sendto() turns out to be mandatory function to work with UDP. It may seem
that connect(addr) + send() would achieve the same effect, but what connect()
appears to do is to set source address filter on a socket to its argument.
Then everything falls apart: socket sends to a broad-/multi-cast address,
but reply is sent from real peer address, which doesn't match filter set
by connect(), so local socket never sees a reply.
This requires root access. And on recent Linux kernels, with
CONFIG_STRICT_DEVMEM option enabled, only address ranges listed in
/proc/iomem can be accessed. The above compiled-time option can be
however overriden with boot-time option "iomem=relaxed".
This also removed separate read/write paths - there unlikely would
be a case when they're different.
I checked the entire codebase, and every place that vstr_init_len
was called, there was a call to mp_obj_new_str_from_vstr after it.
mp_obj_new_str_from_vstr always tries to reallocate a new buffer
1 byte larger than the original to store the terminating null
character.
In many cases, if we allocated the initial buffer to be 1 byte
longer, we can prevent this extra allocation, and just reuse
the originally allocated buffer.
Asking to read 256 bytes and only getting 100 will still cause
the extra allocation, but if you ask to read 256 and get 256
then the extra allocation will be optimized away.
Yes - the reallocation is optimized in the heap to try and reuse
the buffer if it can, but it takes quite a few cycles to figure
this out.
Note by Damien: vstr_init_len should now be considered as a
string-init convenience function and used only when creating
null-terminated objects.
Previous to this patch, if "abcd" and "ab" were possible completions
to tab-completing "a", then tab would expand to "abcd" straight away
if this identifier appeared first in the dict.
The TimeoutError is useful for some modules, specially the the
socket module. TimeoutError can then be alised to socket.timeout
and then Python code can differentiate between socket.error and
socket.timeout.
When "micropython -m pkg.mod" command was used, relative imports in pkg.mod
didn't work, because pkg.mod.__name__ was set to __main__, and the fact that
it's a package submodule was missed. This is an original workaround to this
issue. TODO: investigate and compare how CPython deals with this issue.
