ioucontext is a coöperative multitasking framework built on top of
liburing,
libucontext,
c-ares, &
rustls.
It is the spiritual successor to
liboco.
A thread-local reactor manages asynchronous operations submitted by one
or more fibers, each with a built-in stack. When invoked via
reactor_run, the reactor will run until all fibers terminate. An explicit
choice has been made to use
C11 threads
over pthreads.
A new reactor will be initialized the first time reactor_get is called in
a particular thread; the underlying io_uring will attempt to pin itself to
one processor for which the thread has affinity. The intention is to have
one io_uring running per thread, each pinned to one processor.
Fibers are created via ucontext but context-switching occurs via
sigsetjmp/siglongjmp to avoid the sigprocmask system call. It is not
wise to modify the process signal mask after any fiber has been created,
whether or not it has run yet.
Operations that can not be immediately submitted to the underlying
io_uring will be deferred onto a wait-queue. On completion, operations
return to the calling fiber directly. Thus, fibers are written procedurally
but will coöperatively context-switch during operations. Error codes are
typically returned as negative values.
Operations may be invoked outside of a fiber but may return prior to the
reactor completing all pending work. In that case, reactor_runnable will
be true and an invocation of reactor_run will be required to clear the
work.
Reactors can store a user-data cookie and an optional destructor via
reactor_cookie_jar. When the reactor is torn down, the cookie will be
eaten.
- iou_cat --- moves bytes between one or more input streams and stdout
- iou_dns --- resolve dns forward and reverse lookups asynchronously
- iou_port7 --- TCP & UDP echo service, à la port7
- iou_timers --- use multiple timerfds to make some noise
- iou_tls --- STDIN -> TLS -> STDOUT
- iou_tlsd --- echo/TLS on 12345
This project is a toy, created out of a desire to better understand io_uring and to atone for some of liboco's sins.
Thanks to some wonderful resources, including
License: MIT