add a uuid to each Module that is stable across serialization

Author: vtjnash

src/dump.c

@@ -418,6 +418,8 @@ static void jl_serialize_module(ios_t *s, jl_module_t *m)
         }
     }
     jl_serialize_value(s, m->constant_table);
+    write_int32(s, (uint32_t)m->uuid);
+    write_int32(s, (uint32_t)(m->uuid>>32));
 }
 
 static int is_ast_node(jl_value_t *v)
@@ -1088,6 +1090,8 @@ static jl_value_t *jl_deserialize_value_(ios_t *s, int pos, jl_value_t *vtag, jl
             i++;
         }
         m->constant_table = (jl_array_t*)jl_deserialize_value(s, (jl_value_t**)&m->constant_table);
+        m->uuid = read_int32(s);
+        m->uuid |= ((uint64_t)read_int32(s))<<32;
         return (jl_value_t*)m;
     }
     else if (vtag == (jl_value_t*)SmallInt64_tag) {

src/julia.h

@@ -255,6 +255,7 @@ typedef struct _jl_module_t {
     htable_t bindings;
     arraylist_t usings;  // modules with all bindings potentially imported
     jl_array_t *constant_table;
+    uint64_t uuid;
 } jl_module_t;
 
 typedef struct _jl_methlist_t {

src/module.c

@@ -22,6 +22,7 @@ jl_module_t *jl_new_module(jl_sym_t *name)
     assert(jl_is_symbol(name));
     m->name = name;
     m->constant_table = NULL;
+    m->uuid = uv_now(uv_default_loop());
     htable_new(&m->bindings, 0);
     arraylist_new(&m->usings, 0);
     if (jl_core_module) {
@@ -425,6 +426,7 @@ DLLEXPORT jl_value_t *jl_module_names(jl_module_t *m, int all, int imported)
 
 DLLEXPORT jl_sym_t *jl_module_name(jl_module_t *m) { return m->name; }
 DLLEXPORT jl_module_t *jl_module_parent(jl_module_t *m) { return m->parent; }
+DLLEXPORT uint64_t jl_module_uuid(jl_module_t *m) { return m->uuid; }
 
 int jl_module_has_initializer(jl_module_t *m)
 {