minor method name cleanup in PythonContext.ChildContextData

Author: tomasstupka

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/MultiprocessingModuleBuiltins.java

@@ -245,7 +245,7 @@ Object terminate(long id, PInt sig) {
                 PythonContext.ChildContextData data = language.getChildContextData(convertTid(id));
                 try {
                     data.awaitRunning();
-                    TruffleContext truffleCtx = data.getCtx();
+                    TruffleContext truffleCtx = data.getTruffleContext();
                     if (!truffleCtx.isCancelling() && data.compareAndSetExiting(false, true)) {
                         LOGGER.fine("terminating spawned thread");
                         data.setExitCode(sig.intValue());

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/runtime/PythonContext.java

@@ -473,8 +473,8 @@ public Thread getOwner() {
 
     public static final class ChildContextData {
         private int exitCode = 0;
-        private TruffleContext ctx;
-        private PythonContext parentCtx;
+        @CompilationFinal private TruffleContext ctx;
+        @CompilationFinal private PythonContext parentCtx;
 
         private final AtomicBoolean exiting = new AtomicBoolean(false);
         private final CountDownLatch running = new CountDownLatch(1);
@@ -487,10 +487,20 @@ public int getExitCode() {
             return this.exitCode;
         }
 
-        public TruffleContext getCtx() {
+        private void setTruffleContext(TruffleContext ctx) {
+            assert this.ctx == null;
+            this.ctx = ctx;
+        }
+
+        public TruffleContext getTruffleContext() {
             return ctx;
         }
 
+        private void setParentContext(PythonContext parentCtx) {
+            assert this.parentCtx == null;
+            this.parentCtx = parentCtx;
+        }
+
         public void awaitRunning() throws InterruptedException {
             running.await();
         }
@@ -537,9 +547,9 @@ public ChildContextData getChildContextData() {
     public long spawnTruffleContext(int fd, int sentinel, int[] fdsToKeep) {
         ChildContextData data = new ChildContextData();
         if (!isChildContext()) {
-            data.parentCtx = this;
+            data.setParentContext(this);
         } else {
-            data.parentCtx = childContextData.parentCtx;
+            data.setParentContext(childContextData.parentCtx);
         }
 
         Builder builder = data.parentCtx.env.newContextBuilder().config(PythonContext.CHILD_CONTEXT_DATA, data);
@@ -597,7 +607,7 @@ public void run() {
             try {
                 LOGGER.fine("starting spawned child context");
                 TruffleContext ctx = builder.build();
-                data.ctx = ctx;
+                data.setTruffleContext(ctx);
                 Object parent = ctx.enter(null);
                 try {
                     Source source = Source.newBuilder(PythonLanguage.ID,