Lightwight socket IO wrapper

Chris Angelico rosuav at gmail.com
Mon Sep 21 04:40:03 CEST 2015


On Mon, Sep 21, 2015 at 11:55 AM, Cameron Simpson <cs at zip.com.au> wrote:
> On 21Sep2015 10:34, Chris Angelico <rosuav at gmail.com> wrote:
>>
>> If you're going to add sequencing and acknowledgements to UDP,
>> wouldn't it be easier to use TCP and simply prefix every message with
>> a two-byte length?
>
>
> Frankly, often yes. That's what I do. (different length encoding, but
> otherwise...)

Out of interest, what encoding? With most protocols, I would prefer to
encode in ASCII digits terminated by end-of-line, but for arbitrary
content you're packaging up, it's usually easier to read 2 bytes (or 4
or whatever you want to specify), then read that many bytes, and
that's your content. No buffering required - you'll never read past
the end of a packet.

> UDP's neat if you do not care if a packet fails to arrive and if you can
> guarentee that your data fits in a packet in the face of different MTUs.
> I like TCP myself, most of the time. Another nice thing about TCP is that
> wil a little effort you get to pack multiple data packets (or partial data
> packets) into a network packet, etc.

Emphatically - a little effort sometimes, and other times no effort at
all! If you write a packet of data, then write another one, and
another, and another, and another, without waiting for responses,
Nagling should combine them automatically. And even if they're not
deliberately queued by Nagle's Algorithm, packets can get combined for
other reasons. So, yeah! Definitely can help a lot with packet counts
on small writes.

ChrisA


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