Fix seed bug for generating object ids for put (#120)

* fix seed bug for generating object ids for put

* fix clang-format

src/common/lib/python/common_extension.c

@@ -258,9 +258,9 @@ static PyObject *PyTask_task_id(PyObject *self) {
 }
 
 static PyObject *PyTask_arguments(PyObject *self) {
-  int64_t num_args = task_num_args(((PyTask *) self)->spec);
-  PyObject *arg_list = PyList_New((Py_ssize_t) num_args);
   task_spec *task = ((PyTask *) self)->spec;
+  int64_t num_args = task_num_args(task);
+  PyObject *arg_list = PyList_New((Py_ssize_t) num_args);
   for (int i = 0; i < num_args; ++i) {
     if (task_arg_type(task, i) == ARG_BY_REF) {
       object_id object_id = task_arg_id(task, i);
@@ -281,9 +281,9 @@ static PyObject *PyTask_arguments(PyObject *self) {
 }
 
 static PyObject *PyTask_returns(PyObject *self) {
-  int64_t num_returns = task_num_returns(((PyTask *) self)->spec);
-  PyObject *return_id_list = PyList_New((Py_ssize_t) num_returns);
   task_spec *task = ((PyTask *) self)->spec;
+  int64_t num_returns = task_num_returns(task);
+  PyObject *return_id_list = PyList_New((Py_ssize_t) num_returns);
   for (int i = 0; i < num_returns; ++i) {
     object_id object_id = task_return(task, i);
     PyList_SetItem(return_id_list, i, PyObjectID_make(object_id));
@@ -431,3 +431,14 @@ PyObject *check_simple_value(PyObject *self, PyObject *args) {
   }
   Py_RETURN_FALSE;
 }
+
+PyObject *compute_put_id(PyObject *self, PyObject *args) {
+  int put_index;
+  task_id task_id;
+  if (!PyArg_ParseTuple(args, "O&i", &PyObjectToUniqueID, &task_id,
+                        &put_index)) {
+    return NULL;
+  }
+  object_id put_id = task_compute_put_id(task_id, put_index);
+  return PyObjectID_make(put_id);
+}

src/common/lib/python/common_extension.h

@@ -39,6 +39,8 @@ PyObject *PyObjectID_make(object_id object_id);
 
 PyObject *check_simple_value(PyObject *self, PyObject *args);
 
+PyObject *compute_put_id(PyObject *self, PyObject *args);
+
 PyObject *PyTask_make(task_spec *task_spec);
 
 #endif /* COMMON_EXTENSION_H */

src/common/lib/python/common_module.c

@@ -5,6 +5,8 @@
 static PyMethodDef common_methods[] = {
     {"check_simple_value", check_simple_value, METH_VARARGS,
      "Should the object be passed by value?"},
+    {"compute_put_id", compute_put_id, METH_VARARGS,
+     "Return the object ID for a put call within a task."},
     {NULL} /* Sentinel */
 };
 

src/common/task.c

@@ -112,7 +112,10 @@ task_id compute_task_id(task_spec *spec) {
   return task_id;
 }
 
-object_id compute_return_id(task_id task_id, int64_t return_index) {
+object_id task_compute_return_id(task_id task_id, int64_t return_index) {
+  /* Here, return_indices need to be >= 0, so we can use negative
+   * indices for put. */
+  DCHECK(return_index >= 0);
   /* TODO(rkn): This line requires object and task IDs to be the same size. */
   object_id return_id = task_id;
   int64_t *first_bytes = (int64_t *) &return_id;
@@ -122,6 +125,17 @@ object_id compute_return_id(task_id task_id, int64_t return_index) {
   return return_id;
 }
 
+object_id task_compute_put_id(task_id task_id, int64_t put_index) {
+  DCHECK(put_index >= 0);
+  /* TODO(pcm): This line requires object and task IDs to be the same size. */
+  object_id put_id = task_id;
+  int64_t *first_bytes = (int64_t *) &put_id;
+  /* XOR the first bytes of the object ID with the return index. We add one so
+   * the first return ID is not the same as the task ID. */
+  *first_bytes = *first_bytes ^ (-put_index - 1);
+  return put_id;
+}
+
 task_spec *start_construct_task_spec(task_id parent_task_id,
                                      int64_t parent_counter,
                                      function_id function_id,
@@ -151,7 +165,7 @@ void finish_construct_task_spec(task_spec *spec) {
   spec->task_id = compute_task_id(spec);
   /* Set the object IDs for the return values. */
   for (int64_t i = 0; i < spec->num_returns; ++i) {
-    *task_return_ptr(spec, i) = compute_return_id(spec->task_id, i);
+    *task_return_ptr(spec, i) = task_compute_return_id(spec->task_id, i);
   }
 }
 

src/common/task.h

@@ -220,6 +220,15 @@ int64_t task_args_add_val(task_spec *spec, uint8_t *data, int64_t length);
  */
 object_id task_return(task_spec *spec, int64_t return_index);
 
+/**
+ * Compute the object id associated to a put call.
+ *
+ * @param task_id The task id of the parent task that called the put.
+ * @param put_index The number of put calls in this task so far.
+ * @return The object ID for the object that was put.
+ */
+object_id task_compute_put_id(task_id task_id, int64_t put_index);
+
 /**
  * Free a task_spec.
  *