it started working so commit it

main.c

@@ -0,0 +1,89 @@
+#include <Python.h>
+#include <stdio.h>
+#include <mpi.h>
+
+#define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION
+#include <numpy/arrayobject.h>
+
+#include "library.h"
+
+#define P_READER 0
+#define P_SLAVE 1
+#define P_MASTER 2
+
+#define COMM 100
+#define ITER 20
+#define BS 50
+
+// Reads some data and converts it to 2D float array
+void data_reader() {
+    while (1) {
+        PyArrayObject* batch = mnist_batch(10);
+
+        long* shape = PyArray_SHAPE(batch);
+        MPI_Send(shape, 2, MPI_LONG, P_SLAVE, 0, MPI_COMM_WORLD);
+        MPI_Send(PyArray_DATA(batch), PyArray_SIZE(batch), MPI_FLOAT,
+                P_SLAVE, 0, MPI_COMM_WORLD);
+        Py_DECREF(batch);
+    }
+}
+
+// Receives weight updates and trains, sends learned weights back to master
+void slave_node() {
+    PyObject* net = create_network();
+    for (int i = 0; i < COMM; i++) {
+        char go;
+        MPI_Recv(&go, 1, MPI_CHAR, P_MASTER, MPI_ANY_TAG, MPI_COMM_WORLD,
+                MPI_STATUS_IGNORE);
+        for (int k = 0; k < ITER; k++) {
+            long shape[2];
+            MPI_Recv(shape, 2, MPI_LONG, P_READER, MPI_ANY_TAG, MPI_COMM_WORLD,
+                    MPI_STATUS_IGNORE);
+            long size = shape[0] * shape[1];
+            float* data = malloc(shape[0] * shape[1] * sizeof(float));
+            MPI_Recv(data, size, MPI_FLOAT, P_READER, MPI_ANY_TAG,
+                    MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+            PyArrayObject* batch = PyArray_SimpleNewFromData(
+                    2, shape, NPY_FLOAT32, data);
+            step_net(net, batch);
+        }
+        printf("%f\n", eval_net(net));
+    }
+}
+
+// Stores most up-to-date model, sends it to slaves for training
+void master_node() {
+    for (int i = 0; i < COMM; i++) {
+        char go;
+        MPI_Send(&go, 1, MPI_CHAR, P_SLAVE, 0, MPI_COMM_WORLD);
+    }
+}
+
+int main (int argc, const char **argv) {
+    int node;
+    MPI_Init(NULL, NULL);
+    MPI_Comm_rank(MPI_COMM_WORLD, &node);
+
+    // Cython Boilerplate
+    PyImport_AppendInittab("library", PyInit_library);
+    Py_Initialize();
+    import_array();
+    PyRun_SimpleString("import sys\nsys.path.insert(0,'')");
+    PyObject* library_module = PyImport_ImportModule("library");
+
+    // Actual Code
+    if (node == 0) {
+        data_reader();
+    }
+    else if (node == 1) {
+        slave_node();
+    }
+    else if (node == 2) {
+        master_node();
+    }
+
+    // Cython Finalizing Boilerplate
+    Py_DECREF(library_module);
+    Py_Finalize();
+    MPI_Finalize();
+}