen Nienhuys
2024-04-04 7:32 ` Patrick Steinhardt
2024-04-08 12:23 ` [PATCH v3 " Patrick Steinhardt
2024-04-08 12:23 ` [PATCH v3 01/11] refs/reftable: fix D/F conflict error message on ref copy Patrick Steinhardt
2024-04-08 12:23 ` [PATCH v3 02/11] refs/reftable: perform explicit D/F check when writing symrefs Patrick Steinhardt
2024-04-08 12:24 ` [PATCH v3 03/11] refs/reftable: skip duplicate name checks Patrick Steinhardt
2024-04-08 12:24 ` [PATCH v3 04/11] reftable: remove " Patrick Steinhardt
2024-04-08 12:24 ` [PATCH v3 05/11] refs/reftable: don't recompute committer ident Patrick Steinhardt
2024-04-08 12:24 ` [PATCH v3 06/11] reftable/writer: refactorings for `writer_add_record()` Patrick Steinhardt
2024-04-08 12:24 ` [PATCH v3 07/11] reftable/writer: refactorings for `writer_flush_nonempty_block()` Patrick Steinhardt
2024-04-08 12:24 ` [PATCH v3 08/11] reftable/writer: unify releasing memory Patrick Steinhardt
2024-04-08 12:24 ` [PATCH v3 09/11] reftable/writer: reset `last_key` instead of releasing it Patrick Steinhardt
2024-04-08 12:24 ` [PATCH v3 10/11] reftable/block: reuse zstream when writing log blocks Patrick Steinhardt
2024-04-08 12:24 ` [PATCH v3 11/11] reftable/block: reuse compressed array Patrick Steinhardt
2024-04-09 0:09 ` [PATCH v3 00/11] reftable: optimize write performance Junio C Hamano
2024-04-09 3:16 ` Patrick Steinhardt
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