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/common_protocol.h

@@ -0,0 +1,41 @@
+#ifndef COMMON_PROTOCOL_H
+#define COMMON_PROTOCOL_H
+
+#include "format/common_generated.h"
+
+#include "common.h"
+
+/**
+ * Convert an object ID to a flatbuffer string.
+ *
+ * @param fbb Reference to the flatbuffer builder.
+ * @param object_id The object ID to be converted.
+ * @return The flatbuffer string contining the object ID.
+ */
+flatbuffers::Offset<flatbuffers::String> to_flatbuf(
+    flatbuffers::FlatBufferBuilder &fbb,
+    ObjectID object_id);
+
+/**
+ * Convert a flatbuffer string to an object ID.
+ *
+ * @param string The flatbuffer string.
+ * @return The object ID.
+ */
+ObjectID from_flatbuf(const flatbuffers::String *string);
+
+/**
+ * Convert an array of object IDs to a flatbuffer vector of strings.
+ *
+ * @param fbb Reference to the flatbuffer builder.
+ * @param object_ids Array of object IDs.
+ * @param num_objects Number of elements in the array.
+ * @return Flatbuffer vector of strings.
+ */
+flatbuffers::Offset<
+    flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>>>
+to_flatbuf(flatbuffers::FlatBufferBuilder &fbb,
+           ObjectID object_ids[],
+           int64_t num_objects);
+
+#endif