Re: Timeout parameters

On Wed, Feb 27, 2019 at 10:07 PM Nagaura, Ryohei
<nagaura(dot)ryohei(at)jp(dot)fujitsu(dot)com> wrote:
> I rewrote two TCP_USER_TIMEOUT patches.
> I changed the third argument of setsockopt() from 18 to TCP_USER_TIMEOUT.
>
> This revision has the following two merits.
> * Improve readability of source
> * Even if the definition of TCP_USER_TIMEOUT is changed, it is not affected.
> e.g., in the current linux, TCP_USER_TIMEOUT is defined, but even if it is changed to 19, it 'll be available.

The documentation in TCP_backend_v8.patch needs some work.

+ the system default. This parameter is supported only on
systems that support
+ TCP_USER_TIMEOUT or an equivalent socket option, and on
Windows; on other
+ systems, it must be zero. In sessions connected via a
Unix-domain socket,
+ this parameter is ignored and always reads as zero.

So this says that it works on systems that have TCP_USER_TIMEOUT or an
equivalent socket option and that it also works on Windows, and then a
few lines later....

+ This parameter is not supported on Windows, and must be zero.

This says it actually doesn't work on Windows.

I think the language about an equivalent socket option isn't helpful.
We should document any equivalents we actually support, and not say
anything about anything else.

+ To enable full control under TCP connection use this option
together with
+ keepalive.

That doesn't tell me anything useful.

+ Specify in milliseconds the time to disconnect to the client
+ when there is no ack packet from the client to the server's
data transmission.
+ This parameter is supported on linux version 2.6.37 or later.

Hmm. This looks like a second, and broadly better, definition of the
parameter. Now we have a different definition of where it's
supported. This is the THIRD attempt to tell me which platforms are
supported -- just Linux, 2.6.37 or greater.

+ This parameter is not supported on Windows.

And then, in case I missed the last three attempts to tell me about
platform support, there's this.

Have you checked whether this can be easily supported on FreeBSD and/or NetBSD?

--
Robert Haas
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