Preempting Start

code/clk.c

@@ -34,6 +34,7 @@ int main(int argc, char *argv[]) {
   }
   *shmaddr = clk; /* initialize shared memory */
   while (1) {
+    printf(ANSI_YELLOW "=>CLK:Current time: %d\n" ANSI_RESET, (*shmaddr));
     sleep(1);
     (*shmaddr)++;
   }

code/headers.h

@@ -25,6 +25,7 @@
 #define ANSI_YELLOW "\x1b[33m"
 #define ANSI_BLUE "\x1b[34m"
 #define ANSI_MAGENTA "\x1b[35m"
+#define ANSI_GREY "\x1b[90m"
 #define ANSI_CYAN "\x1b[36m"
 #define ANSI_TEAL "\x1b[96m"
 #define ANSI_WHITE "\x1b[37m"
@@ -39,6 +40,12 @@
 
 #define SHKEY 300
 
+//===============================
+// ARGUMENTS
+//===============================
+const int DEBUG = true;  // set to true to enable debug prints
+const int DELAY = false; // set to true to add delay
+
 ///==============================
 // don't mess with this variable//
 int *shmaddr;
@@ -55,7 +62,8 @@ void initClk() {
   int shmid = shmget(SHKEY, 4, 0444);
   while ((int)shmid == -1) {
     // Make sure that the clock exists
-    printf("Wait! The clock not initialized yet!\n");
+    if (DEBUG)
+      printf("Wait! The clock not initialized yet!\n");
     sleep(1);
     shmid = shmget(SHKEY, 4, 0444);
   }

code/process_generator.c

@@ -211,9 +211,11 @@ void printBanner() {
       "        \\/     \\/            |__|              \\/        \\/        "
       "\\/  \n");
 
-  sleep(1);
+  if (DELAY)
+    sleep(1);
   printf("Welcome to OctopusOS\n");
-  sleep(1);
+  if (DELAY)
+    sleep(1);
   printf(ANSI_RESET);
 }
 
@@ -293,15 +295,12 @@ void sendProcessesToScheduler(queue *processes, int msgQID) {
       continue;
     }
 
-    // TODO: printing current time should be the responsibility of the scheudler
-    // or clock
-    printf(ANSI_YELLOW "=>Current time: %d\n" ANSI_RESET, currentTime);
     if (currentTime < process->AT) {
       lastTime = currentTime;
       continue;
     }
 
-    printf(ANSI_PURPLE "=>Sending process with id: %d, AT: %d, BT: %d, "
+    printf(ANSI_PURPLE "=>GEN:Sending process with id: %d, AT: %d, BT: %d, "
                        "priority: %d to scheduler\n" ANSI_RESET,
            process->id, process->AT, process->BT, process->priority);
 

code/scheduler.c

@@ -26,6 +26,7 @@ int main(int argc, char *argv[]) {
 
   signal(SIGINT, clearSchResources);
   signal(SIGTERM, clearSchResources);
+
   if (atexit(cleanUpScheduler) != 0) {
     perror("atexit");
     exit(1);
@@ -124,6 +125,16 @@ void getProcesses(int gen_msgQID, d_list *processTable) {
            process.id);
     createProcess(processTable, &process);
   }
+  // FIXME: delete later just for testing
+  {
+    sleep(3);
+    preemptProcessByIndex(processTable, 0);
+    sleep(1);
+    resumeProcessByIndex(processTable, 0);
+    preemptProcessByIndex(processTable, 1);
+    sleep(1);
+    resumeProcessByIndex(processTable, 1);
+  }
 }
 
 /**
@@ -205,3 +216,41 @@ void clearSchResources(int signum) {
   cleanUpScheduler();
   exit(0);
 }
+
+/**
+ * preemptProcessByIndex - Preempt a process by its index in the process table
+ * @processTable: pointer to process table
+ * @index: index of the process to preempt
+ */
+void preemptProcessByIndex(d_list *processTable, unsigned int index) {
+  process_entry_t *processEntry = getNode(processTable, index)->data;
+  PCB_t *pcb = processEntry->PCB;
+
+  if (DEBUG)
+    printf(ANSI_GREY "==>SCH: Preempting process with id = %i\n" ANSI_RESET,
+           processEntry->p_id);
+
+  if (pcb->state == RUNNING) {
+    kill(processEntry->p_id, SIGSTOP);
+    pcb->state = READY;
+  }
+}
+
+/**
+ * resumeProcessByIndex - Resume a process by its index in the process table
+ * @processTable: pointer to process table
+ * @index: index of the process to resume
+ */
+void resumeProcessByIndex(d_list *processTable, unsigned int index) {
+  process_entry_t *processEntry = getNode(processTable, index)->data;
+  PCB_t *pcb = processEntry->PCB;
+
+  if (DEBUG)
+    printf(ANSI_GREEN "==>SCH: Resuming process with id = %i\n" ANSI_RESET,
+           processEntry->p_id);
+
+  if (pcb->state == READY) {
+    kill(processEntry->p_id, SIGCONT);
+    pcb->state = RUNNING;
+  }
+}

code/scheduler.h

@@ -9,3 +9,13 @@ void freeProcessEntry(void *processEntry);
 void createProcess(d_list *processTable, process_t *process);
 void cleanUpScheduler();
 void clearSchResources(int signum);
+
+//===============================
+// Preempting Functions
+//===============================
+// TODO: Handle in preempting functions restoring the process state and update
+// stats
+// TODO: make sure that we want to update by the index if not make a version
+// with pid
+void preemptProcessByIndex(d_list *processTable, unsigned int index);
+void resumeProcessByIndex(d_list *processTable, unsigned int index);