Remove GetRef RPC method (#5856)

* Remove `GetRef` RPC method

For now removing `GetRef` again, as the object caches are no longer being evicted and thus the situation where an unknown ref is received should not occur.

* Remove reference to "batch" from `RewriteRpc#parse()`

* Remove `localObjectGenerators` field from `RewriteRpc`

Author: knutwannheden

rewrite-core/src/main/java/org/openrewrite/rpc/RewriteRpc.java

@@ -125,7 +125,6 @@ protected RewriteRpc(JsonRpc jsonRpc, Environment marketplace, Duration timeout)
         Map<String, Recipe> preparedRecipes = new HashMap<>();
         Map<Recipe, Cursor> recipeCursors = new IdentityHashMap<>();
 
-        jsonRpc.rpc("GetRef", new GetRef.Handler(remoteRefs, localRefs, batchSize, traceSendPackets));
         jsonRpc.rpc("Visit", new Visit.Handler(localObjects, preparedRecipes, recipeCursors,
                 this::getObject, this::getCursor));
         jsonRpc.rpc("Generate", new Generate.Handler(localObjects, preparedRecipes, recipeCursors,
@@ -280,11 +279,7 @@ public boolean tryAdvance(Consumer<? super SourceFile> action) {
                 if (ids == null) {
                     // FIXME handle `TimeoutException` gracefully
                     ids = send("Parse", new Parse(mappedInputs, relativeTo != null ? relativeTo.toString() : null), ParseResponse.class);
-
-                    // If batch is empty, we're done
-                    if (ids.isEmpty()) {
-                        return false;
-                    }
+                    assert ids.size() == inputList.size();
                 }
 
                 // Process current item in batch
@@ -364,7 +359,7 @@ public <T> T getObject(String id) {
         String lastKnownId = localObject != null ? id : null;
 
         RpcReceiveQueue q = new RpcReceiveQueue(remoteRefs, traceFile, () -> send("GetObject",
-                new GetObject(id, lastKnownId), GetObjectResponse.class), this::getRef);
+                new GetObject(id, lastKnownId), GetObjectResponse.class));
         Object remoteObject = q.receive(localObject, null);
         if (q.take().getState() != END_OF_OBJECT) {
             throw new IllegalStateException("Expected END_OF_OBJECT");
@@ -377,27 +372,6 @@ public <T> T getObject(String id) {
         return (T) remoteObject;
     }
 
-    private Object getRef(Integer refId) {
-        RpcReceiveQueue q = new RpcReceiveQueue(remoteRefs, traceFile, () -> send("GetRef",
-                new GetRef(refId), GetRefResponse.class), nestedRefId -> {
-            throw new IllegalStateException("Nested ref calls not supported in GetRef: " + nestedRefId);
-        });
-
-        Object ref = q.receive(null, null);
-        if (q.take().getState() != END_OF_OBJECT) {
-            throw new IllegalStateException("Expected END_OF_OBJECT");
-        }
-
-        if (ref == null) {
-            throw new IllegalStateException("Reference " + refId + " not found on remote");
-        }
-
-        remoteRefs.put(refId, ref);
-        localRefs.put(ref, refId);
-
-        return ref;
-    }
-
     protected <P> P send(String method, @Nullable RpcRequest body, Class<P> responseType) {
         try {
             // TODO handle error

rewrite-core/src/main/java/org/openrewrite/rpc/RpcReceiveQueue.java

@@ -46,15 +46,13 @@ public class RpcReceiveQueue {
     private final Map<Integer, Object> refs;
     private final @Nullable PrintStream logFile;
     private final Supplier<List<RpcObjectData>> pull;
-    private final Function<Integer, Object> getRef;
 
     public RpcReceiveQueue(Map<Integer, Object> refs, @Nullable PrintStream logFile,
-                           Supplier<List<RpcObjectData>> pull, Function<Integer, Object> getRef) {
+                           Supplier<List<RpcObjectData>> pull) {
         this.refs = refs;
         this.batch = new ArrayDeque<>();
         this.logFile = logFile;
         this.pull = pull;
-        this.getRef = getRef;
     }
 
     public RpcObjectData take() {
@@ -135,11 +133,7 @@ public <T> T receive(@Nullable T before) {
                         //noinspection unchecked
                         return (T) refs.get(ref);
                     } else {
-                        // Ref was evicted from cache, fetch it
-                        Object refObject = getRef.apply(ref);
-                        refs.put(ref, refObject);
-                        //noinspection unchecked
-                        return (T) refObject;
+                        throw new IllegalStateException("Received a reference to an object that was not previously sent: " + ref);
                     }
                 } else {
                     // This is either a new object or a forward declaration with ref