mirror of
https://github.com/matrix-construct/construct
synced 2024-11-04 21:08:57 +01:00
52 lines
2.2 KiB
Markdown
52 lines
2.2 KiB
Markdown
|
## IRCd Networking
|
||
|
|
|
||
|
|
#### open()
|
||
|
|
|
||
|
|
The open() call combines DNS resolution, TCP connecting and SSL handshaking.
|
||
|
|
A dedicated options structure is provided to tweak the specifics of the process.
|
||
|
|
|
||
|
|
#### close()
|
||
|
|
|
||
|
|
Like the open() sequence, the close() sequence composes a complex of
|
||
|
|
multiple operations to close_notify the SSL session with cryptographic
|
||
|
|
soundness and then disconnect the TCP session. A dedicated options
|
||
|
|
structure is provided to tweak details.
|
||
|
|
|
||
|
|
#### read()
|
||
|
|
|
||
|
|
To keep things simple, this system has no notion of non-blocking or even
|
||
|
|
asynchronous reads. In other words, you call read() when you know there
|
||
|
|
is something to be read(). If there is nothing your ircd::ctx will yield
|
||
|
|
until the call is interrupted/canceled by some timeout etc (which is
|
||
|
|
something you might want too in certain contexts).
|
||
|
|
|
||
|
|
There are two possibilities: either the remote is faster than us or they
|
||
|
|
are slower than us.
|
||
|
|
|
||
|
|
* If the remote is faster than us, or faster than we want: we'll know data
|
||
|
|
is available but ignore it to slow them down (by not calling read()) --
|
||
|
|
a matter in which we may not have a choice anyway.
|
||
|
|
|
||
|
|
* If the remote is slower than us: you have to use a timer to put a limit
|
||
|
|
on how much time (and resource) is going to be spent on receiving their
|
||
|
|
data; eventually the daemon has to move on to serving other clients.
|
||
|
|
|
||
|
|
#### write()
|
||
|
|
|
||
|
|
This system uses two different techniques for sending data to remotes
|
||
|
|
intended for two different categories of transmission:
|
||
|
|
|
||
|
|
* write_all() is an intuitive synchronous send which yields the ircd::ctx
|
||
|
|
until all bytes have been written to the remote. This is intended for
|
||
|
|
serving simple requests or most other ctx-per-client models. A coarse timer
|
||
|
|
is generally used to prevent the remote from being too slow to receive but
|
||
|
|
we have some tolerance to wait a little for them.
|
||
|
|
|
||
|
|
* write_any()/write_one() is a non-blocking send intended for small message
|
||
|
|
mass-push models or some other custom flow control on larger messages. The
|
||
|
|
goal here is to figure out what to do when the socket buffer has filled
|
||
|
|
up because the remote has been too slow to receive data. The choice is
|
||
|
|
usually to either propagate the slowdown to the source or to drop the
|
||
|
|
remote so the daemon can move on without using up memory.
|
||
|
|
|