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-rw-r--r--lib/PodcastView.js127
-rw-r--r--lib/UpdateHandlers.js200
2 files changed, 327 insertions, 0 deletions
diff --git a/lib/PodcastView.js b/lib/PodcastView.js
new file mode 100644
index 0000000..15970cf
--- /dev/null
+++ b/lib/PodcastView.js
@@ -0,0 +1,127 @@
+var _ = require('underscore');
+
+var AWS = require('aws-sdk');
+var s3 = new AWS.S3();
+
+var doc = require('dynamodb-doc');
+var dynamo = new doc.DynamoDB();
+
+var DDB_VIEWS_TABLE = 'podcast-views';
+
+/**
+ * PodcastView represents a pre-rendered view template.
+ *
+ * @param {Object} view - properties to set on the view and pass to the
+ * template.
+ * @constructor
+ */
+modules.exports = function PodcastView(view) {
+ for (var property in view) {
+ if (view.hasOwnProperty(property)) {
+ this[property] = source[property];
+ }
+ }
+};
+
+/**
+ * Find a view in DynamoDB by Id.
+ *
+ * @param {Object} id - The view id.
+ * @param {Function} - Callback to call with an error or view.
+ */
+PodcastView.findById = function(id, callback) {
+ var params = {
+ TableName: DDB_VIEWS_TABLE,
+ Key: id
+ };
+
+ dynamo.getItem(params, function(error, data) {
+ if (error) {
+ callback(error);
+ return;
+ }
+
+ var view = new PodcastView(data.Item);
+ callback(null, view);
+ });
+}
+
+/**
+ * Find all views for a given feed.
+ *
+ * @param {Object} feedId - The feed id.
+ * @param {Function} - Callback with signature function(error, view, last)
+ */
+PodcastView.forEachView = function(feedId, callback) {
+ forEachView(feedId, callback);
+};
+
+function forEachView(feedId, callback, startKey) {
+ var params = {
+ TableName: DDB_VIEWS_TABLE,
+ KeyConditionExpression: "feedId = :feedId",
+ ExpressionAttributeValues: {
+ ':feedId': feedId
+ }
+ };
+
+ if (startKey) {
+ params['ExclusiveStartKey'] = startKey;
+ }
+
+ dynamo.query(params, function(error, data) {
+ if (error != null) {
+ callback(error);
+ return;
+ }
+
+ var lastResponse = !data.LastEvaluatedKey;
+
+ data.Items.forEach(function(viewData, index, array) {
+ var view = new PodcastView(viewData);
+ var last = lastResponse && index == (array.length - 1);
+ callback(null, view, last);
+ });
+
+ // If this is not the last set of responses, get more.
+ if (!lastResponse) {
+ forEachView(feedId, callback, data.LastEvaluatedKey);
+ }
+ });
+}
+
+PodcastView.prototype.render = function(episodes, callback) {
+ var template = this.template;
+
+ var data = {
+ view: this,
+ episodes: episodes,
+ };
+ var renderedView = _.template(template)(data);
+
+ saveView(renderedView, callback);
+};
+
+function saveView(renderedView, callback) {
+ var params = {
+ Bucket: this.bucket,
+ Key: this.key,
+ Body: renderedView
+ };
+
+ s3.putObject(params, callback);
+}
+
+PodcastView.prototype.remove = function(callback) {
+ if (!this.bucket || !this.key) {
+ callback(new Error("View is missing bucket or key"));
+ return;
+ }
+
+ var params = {
+ Bucket: this.bucket,
+ Key: this.key
+ };
+
+ s3.deleteObject(params, callback);
+}
diff --git a/lib/UpdateHandlers.js b/lib/UpdateHandlers.js
new file mode 100644
index 0000000..6483020
--- /dev/null
+++ b/lib/UpdateHandlers.js
@@ -0,0 +1,200 @@
+var AWS = require('aws-sdk');
+AWS.config.update({region: "us-west-2"});
+
+var doc = require('dynamodb-doc');
+var dynamo = new doc.DynamoDB();
+
+var PodcastView = require('./PodcastView');
+
+var DDB_EPISODES_TABLE = 'podcast-episodes';
+
+exports.handleViewUpdate = function(event, context) {
+ // Handle dynamo event for the views table.
+
+ // Each modified view is added as a key in this Object to dedupe multiple
+ // updates for the same key.
+ var viewsToUpdate = {};
+
+ event.Records.forEach(function(record) {
+ var eventName = record.eventName;
+ var viewKey = record.dynamodb.Keys;
+
+ switch (eventName) {
+ case 'INSERT':
+ case 'MODIFY':
+ viewsToUpdate[viewKey] = 'update';
+ break;
+ case 'REMOVE':
+ viewsToUpdate[viewKey] = 'remove';
+ break;
+ default:
+ context.fail(new Error('Unrecognized eventName "' + eventname + '"'));
+ }
+ });
+
+ var viewIds = Object.keys(viewsToUpdate);
+
+ var remainingCount = 0;
+ var errors = [];
+ var callback = function(error, data) {
+ // When all are done, call context callback.
+ remainingCount--;
+ if (error != null) {
+ errors.push(error);
+ }
+
+ if (remainingCount == 0) {
+ if (errors.length == 0) {
+ context.succeed();
+ } else {
+ context.fail(new Error("Failures updating views"), errors);
+ }
+ }
+ };
+
+ // Start each update/remove operation.
+ viewIds.forEach(function(viewId) {
+ var operation = viewsToUpdate[viewId];
+ PodcastView.findById(viewId, function(error, view) {
+ if (operation == 'update') {
+ remainingCount++;
+ view.render(callback);
+ } else if (operation == 'remove') {
+ remainingCount++;
+ view.remove(callback);
+ }
+ });
+ });
+};
+
+exports.handleEpisodeUpdate = function(event, context) {
+ // Handle dynamo event for the episodes table.
+
+ // Each modified feed is added as a key in this Object to dedupe multiple
+ // updates for the same feed.
+ var feedsToUpdate = {};
+
+ event.Records.forEach(function(record) {
+ var eventName = record.eventName;
+
+ switch (eventName) {
+ case 'INSERT':
+ feedsToUpdate[record.dynamodb.NewImage.feedId] = true;
+ break;
+ case 'MODIFY':
+ var oldImageFeed = record.dynamodb.OldImage.feedId;
+ var newImageFeed = record.dynamodb.NewImage.feedId;
+ if (oldImageFeed != newImageFeed) {
+ feedsToUpdate[oldImageFeed] = true;
+ }
+ feedsToUpdate[newImageFeed] = true;
+ break;
+ case 'REMOVE':
+ feedsToUpdate[record.dynamodb.OldImage.feedId] = true;
+ break;
+ default:
+ context.fail(new Error('Unrecognized eventName "' + eventname + '"'));
+ }
+ });
+
+ var feedIds = Object.keys(feedsToUpdate);
+
+ var remainingCount = 0;
+ var errors = [];
+ var callback = function(error, data) {
+ // When all are done, call context callback.
+ remainingCount--;
+ if (error != null) {
+ errors.push(error);
+ }
+
+ if (remainingCount == 0) {
+ if (errors.length == 0) {
+ context.succeed();
+ } else {
+ context.fail(new Error("Failures updating feeds"), errors);
+ }
+ }
+ };
+
+ // Start updates for each feed.
+ feedIds.forEach(function(feedId) {
+ remainingCount++;
+ renderViewsForFeed(feedId, callback);
+ });
+};
+
+function renderViewsForFeed(feedId, callback) {
+ getEpisodesForFeed(feedId, function(error, episodes) {
+ if (error) {
+ callback(error);
+ return;
+ }
+ console.log("Got episodes " + JSON.stringify(episodes));
+
+ var remainingCount = 0;
+ var errors = [];
+ var renderCallback = function(error, data) {
+ // When all are done, call context callback.
+ remainingCount--;
+ console.log("Remaining is " + remainingCount);
+ if (error != null) {
+ errors.push(error);
+ }
+
+ if (remainingCount == 0) {
+ if (errors.length == 0) {
+ callback();
+ } else {
+ callback(new Error("Failures rendering feeds"), errors);
+ }
+ }
+ };
+
+ // Get all of the views for the feed.
+ PodcastView.forEachView(feedId, function(error, view, last) {
+ remainingCount++;
+ if (error != null) {
+ renderCallback(error);
+ } else {
+ view.render(episodes, renderCallback);
+ }
+ });
+ });
+}
+
+function getEpisodesForFeed(feedId, callback, startKey, episodes) {
+ var params = {
+ TableName: DDB_EPISODES_TABLE,
+ ConsistentRead: true,
+ KeyConditionExpression: "feedId = :feedId",
+ ExpressionAttributeValues: {
+ ':feedId': feedId
+ }
+ };
+
+ if (startKey) {
+ params['ExclusiveStartKey'] = startKey;
+ }
+
+ dynamo.query(params, function(error, data) {
+ if (error != null) {
+ callback(error);
+ return;
+ }
+
+ if (!episodes) {
+ episodes = data.Items;
+ } else {
+ episodes = episodes.concat(data.Items);
+ }
+
+ // If this is not the last set of responses, get more.
+ var lastKey = data.LastEvaluatedKey;
+ if (lastKey) {
+ getEpisodesForFeed(feedId, callback, lastKey, episodes);
+ } else {
+ callback(null, episodes);
+ }
+ });
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-10-31 01:41:11 +0000