Fixes problem when the Cypher parser is run concurrently

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

@@ -31,7 +31,7 @@ class CypherParser(version: String) {
   val v19 = new internal.parser.v1_9.CypherParserImpl
 
   @throws(classOf[SyntaxException])
-  def parse(queryText: String): Query = {
+  def parse(queryText: String): Query = synchronized {
 
     val (v, q) = queryText match {
       case hasVersionDefined(v1, q1) => (v1, q1)

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

@@ -1828,6 +1828,39 @@ foreach(x in [1,2,3] :
       ))
   }
 
+  @Ignore("slow test") @Test def multi_thread_parsing() {
+    val q = """start root=node(0) return x"""
+    val parser = new CypherParser()
+
+    val runners = (1 to 10).toList.map(x => {
+      run(() => parser.parse(q))
+    })
+
+    val threads = runners.map(new Thread(_))
+    threads.foreach(_.start())
+    threads.foreach(_.join())
+
+    runners.foreach(_.report())
+  }
+
+  private def run(f: () => Unit) =
+    new Runnable() {
+      var error: Option[Throwable] = None
+
+      def run() {
+        try {
+          (1 until 500).foreach(x => f())
+        } catch {
+          case e: Throwable => error = Some(e)
+        }
+      }
+
+      def report() {
+        error.foreach(e => throw e)
+      }
+    }
+
+
   def test_1_9(query: String, expectedQuery: Query) {
     testQuery(None, query, expectedQuery)
     testQuery(None, query + ";", expectedQuery)