István Cserny
RTOS example - solving the Dining Philosophers problem by using mutexes
Revision 0:bc0e168010f0, committed 2022-02-24
- Comitter:
- cspista
- Date:
- Thu Feb 24 08:09:20 2022 +0000
- Commit message:
- final version
Changed in this revision
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Thu Feb 24 08:09:20 2022 +0000
@@ -0,0 +1,48 @@
+#include "mbed.h"
+#include "rtos.h"
+// Mutex stdio_mutex;
+Mutex chopstick[5]; //Array of mutexes representing the 5 chopsticks
+Serial pc(USBTX,USBRX); //UART via ST-Link
+
+void notify(int num, int state)
+{
+ // stdio_mutex.lock();
+ if(state) {
+ pc.printf("Philospher %d is EATING \n\r", num);
+ } else {
+ pc.printf("Philospher %d is thinking \n\r", num);
+ }
+ // stdio_mutex.unlock();
+}
+
+void philosopher(void const *args)
+{
+ while (true) {
+ if(chopstick[(int)args-1].trylock()) {
+ if(chopstick[(int)args%5].trylock()) {
+ notify((int)args,1); //Start EATING
+ Thread::wait(1000+rand()%1000);
+ chopstick[(int)args%5].unlock(); //Release chopsticks
+ chopstick[(int)args-1].unlock();
+ notify((int)args,0); //Start Thinking
+ Thread::wait(2000+rand()%2000); //Get's hungry after this time...
+ } else {
+ chopstick[(int)args-1].unlock();
+ Thread::wait(100+rand()%100); //Wait for random time if failed
+ }
+ } else {
+ Thread::wait(100+rand()%100); //Wait for random time if failed
+ }
+
+ }
+}
+
+int main()
+{
+ pc.baud(115200);
+ Thread t2(philosopher, (void *)2U);
+ Thread t3(philosopher, (void *)3U);
+ Thread t4(philosopher, (void *)4U);
+ Thread t5(philosopher, (void *)5U);
+ philosopher((void *)1U);
+}
\ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed-rtos.lib Thu Feb 24 08:09:20 2022 +0000 @@ -0,0 +1,1 @@ +https://os.mbed.com/users/mbed_official/code/mbed-rtos/#5713cbbdb706
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Thu Feb 24 08:09:20 2022 +0000 @@ -0,0 +1,1 @@ +https://os.mbed.com/users/mbed_official/code/mbed/builds/65be27845400 \ No newline at end of file