Improve Record#get(String key) complexity to O(1)

driver/src/main/java/org/neo4j/driver/internal/InternalRecord.java

@@ -22,36 +22,43 @@
 import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
+import java.util.function.Function;
 
-import org.neo4j.driver.internal.types.InternalMapAccessorWithDefaultValue;
-import org.neo4j.driver.internal.util.Extract;
 import org.neo4j.driver.Record;
 import org.neo4j.driver.Value;
 import org.neo4j.driver.Values;
-import java.util.function.Function;
+import org.neo4j.driver.internal.types.InternalMapAccessorWithDefaultValue;
+import org.neo4j.driver.internal.util.Extract;
+import org.neo4j.driver.internal.util.QueryKeys;
 import org.neo4j.driver.util.Pair;
 
 import static java.lang.String.format;
-import static org.neo4j.driver.internal.util.Format.formatPairs;
 import static org.neo4j.driver.Values.ofObject;
 import static org.neo4j.driver.Values.ofValue;
+import static org.neo4j.driver.internal.util.Format.formatPairs;
 
 public class InternalRecord extends InternalMapAccessorWithDefaultValue implements Record
 {
-    private final List<String> keys;
+    private final QueryKeys queryKeys;
     private final Value[] values;
     private int hashCode = 0;
 
     public InternalRecord( List<String> keys, Value[] values )
     {
-        this.keys = keys;
+        this.queryKeys = new QueryKeys( keys );
+        this.values = values;
+    }
+
+    public InternalRecord( QueryKeys queryKeys, Value[] values )
+    {
+        this.queryKeys = queryKeys;
         this.values = values;
     }
 
     @Override
     public List<String> keys()
     {
-        return keys;
+        return queryKeys.keys();
     }
 
     @Override
@@ -69,7 +76,7 @@ public List<Pair<String, Value>> fields()
     @Override
     public int index( String key )
     {
-        int result = keys.indexOf( key );
+        int result = queryKeys.indexOf( key );
         if ( result == -1 )
         {
             throw new NoSuchElementException( "Unknown key: " + key );
@@ -83,13 +90,13 @@ public int index( String key )
     @Override
     public boolean containsKey( String key )
     {
-        return keys.contains( key );
+        return queryKeys.contains( key );
     }
 
     @Override
     public Value get( String key )
     {
-        int fieldIndex = keys.indexOf( key );
+        int fieldIndex = queryKeys.indexOf( key );
 
         if ( fieldIndex == -1 )
         {
@@ -146,7 +153,7 @@ else if ( other instanceof Record )
             {
                 return false;
             }
-            if ( ! keys.equals( otherRecord.keys() ) )
+            if ( ! queryKeys.equals( otherRecord.keys() ) )
             {
                 return false;
             }
@@ -172,7 +179,7 @@ public int hashCode()
     {
         if ( hashCode == 0 )
         {
-            hashCode = 31 * keys.hashCode() + Arrays.hashCode( values );
+            hashCode = 31 * queryKeys.hashCode() + Arrays.hashCode( values );
         }
         return hashCode;
     }

driver/src/main/java/org/neo4j/driver/internal/cursor/AsyncResultCursorImpl.java

@@ -45,7 +45,7 @@ public AsyncResultCursorImpl(RunResponseHandler runHandler, PullAllResponseHandl
     @Override
     public List<String> keys()
     {
-        return runHandler.queryKeys();
+        return runHandler.queryKeys().keys();
     }
 
     @Override

driver/src/main/java/org/neo4j/driver/internal/cursor/RxResultCursorImpl.java

@@ -65,7 +65,7 @@ public RxResultCursorImpl(Throwable runError, RunResponseHandler runHandler, Pul
     @Override
     public List<String> keys()
     {
-        return runHandler.queryKeys();
+        return runHandler.queryKeys().keys();
     }
 
     @Override

driver/src/main/java/org/neo4j/driver/internal/handlers/RunResponseHandler.java

@@ -18,23 +18,21 @@
  */
 package org.neo4j.driver.internal.handlers;
 
-import java.util.List;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 
+import org.neo4j.driver.Value;
 import org.neo4j.driver.internal.spi.ResponseHandler;
 import org.neo4j.driver.internal.util.MetadataExtractor;
-import org.neo4j.driver.Value;
-
-import static java.util.Collections.emptyList;
+import org.neo4j.driver.internal.util.QueryKeys;
 
 public class RunResponseHandler implements ResponseHandler
 {
     private final CompletableFuture<Throwable> runCompletedFuture;
     private final MetadataExtractor metadataExtractor;
     private long queryId = MetadataExtractor.ABSENT_QUERY_ID;
 
-    private List<String> queryKeys = emptyList();
+    private QueryKeys queryKeys = QueryKeys.empty();
     private long resultAvailableAfter = -1;
 
     public RunResponseHandler( MetadataExtractor metadataExtractor )
@@ -70,7 +68,7 @@ public void onRecord( Value[] fields )
         throw new UnsupportedOperationException();
     }
 
-    public List<String> queryKeys()
+    public QueryKeys queryKeys()
     {
         return queryKeys;
     }

driver/src/main/java/org/neo4j/driver/internal/util/MetadataExtractor.java

@@ -18,7 +18,6 @@
  */
 package org.neo4j.driver.internal.util;
 
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
@@ -40,11 +39,10 @@
 import org.neo4j.driver.summary.Notification;
 import org.neo4j.driver.summary.Plan;
 import org.neo4j.driver.summary.ProfiledPlan;
+import org.neo4j.driver.summary.QueryType;
 import org.neo4j.driver.summary.ResultSummary;
 import org.neo4j.driver.summary.ServerInfo;
-import org.neo4j.driver.summary.QueryType;
 
-import static java.util.Collections.emptyList;
 import static org.neo4j.driver.internal.summary.InternalDatabaseInfo.DEFAULT_DATABASE_INFO;
 import static org.neo4j.driver.internal.types.InternalTypeSystem.TYPE_SYSTEM;
 
@@ -60,14 +58,14 @@ public MetadataExtractor( String resultAvailableAfterMetadataKey, String resultC
         this.resultConsumedAfterMetadataKey = resultConsumedAfterMetadataKey;
     }
 
-    public List<String> extractQueryKeys(Map<String,Value> metadata )
+    public QueryKeys extractQueryKeys( Map<String,Value> metadata )
     {
         Value keysValue = metadata.get( "fields" );
         if ( keysValue != null )
         {
             if ( !keysValue.isEmpty() )
             {
-                List<String> keys = new ArrayList<>( keysValue.size() );
+                QueryKeys keys = new QueryKeys( keysValue.size() );
                 for ( Value value : keysValue.values() )
                 {
                     keys.add( value.asString() );
@@ -76,7 +74,7 @@ public List<String> extractQueryKeys(Map<String,Value> metadata )
                 return keys;
             }
         }
-        return emptyList();
+        return QueryKeys.empty();
     }
 
     public long extractQueryId( Map<String,Value> metadata )

driver/src/main/java/org/neo4j/driver/internal/util/QueryKeys.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2002-2020 "Neo4j,"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Licensed 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.neo4j.driver.internal.util;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+
+import static java.util.Collections.emptyList;
+import static java.util.Collections.emptyMap;
+
+public class QueryKeys
+{
+    private static final QueryKeys EMPTY = new QueryKeys( emptyList(), emptyMap() );
+
+    private final List<String> keys;
+    private final Map<String,Integer> keyIndex;
+
+    public QueryKeys( int size )
+    {
+        this( new ArrayList<>( size ), new HashMap<>( size ) );
+    }
+
+    public QueryKeys( List<String> keys )
+    {
+        this.keys = keys;
+        Map<String,Integer> keyIndex = new HashMap<>( keys.size() );
+        int i = 0;
+        for ( String key : keys )
+        {
+            keyIndex.put( key, i++ );
+        }
+        this.keyIndex = keyIndex;
+    }
+
+    public QueryKeys( List<String> keys, Map<String,Integer> keyIndex )
+    {
+        this.keys = keys;
+        this.keyIndex = keyIndex;
+    }
+
+    public void add( String key )
+    {
+        int index = keys.size();
+        keys.add( key );
+        keyIndex.put( key, index );
+    }
+
+    public List<String> keys()
+    {
+        return keys;
+    }
+
+    public Map<String,Integer> keyIndex()
+    {
+        return keyIndex;
+    }
+
+    public static QueryKeys empty()
+    {
+        return EMPTY;
+    }
+
+    public int indexOf( String key )
+    {
+        return keyIndex.getOrDefault( key, -1 );
+    }
+
+    public boolean contains( String key )
+    {
+        return keyIndex.containsKey( key );
+    }
+
+    @Override
+    public boolean equals( Object o )
+    {
+        if ( this == o )
+        {
+            return true;
+        }
+        if ( o == null || getClass() != o.getClass() )
+        {
+            return false;
+        }
+        QueryKeys queryKeys = (QueryKeys) o;
+        return keys.equals( queryKeys.keys ) && keyIndex.equals( queryKeys.keyIndex );
+    }
+
+    @Override
+    public int hashCode()
+    {
+        return Objects.hash( keys, keyIndex );
+    }
+}

driver/src/test/java/org/neo4j/driver/internal/reactive/util/ListBasedPullHandler.java

@@ -27,6 +27,7 @@
 import org.neo4j.driver.internal.handlers.pulln.BasicPullResponseHandler;
 import org.neo4j.driver.internal.spi.Connection;
 import org.neo4j.driver.internal.util.MetadataExtractor;
+import org.neo4j.driver.internal.util.QueryKeys;
 import org.neo4j.driver.internal.value.BooleanValue;
 import org.neo4j.driver.Record;
 import org.neo4j.driver.Value;
@@ -72,7 +73,7 @@ private ListBasedPullHandler( List<Record> list, Throwable error )
         if ( list.size() > 1 )
         {
             Record record = list.get( 0 );
-            when( super.runResponseHandler.queryKeys() ).thenReturn( record.keys() );
+            when( super.runResponseHandler.queryKeys() ).thenReturn( new QueryKeys( record.keys() ) );
         }
     }
 

driver/src/test/java/org/neo4j/driver/internal/util/MetadataExtractorTest.java

@@ -20,6 +20,7 @@
 
 import org.junit.jupiter.api.Test;
 
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
@@ -77,15 +78,23 @@ class MetadataExtractorTest
     void shouldExtractQueryKeys()
     {
         List<String> keys = asList( "hello", " ", "world", "!" );
-        List<String> extractedKeys = extractor.extractQueryKeys( singletonMap( "fields", value( keys ) ) );
-        assertEquals( keys, extractedKeys );
+        Map<String, Integer> keyIndex = new HashMap<>();
+        keyIndex.put( "hello", 0 );
+        keyIndex.put( " ", 1 );
+        keyIndex.put( "world", 2 );
+        keyIndex.put( "!", 3 );
+
+        QueryKeys extracted = extractor.extractQueryKeys( singletonMap( "fields", value( keys ) ) );
+        assertEquals( keys, extracted.keys() );
+        assertEquals( keyIndex, extracted.keyIndex() );
     }
 
     @Test
     void shouldExtractEmptyQueryKeysWhenNoneInMetadata()
     {
-        List<String> extractedKeys = extractor.extractQueryKeys( emptyMap() );
-        assertEquals( emptyList(), extractedKeys );
+        QueryKeys extracted = extractor.extractQueryKeys( emptyMap() );
+        assertEquals( emptyList(), extracted.keys() );
+        assertEquals( emptyMap(), extracted.keyIndex() );
     }
 
     @Test