Do not permit return null for ProxyContext.getMetaData() (#8168)

shardingsphere-proxy/shardingsphere-proxy-backend/src/main/java/org/apache/shardingsphere/proxy/backend/communication/DatabaseCommunicationEngineFactory.java

@@ -17,7 +17,6 @@
 
 package org.apache.shardingsphere.proxy.backend.communication;
 
-import com.google.common.base.Preconditions;
 import lombok.AccessLevel;
 import lombok.NoArgsConstructor;
 import org.apache.shardingsphere.infra.binder.LogicSQL;
@@ -62,7 +61,7 @@ public final class DatabaseCommunicationEngineFactory {
      * @return text protocol backend handler
      */
     public DatabaseCommunicationEngine newTextProtocolInstance(final SQLStatement sqlStatement, final String sql, final BackendConnection backendConnection) {
-        ShardingSphereMetaData metaData = getMetaData(backendConnection);
+        ShardingSphereMetaData metaData = ProxyContext.getInstance().getMetaData(backendConnection.getSchemaName());
         LogicSQL logicSQL = createLogicSQL(sqlStatement, sql, Collections.emptyList(), metaData);
         JDBCExecuteEngine jdbcExecuteEngine = new JDBCExecuteEngine(backendConnection, new StatementAccessor());
         return new JDBCDatabaseCommunicationEngine(logicSQL, metaData, jdbcExecuteEngine);
@@ -78,18 +77,12 @@ public final class DatabaseCommunicationEngineFactory {
      * @return binary protocol backend handler
      */
     public DatabaseCommunicationEngine newBinaryProtocolInstance(final SQLStatement sqlStatement, final String sql, final List<Object> parameters, final BackendConnection backendConnection) {
-        ShardingSphereMetaData metaData = getMetaData(backendConnection);
+        ShardingSphereMetaData metaData = ProxyContext.getInstance().getMetaData(backendConnection.getSchemaName());
         LogicSQL logicSQL = createLogicSQL(sqlStatement, sql, new ArrayList<>(parameters), metaData);
         JDBCExecuteEngine jdbcExecuteEngine = new JDBCExecuteEngine(backendConnection, new PreparedStatementAccessor());
         return new JDBCDatabaseCommunicationEngine(logicSQL, metaData, jdbcExecuteEngine);
     }
     
-    private ShardingSphereMetaData getMetaData(final BackendConnection backendConnection) {
-        ShardingSphereMetaData result = ProxyContext.getInstance().getMetaData(backendConnection.getSchemaName());
-        Preconditions.checkNotNull(result);
-        return result;
-    }
-    
     private LogicSQL createLogicSQL(final SQLStatement sqlStatement, final String sql, final List<Object> parameters, final ShardingSphereMetaData metaData) {
         SQLStatementContext<?> sqlStatementContext = SQLStatementContextFactory.newInstance(metaData.getSchema(), parameters, sqlStatement);
         return new LogicSQL(sqlStatementContext, sql, parameters);

shardingsphere-proxy/shardingsphere-proxy-backend/src/main/java/org/apache/shardingsphere/proxy/backend/context/ProxyContext.java

@@ -23,6 +23,7 @@ import org.apache.shardingsphere.infra.context.metadata.MetaDataContexts;
 import org.apache.shardingsphere.infra.context.metadata.impl.StandardMetaDataContexts;
 import org.apache.shardingsphere.infra.metadata.ShardingSphereMetaData;
 import org.apache.shardingsphere.proxy.backend.communication.jdbc.datasource.JDBCBackendDataSource;
+import org.apache.shardingsphere.proxy.backend.exception.NoDatabaseSelectedException;
 import org.apache.shardingsphere.transaction.context.TransactionContexts;
 import org.apache.shardingsphere.transaction.context.impl.StandardTransactionContexts;
 
@@ -30,7 +31,6 @@ import javax.sql.DataSource;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
-import java.util.Objects;
 import java.util.Optional;
 
 /**
@@ -84,13 +84,16 @@ public final class ProxyContext {
     }
     
     /**
-     * Get meta data.
+     * Get ShardingSphere meta data.
      *
      * @param schemaName schema name
-     * @return meta data
+     * @return ShardingSphere meta data
      */
     public ShardingSphereMetaData getMetaData(final String schemaName) {
-        return Strings.isNullOrEmpty(schemaName) ? null : metaDataContexts.getMetaDataMap().get(schemaName);
+        if (Strings.isNullOrEmpty(schemaName) || !metaDataContexts.getMetaDataMap().containsKey(schemaName)) {
+            throw new NoDatabaseSelectedException();
+        }
+        return metaDataContexts.getMetaDataMap().get(schemaName);
     }
     
     /**
@@ -112,7 +115,7 @@ public final class ProxyContext {
         if (schemaNames.isEmpty()) {
             return Optional.empty();
         }
-        Map<String, DataSource> dataSources = Objects.requireNonNull(getMetaData(schemaNames.get(0))).getResource().getDataSources();
+        Map<String, DataSource> dataSources = getMetaData(schemaNames.get(0)).getResource().getDataSources();
         return dataSources.values().stream().findFirst();
     }
 }

shardingsphere-proxy/shardingsphere-proxy-backend/src/main/java/org/apache/shardingsphere/proxy/backend/text/admin/ShowTablesBackendHandler.java

@@ -19,12 +19,10 @@ package org.apache.shardingsphere.proxy.backend.text.admin;
 
 import lombok.RequiredArgsConstructor;
 import org.apache.shardingsphere.infra.executor.sql.raw.execute.result.query.QueryHeader;
-import org.apache.shardingsphere.infra.metadata.ShardingSphereMetaData;
 import org.apache.shardingsphere.proxy.backend.communication.DatabaseCommunicationEngine;
 import org.apache.shardingsphere.proxy.backend.communication.DatabaseCommunicationEngineFactory;
 import org.apache.shardingsphere.proxy.backend.communication.jdbc.connection.BackendConnection;
 import org.apache.shardingsphere.proxy.backend.context.ProxyContext;
-import org.apache.shardingsphere.proxy.backend.exception.NoDatabaseSelectedException;
 import org.apache.shardingsphere.proxy.backend.response.BackendResponse;
 import org.apache.shardingsphere.proxy.backend.response.query.QueryData;
 import org.apache.shardingsphere.proxy.backend.response.query.QueryResponse;
@@ -53,14 +51,10 @@ public final class ShowTablesBackendHandler implements TextProtocolBackendHandle
     
     @Override
     public BackendResponse execute() throws SQLException {
-        ShardingSphereMetaData metaData = ProxyContext.getInstance().getMetaData(backendConnection.getSchemaName());
-        if (null == metaData) {
-            throw new NoDatabaseSelectedException();
-        }
-        if (!metaData.isComplete()) {
+        if (!ProxyContext.getInstance().getMetaData(backendConnection.getSchemaName()).isComplete()) {
             return getDefaultQueryResponse(backendConnection.getSchemaName());
         }
-        // TODO Get all tables from meta data.
+        // TODO Get all tables from meta data
         databaseCommunicationEngine = databaseCommunicationEngineFactory.newTextProtocolInstance(sqlStatement, sql, backendConnection);
         return databaseCommunicationEngine.execute();
     }

shardingsphere-proxy/shardingsphere-proxy-backend/src/main/java/org/apache/shardingsphere/proxy/backend/text/query/QueryBackendHandler.java

@@ -18,12 +18,10 @@
 package org.apache.shardingsphere.proxy.backend.text.query;
 
 import lombok.RequiredArgsConstructor;
-import org.apache.shardingsphere.infra.metadata.ShardingSphereMetaData;
 import org.apache.shardingsphere.proxy.backend.communication.DatabaseCommunicationEngine;
 import org.apache.shardingsphere.proxy.backend.communication.DatabaseCommunicationEngineFactory;
 import org.apache.shardingsphere.proxy.backend.communication.jdbc.connection.BackendConnection;
 import org.apache.shardingsphere.proxy.backend.context.ProxyContext;
-import org.apache.shardingsphere.proxy.backend.exception.NoDatabaseSelectedException;
 import org.apache.shardingsphere.proxy.backend.exception.RuleNotExistsException;
 import org.apache.shardingsphere.proxy.backend.response.BackendResponse;
 import org.apache.shardingsphere.proxy.backend.response.query.QueryData;
@@ -50,11 +48,7 @@ public final class QueryBackendHandler implements TextProtocolBackendHandler {
     
     @Override
     public BackendResponse execute() throws SQLException {
-        ShardingSphereMetaData metaData = ProxyContext.getInstance().getMetaData(backendConnection.getSchemaName());
-        if (null == metaData) {
-            throw new NoDatabaseSelectedException();
-        }
-        if (!metaData.isComplete()) {
+        if (!ProxyContext.getInstance().getMetaData(backendConnection.getSchemaName()).isComplete()) {
             throw new RuleNotExistsException();
         }
         databaseCommunicationEngine = databaseCommunicationEngineFactory.newTextProtocolInstance(sqlStatement, sql, backendConnection);

shardingsphere-proxy/shardingsphere-proxy-backend/src/main/java/org/apache/shardingsphere/proxy/backend/text/sctl/explain/ShardingCTLExplainBackendHandler.java

@@ -29,7 +29,6 @@ import org.apache.shardingsphere.infra.metadata.ShardingSphereMetaData;
 import org.apache.shardingsphere.infra.parser.ShardingSphereSQLParserEngine;
 import org.apache.shardingsphere.proxy.backend.communication.jdbc.connection.BackendConnection;
 import org.apache.shardingsphere.proxy.backend.context.ProxyContext;
-import org.apache.shardingsphere.proxy.backend.exception.NoDatabaseSelectedException;
 import org.apache.shardingsphere.proxy.backend.exception.RuleNotExistsException;
 import org.apache.shardingsphere.proxy.backend.response.BackendResponse;
 import org.apache.shardingsphere.proxy.backend.response.query.QueryData;
@@ -68,9 +67,6 @@ public final class ShardingCTLExplainBackendHandler implements TextProtocolBacke
             throw new InvalidShardingCTLFormatException(sql);
         }
         ShardingSphereMetaData metaData = ProxyContext.getInstance().getMetaData(backendConnection.getSchemaName());
-        if (null == metaData) {
-            throw new NoDatabaseSelectedException();
-        }
         if (!metaData.isComplete()) {
             throw new RuleNotExistsException();
         }

shardingsphere-proxy/shardingsphere-proxy-backend/src/main/java/org/apache/shardingsphere/proxy/backend/text/sctl/hint/internal/executor/HintShowTableStatusExecutor.java

@@ -25,7 +25,6 @@ import org.apache.shardingsphere.infra.merge.result.MergedResult;
 import org.apache.shardingsphere.infra.metadata.ShardingSphereMetaData;
 import org.apache.shardingsphere.proxy.backend.communication.jdbc.connection.BackendConnection;
 import org.apache.shardingsphere.proxy.backend.context.ProxyContext;
-import org.apache.shardingsphere.proxy.backend.exception.NoDatabaseSelectedException;
 import org.apache.shardingsphere.proxy.backend.exception.RuleNotExistsException;
 import org.apache.shardingsphere.proxy.backend.text.sctl.hint.internal.command.HintShowTableStatusCommand;
 import org.apache.shardingsphere.proxy.backend.text.sctl.hint.internal.result.HintShowTableStatusResult;
@@ -60,9 +59,6 @@ public final class HintShowTableStatusExecutor extends AbstractHintQueryExecutor
     protected MergedResult createMergedResult() {
         Map<String, HintShowTableStatusResult> results = new HashMap<>();
         ShardingSphereMetaData metaData = ProxyContext.getInstance().getMetaData(backendConnection.getSchemaName());
-        if (null == metaData) {
-            throw new NoDatabaseSelectedException();
-        }
         if (!metaData.isComplete()) {
             throw new RuleNotExistsException();
         }

shardingsphere-proxy/shardingsphere-proxy-backend/src/test/java/org/apache/shardingsphere/proxy/backend/context/ProxyContextTest.java

@@ -25,6 +25,7 @@ import org.apache.shardingsphere.infra.database.type.dialect.MySQLDatabaseType;
 import org.apache.shardingsphere.infra.executor.kernel.ExecutorKernel;
 import org.apache.shardingsphere.infra.metadata.ShardingSphereMetaData;
 import org.apache.shardingsphere.jdbc.test.MockedDataSource;
+import org.apache.shardingsphere.proxy.backend.exception.NoDatabaseSelectedException;
 import org.apache.shardingsphere.transaction.context.TransactionContexts;
 import org.junit.Test;
 
@@ -86,6 +87,26 @@ public final class ProxyContextTest {
         assertFalse(ProxyContext.getInstance().schemaExists("schema_2"));
     }
     
+    @Test(expected = NoDatabaseSelectedException.class)
+    public void assertGetSchemaWithNull() {
+        assertNull(ProxyContext.getInstance().getMetaData(null));
+    }
+    
+    @Test(expected = NoDatabaseSelectedException.class)
+    public void assertGetSchemaWithEmptyString() {
+        assertNull(ProxyContext.getInstance().getMetaData(""));
+    }
+    
+    @Test(expected = NoDatabaseSelectedException.class)
+    public void assertGetSchemaWhenNotExisted() throws NoSuchFieldException, IllegalAccessException {
+        Map<String, ShardingSphereMetaData> metaDataMap = mockMetaDataMap(Collections.emptyMap());
+        Field metaDataContexts = ProxyContext.getInstance().getClass().getDeclaredField("metaDataContexts");
+        metaDataContexts.setAccessible(true);
+        metaDataContexts.set(ProxyContext.getInstance(),
+                new StandardMetaDataContexts(metaDataMap, mock(ExecutorKernel.class), new Authentication(), new ConfigurationProperties(new Properties()), new MySQLDatabaseType()));
+        ProxyContext.getInstance().getMetaData("schema1");
+    }
+    
     @Test
     public void assertGetSchema() throws NoSuchFieldException, IllegalAccessException {
         Map<String, ShardingSphereMetaData> metaDataMap = mockMetaDataMap(Collections.emptyMap());
@@ -93,9 +114,6 @@ public final class ProxyContextTest {
         metaDataContexts.setAccessible(true);
         metaDataContexts.set(ProxyContext.getInstance(),
                 new StandardMetaDataContexts(metaDataMap, mock(ExecutorKernel.class), new Authentication(), new ConfigurationProperties(new Properties()), new MySQLDatabaseType()));
-        assertNull(ProxyContext.getInstance().getMetaData(null));
-        assertNull(ProxyContext.getInstance().getMetaData(""));
-        assertNull(ProxyContext.getInstance().getMetaData("schema1"));
         assertThat(metaDataMap.get("schema"), is(ProxyContext.getInstance().getMetaData("schema")));
     }
     

shardingsphere-proxy/shardingsphere-proxy-frontend/shardingsphere-proxy-frontend-postgresql/src/main/java/org/apache/shardingsphere/proxy/frontend/postgresql/command/query/binary/bind/PostgreSQLComBindExecutor.java

@@ -32,7 +32,7 @@ import org.apache.shardingsphere.db.protocol.postgresql.packet.generic.PostgreSQ
 import org.apache.shardingsphere.infra.database.type.DatabaseTypeRegistry;
 import org.apache.shardingsphere.infra.executor.sql.QueryResult;
 import org.apache.shardingsphere.infra.executor.sql.raw.execute.result.query.QueryHeader;
-import org.apache.shardingsphere.infra.metadata.ShardingSphereMetaData;
+import org.apache.shardingsphere.infra.parser.ShardingSphereSQLParserEngine;
 import org.apache.shardingsphere.proxy.backend.communication.DatabaseCommunicationEngine;
 import org.apache.shardingsphere.proxy.backend.communication.DatabaseCommunicationEngineFactory;
 import org.apache.shardingsphere.proxy.backend.communication.jdbc.connection.BackendConnection;
@@ -43,7 +43,6 @@ import org.apache.shardingsphere.proxy.backend.response.query.QueryResponse;
 import org.apache.shardingsphere.proxy.backend.response.update.UpdateResponse;
 import org.apache.shardingsphere.proxy.frontend.command.executor.QueryCommandExecutor;
 import org.apache.shardingsphere.proxy.frontend.command.executor.ResponseType;
-import org.apache.shardingsphere.infra.parser.ShardingSphereSQLParserEngine;
 import org.apache.shardingsphere.sql.parser.sql.common.statement.SQLStatement;
 
 import java.sql.ResultSetMetaData;
@@ -69,8 +68,7 @@ public final class PostgreSQLComBindExecutor implements QueryCommandExecutor {
     
     public PostgreSQLComBindExecutor(final PostgreSQLComBindPacket packet, final BackendConnection backendConnection) {
         this.packet = packet;
-        ShardingSphereMetaData metaData = ProxyContext.getInstance().getMetaData(backendConnection.getSchemaName());
-        if (null != packet.getSql() && null != metaData) {
+        if (null != packet.getSql()) {
             ShardingSphereSQLParserEngine sqlStatementParserEngine = new ShardingSphereSQLParserEngine(
                     DatabaseTypeRegistry.getTrunkDatabaseTypeName(ProxyContext.getInstance().getMetaDataContexts().getDatabaseType()));
             SQLStatement sqlStatement = sqlStatementParserEngine.parse(packet.getSql(), true);