#317: Small allocation cleanups in parser, logging, and metadata conversion

doc/changes/changes_18.0.2.md

@@ -20,6 +20,7 @@ Code name: Improve code quality
 * #311: Fixed metadata parsing and conversion diagnostics for missing JSON fields and nullable notes/comments, and made `SqlFunctionScalarCast` tolerate a null argument consistently with related SQL AST nodes.
 * #310: Fixed `SqlStatementSelect.Builder.build()` so empty and partial builders no longer fail with a raw `NullPointerException`.
 * #309: Fixed the `SqlNodeVisitor` API documentation and parameter names for `SqlPredicateIsNotNull` and `SqlPredicateIsNull`.
+* #317: Applied small allocation cleanups in request parsing, logging timestamp formatting, and schema metadata JSON conversion.
 * #308: Fixed `SqlLimit` so `limit` and `offset` stay non-negative for the full object lifetime by making the node immutable and aligning the validation message with the accepted zero values.
 * #307: Fixed `PushdownSqlRenderer` so `HASHTYPE` data types include `bytesize` in rendered pushdown SQL JSON.
 * #312: Fixed logging utility resource and handler lifecycle issues by closing version metadata streams, falling back when the thread context class loader is missing, defaulting absent version properties to `UNKNOWN`, closing replaced root log handlers, and resetting closed remote socket handlers before reuse.

src/main/java/com/exasol/adapter/metadata/converter/SchemaMetadataJsonConverter.java

@@ -53,6 +53,7 @@ public final class SchemaMetadataJsonConverter {
     private static final String COMMENT_KEY = "comment";
     private static final String IDENTITY_KEY = "isIdentity";
     private static final String DEFAULT_KEY = "default";
+    private static final String COLUMNS_KEY = "columns";
     private final JsonBuilderFactory factory = Json.createBuilderFactory(Collections.emptyMap());
 
     /**
@@ -94,7 +95,7 @@ private JsonObjectBuilder convertTableMetadata(final TableMetadata table) {
         final JsonObjectBuilder tableBuilder = this.factory.createObjectBuilder();
         tableBuilder.add(TYPE_KEY, "table");
         tableBuilder.add(TABLE_NAME_KEY, table.getName());
-        final JsonArrayBuilder columnsBuilder = Json.createArrayBuilder();
+        final JsonArrayBuilder columnsBuilder = this.factory.createArrayBuilder();
         for (final ColumnMetadata column : table.getColumns()) {
             columnsBuilder.add(convertColumnMetadata(column));
         }
@@ -104,7 +105,7 @@ private JsonObjectBuilder convertTableMetadata(final TableMetadata table) {
         if (table.hasComment()) {
             tableBuilder.add(COMMENT_KEY, table.getComment());
         }
-        tableBuilder.add("columns", columnsBuilder);
+        tableBuilder.add(COLUMNS_KEY, columnsBuilder);
         return tableBuilder;
     }
 

src/main/java/com/exasol/adapter/request/parser/AbstractRequestParser.java

@@ -2,8 +2,7 @@
 
 import static com.exasol.adapter.request.parser.RequestParserConstants.PROPERTIES_KEY;
 
-import java.io.ByteArrayInputStream;
-import java.nio.charset.StandardCharsets;
+import java.io.StringReader;
 import java.util.*;
 import java.util.Map.Entry;
 
@@ -27,9 +26,7 @@ class AbstractRequestParser {
      * @return JSON reader
      */
     protected JsonReader createJsonReader(final String rawRequest) {
-        final ByteArrayInputStream rawRequestStream = new ByteArrayInputStream(
-                rawRequest.getBytes(StandardCharsets.UTF_8));
-        return Json.createReader(rawRequestStream);
+        return Json.createReader(new StringReader(rawRequest));
     }
 
     /**

src/main/java/com/exasol/adapter/response/converter/ResponseJsonConverter.java

@@ -1,5 +1,7 @@
 package com.exasol.adapter.response.converter;
 
+import static java.util.Collections.emptyMap;
+
 import com.exasol.adapter.capabilities.*;
 import com.exasol.adapter.metadata.converter.SchemaMetadataJsonConverter;
 import com.exasol.adapter.response.*;
@@ -16,6 +18,7 @@ public final class ResponseJsonConverter {
     private static final String LITERAL_PREFIX = "LITERAL_";
     private static final String SCHEMA_METADATA = "schemaMetadata";
     private static final ResponseJsonConverter responseJsonConverter = new ResponseJsonConverter();
+    private final JsonBuilderFactory factory = Json.createBuilderFactory(emptyMap());
 
     private ResponseJsonConverter() {
     }
@@ -37,7 +40,7 @@ public static ResponseJsonConverter getInstance() {
      */
     @SuppressWarnings("squid:S1172")
     public String convertDropVirtualSchemaResponse(final DropVirtualSchemaResponse dropResponse) {
-        return Json.createObjectBuilder() //
+        return this.factory.createObjectBuilder() //
                 .add("type", "dropVirtualSchema") //
                 .build() //
                 .toString();
@@ -50,7 +53,7 @@ public String convertDropVirtualSchemaResponse(final DropVirtualSchemaResponse d
      * @return string representation of a JSON Object
      */
     public String convertCreateVirtualSchemaResponse(final CreateVirtualSchemaResponse createResponse) {
-        return Json.createObjectBuilder() //
+        return this.factory.createObjectBuilder() //
                 .add("type", "createVirtualSchema") //
                 .add(SCHEMA_METADATA,
                         SchemaMetadataJsonConverter.getInstance().convert(createResponse.getSchemaMetadata())) //
@@ -65,7 +68,7 @@ public String convertCreateVirtualSchemaResponse(final CreateVirtualSchemaRespon
      * @return string representation of a JSON Object
      */
     public String convertPushDownResponse(final PushDownResponse pushDownResponse) {
-        return Json.createObjectBuilder() //
+        return this.factory.createObjectBuilder() //
                 .add("type", "pushdown") //
                 .add("sql", pushDownResponse.getPushDownSql()) //
                 .build() //
@@ -79,8 +82,8 @@ public String convertPushDownResponse(final PushDownResponse pushDownResponse) {
      * @return string representation of a JSON Object
      */
     public String convertGetCapabilitiesResponse(final GetCapabilitiesResponse getCapabilitiesResponse) {
-        final JsonObjectBuilder builder = Json.createObjectBuilder().add("type", "getCapabilities");
-        final JsonArrayBuilder arrayBuilder = Json.createArrayBuilder();
+        final JsonObjectBuilder builder = this.factory.createObjectBuilder().add("type", "getCapabilities");
+        final JsonArrayBuilder arrayBuilder = this.factory.createArrayBuilder();
         final Capabilities capabilities = getCapabilitiesResponse.getCapabilities();
         addMainCapabilitiesToBuilder(capabilities, arrayBuilder);
         addScalarFunctionCapabilitiesToBuilder(capabilities, arrayBuilder);
@@ -136,7 +139,7 @@ private void addMainCapabilitiesToBuilder(final Capabilities capabilities, final
      * @return string representation of a JSON Object
      */
     public String convertRefreshResponse(final RefreshResponse refreshResponse) {
-        return Json.createObjectBuilder() //
+        return this.factory.createObjectBuilder() //
                 .add("type", "refresh") //
                 .add(SCHEMA_METADATA,
                         SchemaMetadataJsonConverter.getInstance().convert(refreshResponse.getSchemaMetadata())) //
@@ -151,7 +154,7 @@ public String convertRefreshResponse(final RefreshResponse refreshResponse) {
      * @return string representation of a JSON Object
      */
     public String convertSetPropertiesResponse(final SetPropertiesResponse setPropertiesResponse) {
-        final JsonObjectBuilder builder = Json.createObjectBuilder();
+        final JsonObjectBuilder builder = this.factory.createObjectBuilder();
         builder.add("type", "setProperties");
         if (setPropertiesResponse.getSchemaMetadata() != null) {
             builder.add(SCHEMA_METADATA,

src/main/java/com/exasol/logging/CompactFormatter.java

@@ -3,7 +3,7 @@
 import java.io.PrintWriter;
 import java.io.StringWriter;
 import java.time.Instant;
-import java.time.ZoneId;
+import java.time.ZoneOffset;
 import java.time.format.DateTimeFormatter;
 import java.util.logging.Formatter;
 import java.util.logging.LogRecord;
@@ -13,7 +13,8 @@
  */
 public class CompactFormatter extends Formatter {
     private static final String LOG_LEVEL_FORMAT = "%-8s";
-    private final DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS");
+    private final DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS")
+            .withZone(ZoneOffset.UTC);
 
     /**
      * Formats a log record according in a compact manner.
@@ -24,14 +25,14 @@ public class CompactFormatter extends Formatter {
      * <code>yyyy-MM-dd HH:mm:ss.SSS LEVEL   [c.e.ClassName] The message.</code>
      */
     @Override
-    public String format(final LogRecord record) {
+    public String format(final LogRecord logRecord) {
         final StringBuilder builder = new StringBuilder();
-        builder.append(formatTimestamp(record.getMillis()));
+        builder.append(formatTimestamp(logRecord.getMillis()));
         builder.append(" ");
-        builder.append(String.format(LOG_LEVEL_FORMAT, record.getLevel()));
-        appendClassName(record.getSourceClassName(), builder);
-        builder.append(formatMessage(record));
-        formatException(record, builder);
+        builder.append(String.format(LOG_LEVEL_FORMAT, logRecord.getLevel()));
+        appendClassName(logRecord.getSourceClassName(), builder);
+        builder.append(formatMessage(logRecord));
+        formatException(logRecord, builder);
         builder.append(System.lineSeparator());
         return builder.toString();
     }
@@ -61,16 +62,16 @@ private void appendNonEmptyClassName(final String className, final StringBuilder
 
     private String formatTimestamp(final long millis) {
         final Instant instant = Instant.ofEpochMilli(millis);
-        return this.dateTimeFormatter.format(instant.atZone(ZoneId.of("Z")));
+        return this.dateTimeFormatter.format(instant);
     }
 
-    private void formatException(final LogRecord record, final StringBuilder builder) {
-        final Throwable thrown = record.getThrown();
+    private void formatException(final LogRecord logRecord, final StringBuilder builder) {
+        final Throwable thrown = logRecord.getThrown();
         if (thrown != null) {
             builder.append("\n\t");
             final StringWriter errors = new StringWriter();
             thrown.printStackTrace(new PrintWriter(errors));
             builder.append(errors);
         }
     }
-}
+}

src/test/java/com/exasol/adapter/request/parser/RequestParserTest.java

@@ -64,6 +64,17 @@ void setPropertiesRequest() {
                 () -> assertThat(properties, hasEntry(equalTo("NULL_value"), equalTo(null))));
     }
 
+    @Test
+    void setPropertiesRequestPreservesUtf8Characters() {
+        final String rawRequest = JsonEntry.object(
+                entry("type", "setProperties"),
+                entry("properties", object(entry("CITY", "München"))),
+                SCHEMA_METADATA_INFO).render();
+        final AdapterRequest request = this.parser.parse(rawRequest);
+        final Map<String, String> properties = ((SetPropertiesRequest) request).getProperties();
+        assertThat(properties, hasEntry(equalTo("CITY"), equalTo("München")));
+    }
+
     @Test
     void unsupportedPropertyType() {
         final String rawRequest = JsonEntry.object(//
@@ -157,4 +168,4 @@ private JsonParent createPushDownRequest(final JsonEntry selectListDataTypes) {
                                 )))))))), //
                 SCHEMA_METADATA_INFO);
     }
-}
+}