Refactor and add timeout

Since we're opening up more revisions I realize that this could result
in delays getting the revisions that could cause pain in the app. This
revision sets a new hard timeout at ten seconds so that if for some
reason we haven't been able to load all of the requested revisions we
can at least push out the ones we did get in that time.

Author: dmsnell

src/simperium/channel.js

@@ -643,39 +643,44 @@ LocalQueue.prototype.resendSentChanges = function() {
 }
 
 function collectionRevisions( channel, id, callback ) {
-	var expectedVersions = -1;
-	var onGhostRetrieved = function( ghost ) {
-		// the default bucket options allow for storing
-		// the 60 most-recent revisions of a note plus
-		// 100 archive versions (these store one out of
-		// every ten versions). we'll get up to this many
-		var version = Math.min( ghost.version, 160 );
-		var i;
-		expectedVersions = version;
+	let expectedVersions;
+	let timeout;
+	const TIMEOUT = 10000; // arbitrarily chosen delay
 
-		// Loop through requested revision count and request each version
-		for ( i = 0; i < version; i++ ) {
-			channel.send( 'e:' + id + '.' + ( ghost.version - i ) );
-		}
+	const versions = [];
+
+	const finish = listener => {
+		channel.removeListener( 'version.' + id, listener );
+		callback( null, versions.sort( ( a, b ) => a.version - b.version ) );
+		clearTimeout( timeout );
 	};
 
-	var versions = [];
-	var onVersion = function( id, version, data ) {
-		versions.push( {id: id, version: version, data: data} );
+	const onVersion = ( id, version, data ) => {
+		versions.push( { id, version, data } );
 
 		// Check if all versions have been collected
 		if ( expectedVersions === versions.length ) {
-			channel.removeListener( 'version.' + id, onVersion );
-			callback( null, versions.sort( function( a, b ) {
-				return a.version > b.version ? -1 : 1;
-			} ) );
+			finish( onVersion );
 		}
 	};
 
 	channel.on( 'version.' + id, onVersion );
 
-	channel.store.get( id ).then( onGhostRetrieved, function( e ) {
-		callback( e );
-	} );
+	channel.store.get( id ).then( ghost => {
+		// the default bucket options allow for storing
+		// the 60 most-recent revisions of a note plus
+		// 100 archive versions (these store one out of
+		// every ten versions). we'll get up to this many
+		const version = Math.min( ghost.version, 160 );
+		expectedVersions = version;
+
+		// Loop through requested revision count and request each version
+		for ( let i = 0; i < version; i++ ) {
+			channel.send( 'e:' + id + '.' + ( ghost.version - i ) );
+		}
+	}, callback );
+
+	// give up after a timeout
+	timeout = setTimeout( () => finish( onVersion ), TIMEOUT );
 }