Implement serialization of references to other objects, which makes a cross-reference to another SC if needed, or if the object is in no SC adds it to ours and puts it onto the serialization worklist. Test for circular reference serialization now passes.

Author: jnthn

src/6model/serialization.c

@@ -25,14 +25,18 @@
 /* Possible reference types we can serialize. */
 #define REFVAR_NULL                 1
 #define REFVAR_OBJECT               2
-#define REFVAR_VM_INT               3
-#define REFVAR_VM_NUM               4
-#define REFVAR_VM_STR               5
-#define REFVAR_VM_ARR_VAR           6
-#define REFVAR_VM_ARR_STR           7
-#define REFVAR_VM_ARR_INT           8
-#define REFVAR_VM_HASH_STR_VAR      9
-#define REFVAR_STATIC_CODEREF       10
+#define REFVAR_VM_NULL              3
+#define REFVAR_VM_INT               4
+#define REFVAR_VM_NUM               5
+#define REFVAR_VM_STR               6
+#define REFVAR_VM_ARR_VAR           7
+#define REFVAR_VM_ARR_STR           8
+#define REFVAR_VM_ARR_INT           9
+#define REFVAR_VM_HASH_STR_VAR      10
+#define REFVAR_STATIC_CODEREF       11
+
+/* Cached type IDs. */
+static INTVAL smo_id = 0;
 
 /* ***************************************************************************
  * Serialization (writing related)
@@ -179,11 +183,51 @@ void write_str_func(PARROT_INTERP, SerializationWriter *writer, STRING *value) {
     }
 }
 
+/* Writes an object reference. */
+void write_obj_ref(PARROT_INTERP, SerializationWriter *writer, PMC *ref) {
+    Parrot_Int4 sc_id, idx;
+    
+    if (PMC_IS_NULL(SC_PMC(ref))) {
+        /* This object doesn't belong to an SC yet, so it must be serialized as part of
+         * this compilation unit. Add it to the work list. */
+        SC_PMC(ref) = writer->root.sc;
+        VTABLE_push_pmc(interp, writer->objects_list, ref);
+    }
+    sc_id = get_sc_id(interp, writer, SC_PMC(ref));
+    idx   = (Parrot_Int4)SC_find_object_idx(interp, SC_PMC(ref), ref);
+    
+    expand_storage_if_needed(interp, writer, 8);
+    if (writer->writing_object) {
+        write_int32(writer->root.objects_data, writer->objects_data_offset, sc_id);
+        writer->objects_data_offset += 4;
+        write_int32(writer->root.objects_data, writer->objects_data_offset, idx);
+        writer->objects_data_offset += 4;
+    }
+    else {
+        write_int32(writer->root.stables_data, writer->stables_data_offset, sc_id);
+        writer->stables_data_offset += 4;
+        write_int32(writer->root.stables_data, writer->stables_data_offset, idx);
+        writer->stables_data_offset += 4;
+    }
+}
+
 /* Writing function for references to things. */
 void write_ref_func(PARROT_INTERP, SerializationWriter *writer, PMC *ref) {
     /* Work out what kind of thing we have and determine the discriminator. */
     Parrot_Int2 discrim = 0;
-    /* XXX */
+    if (ref == NULL) {
+        discrim = REFVAR_NULL;
+    }
+    else if (PMC_IS_NULL(ref)) {
+        discrim = REFVAR_VM_NULL;
+    }
+    else if (ref->vtable->base_type == smo_id) {
+        discrim = REFVAR_OBJECT;
+    }
+    else {
+        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
+            "Serialization Error: Unimplemented object type passed to write_ref");
+    }
 
     /* Write the discriminator. */
     expand_storage_if_needed(interp, writer, 2);
@@ -197,8 +241,18 @@ void write_ref_func(PARROT_INTERP, SerializationWriter *writer, PMC *ref) {
     }
 
     /* Now take appropriate action. */
-    Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
-        "write_ref not yet implemented");
+    switch (discrim) {
+        case REFVAR_NULL:
+        case REFVAR_VM_NULL:
+            /* Nothing to do for these. */
+            break;
+        case REFVAR_OBJECT:
+            write_obj_ref(interp, writer, ref);
+            break;
+        default:
+            Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
+                "Serialization Error: Unimplemented object type passed to write_ref");
+    }
 }
 
 /* Concatenates the various output segments into a single binary string. */
@@ -380,6 +434,9 @@ STRING * Serialization_serialize(PARROT_INTERP, PMC *sc, PMC *empty_string_heap)
     writer->write_num = write_num_func;
     writer->write_str = write_str_func;
     writer->write_ref = write_ref_func;
+    
+    /* Other init. */
+    smo_id = Parrot_pmc_get_type_str(interp, Parrot_str_new(interp, "SixModelObject", 0));
 
     /* Start serializing. */
     serialize(interp, writer);
@@ -524,7 +581,28 @@ STRING * read_str_func(PARROT_INTERP, SerializationReader *reader) {
     }
 }
 
-/* Reading function for native strings. */
+/* Reads in and resolves an object references. */
+PMC * read_obj_ref(PARROT_INTERP, SerializationReader *reader) {
+    Parrot_Int4 sc_id, idx;
+    
+    assert_can_read(interp, reader, 8);
+    if (reader->reading_object) {
+        sc_id = read_int32(reader->root.objects_data, reader->objects_data_offset);
+        reader->objects_data_offset += 4;
+        idx = read_int32(reader->root.objects_data, reader->objects_data_offset);
+        reader->objects_data_offset += 4;
+    }
+    else {
+        sc_id = read_int32(reader->root.stables_data, reader->stables_data_offset);
+        reader->stables_data_offset += 4;
+        idx = read_int32(reader->root.stables_data, reader->stables_data_offset);
+        reader->stables_data_offset += 4;
+    }
+    
+    return SC_get_object(interp, locate_sc(interp, reader, sc_id), idx);
+}
+
+/* Reading function for references. */
 PMC * read_ref_func(PARROT_INTERP, SerializationReader *reader) {
     /* Read the discriminator. */
     Parrot_Int2 discrim;
@@ -539,8 +617,17 @@ PMC * read_ref_func(PARROT_INTERP, SerializationReader *reader) {
     }
 
     /* Decide what to do based on it. */
-    Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
-        "read_ref not yet implemented");
+    switch (discrim) {
+        case REFVAR_NULL:
+            return NULL;
+        case REFVAR_OBJECT:
+            return read_obj_ref(interp, reader);
+        case REFVAR_VM_NULL:
+            return PMCNULL;
+        default:
+            Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
+                "Serialization Error: Unimplemented case of read_ref");
+    }
 }
 
 /* Checks the header looks sane and all of the places it points to make sense.
@@ -703,6 +790,9 @@ void Serialization_deserialize(PARROT_INTERP, PMC *sc, PMC *string_heap, STRING
     reader->read_str = read_str_func;
     reader->read_ref = read_ref_func;
 
+    /* Other init. */
+    smo_id = Parrot_pmc_get_type_str(interp, Parrot_str_new(interp, "SixModelObject", 0));
+    
     /* Read header and disect the data into its parts. */
     check_and_disect_input(interp, reader, data);
 

src/6model/serialization_context.c

@@ -81,3 +81,13 @@ PMC * SC_get_stable(PARROT_INTERP, PMC *sc, INTVAL idx) {
             "No STable at index %d", idx);
     return VTABLE_get_pmc_keyed_int(interp, stables, idx);
 }
+
+/* Given an SC and an index, fetch the object stored there. */
+PMC * SC_get_object(PARROT_INTERP, PMC *sc, INTVAL idx) {
+    PMC *objects;
+    GETATTR_SerializationContext_root_objects(interp, sc, objects);
+    if (idx >= VTABLE_elements(interp, objects))
+        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
+            "No object at index %d", idx);
+    return VTABLE_get_pmc_keyed_int(interp, objects, idx);
+}

src/6model/serialization_context.h

@@ -8,4 +8,5 @@ INTVAL SC_find_object_idx(PARROT_INTERP, PMC *sc, PMC *st);
 STRING * SC_get_handle(PARROT_INTERP, PMC *sc);
 STRING * SC_get_description(PARROT_INTERP, PMC *sc);
 PMC * SC_get_stable(PARROT_INTERP, PMC *sc, INTVAL idx);
+PMC * SC_get_object(PARROT_INTERP, PMC *sc, INTVAL idx);
 #endif