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 );

Diff: RoundRobin.hpp

Revision:
0:a8c603b939a7
diff -r 000000000000 -r a8c603b939a7 RoundRobin.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/RoundRobin.hpp	Sat Jul 29 11:53:34 2017 +0000
@@ -0,0 +1,69 @@
+/* @brief Round Robin scheduler for mbed
+      
+   @author John Bailey 
+ 
+   @copyright Copyright 2017 John Bailey
+ 
+   @section LICENSE
+
+   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.
+*/
+
+#if !defined ROUNDROBIN_HPP
+#define      ROUNDROBIN_HPP
+
+#include "rtos.h"
+#include <map>
+
+class RoundRobin
+{
+    protected:
+        EventQueue eventQueue;
+        Thread*    thread;
+        Ticker     ticker;
+        static     RoundRobin *p_instance;
+
+        RoundRobin();
+        static void EventTrigger( void );
+
+        class TaskEntry
+        {
+            void     (*fn)( void );
+            unsigned counter;
+
+            public:
+                TaskEntry( void (*p_fn)( void ) ) : fn(p_fn),counter(0) {}
+                void tick( void ) { counter++; }
+                void triggerIfNeeded( unsigned multiplier )
+                {
+                    if( multiplier == counter )
+                    {
+                        fn();
+                        counter = 0;
+                    }
+                }
+        };
+
+        static std::multimap<unsigned,TaskEntry> p_taskList;
+
+    public:
+        virtual ~RoundRobin();
+
+        static RoundRobin* instance( void );
+
+        static bool addTask( unsigned p_multiplier, void (*p_fn)(void) );
+
+        void SetBaseRate( const float p_rate );
+};
+
+#endif