Rename CachedSupplier to ThreadSafeCachingSupplier and refactor

Author: justin-tay

src/main/java/com/networknt/schema/keyword/DynamicRefValidator.java

@@ -24,7 +24,7 @@
 import com.networknt.schema.Schema;
 import com.networknt.schema.SchemaException;
 import com.networknt.schema.SchemaRef;
-import com.networknt.schema.utils.CachedSupplier;
+import com.networknt.schema.utils.ThreadSafeCachingSupplier;
 import com.networknt.schema.SchemaLocation;
 import com.networknt.schema.SchemaContext;
 
@@ -83,7 +83,7 @@ static SchemaRef getRefSchema(Schema parentSchema, SchemaContext schemaContext,
     }
 
     static <T> Supplier<T> getSupplier(Supplier<T> supplier, boolean cache) {
-        return cache ? new CachedSupplier<>(supplier) : supplier;
+        return cache ? new ThreadSafeCachingSupplier<>(supplier) : supplier;
     }
 
     private static String resolve(Schema parentSchema, String refValue) {

src/main/java/com/networknt/schema/keyword/RecursiveRefValidator.java

@@ -24,7 +24,7 @@
 import com.networknt.schema.Schema;
 import com.networknt.schema.SchemaException;
 import com.networknt.schema.SchemaRef;
-import com.networknt.schema.utils.CachedSupplier;
+import com.networknt.schema.utils.ThreadSafeCachingSupplier;
 import com.networknt.schema.SchemaLocation;
 import com.networknt.schema.SchemaContext;
 
@@ -57,7 +57,7 @@ static SchemaRef getRefSchema(Schema parentSchema, SchemaContext schemaContext,
     }
 
     static <T> Supplier<T> getSupplier(Supplier<T> supplier, boolean cache) {
-        return cache ? new CachedSupplier<>(supplier) : supplier;
+        return cache ? new ThreadSafeCachingSupplier<>(supplier) : supplier;
     }
 
     static Schema getSchema(Schema parentSchema, SchemaContext schemaContext, String refValue,

src/main/java/com/networknt/schema/keyword/RefValidator.java

@@ -24,7 +24,7 @@
 import com.networknt.schema.Schema;
 import com.networknt.schema.SchemaException;
 import com.networknt.schema.SchemaRef;
-import com.networknt.schema.utils.CachedSupplier;
+import com.networknt.schema.utils.ThreadSafeCachingSupplier;
 import com.networknt.schema.SchemaLocation;
 import com.networknt.schema.SchemaContext;
 
@@ -126,7 +126,7 @@ static SchemaRef getRefSchema(Schema parentSchema, SchemaContext schemaContext,
     }
 
     static <T> Supplier<T> getSupplier(Supplier<T> supplier, boolean cache) {
-        return cache ? new CachedSupplier<>(supplier) : supplier;
+        return cache ? new ThreadSafeCachingSupplier<>(supplier) : supplier;
     }
 
     private static void copySchemaResources(SchemaContext schemaContext, Schema schemaResource) {

src/main/java/com/networknt/schema/utils/CachingSupplier.java

@@ -22,22 +22,23 @@
  * {@link Supplier} that caches the value.
  * <p>
  * This is not threadsafe.
- * 
- * @param <T> the type of results supplied by this supplier
+ *
+ * @param <T> the type of results cached by this supplier
  */
 public class CachingSupplier<T> implements Supplier<T> {
-    private final Supplier<T> delegate;
-    private T cached = null;
+    private Supplier<T> delegate;
+    private T cache = null;
 
-    public CachingSupplier(Supplier<T> supplier) {
-        this.delegate = supplier;
+    public CachingSupplier(Supplier<T> delegate) {
+        this.delegate = delegate;
     }
 
     @Override
     public T get() {
-        if (this.cached == null) {
-            this.cached = this.delegate.get();
+        if (this.cache == null && this.delegate != null) {
+            this.cache = this.delegate.get();
+            this.delegate = null;
         }
-        return this.cached;
+        return this.cache;
     }
 }

src/main/java/com/networknt/schema/utils/CachedSupplier.java renamed to src/main/java/com/networknt/schema/utils/ThreadSafeCachingSupplier.java

@@ -18,15 +18,15 @@
 import java.util.function.Supplier;
 
 /**
- * Supplier that caches the output.
+ * {@link Supplier} that caches the value.
  * 
- * @param <T> the type cached
+ * @param <T> the type of results cached by this supplier
  */
-public class CachedSupplier<T> implements Supplier<T> {
+public class ThreadSafeCachingSupplier<T> implements Supplier<T> {
     private volatile Supplier<T> delegate;
     private volatile T cache = null;
 
-    public CachedSupplier(Supplier<T> delegate) {
+    public ThreadSafeCachingSupplier(Supplier<T> delegate) {
         this.delegate = delegate;
     }
 

src/test/java/com/networknt/schema/utils/CachedSupplierTest.java renamed to src/test/java/com/networknt/schema/utils/ThreadSafeCachingSupplierTest.java

@@ -28,18 +28,18 @@
 /**
  * Test for CachedSupplier.
  */
-class CachedSupplierTest {
+class ThreadSafeCachingSupplierTest {
     @Test
     void nullValue() {
-        CachedSupplier<String> supplier = new CachedSupplier<>(null);
+        ThreadSafeCachingSupplier<String> supplier = new ThreadSafeCachingSupplier<>(null);
         assertNull(supplier.get());
     }
 
     @Test
     void concurrency() throws Exception {
         AtomicInteger value = new AtomicInteger(0);
 
-        CachedSupplier<Integer> supplier = new CachedSupplier<>(() -> {
+        ThreadSafeCachingSupplier<Integer> supplier = new ThreadSafeCachingSupplier<>(() -> {
             return value.addAndGet(1);
         });
         Exception[] instance = new Exception[1];