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Posted to oak-commits@jackrabbit.apache.org by mr...@apache.org on 2013/10/29 16:31:23 UTC

svn commit: r1536758 - in /jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk: MongoMK.java MongoNodeBuilder.java MongoNodeState.java MongoNodeStore.java MongoNodeStoreBranch.java MongoRootBuilder.java

Author: mreutegg
Date: Tue Oct 29 15:31:22 2013
New Revision: 1536758

URL: http://svn.apache.org/r1536758
Log:
OAK-1080: MongoMK: improved concurrency

Added:
    jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeBuilder.java   (with props)
    jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeStoreBranch.java   (with props)
    jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoRootBuilder.java   (with props)
Modified:
    jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoMK.java
    jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeState.java
    jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeStore.java

Modified: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoMK.java
URL: http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoMK.java?rev=1536758&r1=1536757&r2=1536758&view=diff
==============================================================================
--- jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoMK.java (original)
+++ jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoMK.java Tue Oct 29 15:31:22 2013
@@ -405,34 +405,9 @@ public class MongoMK implements MicroKer
         try {
             Revision baseRev = commit.getBaseRevision();
             isBranch = baseRev != null && baseRev.isBranch();
-            rev = commit.getRevision();
             parseJsonDiff(commit, jsonDiff, rootPath);
-            if (isBranch) {
-                rev = rev.asBranchRevision();
-                // remember branch commit
-                Branch b = nodeStore.getBranches().getBranch(baseRev);
-                if (b == null) {
-                    // baseRev is marker for new branch
-                    b = nodeStore.getBranches().create(baseRev.asTrunkRevision(), rev);
-                } else {
-                    b.addCommit(rev);
-                }
-                try {
-                    // prepare commit
-                    commit.prepare(baseRev);
-                    success = true;
-                } finally {
-                    if (!success) {
-                        b.removeCommit(rev);
-                        if (!b.hasCommits()) {
-                            nodeStore.getBranches().remove(b);
-                        }
-                    }
-                }
-            } else {
-                commit.apply();
-                success = true;
-            }
+            rev = nodeStore.apply(commit);
+            success = true;
         } finally {
             if (!success) {
                 nodeStore.canceled(commit);
@@ -460,43 +435,7 @@ public class MongoMK implements MicroKer
         if (!revision.isBranch()) {
             throw new MicroKernelException("Not a branch: " + branchRevisionId);
         }
-        Branch b = nodeStore.getBranches().getBranch(revision);
-        Revision base = revision;
-        if (b != null) {
-            base = b.getBase(revision);
-        }
-        boolean success = false;
-        Commit commit = nodeStore.newCommit(base);
-        try {
-            // make branch commits visible
-            UpdateOp op = new UpdateOp(Utils.getIdFromPath("/"), false);
-            NodeDocument.setModified(op, commit.getRevision());
-            if (b != null) {
-                String commitTag = "c-" + commit.getRevision().toString();
-                for (Revision rev : b.getCommits()) {
-                    rev = rev.asTrunkRevision();
-                    NodeDocument.setRevision(op, rev, commitTag);
-                    op.containsMapEntry(NodeDocument.COLLISIONS, rev, false);
-                }
-                if (store.findAndUpdate(Collection.NODES, op) != null) {
-                    // remove from branchCommits map after successful update
-                    b.applyTo(nodeStore.getPendingModifications(), commit.getRevision());
-                    nodeStore.getBranches().remove(b);
-                } else {
-                    throw new MicroKernelException("Conflicting concurrent change. Update operation failed: " + op);
-                }
-            } else {
-                // no commits in this branch -> do nothing
-            }
-            success = true;
-        } finally {
-            if (!success) {
-                nodeStore.canceled(commit);
-            } else {
-                nodeStore.done(commit, false);
-            }
-        }
-        return commit.getRevision().toString();
+        return nodeStore.merge(revision).toString();
     }
 
     @Override
@@ -504,24 +443,11 @@ public class MongoMK implements MicroKer
     public String rebase(@Nonnull String branchRevisionId,
                          @Nullable String newBaseRevisionId)
             throws MicroKernelException {
-        // TODO conflict handling
         Revision r = Revision.fromString(branchRevisionId);
         Revision base = newBaseRevisionId != null ?
                 Revision.fromString(newBaseRevisionId) :
                 nodeStore.getHeadRevision();
-        Branch b = nodeStore.getBranches().getBranch(r);
-        if (b == null) {
-            // empty branch
-            return base.asBranchRevision().toString();
-        }
-        if (b.getBase().equals(base)) {
-            return branchRevisionId;
-        }
-        // add a pseudo commit to make sure current head of branch
-        // has a higher revision than base of branch
-        Revision head = nodeStore.newRevision().asBranchRevision();
-        b.rebase(head, base);
-        return head.toString();
+        return nodeStore.rebase(r, base).toString();
     }
 
     @Override

Added: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeBuilder.java
URL: http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeBuilder.java?rev=1536758&view=auto
==============================================================================
--- jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeBuilder.java (added)
+++ jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeBuilder.java Tue Oct 29 15:31:22 2013
@@ -0,0 +1,38 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.jackrabbit.oak.plugins.mongomk;
+
+import org.apache.jackrabbit.oak.plugins.memory.MemoryNodeBuilder;
+
+/**
+ * A node builder implementation for MongoMK.
+ */
+class MongoNodeBuilder extends MemoryNodeBuilder {
+
+    protected MongoNodeBuilder(MongoNodeState base) {
+        super(base);
+    }
+
+    private MongoNodeBuilder(MongoNodeBuilder parent, String name) {
+        super(parent, name);
+    }
+
+    @Override
+    protected MongoNodeBuilder createChildBuilder(String name) {
+        return new MongoNodeBuilder(this, name);
+    }
+}

Propchange: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeBuilder.java
------------------------------------------------------------------------------
    svn:eol-style = native

Propchange: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeBuilder.java
------------------------------------------------------------------------------
    svn:keywords = Author Date Id Revision Rev URL

Modified: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeState.java
URL: http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeState.java?rev=1536758&r1=1536757&r2=1536758&view=diff
==============================================================================
--- jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeState.java (original)
+++ jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeState.java Tue Oct 29 15:31:22 2013
@@ -81,7 +81,6 @@ class MongoNodeState extends AbstractNod
 
     @Override
     public boolean exists() {
-        // TODO: implement
         return true;
     }
 
@@ -112,4 +111,7 @@ class MongoNodeState extends AbstractNod
         // TODO: implement
         return new MemoryNodeBuilder(this);
     }
+
+    //------------------------------< internal >--------------------------------
+
 }

Modified: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeStore.java
URL: http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeStore.java?rev=1536758&r1=1536757&r2=1536758&view=diff
==============================================================================
--- jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeStore.java (original)
+++ jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeStore.java Tue Oct 29 15:31:22 2013
@@ -495,8 +495,8 @@ public final class MongoNodeStore
         }
     }
 
-    public Node.Children getChildren(final String path, final Revision rev, final int limit)  throws
-            MicroKernelException {
+    Node.Children getChildren(final String path, final Revision rev, final int limit)
+            throws MicroKernelException {
         checkRevisionAge(rev, path);
 
         //Preemptive check. If we know there are no child then
@@ -728,10 +728,120 @@ public final class MongoNodeStore
      * @return the root node state at the given revision.
      */
     @Nonnull
-    NodeState getRoot(@Nonnull Revision revision) {
+    MongoNodeState getRoot(@Nonnull Revision revision) {
         return new MongoNodeState(this, "/", revision);
     }
 
+    @Nonnull
+    MongoNodeStoreBranch createBranch(MongoNodeState base) {
+        return new MongoNodeStoreBranch(this, base);
+    }
+
+    @Nonnull
+    Revision rebase(@Nonnull Revision branchHead, @Nonnull Revision base) {
+        checkNotNull(branchHead);
+        checkNotNull(base);
+        // TODO conflict handling
+        Branch b = getBranches().getBranch(branchHead);
+        if (b == null) {
+            // empty branch
+            return base.asBranchRevision();
+        }
+        if (b.getBase().equals(base)) {
+            return branchHead;
+        }
+        // add a pseudo commit to make sure current head of branch
+        // has a higher revision than base of branch
+        Revision head = newRevision().asBranchRevision();
+        b.rebase(head, base);
+        return head;
+    }
+
+    @Nonnull
+    Revision merge(@Nonnull Revision branchHead) {
+        Branch b = getBranches().getBranch(branchHead);
+        Revision base = branchHead;
+        if (b != null) {
+            base = b.getBase(branchHead);
+        }
+        boolean success = false;
+        Commit commit = newCommit(base);
+        try {
+            // make branch commits visible
+            UpdateOp op = new UpdateOp(Utils.getIdFromPath("/"), false);
+            NodeDocument.setModified(op, commit.getRevision());
+            if (b != null) {
+                String commitTag = "c-" + commit.getRevision().toString();
+                for (Revision rev : b.getCommits()) {
+                    rev = rev.asTrunkRevision();
+                    NodeDocument.setRevision(op, rev, commitTag);
+                    op.containsMapEntry(NodeDocument.COLLISIONS, rev, false);
+                }
+                if (store.findAndUpdate(Collection.NODES, op) != null) {
+                    // remove from branchCommits map after successful update
+                    b.applyTo(getPendingModifications(), commit.getRevision());
+                    getBranches().remove(b);
+                } else {
+                    // TODO: use non-MK exception type
+                    throw new MicroKernelException("Conflicting concurrent change. Update operation failed: " + op);
+                }
+            } else {
+                // no commits in this branch -> do nothing
+            }
+            success = true;
+        } finally {
+            if (!success) {
+                canceled(commit);
+            } else {
+                done(commit, false);
+            }
+        }
+        return commit.getRevision();
+    }
+
+    /**
+     * Applies a commit to the store and updates the caches accordingly.
+     *
+     * @param commit the commit to apply.
+     * @return the commit revision.
+     * @throws MicroKernelException if the commit cannot be applied.
+     *              TODO: use non-MK exception type
+     */
+    @Nonnull
+    Revision apply(@Nonnull Commit commit) throws MicroKernelException {
+        checkNotNull(commit);
+        boolean success = false;
+        Revision baseRev = commit.getBaseRevision();
+        boolean isBranch = baseRev != null && baseRev.isBranch();
+        Revision rev = commit.getRevision();
+        if (isBranch) {
+            rev = rev.asBranchRevision();
+            // remember branch commit
+            Branch b = getBranches().getBranch(baseRev);
+            if (b == null) {
+                // baseRev is marker for new branch
+                b = getBranches().create(baseRev.asTrunkRevision(), rev);
+            } else {
+                b.addCommit(rev);
+            }
+            try {
+                // prepare commit
+                commit.prepare(baseRev);
+                success = true;
+            } finally {
+                if (!success) {
+                    b.removeCommit(rev);
+                    if (!b.hasCommits()) {
+                        getBranches().remove(b);
+                    }
+                }
+            }
+        } else {
+            commit.apply();
+        }
+        return rev;
+    }
+
     //------------------------< Observable >------------------------------------
 
     @Override
@@ -743,7 +853,7 @@ public final class MongoNodeStore
 
     @Nonnull
     @Override
-    public NodeState getRoot() {
+    public MongoNodeState getRoot() {
         return getRoot(headRevision);
     }
 
@@ -753,21 +863,18 @@ public final class MongoNodeStore
                            @Nonnull CommitHook commitHook,
                            @Nullable CommitInfo info)
             throws CommitFailedException {
-        // TODO: implement
-        return null;
+        return asMongoRootBuilder(builder).merge(commitHook, info);
     }
 
     @Nonnull
     @Override
     public NodeState rebase(@Nonnull NodeBuilder builder) {
-        // TODO: implement
-        return null;
+        return asMongoRootBuilder(builder).rebase();
     }
 
     @Override
     public NodeState reset(@Nonnull NodeBuilder builder) {
-        // TODO: implement
-        return null;
+        return asMongoRootBuilder(builder).reset();
     }
 
     @Override
@@ -1020,6 +1127,15 @@ public final class MongoNodeStore
 
     //-----------------------------< internal >---------------------------------
 
+    private static MongoRootBuilder asMongoRootBuilder(NodeBuilder builder)
+            throws IllegalArgumentException {
+        if (!(builder instanceof MongoRootBuilder)) {
+            throw new IllegalArgumentException("builder must be a " +
+                    MongoRootBuilder.class.getName());
+        }
+        return (MongoRootBuilder) builder;
+    }
+
     private void moveOrCopyNode(boolean move,
                                 String sourcePath,
                                 String targetPath,

Added: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeStoreBranch.java
URL: http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeStoreBranch.java?rev=1536758&view=auto
==============================================================================
--- jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeStoreBranch.java (added)
+++ jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeStoreBranch.java Tue Oct 29 15:31:22 2013
@@ -0,0 +1,102 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.jackrabbit.oak.plugins.mongomk;
+
+import org.apache.jackrabbit.oak.plugins.observation.ChangeDispatcher;
+import org.apache.jackrabbit.oak.spi.state.AbstractNodeStoreBranch;
+import org.apache.jackrabbit.oak.spi.state.NodeState;
+
+/**
+ * Implementation of a MongoMK based node store branch.
+ */
+public class MongoNodeStoreBranch
+        extends AbstractNodeStoreBranch<MongoNodeStore, MongoNodeState> {
+
+    public MongoNodeStoreBranch(MongoNodeStore store,
+                                MongoNodeState base) {
+        super(store, new ChangeDispatcher(store), base);
+    }
+
+    @Override
+    protected MongoNodeState getRoot() {
+        return store.getRoot();
+    }
+
+    @Override
+    protected MongoNodeState createBranch(MongoNodeState state) {
+        return store.getRoot(state.getRevision().asBranchRevision());
+    }
+
+    @Override
+    protected MongoNodeState rebase(MongoNodeState branchHead,
+                                    MongoNodeState base) {
+        return store.getRoot(store.rebase(branchHead.getRevision(), base.getRevision()));
+    }
+
+    @Override
+    protected MongoNodeState merge(MongoNodeState branchHead) {
+        return store.getRoot(store.merge(branchHead.getRevision()));
+    }
+
+    @Override
+    protected MongoNodeState persist(NodeState toPersist, MongoNodeState base) {
+        // TODO
+        return null;
+    }
+
+    @Override
+    protected MongoNodeState copy(String source,
+                                  String target,
+                                  MongoNodeState base) {
+        boolean success = false;
+        Commit c = store.newCommit(base.getRevision());
+        Revision rev;
+        try {
+            store.copyNode(source, target, c);
+            rev = store.apply(c);
+            success = true;
+        } finally {
+            if (success) {
+                store.done(c, base.getRevision().isBranch());
+            } else {
+                store.canceled(c);
+            }
+        }
+        return store.getRoot(rev);
+    }
+
+    @Override
+    protected MongoNodeState move(String source,
+                                  String target,
+                                  MongoNodeState base) {
+        boolean success = false;
+        Commit c = store.newCommit(base.getRevision());
+        Revision rev;
+        try {
+            store.moveNode(source, target, c);
+            rev = store.apply(c);
+            success = true;
+        } finally {
+            if (success) {
+                store.done(c, base.getRevision().isBranch());
+            } else {
+                store.canceled(c);
+            }
+        }
+        return store.getRoot(rev);
+    }
+}

Propchange: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeStoreBranch.java
------------------------------------------------------------------------------
    svn:eol-style = native

Propchange: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoNodeStoreBranch.java
------------------------------------------------------------------------------
    svn:keywords = Author Date Id Revision Rev URL

Added: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoRootBuilder.java
URL: http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoRootBuilder.java?rev=1536758&view=auto
==============================================================================
--- jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoRootBuilder.java (added)
+++ jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoRootBuilder.java Tue Oct 29 15:31:22 2013
@@ -0,0 +1,153 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.jackrabbit.oak.plugins.mongomk;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import org.apache.jackrabbit.oak.api.CommitFailedException;
+import org.apache.jackrabbit.oak.spi.commit.CommitHook;
+import org.apache.jackrabbit.oak.spi.commit.CommitInfo;
+import org.apache.jackrabbit.oak.spi.state.NodeState;
+
+/**
+ * This implementation tracks the number of pending changes and purges them to
+ * a private branch of the underlying store if a certain threshold is met.
+ */
+class MongoRootBuilder extends MongoNodeBuilder {
+
+    /**
+     * Number of content updates that need to happen before the updates
+     * are automatically purged to the private branch.
+     */
+    private static final int UPDATE_LIMIT = Integer.getInteger("update.limit", 1000);
+
+    /**
+     * The underlying store
+     */
+    private final MongoNodeStore store;
+
+    /**
+     * The base state of this builder, possibly non-existent if this builder
+     * represents a new node that didn't yet exist in the base content tree.
+     * This differs from the base state of super since the latter one reflects
+     * the base created by the last purge.
+     */
+    private NodeState base;
+
+    /**
+     * Private branch used to hold pending changes exceeding {@link #UPDATE_LIMIT}
+     */
+    private MongoNodeStoreBranch branch;
+
+    /**
+     * Number of updated not yet persisted to the private {@link #branch}
+     */
+    private int updates = 0;
+
+    MongoRootBuilder(MongoNodeState base, MongoNodeStore store) {
+        super(checkNotNull(base));
+        this.base = base;
+        this.store = store;
+        this.branch = store.createBranch(base);
+    }
+
+    //--------------------------------------------------< MemoryNodeBuilder >---
+
+
+    @Override
+    public NodeState getBaseState() {
+        return base;
+    }
+
+    @Override
+    public void reset(NodeState newBase) {
+        base = newBase;
+        super.reset(newBase);
+    }
+
+    @Override
+    protected void updated() {
+        if (updates++ > UPDATE_LIMIT) {
+            purge();
+        }
+    }
+
+    //------------------------------------------------------------< internal >---
+
+    /**
+     * Rebase this builder on top of the head of the underlying store
+     */
+    NodeState rebase() {
+        purge();
+        branch.rebase();
+        NodeState head = branch.getHead();
+        reset(head);
+        return head;
+    }
+
+    /**
+     * Reset this builder by creating a new branch and setting the head
+     * state of that branch as the new base state of this builder.
+     */
+    NodeState reset() {
+        branch = store.createBranch(store.getRoot());
+        NodeState head = branch.getHead();
+        reset(head);
+        return head;
+    }
+
+    /**
+     * Merge all changes tracked in this builder into the underlying store.
+     */
+    NodeState merge(CommitHook hook, CommitInfo info) throws CommitFailedException {
+        purge();
+        branch.merge(hook, info);
+        return reset();
+    }
+
+    /**
+     * Applied all pending changes to the underlying branch and then
+     * move the node as a separate operation on the underlying store.
+     * This allows stores to optimise move operations instead of
+     * seeing them as an added node followed by a deleted node.
+     */
+    boolean move(String source, String target) {
+        purge();
+        boolean success = branch.move(source, target);
+        super.reset(branch.getHead());
+        return success;
+    }
+
+    /**
+     * Applied all pending changes to the underlying branch and then
+     * copy the node as a separate operation on the underlying store.
+     * This allows stores to optimise copy operations instead of
+     * seeing them as an added node.
+     */
+    boolean copy(String source, String target) {
+        purge();
+        boolean success = branch.copy(source, target);
+        super.reset(branch.getHead());
+        return success;
+    }
+
+    private void purge() {
+        branch.setRoot(getNodeState());
+        super.reset(branch.getHead());
+        updates = 0;
+    }
+}

Propchange: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoRootBuilder.java
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Propchange: jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/mongomk/MongoRootBuilder.java
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