Towards transactional application delete

4 files changed, 60 insertions, 48 deletions

diff --git a/zkfacade/src/main/java/com/yahoo/vespa/curator/recipes/CuratorCounter.java b/zkfacade/src/main/java/com/yahoo/vespa/curator/recipes/CuratorCounter.java
index 8a5c2d35851..950d29d8070 100644
--- a/zkfacade/src/main/java/com/yahoo/vespa/curator/recipes/CuratorCounter.java
+++ b/zkfacade/src/main/java/com/yahoo/vespa/curator/recipes/CuratorCounter.java
@@ -14,25 +14,46 @@ import org.apache.curator.framework.recipes.atomic.DistributedAtomicLong;
 public class CuratorCounter {
 
     private final DistributedAtomicLong counter;
+    private final String counterPath;
 
     public CuratorCounter(Curator curator, String counterPath) {
         this.counter = curator.createAtomicCounter(counterPath);
+        this.counterPath = counterPath;
     }
 
     /**
-     * Atomically increment and return next value.
+     * Atomically increment and return resulting value.
      *
-     * @return the new value.
+     * @return the resulting value
+     * @throws IllegalStateException if increment fails
      */
     public synchronized long next() {
         try {
             AtomicValue<Long> value = counter.increment();
             if (!value.succeeded()) {
-                throw new RuntimeException("Increment did not succeed");
+                throw new IllegalStateException("Increment did not succeed");
             }
             return value.postValue();
         } catch (Exception e) {
-            throw new RuntimeException("Unable to get next value", e);
+            throw new IllegalStateException("Unable to get next value", e);
+        }
+    }
+
+    /**
+     * Atomically decrement and return the resulting value.
+     *
+     * @return the resulting value
+     * @throws IllegalStateException if decrement fails
+     */
+    public synchronized long previous() {
+        try {
+            AtomicValue<Long> value = counter.subtract(1L);
+            if (!value.succeeded()) {
+                throw new IllegalStateException("Decrement did not succeed");
+            }
+            return value.postValue();
+        } catch (Exception e) {
+            throw new IllegalStateException("Unable to get previous value", e);
         }
     }
 
@@ -40,7 +61,7 @@ public class CuratorCounter {
         try {
             counter.trySet(current);
         } catch (Exception e) {
-            throw new RuntimeException("Unable to set value", e);
+            throw new IllegalStateException("Unable to set value", e);
         }
     }
 
@@ -60,8 +81,13 @@ public class CuratorCounter {
         try {
             counter.initialize(value);
         } catch (Exception e) {
-            throw new RuntimeException("Error initializing atomic counter", e);
+            throw new IllegalStateException("Error initializing atomic counter", e);
         }
     }
+    
+    @Override
+    public String toString() {
+        return "curator counter " + counterPath;
+    }
 
 }
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 c9e180b4827..5ff0d4a143f 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
@@ -12,14 +12,16 @@ import org.apache.curator.framework.api.transaction.CuratorTransaction;
 class CuratorDeleteOperation implements CuratorOperation {
 
     private final String path;
+    private final boolean throwIfNotExist;
 
-    CuratorDeleteOperation(String path) {
+    CuratorDeleteOperation(String path, boolean throwIfNotExist) {
         this.path = path;
+        this.throwIfNotExist = throwIfNotExist;
     }
 
     @Override
     public void check(Curator curator) {
-        if ( ! curator.exists(Path.fromString(path)) )
+        if ( throwIfNotExist && ! curator.exists(Path.fromString(path)) )
             throw new IllegalStateException("Cannot perform " + this + ": Path does not exist");
     }
 
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 6dc009b4cfd..55ec5eab2d8 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
@@ -22,8 +22,19 @@ public class CuratorOperations {
         return new CuratorCreateOperation(path, Optional.empty());
     }
 
+    /** 
+     * Deletes this path recursively.
+     * Throws an IllegalStateException in check() if the path does not exist.
+     */
+    public static CuratorOperation deleteOrThrow(String path) {
+        return new CuratorDeleteOperation(path, true);
+    }
+
+    /**
+     * Deletes this path recursively. Does nothing if the path does not exist.
+     */
     public static CuratorOperation delete(String path) {
-        return new CuratorDeleteOperation(path);
+        return new CuratorDeleteOperation(path, false);
     }
 
 }
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 886a08a3ca0..aa7643fb7ae 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
@@ -1,58 +1,42 @@
 // 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.transaction.Transaction;
+import com.yahoo.transaction.AbstractTransaction;
 import com.yahoo.vespa.curator.Curator;
-import org.apache.curator.framework.CuratorFramework;
 import org.apache.curator.framework.api.transaction.CuratorTransactionFinal;
 
-import java.util.ArrayList;
-import java.util.List;
-import java.util.logging.Logger;
-
 /**
  * Transaction implementation against ZooKeeper.
  *
  * @author lulf
  */
-public class CuratorTransaction implements Transaction {
+public class CuratorTransaction extends AbstractTransaction<CuratorOperation> {
 
-    private static final Logger log = Logger.getLogger(CuratorTransaction.class.getName());
-    private final List<Operation> operations = new ArrayList<>();
     private final Curator curator;
 
     public CuratorTransaction(Curator curator) {
         this.curator = curator;
     }
-
-    @Override
-    public Transaction add(Operation operation) {
-        this.operations.add(operation);
-        return this;
+    
+    /** Returns a curator transaction having a single operation */
+    public static CuratorTransaction from(CuratorOperation operation, Curator curator) {
+        CuratorTransaction transaction = new CuratorTransaction(curator);
+        transaction.add(operation);
+        return transaction;
     }
 
     @Override
-    public Transaction add(List<Operation> operations) {
-        this.operations.addAll(operations);
-        return this;
-    }
-
-    @Override
-    public List<Operation> operations() { return operations; }
-
-    @Override
     public void prepare() {
-        for (Operation operation : operations)
-            ((CuratorOperation)operation).check(curator);
+        for (CuratorOperation operation : operations())
+            operation.check(curator);
     }
 
     @Override
     public void commit() {
         try {
             org.apache.curator.framework.api.transaction.CuratorTransaction transaction = curator.framework().inTransaction();
-            for (Operation operation : operations) {
-                CuratorOperation zkOperation = (CuratorOperation) operation;
-                transaction = zkOperation.and(transaction);
+            for (CuratorOperation operation : operations()) {
+                transaction = operation.and(transaction);
             }
             ((CuratorTransactionFinal) transaction).commit();
         } catch (Exception e) {
@@ -60,15 +44,4 @@ public class CuratorTransaction implements Transaction {
         }
     }
 
-    @Override
-    public void rollbackOrLog() {
-        log.severe("The following ZooKeeper operations were incorrectly committed and probably require " +
-                   "manual correction: " + operations);
-    }
-
-    @Override
-    public void close() {
-        operations.clear();
-    }
-
 }