Untrusted IPC with maximum performance and minimum latency. On Rust, on Linux.

Hey there! First of all, great work!

Right now I am playing around with shmem_ipc as a potential backend for my tiny RPC library. However, I am encountering a problem where after writing > CAPACITY via send_raw data on the other side becomes garbled and incomplete, failing my validation. It seems to me like buffer just gets completely saturated and stops the flow of data.

Is there a way around it? Maybe I can somehow reset the pointer of this buffer to zero before I send each new message or something like that?

Thanks!

Hi, I'm trying to add hugetlb and mlock support for the shared memory region to further increase the performance at https://github.com/dovahcrow/shmem-ipc. I can create a PR if you want to make these changes into the main repo.

~Note that the implementation is not finished: I am stuck at using set_len to increase the size of the memfd (https://github.com/dovahcrow/shmem-ipc/blob/master/src/mem.rs#L81): it always returns EINVAL, and I haven't found a solution yet.~ By reading the Linux source code, it turned out hugetlb does not need set_len!

Any suggestion is welcomed!

The eventfds are only read in the block* method on the sender and receiver. It seems possible that writing to these eventfd will block if they are never read, once the counter in the eventfd reaches maximum

A write(2) call adds the 8-byte integer value supplied in its buffer to the counter. The maximum value that may be stored in the counter is the largest unsigned 64-bit value minus 1 (i.e., 0xfffffffffffffffe). If the addition would cause the counter's value to exceed the maximum, then the write(2) either blocks until a read(2) is performed on the file descriptor, or fails with the error EAGAIN if the file descriptor has been made nonblocking.

It seems to me that it is safe to implement Sync for Receiver and Sender because the recv and send methods require &mut which implies at most one reader and writer as https://docs.rs/shmem-ipc/latest/shmem_ipc/sharedring/struct.Sender.html#safety required.