Fix multi-threaded mode insert exception "Unique index or primary key…

Fix multi-threaded mode insert exception "Unique index or primary key violation", test case by Anatolii K

h2/src/docsrc/html/changelog.html

@@ -21,6 +21,8 @@ Change Log
 
 <h2>Next Version (unreleased)</h2>
 <ul>
+<li>Fix multi-threaded mode insert exception "Unique index or primary key violation", test case by Anatolii K
+</li>
 <li>Implement ILIKE operator for case-insensitive matching
 </li>
 <li>Optimise LIKE queries for the common cases of '%Foo' and '%Foo%'

h2/src/main/org/h2/index/MultiVersionIndex.java

@@ -57,7 +57,7 @@ public class MultiVersionIndex implements Index {
         synchronized (sync) {
             base.add(session, row);
             if (removeIfExists(session, row)) {
-                // for example rolling back an delete operation
+                // for example rolling back a delete operation
             } else if (row.getSessionId() != 0) {
                 // don't insert rows that are added when creating an index
                 delta.add(session, row);

h2/src/main/org/h2/mvstore/db/MVPrimaryIndex.java

@@ -11,6 +11,7 @@ import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map.Entry;
+import java.util.concurrent.atomic.AtomicLong;
 import org.h2.api.ErrorCode;
 import org.h2.engine.Database;
 import org.h2.engine.Session;
@@ -55,7 +56,7 @@ public class MVPrimaryIndex extends BaseIndex {
     private final MVTable mvTable;
     private final String mapName;
     private TransactionMap<Value, Value> dataMap;
-    private long lastKey;
+    private final AtomicLong lastKey = new AtomicLong(0);
     private int mainIndexColumn = -1;
 
     public MVPrimaryIndex(Database db, MVTable table, int id,
@@ -77,7 +78,7 @@ public class MVPrimaryIndex extends BaseIndex {
             dataMap.map.setVolatile(true);
         }
         Value k = dataMap.lastKey();
-        lastKey = k == null ? 0 : k.getLong();
+        lastKey.set(k == null ? 0 : k.getLong());
     }
 
     @Override
@@ -107,7 +108,7 @@ public class MVPrimaryIndex extends BaseIndex {
     public void add(Session session, Row row) {
         if (mainIndexColumn == -1) {
             if (row.getKey() == 0) {
-                row.setKey(++lastKey);
+                row.setKey(lastKey.incrementAndGet());
             }
         } else {
             long c = row.getValue(mainIndexColumn).getLong();
@@ -144,7 +145,10 @@ public class MVPrimaryIndex extends BaseIndex {
         } catch (IllegalStateException e) {
             throw mvTable.convertException(e);
         }
-        lastKey = Math.max(lastKey, row.getKey());
+        // because it's possible to directly update the key using the _rowid_ syntax
+        if (row.getKey() > lastKey.get()) {
+            lastKey.set(row.getKey());
+        }
     }
 
     @Override

h2/src/test/org/h2/test/db/TestMultiThread.java

@@ -71,6 +71,7 @@ public class TestMultiThread extends TestBase implements Runnable {
         testConcurrentInsertUpdateSelect();
         testLockModeWithMultiThreaded();
         testViews();
+        testConcurrentInsert();
     }
 
     private void testConcurrentSchemaChange() throws Exception {
@@ -378,4 +379,55 @@ public class TestMultiThread extends TestBase implements Runnable {
 
         deleteDb("lockMode");
     }
+
+    private void testConcurrentInsert() throws Exception {
+        deleteDb("lockMode");
+
+        final String url = getURL("lockMode;MULTI_THREADED=1", true);
+        final Connection conn = getConnection(url);
+        conn.createStatement().execute(
+                "CREATE TABLE IF NOT EXISTS TRAN (ID NUMBER(18,0) not null PRIMARY KEY)");
+
+        final int threadCount = 100;
+        final ArrayList<Callable<Integer>> callables = new ArrayList<Callable<Integer>>();
+        for (int i = 0; i < threadCount; i++) {
+            final Connection taskConn = getConnection(url);
+            taskConn.setAutoCommit(false);
+            final PreparedStatement insertTranStmt = taskConn
+                    .prepareStatement("INSERT INTO tran (id) values(?)");
+            // to guarantee uniqueness
+            final long initialTransactionId = i * 1000000L;
+            callables.add(new Callable<Integer>() {
+                @Override
+                public Integer call() throws Exception {
+                    long tranId = initialTransactionId;
+                    for (int j = 0; j < 10000; j++) {
+                        insertTranStmt.setLong(1, tranId++);
+                        insertTranStmt.execute();
+                        taskConn.commit();
+                    }
+                    return 1;
+                }
+            });
+        }
+
+        final ExecutorService executor = Executors
+                .newFixedThreadPool(threadCount);
+        try {
+            final ArrayList<Future<Integer>> jobs = new ArrayList<Future<Integer>>();
+            for (int i = 0; i < threadCount; i++) {
+                jobs.add(executor.submit(callables.get(i)));
+            }
+            // check for exceptions
+            for (Future<Integer> job : jobs) {
+                if (job.get(180, TimeUnit.SECONDS) == null) {
+                    throw new RuntimeException("timed out");
+                }
+            }
+        } finally {
+            conn.close();
+            executor.shutdown();
+            executor.awaitTermination(20, TimeUnit.SECONDS);
+        }
+    }
 }