The existing implementation had a flaw: when the buffer was getting full,
mavlink started to busy-loop, as the uart has data (poll returns immediately)
but no new data was read from the uart due to the buffer being full.
As rtps is running at lower prio, it never got the chance to read again,
making the problem even worse.
After 1s the timeout triggered and the buffer was cleared, so it recovered.
Instead of allowing for CPU spikes, we now immediately clear the buffer
(only as much as we have to), ensuring that new data is read from the uart.
This is to avoid blocking in any case.
If we don't do that, ioctl() may signal data available while the other
protocol does a read(), and when the first protocol tries to do a read(),
it would not have data anymore and would block (so this avoids a race
condition).
This is an attempt to implement the protocol_splitter with one
read buffer only. The idea is to prevent additional copy
operations from an incoming buffer to the respective protocol buffer.
Right now the benefit is not really there because we are not using a
ringbuffer and have to shift data around quite a bit.
We also try to parse and copy data to the reader immediately without
doing a read from the device which potentially takes 100ms.
We further use a timeout mechanism to prevent starvation if one reader
disconnects and the buffer would fill up from unread data.
and remove the px4_ prefix, except for px4_config.h.
command to update includes:
for k in app.h atomic.h cli.h console_buffer.h defines.h getopt.h i2c.h init.h log.h micro_hal.h module.h module_params.h param.h param_macros.h posix.h sem.h sem.hpp shmem.h shutdown.h tasks.h time.h workqueue.h; do for i in $(grep -rl 'include <px4_'$k src platforms boards); do sed -i 's/#include <px4_'$k'/#include <px4_platform_common\/'$k/ $i; done; done
for in $(grep -rl 'include <px4_config.h' src platforms boards); do sed -i 's/#include <px4_config.h/#include <px4_platform_common\/px4_config.h'/ $i; done
Transitional headers for submodules are added (px4_{defines,log,time}.h)
Beat Küng