Lazy values: change encoding, now NOT_COMPUTED is an explicit object, and null is stored as such

core/descriptors/src/org/jetbrains/jet/lang/resolve/lazy/storage/LockBasedStorageManager.java

@@ -114,7 +114,7 @@ public class LockBasedStorageManager implements StorageManager {
         return new LockBasedLazyValue<T>(lock, computable) {
             @Override
             protected Object recursionDetected() {
-                return WrappedValues.escapeNull(onRecursiveCall);
+                return onRecursiveCall;
             }
         };
     }
@@ -141,13 +141,14 @@ public class LockBasedStorageManager implements StorageManager {
 
     private static class LockBasedLazyValue<T> implements NullableLazyValue<T> {
 
+        private static final Object NOT_COMPUTED = new Object();
         private static final Object COMPUTING = new Object();
 
         private final Object lock;
         private final Computable<T> computable;
 
         @Nullable
-        private volatile Object value = null;
+        private volatile Object value = NOT_COMPUTED;
 
         public LockBasedLazyValue(@NotNull Object lock, @NotNull Computable<T> computable) {
             this.lock = lock;
@@ -157,23 +158,23 @@ public class LockBasedStorageManager implements StorageManager {
         @Override
         public T compute() {
             Object _value = value;
-            if (_value != null && _value != COMPUTING) return WrappedValues.unescapeExceptionOrNull(_value);
+            if (_value != NOT_COMPUTED && _value != COMPUTING) return WrappedValues.unescapeThrowable(_value);
 
             synchronized (lock) {
                 _value = value;
                 if (_value == COMPUTING) {
                     Object result = recursionDetected();
-                    if (result != null) {
-                        return WrappedValues.unescapeExceptionOrNull(result);
+                    if (result != NOT_COMPUTED) {
+                        return WrappedValues.unescapeThrowable(result);
                     }
                 }
 
-                if (_value != null) return WrappedValues.unescapeExceptionOrNull(_value);
+                if (_value != NOT_COMPUTED) return WrappedValues.unescapeThrowable(_value);
 
                 value = COMPUTING;
                 try {
                     T typedValue = computable.compute();
-                    value = WrappedValues.escapeNull(typedValue);
+                    value = typedValue;
                     postCompute(typedValue);
                     return typedValue;
                 }
@@ -185,7 +186,7 @@ public class LockBasedStorageManager implements StorageManager {
         }
 
         /**
-         * @return {@code null} to proceed, a wrapped value otherwise, see WrappedValues
+         * @return {@code NOT_COMPUTED} to proceed, a value or wrapped exception otherwise, see WrappedValues
          * @throws DO NOT throw exceptions from implementations of this method, instead return WrappedValues.escapeThrowable(exception)
          */
         @Nullable

core/descriptors/src/org/jetbrains/jet/lang/resolve/lazy/storage/StorageManager.java

@@ -44,9 +44,8 @@ public interface StorageManager {
 
     /**
      * @param onRecursiveCall is called if the computation calls itself recursively.
-     *                        If this parameter is null, an exception will be thrown on a recursive call.
-     *                        If this function returns null, the computation proceeds recursively,
-     *                        otherwise it should return a result of WrappedValues.escape*() method
+     *                        If this parameter is null, an exception will be thrown on a recursive call,
+     *                        otherwise it should return a result of WrappedValues.escapeThrowable() method
      * @param postCompute is called after the value is computed, but before any other thread sees it (the current thread may
      * see it in between)
      */

core/util.runtime/src/org/jetbrains/jet/utils/WrappedValues.java

@@ -58,10 +58,16 @@ public class WrappedValues {
 
     @Nullable
     public static <V> V unescapeExceptionOrNull(@NotNull Object value) {
+        return unescapeNull(unescapeThrowable(value));
+    }
+
+    @Nullable
+    public static <V> V unescapeThrowable(@Nullable Object value) {
         if (value instanceof ThrowableWrapper) {
             throw ExceptionUtils.rethrow(((ThrowableWrapper) value).getThrowable());
         }
 
-        return unescapeNull(value);
+        //noinspection unchecked
+        return (V) value;
     }
 }