From 39050a45d4eb0acacedf1f4a32bc493a07fb61a0 Mon Sep 17 00:00:00 2001
From: Louis Chatriot <louis.chatriot@gmail.com>
Date: Fri, 31 May 2013 19:04:29 +0200
Subject: [PATCH] Can revert updates, simple or batch

---
 lib/datastore.js     | 34 +++++++++++++++++++-------
 lib/indexes.js       | 17 +++++++++++++
 test/indexes.test.js | 57 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 99 insertions(+), 9 deletions(-)

diff --git a/lib/datastore.js b/lib/datastore.js
index 83ad0f6..03cd1e3 100644
--- a/lib/datastore.js
+++ b/lib/datastore.js
@@ -84,8 +84,7 @@ Datastore.prototype.ensureIndex = function (options, cb) {
  * Add one or several document(s) to all indexes
  */
 Datastore.prototype.addToIndexes = function (doc) {
-  var self = this
-    , i, failingIndex, error
+  var i, failingIndex, error
     , keys = Object.keys(this.indexes)
     ;
 
@@ -123,15 +122,32 @@ Datastore.prototype.removeFromIndexes = function (doc) {
 
 
 /**
- * Update a document in all indexes
- * TODO: enable rollback if an update fails
+ * Update one or several documents in all indexes
+ * If one update violates a constraint, all changes are rolled back
  */
-Datastore.prototype.updateIndexes = function (doc, newDoc) {
-  var self = this;
+Datastore.prototype.updateIndexes = function (oldDoc, newDoc) {
+  var i, failingIndex, error
+    , keys = Object.keys(this.indexes)
+    ;
 
-  Object.keys(this.indexes).forEach(function (i) {
-    self.indexes[i].update(doc, newDoc);
-  });
+  for (i = 0; i < keys.length; i += 1) {
+    try {
+      this.indexes[keys[i]].update(oldDoc, newDoc);
+    } catch (e) {
+      failingIndex = i;
+      error = e;
+      break;
+    }
+  }
+
+  // If an error happened, we need to rollback the insert on all other indexes
+  if (error) {
+    for (i = 0; i < failingIndex; i += 1) {
+      this.indexes[keys[i]].remove(doc);
+    }
+
+    throw error;
+  }
 };
 
 
diff --git a/lib/indexes.js b/lib/indexes.js
index ca5ed29..565bf7a 100644
--- a/lib/indexes.js
+++ b/lib/indexes.js
@@ -131,6 +131,23 @@ Index.prototype.update = function (oldDoc, newDoc) {
 };
 
 
+/**
+ * Revert an update
+ */
+Index.prototype.revertUpdate = function (oldDoc, newDoc) {
+  var revert = [];
+
+  if (!util.isArray(oldDoc)) {
+    this.update(newDoc, oldDoc);
+  } else {
+    oldDoc.forEach(function (pair) {
+      revert.push({ oldDoc: pair.newDoc, newDoc: pair.oldDoc });
+    });
+    this.update(revert);
+  }
+};
+
+
 /**
  * Update multiple documents in the index
  * If a constraint is violated, the changes need to be rolled back
diff --git a/test/indexes.test.js b/test/indexes.test.js
index baa99a1..b8c45d2 100644
--- a/test/indexes.test.js
+++ b/test/indexes.test.js
@@ -330,6 +330,63 @@ describe('Indexes', function () {
       assert.deepEqual(idx.tree.search('world'), [noChange]);
     });
 
+    it('Can revert normal and batch updates', function () {
+      var idx = new Index({ fieldName: 'tf' })
+        , doc1 = { a: 5, tf: 'hello' }
+        , doc2 = { a: 8, tf: 'world' }
+        , doc3 = { a: 2, tf: 'bloup' }
+        , doc1b = { a: 23, tf: 'world' }
+        , doc2b = { a: 1, tf: 'changed' }
+        , doc3b = { a: 44, tf: 'bloup' }
+        , batchUpdate = [{ oldDoc: doc1, newDoc: doc1b }, { oldDoc: doc2, newDoc: doc2b }, { oldDoc: doc3, newDoc: doc3b }]
+        ;
+
+      idx.insert(doc1);
+      idx.insert(doc2);
+      idx.insert(doc3);
+      idx.tree.getNumberOfKeys().should.equal(3);
+
+      idx.update(batchUpdate);
+
+      idx.tree.getNumberOfKeys().should.equal(3);
+      idx.getMatching('world').length.should.equal(1);
+      idx.getMatching('world')[0].should.equal(doc1b);
+      idx.getMatching('changed').length.should.equal(1);
+      idx.getMatching('changed')[0].should.equal(doc2b);
+      idx.getMatching('bloup').length.should.equal(1);
+      idx.getMatching('bloup')[0].should.equal(doc3b);
+
+      idx.revertUpdate(batchUpdate);
+
+      idx.tree.getNumberOfKeys().should.equal(3);
+      idx.getMatching('hello').length.should.equal(1);
+      idx.getMatching('hello')[0].should.equal(doc1);
+      idx.getMatching('world').length.should.equal(1);
+      idx.getMatching('world')[0].should.equal(doc2);
+      idx.getMatching('bloup').length.should.equal(1);
+      idx.getMatching('bloup')[0].should.equal(doc3);
+
+      // Now a simple update
+      idx.update(doc2, doc2b);
+
+      idx.tree.getNumberOfKeys().should.equal(3);
+      idx.getMatching('hello').length.should.equal(1);
+      idx.getMatching('hello')[0].should.equal(doc1);
+      idx.getMatching('changed').length.should.equal(1);
+      idx.getMatching('changed')[0].should.equal(doc2b);
+      idx.getMatching('bloup').length.should.equal(1);
+      idx.getMatching('bloup')[0].should.equal(doc3);
+
+      idx.revertUpdate(doc2, doc2b);
+
+      idx.tree.getNumberOfKeys().should.equal(3);
+      idx.getMatching('hello').length.should.equal(1);
+      idx.getMatching('hello')[0].should.equal(doc1);
+      idx.getMatching('world').length.should.equal(1);
+      idx.getMatching('world')[0].should.equal(doc2);
+      idx.getMatching('bloup').length.should.equal(1);
+      idx.getMatching('bloup')[0].should.equal(doc3);
+    });
 
   });   // ==== End of 'Update' ==== //