Convert task_spec to flatbuffers (#255)

* convert Ray to C++

* convert task_spec to flatbuffers

* fix

* it compiles

* latest

* tests are passing

* task2 -> task

* fix

* fix

* fix

* fix

* fix

* linting

* fix valgrind

* upgrade flatbuffers

* use debug mode for valgrind

* fix naming and comments

* downgrade flatbuffers

* fix linting

* reintroduce TaskSpec_free

* rename TaskSpec -> TaskInfo

* refactoring

* linting

src/common/lib/python/common_extension.h

@@ -6,7 +6,9 @@
 #include "structmember.h"
 
 #include "common.h"
-#include "task.h"
+
+typedef uint8_t TaskSpec;
+struct TaskBuilder;
 
 extern PyObject *CommonError;
 
@@ -18,7 +20,8 @@ typedef struct {
 
 typedef struct {
   PyObject_HEAD
-  task_spec *spec;
+  int64_t size;
+  TaskSpec *spec;
 } PyTask;
 // clang-format on
 
@@ -33,9 +36,11 @@ extern PyObject *pickle_loads;
 
 void init_pickle_module(void);
 
+extern TaskBuilder *g_task_builder;
+
 int PyStringToUniqueID(PyObject *object, ObjectID *object_id);
 
-int PyObjectToUniqueID(PyObject *object, ObjectID *objectid);
+int PyObjectToUniqueID(PyObject *object, ObjectID *object_id);
 
 PyObject *PyObjectID_make(ObjectID object_id);
 
@@ -46,6 +51,6 @@ PyObject *PyTask_from_string(PyObject *, PyObject *args);
 
 PyObject *compute_put_id(PyObject *self, PyObject *args);
 
-PyObject *PyTask_make(task_spec *task_spec);
+PyObject *PyTask_make(TaskSpec *task_spec, int64_t task_size);
 
 #endif /* COMMON_EXTENSION_H */