Throw if commit() is called more than once

2 files changed, 19 insertions, 0 deletions

diff --git a/vespajlib/src/main/java/com/yahoo/transaction/NestedTransaction.java b/vespajlib/src/main/java/com/yahoo/transaction/NestedTransaction.java
index c860e9ead4f..af22cb77690 100644
--- a/vespajlib/src/main/java/com/yahoo/transaction/NestedTransaction.java
+++ b/vespajlib/src/main/java/com/yahoo/transaction/NestedTransaction.java
@@ -24,6 +24,9 @@ public final class NestedTransaction implements AutoCloseable {
     /** A list of (non-transactional) operations to execute after this transaction has committed successfully */
     private final List<Runnable> onCommitted = new ArrayList<>(2);
 
+    /** Updated when commit() is done, to be able to track if someone tries to commit a second time */
+    private boolean committed = false;
+
     /**
      * Adds a transaction to this.
      *
@@ -45,6 +48,8 @@ public final class NestedTransaction implements AutoCloseable {
 
     /** Perform a 2 phase commit */
     public void commit() {
+        if (committed) throw new IllegalStateException("Transaction already committed");
+
         List<Transaction> organizedTransactions = organizeTransactions(transactions);
 
         // First phase
@@ -75,6 +80,7 @@ public final class NestedTransaction implements AutoCloseable {
                 log.log(Level.WARNING, "A committed task in " + this + " caused an exception", e);
             }
         }
+        committed = true;
     }
 
     public void onCommitted(Runnable runnable) {
diff --git a/vespajlib/src/test/java/com/yahoo/transaction/NestedTransactionTestCase.java b/vespajlib/src/test/java/com/yahoo/transaction/NestedTransactionTestCase.java
index 4feb0869aa0..60facf7e4af 100644
--- a/vespajlib/src/test/java/com/yahoo/transaction/NestedTransactionTestCase.java
+++ b/vespajlib/src/test/java/com/yahoo/transaction/NestedTransactionTestCase.java
@@ -91,6 +91,19 @@ public class NestedTransactionTestCase {
         }
     }
 
+    @Test
+    public void testMoreThanOneCommitThrows() {
+        NestedTransaction t = new NestedTransaction();
+        t.add(new TransactionTypeA("A1"), TransactionTypeB.class);
+        t.commit();
+        try {
+            t.commit();
+            fail("Expected exception");
+        }
+        catch (IllegalStateException expected) {
+        }
+    }
+
     private static class TransactionTypeA extends MockTransaction {
         public TransactionTypeA(String name) { super(name); }
     }