allow connection serialization

com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/RSerialize.java

@@ -727,7 +727,9 @@ public class RSerialize {
         /**
          * GnuR uses a pairlist to represent attributes, whereas FastR uses the abstract RAttributes
          * class. FastR also uses different types to represent data/frame and factor which is
-         * handled in the setClassAttr
+         * handled in the setClassAttr. N.B. In theory connections can be unserialized but they are
+         * unusable, so we don't go to the trouble of converting the {@link RIntVector}
+         * representation into an {@link RConnection}.
          */
         private static Object setAttributes(final Object object, Object attr) {
             RAttributable rAttributable = (RAttributable) object;
@@ -738,7 +740,8 @@ public class RSerialize {
                 String tag = tagSym.getName().intern();
                 // this may convert a plain vector to a data.frame or factor
                 if (result instanceof RVector && tag.equals(RRuntime.CLASS_ATTR_KEY)) {
-                    result = ((RVector) result).setClassAttr((RStringVector) pl.car(), false);
+                    RStringVector classes = (RStringVector) pl.car();
+                    result = ((RVector) result).setClassAttr(classes, false);
                 } else {
                     rAttributable.setAttr(tag, pl.car());
                 }
@@ -1198,6 +1201,8 @@ public class RSerialize {
                 case FASTR_DATAFRAME:
                 case FASTR_FACTOR:
                     return SEXPTYPE.VECSXP;
+                case FASTR_CONNECTION:
+                    return SEXPTYPE.INTSXP;
                 default:
                     return type;
             }
@@ -1262,10 +1267,6 @@ public class RSerialize {
                 RFactor factor = (RFactor) obj;
                 writeItem(factor.getVector());
                 return;
-            } else if (type == SEXPTYPE.FASTR_SOCKET_CONN || type == SEXPTYPE.FASTR_FILE_CONN) {
-                // serializing a socket or file connection is not meaningful
-                writeItem(RDataFactory.createIntVectorFromScalar(RRuntime.INT_NA));
-                return;
             } else {
                 // flags
                 RAttributes attributes = null;
@@ -1391,6 +1392,14 @@ public class RSerialize {
                         break;
                     }
 
+                    case EXTPTRSXP: {
+                        addReadRef(obj);
+                        RExternalPtr xptr = (RExternalPtr) obj;
+                        writeItem(RNull.instance);
+                        writeItem(RDataFactory.createSymbol(xptr.tag));
+                        break;
+                    }
+
                     /*
                      * FastR scalar, (length 1) "vectors"
                      */
@@ -1428,6 +1437,13 @@ public class RSerialize {
                         break;
                     }
 
+                    case FASTR_CONNECTION: {
+                        RConnection con = (RConnection) obj;
+                        stream.writeInt(1);
+                        stream.writeInt(con.getDescriptor());
+                        break;
+                    }
+
                     case LANGSXP: {
                         RPairList pl = (RPairList) RContext.getRRuntimeASTAccess().serialize(state, obj);
                         writeItem(pl.car());

com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/conn/ConnectionSupport.java

@@ -412,6 +412,8 @@ public class ConnectionSupport implements RContext.StateFactory {
             classes[0] = conClass.printName;
             classes[1] = "connection";
             getAttributes().put(RRuntime.CLASS_ATTR_KEY, RDataFactory.createStringVector(classes, RDataFactory.COMPLETE_VECTOR));
+            // For GnuR compatibility we define the "conn_id" attribute
+            getAttributes().put("conn_id", RDataFactory.createExternalPtr(0, "connection"));
         }
 
         protected void openNonLazyConnection() throws IOException {

com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/gnur/SEXPTYPE.java

@@ -43,7 +43,7 @@ public enum SEXPTYPE {
     VECSXP(19, RList.class), /* generic vectors */
     EXPRSXP(20, RExpression.class), /* expressions vectors */
     BCODESXP(21), /* byte code */
-    EXTPTRSXP(22), /* external pointer */
+    EXTPTRSXP(22, RExternalPtr.class), /* external pointer */
     WEAKREFSXP(23), /* weak reference */
     RAWSXP(24, RRawVector.class), /* raw bytes */
     S4SXP(25), /* S4 non-vector */
@@ -83,10 +83,7 @@ public enum SEXPTYPE {
     FASTR_FACTOR(305, RFactor.class),
     // very special case
     FASTR_SOURCESECTION(306, SourceSection.class),
-
-    // Other FastR internals
-    FASTR_SOCKET_CONN(400, SocketConnections.RSocketConnection.class),
-    FASTR_FILE_CONN(401, FileConnections.FileRConnection.class),
+    FASTR_CONNECTION(307, RConnection.class),
 
     EMPTYARG_SXP(500, REmpty.class);
 
@@ -133,9 +130,11 @@ public enum SEXPTYPE {
                 }
             }
         }
-        // (only) environments have subtypes
+        // (only) environments and connections have subtypes
         if (REnvironment.class.isAssignableFrom(fastRClass)) {
             return ENVSXP;
+        } else if (RConnection.class.isAssignableFrom(fastRClass)) {
+            return FASTR_CONNECTION;
         }
         throw RInternalError.shouldNotReachHere(fastRClass.getName());
     }