Add column name index mapping in PostgresqlRow.

Avoid looping through the fields unnecessarily.

[resolves #636][#640]

Author: cty123

src/main/java/io/r2dbc/postgresql/PostgresqlRow.java

@@ -24,6 +24,9 @@
 import io.r2dbc.postgresql.message.backend.RowDescription;
 import io.r2dbc.postgresql.util.Assert;
 import io.r2dbc.spi.Row;
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Map;
 import reactor.core.publisher.Mono;
 import reactor.util.annotation.Nullable;
 
@@ -47,6 +50,8 @@ final class PostgresqlRow implements io.r2dbc.postgresql.api.PostgresqlRow {
 
     private volatile boolean isReleased = false;
 
+    private Map<String, Integer> columnNameIndexCacheMap;
+
     PostgresqlRow(ConnectionResources context, io.r2dbc.postgresql.api.PostgresqlRowMetadata metadata, List<RowDescription.Field> fields, ByteBuf[] data) {
         this.context = Assert.requireNonNull(context, "context must not be null");
         this.metadata = Assert.requireNonNull(metadata, "metadata must not be null");
@@ -138,6 +143,15 @@ public String toString() {
             '}';
     }
 
+    static Map<String, Integer> createColumnNameIndexMap(List<RowDescription.Field> fields) {
+        Map<String, Integer> columnNameIndexMap = new HashMap<>(fields.size() * 2);
+        for (int i = fields.size() - 1; i >= 0; i--) {
+            columnNameIndexMap.put(fields.get(i).getName().toLowerCase(Locale.US), i);
+        }
+
+        return columnNameIndexMap;
+    }
+
     static PostgresqlRow toRow(ConnectionResources context, DataRow dataRow, Codecs codecs, RowDescription rowDescription) {
         Assert.requireNonNull(dataRow, "dataRow must not be null");
         Assert.requireNonNull(codecs, "rowDescription must not be null");
@@ -165,12 +179,19 @@ void release() {
     }
 
     private int getColumn(String name) {
-        for (int i = 0; i < this.fields.size(); i++) {
-            RowDescription.Field field = this.fields.get(i);
+        if (this.columnNameIndexCacheMap == null) {
+            this.columnNameIndexCacheMap = createColumnNameIndexMap(this.fields);
+        }
 
-            if (field.getName().equalsIgnoreCase(name)) {
-                return i;
-            }
+        Integer index = this.columnNameIndexCacheMap.get(name);
+        if (index != null) {
+            return index;
+        }
+
+        index = this.columnNameIndexCacheMap.get(name.toLowerCase(Locale.US));
+        if (index != null) {
+            this.columnNameIndexCacheMap.put(name, index);
+            return index;
         }
 
         throw new NoSuchElementException(String.format("Column name '%s' does not exist in column names %s", name, toColumnNames()));

src/test/java/io/r2dbc/postgresql/PostgresqlRowUnitTests.java

@@ -132,6 +132,7 @@ void getName() {
             .build();
 
         assertThat(new PostgresqlRow(MockContext.builder().codecs(codecs).build(), new PostgresqlRowMetadata(Collections.emptyList()), this.columns, this.data).get("test-name-2", Object.class)).isSameAs(value);
+        assertThat(new PostgresqlRow(MockContext.builder().codecs(codecs).build(), new PostgresqlRowMetadata(Collections.emptyList()), this.columns, this.data).get("tEsT-nAme-2", Object.class)).isSameAs(value);
     }
 
     @Test