commiting halfways because i'm feeling stuck

main.c

@@ -11,11 +11,13 @@
 #define TAG_IDGAF 0
 #define TAG_BATCH 1
 #define TAG_NETWK 2
-#define TAG_WEIGH 2
+#define TAG_WEIGH 3
+#define TAG_READY 4
 
 #define COMM 500
 #define ITER 40
 #define BS 50
+#define FSPC 0.2
 
 #define sid(s) s + P_SLAVE
 
@@ -29,20 +31,54 @@ typedef enum{
     MASTER
 } Role;
 
+
+typedef struct IntQueue IntQueue;
+struct IntQueue {
+    int head;
+    int tail;
+    size_t size;
+    int* data;
+};
+
+void queue_from_size(IntQueue* q, size_t s) {
+    q->data = malloc(s * sizeof(int));
+    q->size = s+1;
+    q->head = 0;
+    q->tail = 0;
+}
+
+void push_queue(IntQueue *q, int d) {
+    // Assuming queue is not full
+    q->data[q->tail] = d;
+    q->tail = (q->tail + 1) % q->size;
+}
+
+int pop_queue(IntQueue *q) {
+    int d = q->data[q->head];
+    q->head = (q->head + 1) % q->size;
+    return d;
+}
+
+int queue_empty(IntQueue *q) {
+    return q->head == q->tail;
+}
+
+int queue_full(IntQueue *q) {
+    return ((q->tail + 1) % q->size) == q->head;
+}
+
 void data_reader() {
     // Reads some data and converts it to a float array
     printf("Start reader\n");
     size_t batch_numel = (784 + 10) * BS;
     float* batch = malloc(batch_numel * sizeof(float));
     int s = 0;
-    int num_slaves;
-    MPI_Comm_size(MPI_COMM_WORLD, &num_slaves);
-    num_slaves -= P_SLAVE;
+
     while (1) {
+        MPI_Recv(&s, 1, MPI_INT, MPI_ANY_SOURCE, TAG_READY, MPI_COMM_WORLD,
+                MPI_STATUS_IGNORE);
         mnist_batch(batch, BS);
-        MPI_Send(batch, batch_numel, MPI_FLOAT, sid(s),
-                TAG_BATCH, MPI_COMM_WORLD);
-        s = (s + 1) % num_slaves;
+        MPI_Send(batch, batch_numel, MPI_FLOAT, s, TAG_BATCH, MPI_COMM_WORLD);
     }
     free(batch);
 }
@@ -73,8 +109,6 @@ void recv_weights(const Network* c_net, int src, int tag) {
     }
 }
 
-
-
 void send_network(const Network* c_net, int dest, int tag) {
     // Send a network to the expecting destination
     // It's best to receive with `recv_network`
@@ -130,14 +164,19 @@ void free_network_contents(Network* c_net) {
 void slave_node() {
     printf("Start slave\n");
 
+    int me;
+    MPI_Comm_rank(MPI_COMM_WORLD, &me);
+
     size_t batch_numel = (784 + 10) * BS;
     float* batch = malloc(batch_numel * sizeof(float));
     Network net;
     create_c_network(&net);
 
     for i_in_range(COMM) {
+        MPI_Send(&me, 1, MPI_INT, P_MASTER, TAG_READY, MPI_COMM_WORLD);
         recv_weights(&net, P_MASTER, TAG_NETWK);
         for (int k = 0; k < ITER; k++) {
+            MPI_Send(&me, 1, MPI_INT, P_READER, TAG_READY, MPI_COMM_WORLD);
             MPI_Recv(batch, batch_numel, MPI_FLOAT, P_READER, TAG_BATCH,
                     MPI_COMM_WORLD, MPI_STATUS_IGNORE);
             step_net(&net, batch, BS);
@@ -153,9 +192,11 @@ void master_node() {
     // Stores most up-to-date model, sends it to slaves for training
     // First do it synchronously
     // Need a "slave registry"
+    printf("Start master\n");
+
     int world_size;
     MPI_Comm_size(MPI_COMM_WORLD, &world_size);
-    printf("Start master\n");
+
     Network frank;
     create_c_network(&frank);
 
@@ -165,6 +206,9 @@ void master_node() {
     Network* nets = malloc(sizeof(Network) * world_size);
     for s_in_slaves(world_size) create_c_network(nets + s);
 
+    IntQueue slave_queue;
+    queue_from_size(&slave_queue, world_size - P_SLAVE);
+
     for i_in_range(COMM) {
         for s_in_slaves(world_size) {
             send_weights(&frank, sid(s), TAG_WEIGH);