Merge pull request #430 from tronprotocol/add_lock_for_dialogoptional

add lock for DialogOptional

Author: zhaohong

src/main/java/org/tron/common/utils/DialogOptional.java

@@ -1,42 +1,50 @@
 package org.tron.common.utils;
 
+import java.util.Optional;
 import org.tron.core.db.AbstractRevokingStore.Dialog;
 
-import java.util.Optional;
+public final class DialogOptional {
 
-public class DialogOptional<T extends Dialog> {
-  private static final DialogOptional<?> EMPTY = new DialogOptional<>();
+  private static final DialogOptional INSTANCE = OptionalEnum.INSTANCE.getInstance();
 
-  private Optional<T> value;
+  private Optional<Dialog> value;
 
   private DialogOptional() {
     this.value = Optional.empty();
   }
 
-  public static <T extends Dialog> DialogOptional<T> empty() {
-    @SuppressWarnings("unchecked")
-    DialogOptional<T> t = (DialogOptional<T>) EMPTY;
-    return t;
+  public synchronized DialogOptional setValue(Dialog value) {
+    if (!this.value.isPresent()) {
+      this.value = Optional.of(value);
+    }
+    return this;
   }
 
-  private DialogOptional(T value) {
-    this.value = Optional.of(value);
+  public synchronized boolean valid() {
+    return value.isPresent();
   }
 
-  public static <T extends Dialog> DialogOptional<T> of(T value) {
-    return new DialogOptional<>(value);
+  public synchronized void reset() {
+    value.ifPresent(Dialog::destroy);
+    value = Optional.empty();
   }
 
-  public static <T extends Dialog> DialogOptional<T> ofNullable(T value) {
-    return value == null ? empty() : of(value);
+  public static DialogOptional instance() {
+    return INSTANCE;
   }
 
-  public boolean valid() {
-    return value.isPresent();
-  }
+  private enum OptionalEnum {
+    INSTANCE;
 
-  public void reset() {
-    value.ifPresent(Dialog::destroy);
-    value = Optional.empty();
+    private DialogOptional instance;
+
+    OptionalEnum() {
+      instance = new DialogOptional();
+    }
+
+    private DialogOptional getInstance() {
+      return instance;
+    }
   }
+
 }

src/main/java/org/tron/core/db/Manager.java

@@ -84,7 +84,7 @@ public class Manager {
   private KhaosDatabase khaosDb;
   private RevokingDatabase revokingStore;
   @Getter
-  private DialogOptional<Dialog> dialog = DialogOptional.empty();
+  private DialogOptional dialog = DialogOptional.instance();
 
   @Getter
   @Setter
@@ -350,7 +350,7 @@ public synchronized boolean pushTransactions(final TransactionCapsule trx)
     validateFreq(trx);
 
     if (!dialog.valid()) {
-      dialog = DialogOptional.of(revokingStore.buildDialog());
+      dialog.setValue(revokingStore.buildDialog());
     }
 
     try (
@@ -697,7 +697,7 @@ public synchronized BlockCapsule generateBlock(final WitnessCapsule witnessCapsu
         witnessCapsule.getAddress());
 
     dialog.reset();
-    dialog = DialogOptional.of(revokingStore.buildDialog());
+    dialog.setValue(revokingStore.buildDialog());
 
     Iterator iterator = pendingTransactions.iterator();
     while (iterator.hasNext()) {

src/test/java/org/tron/core/db/RevokingStoreTest.java

@@ -40,7 +40,7 @@ public synchronized void testUndo() throws RevokingStoreIllegalStateException {
         "testrevokingtronstore-testUndo", revokingDatabase);
     TestProtoCapsule testProtoCapsule = new TestProtoCapsule();
 
-    DialogOptional dialog = DialogOptional.of(revokingDatabase.buildDialog());
+    DialogOptional dialog = DialogOptional.instance().setValue(revokingDatabase.buildDialog());
     for (int i = 0; i < 10; i++) {
       try (Dialog tmpDialog = revokingDatabase.buildDialog()) {
         tronDatabase.put(testProtoCapsule.getData(), testProtoCapsule);