From d45300abe9e04c925e02578fed2355f0e51a2a85 Mon Sep 17 00:00:00 2001
From: amir-kedis <amir.kedis@gmail.com>
Date: Sat, 20 Apr 2024 22:30:12 +0200
Subject: [PATCH] feat: preempting and resuming basic form

---
 code/headers.h   |  3 ++-
 code/scheduler.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++
 code/scheduler.h | 10 ++++++++++
 3 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/code/headers.h b/code/headers.h
index bb29a68..b82aff8 100644
--- a/code/headers.h
+++ b/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"
@@ -42,7 +43,7 @@
 //===============================
 // ARGUMENTS
 //===============================
-const int DEBUG = false; // set to true to enable debug prints
+const int DEBUG = true;  // set to true to enable debug prints
 const int DELAY = false; // set to true to add delay
 
 ///==============================
diff --git a/code/scheduler.c b/code/scheduler.c
index cfcf21d..a1b857c 100644
--- a/code/scheduler.c
+++ b/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;
+  }
+}
diff --git a/code/scheduler.h b/code/scheduler.h
index 285fbb5..435320e 100644
--- a/code/scheduler.h
+++ b/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);