Add comments and reformat

Assignment3/main.c

@@ -15,7 +15,7 @@
 #define MAX_TIME_FOR_TRUCKER 3
 #define MIN_TRIP_TIME 5
 #define MAX_TRIP_TIME 10
-#define RANDOM_WITHIN_RANGE(a,b,seed) (a+rand_r(&seed)%(b-a))
+#define RANDOM_WITHIN_RANGE(a, b, seed) (a+rand_r(&seed)%(b-a))
 // For pipes
 #define READ_END 0
 #define WRITE_END 1
@@ -25,37 +25,43 @@ int houseFloor[2];
 // Pipe between movers and truckers
 int nextToTrucks[2];
 
+//TODO: See if you can just use arg structure instead of making stack vars from the args
+
+// Arg structure, need to assign id in loop, and a reference to a seed for rand_r(), since it mutates the seed
 typedef struct args {
     int id;
     unsigned int seed;
 } Args;
 
-void* dweller(void* arg) {
+// Routine for house dwellers
-    Args *args = (Args*) arg;
+void *dweller(void *arg) {
+    Args *args = (Args *) arg; // Cast void* to Args*, as pthread_create() requires void*
     int id = args->id;
     unsigned int seed = args->seed;
     printf("Hello from house dweller %d\n", id);
 
-    for(int i = 0; i < NUMBER_OF_BOXES_PER_DWELLER; i++) {
+    for (int i = 0; i < NUMBER_OF_BOXES_PER_DWELLER; i++) {
-        int weight = RANDOM_WITHIN_RANGE(MIN_BOX_WEIGHT, MAX_BOX_WEIGHT, seed);
+        int weight = RANDOM_WITHIN_RANGE(MIN_BOX_WEIGHT, MAX_BOX_WEIGHT, seed); // Generate random weight
-        int time = RANDOM_WITHIN_RANGE(MIN_TIME_FOR_HOUSE_DWELLER, MAX_TIME_FOR_HOUSE_DWELLER, seed);
+        int time = RANDOM_WITHIN_RANGE(MIN_TIME_FOR_HOUSE_DWELLER, MAX_TIME_FOR_HOUSE_DWELLER, seed); // Time to pack box
-        sleep(time);
+        sleep(time); // Simulate packing time
-        write(houseFloor[WRITE_END], &weight, sizeof(int));
+        write(houseFloor[WRITE_END], &weight, sizeof(int)); // Write weight to pipe
         printf("House dweller %d created a box that weights %d in %d units of time\n", id, weight, time);
     }
     printf("House dweller %d is done packing\n", id);
-    free(args);
+    free(args); // Make sure to free the args struct
     return NULL;
 }
 
-void* mover(void* arg) {
+// Routine for movers
-    Args *args = (Args*) arg;
+// Comments from dweller() apply here as well
+void *mover(void *arg) {
+    Args *args = (Args *) arg;
     int id = args->id;
     unsigned int seed = args->seed;
     int weight;
 
     printf("Hello from mover %d\n", id);
-    while (read(houseFloor[READ_END], &weight, sizeof(int)) > 0) {
+    while (read(houseFloor[READ_END], &weight, sizeof(int)) > 0) { // Read from pipe, until dwellers are all done
         int time = RANDOM_WITHIN_RANGE(MIN_TIME_FOR_MOVER, MAX_TIME_FOR_MOVER, seed);
         sleep(time);
         write(nextToTrucks[WRITE_END], &weight, sizeof(int));
@@ -66,8 +72,9 @@ void* mover(void* arg) {
     return NULL;
 }
 
-void* trucker(void* arg) {
+// Routine for truckers
-    Args *args = (Args*) arg;
+void *trucker(void *arg) {
+    Args *args = (Args *) arg;
     int id = args->id;
     unsigned int seed = args->seed;
     int capacity = ROOM_IN_TRUCK;
@@ -75,14 +82,14 @@ void* trucker(void* arg) {
     int weight;
 
     printf("Hello from trucker %d\n", id);
-    while (read(nextToTrucks[READ_END], &weight, sizeof(int)) > 0) {
+    while (read(nextToTrucks[READ_END], &weight, sizeof(int)) > 0) { // Read from pipe, until movers are all done
         capacity--;
         truckWeight += weight;
         int time = RANDOM_WITHIN_RANGE(MIN_TIME_FOR_TRUCKER, MAX_TIME_FOR_TRUCKER, seed);
         sleep(time);
         printf("Trucker %d loaded up box of weight %d in %d units of time, room left: %d\n", id, weight, time, capacity);
 
-        if (capacity == 0) {
+        if (capacity == 0) { // If truck is full, go on trip, and reset
             time = RANDOM_WITHIN_RANGE(MIN_TRIP_TIME, MAX_TRIP_TIME, seed);
             printf("Full truck %d with load of %d units of mass departed. Round trip will take %d units of time\n", id, truckWeight, time);
             sleep(time);
@@ -90,7 +97,8 @@ void* trucker(void* arg) {
             truckWeight = 0;
         }
     }
-    int time = RANDOM_WITHIN_RANGE(MIN_TRIP_TIME, MAX_TRIP_TIME, seed); // One way trip, so half the time
+    // If truck is not full, go on trip, and end, as there are no more boxes
+    int time = RANDOM_WITHIN_RANGE(MIN_TRIP_TIME, MAX_TRIP_TIME, seed);
     printf("Not full truck %d with load of %d units of mass departed. One way will take %d units of time\n", id, truckWeight, time);
     sleep(time);
     printf("Truck %d is finished\n", id);
@@ -105,46 +113,52 @@ int main(int argc, char **argv) {
     pipe(houseFloor);
     pipe(nextToTrucks);
 
+    // Get number of house dwellers, movers, and truckers
     int numberOfHouseDwellers, numberOfMovers, numberOfTruckers;
     printf("Please input number of people living in the house, number of movers and number of truck drivers\n");
     scanf("%d %d %d", &numberOfHouseDwellers, &numberOfMovers, &numberOfTruckers);
 
+    // Create thread pools, and pass in args
     pthread_t dwellerThreads[numberOfHouseDwellers];
     pthread_t moverThreads[numberOfMovers];
     pthread_t truckerThreads[numberOfTruckers];
 
-    for(int i = 0; i < numberOfHouseDwellers; i++) {
+    for (int i = 0; i < numberOfHouseDwellers; i++) {
-        Args *args = (Args*) malloc(sizeof(Args));
+        Args *args = (Args *) malloc(sizeof(Args));
         args->id = i;
         args->seed = rand();
-        pthread_create(&dwellerThreads[i], NULL, &dweller, (void*) args);
+        pthread_create(&dwellerThreads[i], NULL, &dweller, (void *) args);
     }
-    for(int i = 0; i < numberOfMovers; i++) {
+    for (int i = 0; i < numberOfMovers; i++) {
-        Args *args = (Args*) malloc(sizeof(Args));
+        Args *args = (Args *) malloc(sizeof(Args));
         args->id = i;
         args->seed = rand();
-        pthread_create(&moverThreads[i], NULL, &mover, (void*) args);
+        pthread_create(&moverThreads[i], NULL, &mover, (void *) args);
     }
-    for(int i = 0; i < numberOfTruckers; i++) {
+    for (int i = 0; i < numberOfTruckers; i++) {
-        Args *args = (Args*) malloc(sizeof(Args));
+        Args *args = (Args *) malloc(sizeof(Args));
         args->id = i;
         args->seed = rand();
-        pthread_create(&truckerThreads[i], NULL, &trucker, (void*) args);
+        pthread_create(&truckerThreads[i], NULL, &trucker, (void *) args);
     }
+    // Wait for dwellers to finish and then close the house floor write, so movers know to stop
     for (int i = 0; i < numberOfHouseDwellers; i++) {
         pthread_join(dwellerThreads[i], NULL);
     }
     close(houseFloor[WRITE_END]);
+    // Wait for movers to finish and then close the next to trucks write, so truckers know to stop
+    // Also endings the read end of the house floor pipe, as no more boxes will be written to it
     for (int i = 0; i < numberOfMovers; i++) {
         pthread_join(moverThreads[i], NULL);
     }
     close(houseFloor[READ_END]);
     close(nextToTrucks[WRITE_END]);
+    // Wait for truckers to finish, and close the read end of the next to trucks pipe, as no more boxes will be written to it
     for (int i = 0; i < numberOfTruckers; i++) {
         pthread_join(truckerThreads[i], NULL);
     }
     close(nextToTrucks[READ_END]);
 
     printf("Moving is finished!\n");
-    return 0;
+    return EXIT_SUCCESS;
 }