John Bailey / RoundRobin

Simple round-robin scheduler for mbed

Overview

This library provides simple round-robin scheduling based on the mbed-os.

Why would you want to use this?

  • Tasks are not run from within interrupt sub-routines (as they are using Tickers)
  • Ordering/priority of tasks is deterministic (rate monotonic)

It's not rocket science, just a handy wrapper around the RTOS functions.

Example

#define BASE_RATE 0.1f
#define TASK1_MULTIPLIER 1
#define TASK2_MULTIPLIER 2
....
    RoundRobin::instance()->SetBaseRate( BASE_RATE );
    RoundRobin::instance()->addTask( TASK1_MULTIPLIER, lcdRefresh );
    RoundRobin::instance()->addTask( TASK2_MULTIPLIER, watchButtons );

RoundRobin.cpp

Committer:
johnb
Date:
2017-07-29
Revision:
1:549bc1cd1f3d
Parent:
0:a8c603b939a7

File content as of revision 1:549bc1cd1f3d:

/* Copyright 2017 John Bailey
 
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

#include "RoundRobin.hpp"

RoundRobin* RoundRobin::p_instance = NULL;
std::multimap<unsigned,RoundRobin::TaskEntry> RoundRobin::p_taskList;

RoundRobin* RoundRobin::instance( void )
{
    if (!p_instance)
    {
        p_instance = new RoundRobin();
    }
    return p_instance;
}

RoundRobin::RoundRobin()
{
    thread = new Thread(osPriorityLow);
    thread->start(callback(&eventQueue, &EventQueue::dispatch_forever));
}

void RoundRobin::SetBaseRate( const float p_rate )
{
    ticker.attach( eventQueue.event( &EventTrigger ), p_rate );
}

RoundRobin::~RoundRobin()
{
    delete( thread );
}

void RoundRobin::EventTrigger( void )
{
    for( std::multimap<unsigned,TaskEntry>::iterator i = p_taskList.begin();
         i != p_taskList.end();
         i++ )
    {
        i->second.tick();
        i->second.triggerIfNeeded(i->first);
    }
}

bool RoundRobin::addTask( unsigned p_multiplier, void (*p_fn)(void) )
{
    bool success = false;
    if( p_multiplier > 0 )
    {
        TaskEntry newTask ( p_fn );

        p_taskList.insert( std::pair<unsigned,TaskEntry>(p_multiplier, newTask ));
    
        success = true;
    }
    return success;
}