On Fri, 11 Mar 2022, Chris Vine <vine24683...@gmail.com> wrote: > On Thu, 10 Mar 2022 18:46:34 -0500 > Olivier Dion via General Guile related discussions <guile-user@gnu.org> > wrote: >> On Thu, 10 Mar 2022, Zelphir Kaltstahl <zelphirkaltst...@posteo.de> wrote: >> >> > Just one question: Why is get-bytevector-some better than >> > get-bytevector-n and specifying a number of bytes? >> >> I haven't check the implementation details, but I think it's just a >> question of buffering. `get-bytevector-n` will block just like >> `get-bytevector-some` when the port is empty. The former will return up >> to N bytes and the latter might return more than N bytes. The former >> probably also lead to less memory allocation since N is known in >> advanced, a singled allocation can be made, while the latter might do >> multiple allocations. This can be useful depending on your usage of the >> port. For example, you could make a web server that only accepts HTTP >> body up to 4096 bytes (1 system page). This is what some web server >> does I think. >> >> There's also `get-bytevector-all`, but this would lead to more memory >> usage and multiple allocations. Again, it depends on the usage. > > Avoid using get-bytevector-n!, get-bytevector-some and > get-bytevector-all if you are going to use something like fibers or > some other asynchronous i/o, as those procedures are not suspendable > (they can block). get-bytevector-n (note the difference from > get-bytevector-n!) and get-string-all are suspendable and should > generally be preferred where suspension is required.
I'm not sure this is related to the functions themself but instead the underlying filedescriptor opened iwth ON_NONBLOCK? -- Olivier Dion Polymtl
