Towards transactional application delete

3 files changed, 60 insertions, 10 deletions

diff --git a/vespajlib/src/main/java/com/yahoo/transaction/AbstractTransaction.java b/vespajlib/src/main/java/com/yahoo/transaction/AbstractTransaction.java
new file mode 100644
index 00000000000..667e4406277
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/transaction/AbstractTransaction.java
@@ -0,0 +1,50 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.transaction;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.logging.Logger;
+
+/**
+ * A convenience base transaction class for multi-operation transactions
+ * which maintains the list of operations to commit and provides a default
+ * implementation of rollbackOrLog which logs a SEVERE message.
+ * 
+ * @author bratseth
+ */
+public abstract class AbstractTransaction<OPERATION extends Transaction.Operation> implements Transaction<OPERATION> {
+
+    private static final Logger log = Logger.getLogger(AbstractTransaction.class.getName());
+    private final List<OPERATION> operations = new ArrayList<>();
+
+    protected AbstractTransaction() { }
+
+    @Override
+    public Transaction add(OPERATION operation) {
+        this.operations.add(operation);
+        return this;
+    }
+
+    @Override
+    public Transaction add(List<OPERATION> operations) {
+        this.operations.addAll(operations);
+        return this;
+    }
+
+    @Override
+    public List<OPERATION> operations() { return operations; }
+
+    /** Default implementations which logs a severe message. Operations should implement toString to use this. */
+    @Override
+    public void rollbackOrLog() {
+        log.severe("The following operations were incorrectly committed and probably require " +
+                   "manual correction: " + operations());
+    }
+
+    /** Default implementation which only clears operations */
+    @Override
+    public void close() {
+        operations.clear();
+    }
+
+}
diff --git a/vespajlib/src/main/java/com/yahoo/transaction/NestedTransaction.java b/vespajlib/src/main/java/com/yahoo/transaction/NestedTransaction.java
index 4be0a32ffe8..f437aa8ac19 100644
--- a/vespajlib/src/main/java/com/yahoo/transaction/NestedTransaction.java
+++ b/vespajlib/src/main/java/com/yahoo/transaction/NestedTransaction.java
@@ -21,9 +21,6 @@ public final class NestedTransaction implements AutoCloseable {
     /** Nested transactions with ordering constraints, in the order they are added */
     private final List<ConstrainedTransaction> transactions = new ArrayList<>(2);
 
-    /** Transaction ordering pairs */
-    //private final List<OrderingConstraint> transactionOrders = new ArrayList<>(2);
-
     /** A list of (non-transactional) operations to execute after this transaction has committed successfully */
     private final List<Runnable> onCommitted = new ArrayList<>(2);
 
diff --git a/vespajlib/src/main/java/com/yahoo/transaction/Transaction.java b/vespajlib/src/main/java/com/yahoo/transaction/Transaction.java
index 642438dda0a..e1983e13933 100644
--- a/vespajlib/src/main/java/com/yahoo/transaction/Transaction.java
+++ b/vespajlib/src/main/java/com/yahoo/transaction/Transaction.java
@@ -4,13 +4,15 @@ package com.yahoo.transaction;
 import java.util.List;
 
 /**
- * An interface for building a transaction and committing it. Implementations are required to atomically apply changes
+ * A transaction against a single system, which may include several operations against the system, 
+ * to be committed as one.
+ * Implementations are required to atomically apply changes
  * in the commit step or throw an exception if it fails.
  *
  * @author lulf
  * @author bratseth
  */
-public interface Transaction extends AutoCloseable {
+public interface Transaction<OPERATION extends Transaction.Operation> extends AutoCloseable {
 
     /**
      * Adds an operation to this transaction. Return self for chaining.
@@ -18,7 +20,7 @@ public interface Transaction extends AutoCloseable {
      * @param operation {@link Operation} to append
      * @return self, for chaining
      */
-    Transaction add(Operation operation);
+    Transaction add(OPERATION operation);
 
     /**
      * Adds multiple operations to this transaction. Return self for chaining.
@@ -26,13 +28,13 @@ public interface Transaction extends AutoCloseable {
      * @param operation {@link Operation} to append
      * @return self, for chaining
      */
-    Transaction add(List<Operation> operation);
+    Transaction add(List<OPERATION> operation);
 
     /**
      * Returns the operations of this.
      * Ownership of the returned list is transferred to the caller. The ist may be ready only.
      */
-    List<Operation> operations();
+    List<OPERATION> operations();
 
     /**
      * Checks whether or not the transaction is able to commit in its current state and do any transient preparatory
@@ -65,8 +67,9 @@ public interface Transaction extends AutoCloseable {
 
     /**
      * Operations that a transaction supports should implement this interface.
+     * It does not define any methods because the interface to use is a contract between the
+     * specific transaction and operation type used.
      */
-    public interface Operation {
-    }
+    interface Operation { }
 
 }