[ISSUE #1906] The BooleanConstantExpression might lead to class loading deadlock

[ISSUE #1906] The BooleanConstantExpression might lead to class loading deadlock

filter/src/main/java/org/apache/rocketmq/filter/expression/BooleanConstantExpression.java

+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.rocketmq.filter.expression;
+
+/**
+ * BooleanConstantExpression
+ */
+public class BooleanConstantExpression extends ConstantExpression implements BooleanExpression {
+
+    public static final BooleanConstantExpression NULL = new BooleanConstantExpression(null);
+    public static final BooleanConstantExpression TRUE = new BooleanConstantExpression(Boolean.TRUE);
+    public static final BooleanConstantExpression FALSE = new BooleanConstantExpression(Boolean.FALSE);
+
+    public BooleanConstantExpression(Object value) {
+        super(value);
+    }
+
+    public boolean matches(EvaluationContext context) throws Exception {
+        Object object = evaluate(context);
+        return object != null && object == Boolean.TRUE;
+    }
+}

filter/src/main/java/org/apache/rocketmq/filter/expression/ComparisonExpression.java

@@ -90,11 +90,11 @@ public abstract class ComparisonExpression extends BinaryExpression implements B
     }
 
     public static BooleanExpression createIsNull(Expression left) {
-        return doCreateEqual(left, ConstantExpression.NULL);
+        return doCreateEqual(left, BooleanConstantExpression.NULL);
     }
 
     public static BooleanExpression createIsNotNull(Expression left) {
-        return UnaryExpression.createNOT(doCreateEqual(left, ConstantExpression.NULL));
+        return UnaryExpression.createNOT(doCreateEqual(left, BooleanConstantExpression.NULL));
     }
 
     public static BooleanExpression createNotEqual(Expression left, Expression right) {

filter/src/main/java/org/apache/rocketmq/filter/expression/ConstantExpression.java

@@ -30,21 +30,6 @@ package org.apache.rocketmq.filter.expression;
  */
 public class ConstantExpression implements Expression {
 
-    static class BooleanConstantExpression extends ConstantExpression implements BooleanExpression {
-        public BooleanConstantExpression(Object value) {
-            super(value);
-        }
-
-        public boolean matches(EvaluationContext context) throws Exception {
-            Object object = evaluate(context);
-            return object != null && object == Boolean.TRUE;
-        }
-    }
-
-    public static final BooleanConstantExpression NULL = new BooleanConstantExpression(null);
-    public static final BooleanConstantExpression TRUE = new BooleanConstantExpression(Boolean.TRUE);
-    public static final BooleanConstantExpression FALSE = new BooleanConstantExpression(Boolean.FALSE);
-
     private Object value;
 
     public ConstantExpression(Object value) {
@@ -60,16 +45,10 @@ public class ConstantExpression implements Expression {
 
         // only support Long.MIN_VALUE ~ Long.MAX_VALUE
         Number value = new Long(text);
-//        try {
-//            value = new Long(text);
-//        } catch (NumberFormatException e) {
-//            // The number may be too big to fit in a long.
-//            value = new BigDecimal(text);
-//        }
 
         long l = value.longValue();
         if (Integer.MIN_VALUE <= l && l <= Integer.MAX_VALUE) {
-            value = Integer.valueOf(value.intValue());
+            value = value.intValue();
         }
         return new ConstantExpression(value);
     }
@@ -106,7 +85,7 @@ public class ConstantExpression implements Expression {
             return "NULL";
         }
         if (value instanceof Boolean) {
-            return ((Boolean) value).booleanValue() ? "TRUE" : "FALSE";
+            return (Boolean) value ? "TRUE" : "FALSE";
         }
         if (value instanceof String) {
             return encodeString((String) value);
@@ -138,17 +117,19 @@ public class ConstantExpression implements Expression {
      * it was provided in a selector.
      */
     public static String encodeString(String s) {
-        StringBuffer b = new StringBuffer();
-        b.append('\'');
+
+        StringBuilder builder = new StringBuilder();
+
+        builder.append('\'');
         for (int i = 0; i < s.length(); i++) {
             char c = s.charAt(i);
             if (c == '\'') {
-                b.append(c);
+                builder.append(c);
             }
-            b.append(c);
+            builder.append(c);
         }
-        b.append('\'');
-        return b.toString();
+        builder.append('\'');
+        return builder.toString();
     }
 
 }

filter/src/main/java/org/apache/rocketmq/filter/parser/SelectorParser.java

@@ -20,6 +20,7 @@ package org.apache.rocketmq.filter.parser;
 
 import com.google.common.cache.Cache;
 import com.google.common.cache.CacheBuilder;
+import org.apache.rocketmq.filter.expression.BooleanConstantExpression;
 import org.apache.rocketmq.filter.expression.BooleanExpression;
 import org.apache.rocketmq.filter.expression.ComparisonExpression;
 import org.apache.rocketmq.filter.expression.ConstantExpression;
@@ -437,15 +438,15 @@ public class SelectorParser implements SelectorParserConstants {
                 break;
             case TRUE:
                 jj_consume_token(TRUE);
-                left = ConstantExpression.TRUE;
+                left = BooleanConstantExpression.TRUE;
                 break;
             case FALSE:
                 jj_consume_token(FALSE);
-                left = ConstantExpression.FALSE;
+                left = BooleanConstantExpression.FALSE;
                 break;
             case NULL:
                 jj_consume_token(NULL);
-                left = ConstantExpression.NULL;
+                left = BooleanConstantExpression.NULL;
                 break;
             default:
                 jjLa1[12] = jjGen;