Eventloop in main thread to master

[TeroJaasko]

Description

This has the same content as ARMmbed/mbed-os-confidential-m#7 and #5752, just the target repo and branch are different.

Copypasta from commit:
--8<--8<--8<--8<--8<
The separate eventloop thread may not be necessary on all uses, as one
can use the existing main thread for event dispatching. Add a
conditional nanostack-hal.event-loop-dispatch-from-application, which
disables the thread creation.

Note: the ns_hal_init must be ran from the same thread which will be
used to execute the event loop later.
--8<--8<--8<--8<--8<

By removing the separate event loop thread, one saves about 6KB of RAM in mbed cloud client example side.

Status

READY

Migrations

Unless one sets the "nanostack-hal.event-loop-dispatch-from-application" to true, the existing behavior is not changed.

NO

Related PRs

Todos

• Tests
• Documentation

Deploy notes

Steps to test or reproduce

Testing can be done by adding following code to the end of main(), where one has already initialized the event loop and the application code:

#if MBED_CONF_NANOSTACK_HAL_EVENT_LOOP_DISPATCH_FROM_APPLICATION

    printf("Starting eventloop..\n");
    eventOS_scheduler_mutex_wait();
    // this will block for ever
    eventOS_scheduler_run();

#else
<normal wait-forever code>
#endif

[0xc0170]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 1256
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/6186/

Triggering tests

/morph test
/morph uvisor-test
/morph export-build
/morph mbed2-build

[mbed-ci]

Exporter Build : SUCCESS

Build number : 920
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/6186/

[mbed-ci]

Test : SUCCESS

Build number : 1053
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/6186/1053