The `Socket` abstraction was refactored to only comprise of methods that
can be generically used/applied to all socket domains and protocols.
A more comprehensive IPv4/IPv6 module derived from @LemonBoy's earlier
work was implemented under `std.x.os.IPv4` and `std.x.os.IPv6`. Using
this module, one can then combine them together into a union for example
in order to optimize memory usage when dealing with socket addresses.
A `TCP.Client` and `TCP.Listener` abstraction is introduced that is one
layer over the `Socket` abstraction, which isolates methods that can
only be applied to a "client socket" and a "listening socket". All prior
tests from the `Socket` abstraction, which all previously operated
assuming the socket is operating via. TCP/IP, were moved. All TCP socket
options were also moved into the `TCP.Client` and `TCP.Listener`
abstractions respectively away from the `Socket` abstraction.
Some additional socket options from @LemonBoy's prior PR for Darwin were
also moved in (i.e. SIGNOPIPE).
Kick-start initial work on new cross-platform abstraction for
sockets. Adds a test for read timeouts and a test for creating
a non-blocking socket pair on Linux.
The new Socket abstraction is barebones and is made to support both
blocking and non-blocking abstractions, alongside different socket
protocols and domains.
Support for platform-dependant socket options that handles unsupported
platforms gracefully via. comptime checks is provided for the new Socket
abstraction.
This also marks the first out of many commits for introducing breaking
changes to the standard library in a separate `x` folder, which was
pre-approved by @andrewrk.
The intent for the new `x` package is to introduce new async, event loop,
networking, and operating system abstractions that would require breaking
the standard library significantly. By having the `x` package, code in the
standard library and compiler may then slowly be refactored to use the `x`
package. Once modules in the `x` package are stabilized, they can be moved
out of the `x` package, and a global 'grep' can be done to update import
paths that resolve to the stabilized module in the `x` package.
