From: Lars Schneider <larsxschneider@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org, peff@peff.net, sbeller@google.com,
Johannes.Schindelin@gmx.de, jnareb@gmail.com, mlbright@gmail.com
Subject: Re: [PATCH v6 05/13] pkt-line: add packet_write_gently()
Date: Fri, 26 Aug 2016 11:40:44 +0200 [thread overview]
Message-ID: <0BD3A97F-A9FD-45A6-AF82-E01CC6B9BA89@gmail.com> (raw)
In-Reply-To: <xmqq4m68ldrg.fsf@gitster.mtv.corp.google.com>
> On 25 Aug 2016, at 23:50, Junio C Hamano <gitster@pobox.com> wrote:
>
> larsxschneider@gmail.com writes:
>
>> From: Lars Schneider <larsxschneider@gmail.com>
>>
>> packet_write_fmt() has two shortcomings. First, it uses format_packet()
>> which lets the caller only send string data via "%s". That means it
>> cannot be used for arbitrary data that may contain NULs. Second, it will
>> always die on error.
>
> As you introduced _gently in 3/13, the latter is no longer a valid
> excuse to add this function. Just remove the sentence "Second, ...".
Agreed!
>> Add packet_write_gently() which writes arbitrary data and returns `0`
>> for success and `-1` for an error. This function is used by other
>> pkt-line functions in a subsequent patch.
>>
>> Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
>> ---
>> pkt-line.c | 12 ++++++++++++
>> 1 file changed, 12 insertions(+)
>>
>> diff --git a/pkt-line.c b/pkt-line.c
>> index cad26df..7e8a803 100644
>> --- a/pkt-line.c
>> +++ b/pkt-line.c
>> @@ -3,6 +3,7 @@
>> #include "run-command.h"
>>
>> char packet_buffer[LARGE_PACKET_MAX];
>> +static char packet_write_buffer[LARGE_PACKET_MAX];
>> static const char *packet_trace_prefix = "git";
>> static struct trace_key trace_packet = TRACE_KEY_INIT(PACKET);
>> static struct trace_key trace_pack = TRACE_KEY_INIT(PACKFILE);
>> @@ -155,6 +156,17 @@ int packet_write_fmt_gently(int fd, const char *fmt, ...)
>> return (write_in_full(fd, buf.buf, buf.len) == buf.len ? 0 : -1);
>> }
>>
>> +int packet_write_gently(const int fd_out, const char *buf, size_t size)
>> +{
>> + if (size > sizeof(packet_write_buffer) - 4)
>> + return -1;
>> + packet_trace(buf, size, 1);
>> + memmove(packet_write_buffer + 4, buf, size);
>> + size += 4;
>> + set_packet_header(packet_write_buffer, size);
>
> It may not matter all that much, but from code-reader's point of
> view, when you know packet_write_buffer[] will contain things A and
> B in this order, and when you have enough information to compute A
> before stasrting to fill packet_write_buffer[], I would prefer to
> see you actually fill the buffer in that natural order.
I did that because when packet_write_stream_with_flush_from_fd()
calls packet_write_gently() then buf[] is actually packet_write_buffer[]:
https://github.com/larsxschneider/git/blob/d474e6a4c2523b87624a07111eb7a4f2dcd12426/pkt-line.c#L185-L192
Therefore I would override the first 4 bytes. However, the code evolved for
some reason in that way but looking at it now I think that is an obscure,
likely meaningless optimization. I'll use a separate buffer in
packet_write_stream_with_flush_from_fd() and then fix the order here
following your advice.
> Do you anticipate future need of non-gently variant of this
> function? If so, perhaps a helper that takes a boolean "am I
> working for the gently variant?" may help share more code.
With helper you mean "an additional boolean parameter"? I don't
see a need for a non-gently variant right now but I will
add this parameter if you think it is a good idea. How would the
signature look like?
int packet_write_gently(const int fd_out, const char *buf, size_t size, int gentle)
This would follow type_from_string_gently() in object.h.
Thanks,
Lars
next prev parent reply other threads:[~2016-08-26 9:40 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-25 11:07 [PATCH v6 00/13] Git filter protocol larsxschneider
2016-08-25 11:07 ` [PATCH v6 01/13] pkt-line: rename packet_write() to packet_write_fmt() larsxschneider
2016-08-25 11:07 ` [PATCH v6 02/13] pkt-line: extract set_packet_header() larsxschneider
2016-08-25 11:07 ` [PATCH v6 03/13] pkt-line: add packet_write_fmt_gently() larsxschneider
2016-08-25 18:12 ` Stefan Beller
2016-08-25 18:47 ` Lars Schneider
2016-08-25 21:41 ` Junio C Hamano
2016-08-26 9:17 ` Lars Schneider
2016-08-26 17:10 ` Junio C Hamano
2016-08-26 17:23 ` Jeff King
2016-08-25 11:07 ` [PATCH v6 04/13] pkt-line: add packet_flush_gently() larsxschneider
2016-08-25 11:07 ` [PATCH v6 05/13] pkt-line: add packet_write_gently() larsxschneider
2016-08-25 21:50 ` Junio C Hamano
2016-08-26 9:40 ` Lars Schneider [this message]
2016-08-26 17:15 ` Junio C Hamano
2016-08-29 9:40 ` Lars Schneider
2016-08-25 11:07 ` [PATCH v6 06/13] pkt-line: add functions to read/write flush terminated packet streams larsxschneider
2016-08-25 18:46 ` Stefan Beller
2016-08-25 19:33 ` Lars Schneider
2016-08-25 22:31 ` Junio C Hamano
2016-08-26 0:55 ` Jacob Keller
2016-08-26 17:02 ` Stefan Beller
2016-08-26 17:21 ` Jeff King
2016-08-26 17:17 ` Junio C Hamano
2016-08-25 22:27 ` Junio C Hamano
2016-08-26 10:13 ` Lars Schneider
2016-08-26 17:21 ` Junio C Hamano
2016-08-29 9:43 ` Lars Schneider
2016-08-25 11:07 ` [PATCH v6 07/13] pack-protocol: fix maximum pkt-line size larsxschneider
2016-08-25 18:59 ` Stefan Beller
2016-08-25 19:35 ` Lars Schneider
2016-08-26 19:44 ` Junio C Hamano
2016-08-25 11:07 ` [PATCH v6 08/13] convert: quote filter names in error messages larsxschneider
2016-08-26 19:45 ` Junio C Hamano
2016-08-25 11:07 ` [PATCH v6 09/13] convert: modernize tests larsxschneider
2016-08-26 20:03 ` Junio C Hamano
2016-08-29 10:09 ` Lars Schneider
2016-08-25 11:07 ` [PATCH v6 10/13] convert: generate large test files only once larsxschneider
2016-08-25 19:17 ` Stefan Beller
2016-08-25 19:54 ` Lars Schneider
2016-08-29 17:52 ` Junio C Hamano
2016-08-30 11:47 ` Lars Schneider
2016-08-30 16:55 ` Junio C Hamano
2016-08-29 17:46 ` Junio C Hamano
2016-08-30 11:41 ` Lars Schneider
2016-08-30 16:37 ` Jeff King
2016-08-25 11:07 ` [PATCH v6 11/13] convert: make apply_filter() adhere to standard Git error handling larsxschneider
2016-08-25 11:07 ` [PATCH v6 12/13] convert: add filter.<driver>.process option larsxschneider
2016-08-29 22:21 ` Junio C Hamano
2016-08-30 16:27 ` Lars Schneider
2016-08-30 18:59 ` Junio C Hamano
2016-08-30 20:38 ` Lars Schneider
2016-08-30 22:23 ` Junio C Hamano
2016-08-31 4:57 ` Torsten Bögershausen
2016-08-31 13:14 ` Jakub Narębski
2016-08-30 20:46 ` Jakub Narębski
2016-09-05 19:47 ` Lars Schneider
2016-08-25 11:07 ` [PATCH v6 13/13] read-cache: make sure file handles are not inherited by child processes larsxschneider
2016-08-29 18:05 ` Junio C Hamano
2016-08-29 19:03 ` Lars Schneider
2016-08-29 19:45 ` Junio C Hamano
2016-08-30 12:32 ` Lars Schneider
2016-08-30 14:54 ` Torsten Bögershausen
2016-09-01 17:15 ` Junio C Hamano
2016-08-29 15:39 ` [PATCH v6 00/13] Git filter protocol Lars Schneider
2016-08-29 18:09 ` Junio C Hamano
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