Start assignment 4

Assignment4/lib/process.c

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+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "process.h"
+
+//Assume that the string passed in is null terminated
+
+Process *createProcess(char *username, char job, int arrival_time, int duration) {
+    // Allocate memory for the process, and check if it was successful
+    Process *node = calloc(1, sizeof(Process));
+    if (node == NULL) {
+        printf("Error allocating memory for process\n");
+        exit(EXIT_FAILURE);
+    }
+	// Free the data first, then allocate memory for the new data
+	node->username = calloc(strlen(username) + 1, sizeof(char));
+	if (node->username == NULL) {
+		printf("Error allocating memory for username data\n");
+		exit(EXIT_FAILURE);
+	}
+	// Copy data from the string passed in to the process's data
+	// Makes sure if the string passed in is changed, the process's data is not changed
+	// Also makes sure that if the data is on the stack, it is not freed at some other point
+	strcpy(node->username, username);
+	node->job = job;
+	node->arrival_time = arrival_time;
+	node->duration = duration;
+	node->next_elem = NULL;
+    return node;
+}
+
+void destroyProcess(Process *node) {
+    // Free the data first, then free the process
+    free(node->username);
+    free(node);
+}

Assignment4/lib/process.h

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+#ifndef NODE_H
+#define NODE_H
+
+typedef struct Process {
+	struct process *prev_elem;
+	struct process *next_elem;
+    char *username;
+	char job;
+	int arrival_time;
+	int duration;
+} Process;
+
+Process *createProcess(char *username, char job, int arrival_time, int duration);
+
+void destroyProcess(Process *node);
+
+#endif //NODE_H

Assignment4/lib/queue.c

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+#include <stdio.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <string.h>
+#include <stdlib.h>
+#include "process.h"
+#include "queue.h"
+
+/*
+ * Queue implementation
+ * 5	4	3	2	1
+ * START			END
+ *
+ * If you were to visualize the queue as a line, the end is the first person in line and the start is the last person in line
+ * So when you enqueue, you are adding to the start of the line
+ * And when you dequeue, you are exiting from the end of the line
+ */
+
+//TODO: Refactor
+int contains(Queue *queue, char *job) {
+    Process *current = queue->start;
+    while (current != NULL) {
+        if (strcmp(current->username, job) == 0) {
+            return true;
+        }
+        current = current->next_elem;
+    }
+    return false;
+}
+
+//TODO: Refactor
+Process *search(Queue *queue, char *job) {
+    Process *current = queue->start;
+
+    while (current != NULL) {
+        if (strcmp(current->username, job) == 0) {
+            return current;
+        }
+        current = current->next_elem;
+    }
+    return NULL;
+}
+
+
+void enqueue(Queue *queue, Process *process) {
+	if (queue->end == NULL) { // If the queue is empty, set the start and end to the new process
+		queue->end = process;
+		queue->start = queue->end;
+	} else {
+		process->next_elem = queue->start; // Set the next element of the new process to the start of the queue
+		queue->start->prev_elem = process; // Set the previous element of the start of the queue to the new process
+		queue->start = process; // Set the start of the queue to the new process
+	}
+	queue->size++;
+}
+
+
+// WARNING: Returns a pointer to a process that is not in the queue, it is your responsibility to free it
+Process *dequeue(Queue *queue) {
+    if (queue->end == NULL) { // If the queue is empty, return NULL
+        return NULL;
+    }
+	Process *temp = queue->end; // Store the end of the queue for returning later
+
+	queue->end = queue->end->prev_elem; // Set the end to the previous element
+	queue->end->next_elem = NULL; // Set the next element of the new end to NULL
+
+	if (queue->end == NULL) { // If the queue is empty, set the start to NULL
+		queue->start = NULL;
+	}
+
+	temp->prev_elem = NULL; // The dequeued element should not point to anything
+	queue->size--;
+	return temp;
+}
+
+//TODO: Refactor
+void printList(Queue *queue) {
+    Process *current = queue->start;
+    while (current != NULL) {
+        // printf("%s %d\n", current->username, current->duration);
+        current = current->next_elem;
+    }
+}
+
+//TODO: Refactor
+int stop(Queue *queue) {
+    Process *current = queue->end;
+    while (current != NULL) {
+        Process *next = current->prev_elem;
+		destroyProcess(current);
+        current = next;
+    }
+	free(queue);
+    return true;
+}
+
+Queue *createQueue() {
+	Queue *queue = calloc(1, sizeof(Queue));
+	if (queue == NULL) {
+		printf("Error allocating memory for queue\n");
+		exit(EXIT_FAILURE);
+	}
+	queue->start = NULL;
+	queue->end = NULL;
+	queue->size = 0;
+	return queue;
+}
+

Assignment4/lib/queue.h

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+#ifndef QUEUE_H
+#define QUEUE_H
+
+#include <stdbool.h>
+#include "process.h"
+
+typedef struct Queue {
+	Process *start;
+	Process *end;
+	int size;
+} Queue;
+
+int contains(Queue *queue, char *job);
+
+Process *search(Queue *queue, char *job);
+
+void enqueue(Queue *queue, Process *process);
+
+Process *dequeue(Queue *queue);
+
+void printList(Queue *queue);
+
+int stop(Queue *queue);
+
+Queue* createQueue();
+
+#endif //QUEUE_H