Support recursivetransactional delete in zk

4 files changed, 46 insertions, 3 deletions

diff --git a/zkfacade/src/main/java/com/yahoo/vespa/curator/Curator.java b/zkfacade/src/main/java/com/yahoo/vespa/curator/Curator.java
index c037f7e8ae2..4c08924f8de 100644
--- a/zkfacade/src/main/java/com/yahoo/vespa/curator/Curator.java
+++ b/zkfacade/src/main/java/com/yahoo/vespa/curator/Curator.java
@@ -227,7 +227,7 @@ public class Curator {
     }
 
     /**
-     * Returns the children at the given path.
+     * Returns the names of the children at the given path.
      * If the path does not exist or have no children an empty list (never null) is returned.
      */
     public List<String> getChildren(Path path) {
diff --git a/zkfacade/src/main/java/com/yahoo/vespa/curator/transaction/CuratorDeleteOperation.java b/zkfacade/src/main/java/com/yahoo/vespa/curator/transaction/CuratorDeleteOperation.java
index e49a4cca9d2..95c8a1b732f 100644
--- a/zkfacade/src/main/java/com/yahoo/vespa/curator/transaction/CuratorDeleteOperation.java
+++ b/zkfacade/src/main/java/com/yahoo/vespa/curator/transaction/CuratorDeleteOperation.java
@@ -21,10 +21,17 @@ class CuratorDeleteOperation implements CuratorOperation {
     public void check(Curator curator, TransactionChanges changes) {
         if (  ! curator.exists(Path.fromString(path)) && ! changes.create(path))
             throw new IllegalStateException("Cannot perform " + this + ": Path does not exist");
-        if (curator.getChildren(Path.fromString(path)).size() > 0 || changes.createsChildrenOf(path))
+        if (hasNondeletedChildren(Path.fromString(path), curator, changes) || changes.createsChildrenOf(path))
             throw new IllegalStateException("Cannot perform " + this + ": Path is not empty");
         changes.addDelete(path);
     }
+    
+    private boolean hasNondeletedChildren(Path path, Curator curator, TransactionChanges changes) {
+        for (String childName : curator.getChildren(path))
+            if ( ! changes.delete(path.append(childName).getAbsolute()))
+                return true;
+        return false;
+    }
 
     @Override
     public CuratorTransaction and(CuratorTransaction transaction) throws Exception {
diff --git a/zkfacade/src/main/java/com/yahoo/vespa/curator/transaction/CuratorOperations.java b/zkfacade/src/main/java/com/yahoo/vespa/curator/transaction/CuratorOperations.java
index f1af85bcb1b..84a98dab7eb 100644
--- a/zkfacade/src/main/java/com/yahoo/vespa/curator/transaction/CuratorOperations.java
+++ b/zkfacade/src/main/java/com/yahoo/vespa/curator/transaction/CuratorOperations.java
@@ -1,12 +1,18 @@
 // Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.curator.transaction;
 
+import com.yahoo.path.Path;
+import com.yahoo.vespa.curator.Curator;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 import java.util.Optional;
 
 /**
  * Factory for transactional ZooKeeper operations.
  * This mirrors the operations which are actually available in Curator, which unfortunately does not include
- * convenient variants that deletes children, creates parents etc.
+ * variants that deletes children, creates parents etc. in a single operation.
  *
  * @author lulf
  * @author bratseth
@@ -49,4 +55,24 @@ public class CuratorOperations {
         return new CuratorDeleteOperation(path);
     }
 
+    /**
+     * Returns operations deleting this path and everything below it, in an order where a parent
+     * is ordered after all its children,
+     * such that the operations will succeed when executed in the returned order.
+     * This does not fail, but returns an empty list if the path does not exist.
+     */
+    public static List<CuratorOperation> deleteAll(String path, Curator curator) {
+        if ( ! curator.exists(Path.fromString(path))) return Collections.emptyList();
+
+        List<CuratorOperation> operations = new ArrayList<>();
+        deleteRecursively(Path.fromString(path), operations, curator);
+        return operations;
+    }
+    
+    private static void deleteRecursively(Path path, List<CuratorOperation> operations, Curator curator) {
+        for (String childName : curator.getChildren(path))
+            deleteRecursively(path.append(childName), operations, curator);
+        operations.add(delete(path.getAbsolute()));
+    }
+
 }
diff --git a/zkfacade/src/main/java/com/yahoo/vespa/curator/transaction/CuratorTransaction.java b/zkfacade/src/main/java/com/yahoo/vespa/curator/transaction/CuratorTransaction.java
index 1345cabcd40..551fb9c1501 100644
--- a/zkfacade/src/main/java/com/yahoo/vespa/curator/transaction/CuratorTransaction.java
+++ b/zkfacade/src/main/java/com/yahoo/vespa/curator/transaction/CuratorTransaction.java
@@ -5,6 +5,8 @@ import com.yahoo.transaction.AbstractTransaction;
 import com.yahoo.vespa.curator.Curator;
 import org.apache.curator.framework.api.transaction.CuratorTransactionFinal;
 
+import java.util.List;
+
 /**
  * Transaction implementation against ZooKeeper.
  *
@@ -31,6 +33,14 @@ public class CuratorTransaction extends AbstractTransaction {
         return transaction;
     }
 
+    /** Returns a curator transaction having a list of operations */
+    public static CuratorTransaction from(List<CuratorOperation> operations, Curator curator) {
+        CuratorTransaction transaction = new CuratorTransaction(curator);
+        for (Operation operation : operations)
+            transaction.add(operation);
+        return transaction;
+    }
+
     @Override
     public void prepare() {
         TransactionChanges changes = new TransactionChanges();