Merge pull request #955 from jakewins/cypher-configurable-cache

Added config setting for cypher query cache

cypher/src/main/scala/org/neo4j/cypher/ExecutionEngine.scala

@@ -25,9 +25,10 @@ import internal.LRUCache
 import scala.collection.JavaConverters._
 import java.lang.Error
 import java.util.{Map => JavaMap}
-import scala.deprecated
+import scala.{Int, deprecated}
 import org.neo4j.kernel.InternalAbstractGraphDatabase
 import org.neo4j.graphdb.GraphDatabaseService
+import org.neo4j.graphdb.factory.GraphDatabaseSettings
 
 class ExecutionEngine(graph: GraphDatabaseService) {
   checkScalaVersion()
@@ -38,9 +39,9 @@ class ExecutionEngine(graph: GraphDatabaseService) {
 
   private def createCorrectParser() = if (graph.isInstanceOf[InternalAbstractGraphDatabase]) {
     val database = graph.asInstanceOf[InternalAbstractGraphDatabase]
-    database.getConfig.getParams.asScala.get("cypher_parser_version") match {
-      case None => new CypherParser()
-      case Some(v) => new CypherParser(v)
+    database.getConfig.get(GraphDatabaseSettings.cypher_parser_version) match {
+      case v:String => new CypherParser(v)
+      case _ => new CypherParser()
     }
   }
   else {
@@ -61,6 +62,9 @@ class ExecutionEngine(graph: GraphDatabaseService) {
   def prepare(query: String): ExecutionPlan =
     executionPlanCache.getOrElseUpdate(query, new ExecutionPlanImpl(parser.parse(query), graph))
 
+  def isPrepared(query : String) : Boolean =
+    executionPlanCache.containsKey(query)
+
   @throws(classOf[SyntaxException])
   @deprecated(message = "You should not parse queries manually any more. Use the execute(String) instead")
   def execute(query: Query): ExecutionResult = execute(query, Map[String, Any]())
@@ -80,7 +84,16 @@ class ExecutionEngine(graph: GraphDatabaseService) {
     }
   }
 
-  private val cacheSize: Int = 100
-  private val executionPlanCache = new LRUCache[String, ExecutionPlan](cacheSize) {}
+  private val executionPlanCache = new LRUCache[String, ExecutionPlan]( getQueryCacheSize() ) {}
+
+  private def getQueryCacheSize() : Int = if (graph.isInstanceOf[InternalAbstractGraphDatabase]) {
+    val database = graph.asInstanceOf[InternalAbstractGraphDatabase]
+    database.getConfig.get(GraphDatabaseSettings.query_cache_size) match {
+      case v:java.lang.Integer => v
+      case _ => 100
+    }
+  } else {
+    100
+  }
 }
 

cypher/src/test/scala/org/neo4j/cypher/ConfigureQueryCacheTest.scala

@@ -0,0 +1,54 @@
+/**
+ * Copyright (c) 2002-2012 "Neo Technology,"
+ * Network Engine for Objects in Lund AB [http://neotechnology.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.cypher
+
+import org.scalatest.Assertions
+import org.junit.Test
+import org.neo4j.kernel.InternalAbstractGraphDatabase
+import org.junit.Assert._
+import java.util
+import org.neo4j.graphdb.factory.GraphDatabaseSettings
+
+
+class ConfigureQueryCacheTest extends GraphDatabaseTestBase with Assertions
+{
+
+  @Test
+  def shouldBeAbleToChangeCacheSize()
+  {
+    // Given
+    val config: util.Map[String, String] = graph.asInstanceOf[InternalAbstractGraphDatabase].getConfig.getParams
+    config.put(GraphDatabaseSettings.query_cache_size.name(), "2");
+    graph.asInstanceOf[InternalAbstractGraphDatabase].getConfig.applyChanges(config)
+
+    val engine = new ExecutionEngine(graph);
+
+    // When
+    engine.prepare("START n=node(1) RETURN n")
+    engine.prepare("START n=node(2) RETURN n")
+    engine.prepare("START n=node(3) RETURN n")
+
+    // Then
+    assertTrue("Should have cached last query", engine.isPrepared("START n=node(3) RETURN n"))
+    assertTrue("Should have cached second query", engine.isPrepared("START n=node(2) RETURN n"))
+    assertFalse("Should not have cached first query", engine.isPrepared("START n=node(1) RETURN n"))
+  }
+
+}

kernel/src/main/java/org/neo4j/graphdb/config/Setting.java

@@ -23,7 +23,7 @@
  * This interface is available only for use, not for implementing. Implementing this interface is not expected, and
  * backwards compatibility is not guaranteed for implementors.
  */
-public interface Setting
+public interface Setting<T>
 {
     public String name();
 

kernel/src/main/java/org/neo4j/graphdb/factory/GraphDatabaseSetting.java

@@ -49,7 +49,7 @@
  */
 // Deprecated because we want to make this internal. Users should use Setting<T> instead.
 @Deprecated
-public abstract class GraphDatabaseSetting<T> implements Setting
+public abstract class GraphDatabaseSetting<T> implements Setting<T>
 {
     public static final String TRUE = "true";
     public static final String FALSE = "false";

kernel/src/main/java/org/neo4j/graphdb/factory/GraphDatabaseSettings.java

@@ -24,6 +24,7 @@
 import static org.neo4j.graphdb.factory.GraphDatabaseSetting.FALSE;
 import static org.neo4j.graphdb.factory.GraphDatabaseSetting.TRUE;
 
+import org.neo4j.graphdb.config.Setting;
 import org.neo4j.graphdb.factory.GraphDatabaseSetting.BooleanSetting;
 import org.neo4j.graphdb.factory.GraphDatabaseSetting.DefaultValue;
 import org.neo4j.graphdb.factory.GraphDatabaseSetting.FloatSetting;
@@ -99,10 +100,17 @@ public abstract class GraphDatabaseSettings
     @Default(FALSE)
     public static final BooleanSetting intercept_deserialized_transactions = new BooleanSetting( "intercept_deserialized_transactions" );
 
-    // Cypher version
+    // Cypher settings
+    // TODO: These should live with cypher
     @Description( "Enable this to specify a parser other than the default one." )
     public static final OptionsSetting cypher_parser_version = new CypherParserSetting();
 
+    @Description( "Used to set the number of Cypher query execution plans that are cached." )
+    @Default( "100" )
+    public static GraphDatabaseSetting<Integer> query_cache_size = new IntegerSetting( "query_cache_size",
+            "Query cache size must be at least 0.", 0, Integer.MAX_VALUE  );
+
+
     // Store files
 
     @Description("The directory where the database files are located.")

kernel/src/main/java/org/neo4j/kernel/configuration/Config.java

@@ -29,6 +29,7 @@
 import java.util.List;
 import java.util.Map;
 
+import org.neo4j.graphdb.config.Setting;
 import org.neo4j.graphdb.factory.GraphDatabaseSetting;
 import org.neo4j.helpers.Function;
 import org.neo4j.helpers.TimeUtil;
@@ -95,7 +96,7 @@ public Collection<String> getKeys()
         return params.keySet();
     }
 
-    public boolean isSet( GraphDatabaseSetting<?> graphDatabaseSetting )
+    public boolean isSet( Setting<?> graphDatabaseSetting )
     {
         return params.containsKey( graphDatabaseSetting.name() ) && params.get( graphDatabaseSetting.name() ) != null;
     }