algorithm.js

console.log("constructing relations")
// for each post in g reader
after.forEach(this.data, createForwardAndBackwardLinks,
    this, this.finish)

function createForwardAndBackwardLinks(item, callback) {
    var collection = this.collection
    console.log("looping over links in", item)
    // for each link in post
    after.forEach(item.uris, insertForwardLinks, 
        this, insertBackwardLinks)

    function insertForwardLinks(uri, key, callback) {
        // find all posts of that link
        if (key % 300 === 0) {
            console.log("updating a collection with the uri", uri,
                item.uris.length)    
        }
        // and insert the item.link into the forwardLinks
        collection.update({
            uri: uri
        }, {
            $addToSet: {
                forwardLinks: item.link
            }
        }, {
            multi: true,
            safe: true
        // inner loop done
        }, callback)
    }

    function insertBackwardLinks() {
        console.log("done updating ever uri in items.uri", item)
        // find all documents which contain me in forwardLinks
        collection.find({
            forwardLinks: item.uri
        }).toArray(updateItemWithBackwardLinks)

        function updateItemWithBackwardLinks(err, array) {
            console.log("found all forwardLinks, now updating")
            // map the documents to their links
            array = array.map(extractUri)

            // add all those links into my backLinks

            collect.update({
                uri: item.uri
            }, {
                $addToSet: {
                    backLinks: array
                }
            }, {
                multi: true,
                safe: true
            // outer loop done
            }, callback)
        }
    }
// all data is done
}

function extractUri(item) {
    return item.uri
}