From 86d02161595b6ac6a1d5ef28ceea40af5cd91c2b Mon Sep 17 00:00:00 2001
From: rob bygrave <robin.bygrave@gmail.com>
Date: Mon, 4 Mar 2019 12:42:08 +1300
Subject: [PATCH] #1644 - ENH: Improve batch flush when multiple "top level"
 (unrelated) types are persisted

---
 .../server/persist/BatchControl.java          |  8 +--
 .../transaction/TestBatchModelFlush.java      | 64 +++++++++++++++++++
 2 files changed, 68 insertions(+), 4 deletions(-)

diff --git a/src/main/java/io/ebeaninternal/server/persist/BatchControl.java b/src/main/java/io/ebeaninternal/server/persist/BatchControl.java
index 4a3cafa8b..0b6fd3a66 100644
--- a/src/main/java/io/ebeaninternal/server/persist/BatchControl.java
+++ b/src/main/java/io/ebeaninternal/server/persist/BatchControl.java
@@ -69,6 +69,7 @@ public final class BatchControl {
    * Size of the largest buffer.
    */
   private int bufferMax;
+  private int topCounter;
 
   private Queue earlyQueue;
   private Queue lateQueue;
@@ -246,6 +247,7 @@ public final class BatchControl {
     pstmtHolder.clear();
     beanHoldMap.clear();
     maxDepth = 0;
+    topCounter = 0;
   }
 
   private void flushBuffer(boolean resetTop) throws BatchedSqlException {
@@ -319,10 +321,8 @@ public final class BatchControl {
         if (maybe != -1) {
           beanDepth = maybe;
         } else {
-          // we can't be certain of the relative ordering for this type so
-          // flush and reset the batch as we are changing the type of our top level
-          // bean so just keep it simple and flush and reset the top
-          flushReset();
+          // additional "top level" bean type ordered by save() order
+          beanDepth += ++topCounter;
         }
       }
 
diff --git a/src/test/java/org/tests/transaction/TestBatchModelFlush.java b/src/test/java/org/tests/transaction/TestBatchModelFlush.java
index c176392a1..a8195ec96 100644
--- a/src/test/java/org/tests/transaction/TestBatchModelFlush.java
+++ b/src/test/java/org/tests/transaction/TestBatchModelFlush.java
@@ -1,10 +1,19 @@
 package org.tests.transaction;
 
 import io.ebean.BaseTestCase;
+import io.ebean.DB;
 import io.ebean.Ebean;
+import io.ebean.Transaction;
 import io.ebean.annotation.Transactional;
+import org.ebeantest.LoggedSqlCollector;
 import org.junit.Test;
 import org.tests.model.m2m.MnyB;
+import org.tests.model.m2m.MnyTopic;
+import org.tests.model.m2m.Role;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
 
 public class TestBatchModelFlush extends BaseTestCase {
 
@@ -30,4 +39,59 @@ public class TestBatchModelFlush extends BaseTestCase {
     // the rest is flushed on commit
     new MnyB("TestBatchModelFlush_5").save();
   }
+
+  @Test
+  public void multipleTopLevel_expect_singleFlush() {
+
+    LoggedSqlCollector.start();
+
+    // 2 unrelated "top level" beans being persisted
+    MnyB m0 = new MnyB("BatchMultipleTop_0");
+    MnyB m1 = new MnyB("BatchMultipleTop_1");
+    Role r0 = new Role("Role_0");
+    Role r1 = new Role("Role_1");
+
+    MnyTopic t0 = new MnyTopic("MnyTopic_0");
+    MnyTopic t1 = new MnyTopic("MnyTopic_1");
+
+    try (Transaction transaction = DB.beginTransaction()) {
+      transaction.setBatchMode(true);
+
+      m0.save();
+      DB.save(r0);
+      DB.save(t0);
+      DB.save(t1);
+
+      m1.save();
+      DB.save(r1);
+
+      transaction.commit();
+    }
+
+    List<String> sql = LoggedSqlCollector.stop();
+
+    // DEBUG io.ebean.SUM - txn[1001] BatchControl flush [MnyB:100 i:2, Role:101 i:2, MnyTopic:102 i:2]
+
+    assertThat(sql).hasSize(9);
+
+    // first saved to batch - (depth 100)
+    assertThat(sql.get(0)).contains("insert into mny_b");
+    assertThat(sql.get(1)).contains(" -- bind(BatchMultipleTop_0");
+    assertThat(sql.get(2)).contains(" -- bind(BatchMultipleTop_1");
+    // second saved to batch - (depth 101)
+    assertThat(sql.get(3)).contains("insert into mt_role");
+    assertThat(sql.get(4)).contains(" -- bind(");
+    assertThat(sql.get(5)).contains(" -- bind(");
+    // third saved to batch - (depth 102)
+    assertThat(sql.get(6)).contains("insert into mny_topic");
+    assertThat(sql.get(7)).contains(" -- bind(MnyTopic_0");
+    assertThat(sql.get(8)).contains(" -- bind(MnyTopic_1");
+
+    DB.delete(t0);
+    DB.delete(t1);
+    DB.delete(r0);
+    DB.delete(r1);
+    DB.delete(m0);
+    DB.delete(m1);
+  }
 }