[shardingsphere] branch master updated: Avoid using Optional and null-check together in PostgreSQLCommand (#25645)

[duanzhengqiang]

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duanzhengqiang pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/shardingsphere.git


The following commit(s) were added to refs/heads/master by this push:
     new 5ef3e0b6530 Avoid using Optional and null-check together in 
PostgreSQLCommand (#25645)
5ef3e0b6530 is described below

commit 5ef3e0b65300b99aeda24100ab9ffb029ccbfdf8
Author: 吴伟杰 <wuwei...@apache.org>
AuthorDate: Sat May 13 22:06:26 2023 +0800

    Avoid using Optional and null-check together in PostgreSQLCommand (#25645)
    
    * Avoid using Optional and null-check together in PostgreSQLCommand
    
    * Rename EMPTY_RESULT to EMPTY
---
 .../command/query/PostgreSQLCommand.java           | 28 ++++++++++++++++------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git 
a/proxy/frontend/type/postgresql/src/main/java/org/apache/shardingsphere/proxy/frontend/postgresql/command/query/PostgreSQLCommand.java
 
b/proxy/frontend/type/postgresql/src/main/java/org/apache/shardingsphere/proxy/frontend/postgresql/command/query/PostgreSQLCommand.java
index 92ec40d9d89..96fe3a6a368 100644
--- 
a/proxy/frontend/type/postgresql/src/main/java/org/apache/shardingsphere/proxy/frontend/postgresql/command/query/PostgreSQLCommand.java
+++ 
b/proxy/frontend/type/postgresql/src/main/java/org/apache/shardingsphere/proxy/frontend/postgresql/command/query/PostgreSQLCommand.java
@@ -18,6 +18,7 @@
 package org.apache.shardingsphere.proxy.frontend.postgresql.command.query;
 
 import lombok.Getter;
+import lombok.RequiredArgsConstructor;
 import org.apache.shardingsphere.distsql.parser.statement.DistSQLStatement;
 import org.apache.shardingsphere.sql.parser.sql.common.statement.SQLStatement;
 import 
org.apache.shardingsphere.sql.parser.sql.common.statement.dal.AnalyzeTableStatement;
@@ -131,7 +132,7 @@ public enum PostgreSQLCommand {
     CLOSE_CURSOR(CloseStatement.class),
     SUCCESS(DistSQLStatement.class);
     
-    private static final Map<Class<? extends SQLStatement>, 
Optional<PostgreSQLCommand>> COMPUTED_CLASSES = new ConcurrentHashMap<>(64, 1);
+    private static final Map<Class<? extends SQLStatement>, CachedResult> 
COMPUTED_STATEMENTS = new ConcurrentHashMap<>(64, 1);
     
     private final Collection<Class<? extends SQLStatement>> 
sqlStatementClasses;
     
@@ -156,16 +157,29 @@ public enum PostgreSQLCommand {
     /*
      * Refer to <a 
href="https://bugs.openjdk.java.net/browse/JDK-8161372";>JDK-8161372</a>.
      */
-    @SuppressWarnings("OptionalAssignedToNull")
     private static Optional<PostgreSQLCommand> getPostgreSQLCommand(final 
Class<? extends SQLStatement> sqlStatementClass) {
-        Optional<PostgreSQLCommand> result;
-        if (null == (result = COMPUTED_CLASSES.get(sqlStatementClass))) {
-            result = COMPUTED_CLASSES.computeIfAbsent(sqlStatementClass, 
target -> Arrays.stream(PostgreSQLCommand.values()).filter(each -> 
matches(target, each)).findAny());
-        }
-        return result;
+        CachedResult result = COMPUTED_STATEMENTS.get(sqlStatementClass);
+        return null != result ? result.get() : 
COMPUTED_STATEMENTS.computeIfAbsent(sqlStatementClass, 
PostgreSQLCommand::compute).get();
+    }
+    
+    private static CachedResult compute(final Class<? extends SQLStatement> 
target) {
+        Optional<PostgreSQLCommand> result = 
Arrays.stream(PostgreSQLCommand.values()).filter(each -> matches(target, 
each)).findAny();
+        return result.map(CachedResult::new).orElse(CachedResult.EMPTY);
     }
     
     private static boolean matches(final Class<? extends SQLStatement> 
sqlStatementClass, final PostgreSQLCommand postgreSQLCommand) {
         return postgreSQLCommand.sqlStatementClasses.stream().anyMatch(each -> 
each.isAssignableFrom(sqlStatementClass));
     }
+    
+    @RequiredArgsConstructor
+    private static final class CachedResult {
+        
+        private static final CachedResult EMPTY = new CachedResult(null);
+        
+        private final PostgreSQLCommand result;
+        
+        private Optional<PostgreSQLCommand> get() {
+            return Optional.ofNullable(result);
+        }
+    }
 }