From 1c8c7d171cf4fa32c1aa63edfc71ee89481db871 Mon Sep 17 00:00:00 2001
From: David Glasser <glasser@meteor.com>
Date: Mon, 19 Aug 2013 20:23:52 -0700
Subject: [PATCH] very basic insert support

---
 packages/mongo-livedata/id_map.js       | 27 ++++++++++++++
 packages/mongo-livedata/mongo_driver.js | 48 +++++++++++++++++++++----
 packages/mongo-livedata/package.js      |  1 +
 3 files changed, 69 insertions(+), 7 deletions(-)
 create mode 100644 packages/mongo-livedata/id_map.js

diff --git a/packages/mongo-livedata/id_map.js b/packages/mongo-livedata/id_map.js
new file mode 100644
index 0000000000..fa093c305e
--- /dev/null
+++ b/packages/mongo-livedata/id_map.js
@@ -0,0 +1,27 @@
+IdMap = function () {
+  var self = this;
+  self.map = {};
+};
+
+_.extend(IdMap.prototype, {
+  get: function (id) {
+    var self = this;
+    var key = LocalCollection._idStringify(id);
+    return self.map[key];
+  },
+  set: function (id, value) {
+    var self = this;
+    var key = LocalCollection._idStringify(id);
+    self.map[key] = value;
+  },
+  remove: function(id) {
+    var self = this;
+    var key = LocalCollection._idStringify(id);
+    delete self.map[key];
+  },
+  has: function(id) {
+    var self = this;
+    var key = LocalCollection._idStringify(id);
+    return _.has(self.map, key);
+  }
+});
diff --git a/packages/mongo-livedata/mongo_driver.js b/packages/mongo-livedata/mongo_driver.js
index d84c486e3a..5d73a2dcc0 100644
--- a/packages/mongo-livedata/mongo_driver.js
+++ b/packages/mongo-livedata/mongo_driver.js
@@ -237,7 +237,7 @@ MongoConnection.prototype._startOplogTailing = function (oplogUrl, dbName) {
     var collectionName = doc.ns.substr(dbName.length + 1);
 
     _.each(callbacksByCollection[collectionName], function (callback) {
-      callback(doc);
+      callback(EJSON.clone(doc));
     });
   });
 
@@ -260,18 +260,52 @@ MongoConnection.prototype._observeChangesWithOplog = function (
   var self = this;
 
   // XXX let's do this with race conditions first!
+  //
+  // the real way will involve special oplog handling during the initial cursor
+  // read. specifically:
+  //
+  // 1) start reading the oplog. for every document that could conceivably be
+  // relevant, cache a bit of information about what we saw.  (eg, cache
+  // document for inserts, removal fact for removes, "needs poll" for updates.
+  // most recent overrides.)
+  //
+  // 2) read the initial set and send added messages.
+  //
+  // 3) write a sentinel to some field.
+  //
+  // 4) wait until that sentinel comes up through the oplog.
+  //
+  // 5) use the cached information (compared to what we already know) to send
+  //    messages about things that changed right about then
+  //
+  // 6) now that we're in the "steady state", process ops more directly
 
-  var idSet = {};
+  var idSet = new IdMap;
+
+  var selector = LocalCollection._compileSelector(cursorDescription.selector);
 
   var oplogHandle = self._oplogHandle.onOplogEntry(cursorDescription.collectionName, function (op) {
+    var id;
     if (op.op === 'd') {
-      // XXX check that ObjectId works here.  (ie use idStringify or something)
-      var id = op.o._id;
-      if (_.has(idSet, id)) {
-        delete idSet[id];
+      // XXX check that ObjectId works here
+      id = op.o._id;
+      if (idSet.has(id)) {
+        idSet.remove(id);
         if (callbacks.removed)
           callbacks.removed(id);
       }
+    } else if (op.op ==='i') {
+      id = op.o._id;
+      if (idSet.has(id))
+        throw new Error("insert found for already-existing ID");
+
+      if (selector(op.o)) {
+        idSet.set(id, true);
+        if (callbacks.added) {
+          delete op.o._id;
+          callbacks.added(id, op.o);
+        }
+      }
     } else {
       console.log("A CHANGE TO THE DOC", op);
     }
@@ -282,7 +316,7 @@ MongoConnection.prototype._observeChangesWithOplog = function (
     initialCursor.forEach(function (initialDoc) {
       var id = initialDoc._id;
       delete initialDoc._id;
-      idSet[id] = true;
+      idSet.set(id, true);
       callbacks.added(id, initialDoc);
     });
   }
diff --git a/packages/mongo-livedata/package.js b/packages/mongo-livedata/package.js
index 194ac21192..3827dbb929 100644
--- a/packages/mongo-livedata/package.js
+++ b/packages/mongo-livedata/package.js
@@ -38,6 +38,7 @@ Package.on_use(function (api) {
   // For tests only.
   api.export('MongoTest', 'server');
 
+  api.add_files('id_map.js', 'server');
   api.add_files('mongo_driver.js', 'server');
   api.add_files('local_collection_driver.js', ['client', 'server']);
   api.add_files('remote_collection_driver.js', 'server');