Load data for StocksApp incrementally

Previously we would spend a lot of time during startup processing all 3k stocks
in the data set. This CL breaks the data up into 100 stock chunks and loads
them incrementally off the network. A future CL will switch to loading them on
demand.

R=ojan@chromium.org

Review URL: https://codereview.chromium.org/1038533002

examples/stocks-fn/data/stock_data_29.json

@@ -0,0 +1,632 @@
+[
+  [
+    "WSFSL", 
+    "WSFS Financial Corporation", 
+    "26.3499", 
+    "n/a", 
+    "n/a", 
+    "Finance", 
+    "Major Banks", 
+    "http://www.nasdaq.com/symbol/wsfsl"
+  ], 
+  [
+    "WSTC", 
+    "West Corporation", 
+    "34.78", 
+    "$2.93B", 
+    "2013", 
+    "Miscellaneous", 
+    "Business Services", 
+    "http://www.nasdaq.com/symbol/wstc"
+  ], 
+  [
+    "WSTG", 
+    "Wayside Technology Group, Inc.", 
+    "17.08", 
+    "$83.72M", 
+    "n/a", 
+    "Technology", 
+    "Retail: Computer Software & Peripheral Equipment", 
+    "http://www.nasdaq.com/symbol/wstg"
+  ], 
+  [
+    "WSTL", 
+    "Westell Technologies, Inc.", 
+    "1.54", 
+    "$92.7M", 
+    "1995", 
+    "Public Utilities", 
+    "Telecommunications Equipment", 
+    "http://www.nasdaq.com/symbol/wstl"
+  ], 
+  [
+    "WTBA", 
+    "West Bancorporation", 
+    "17.99", 
+    "$288.18M", 
+    "n/a", 
+    "Finance", 
+    "Major Banks", 
+    "http://www.nasdaq.com/symbol/wtba"
+  ], 
+  [
+    "WTFC", 
+    "Wintrust Financial Corporation", 
+    "47.69", 
+    "$2.23B", 
+    "n/a", 
+    "Finance", 
+    "Major Banks", 
+    "http://www.nasdaq.com/symbol/wtfc"
+  ], 
+  [
+    "WTFCW", 
+    "Wintrust Financial Corporation", 
+    "25.25", 
+    "n/a", 
+    "n/a", 
+    "Finance", 
+    "Major Banks", 
+    "http://www.nasdaq.com/symbol/wtfcw"
+  ], 
+  [
+    "WVFC", 
+    "WVS Financial Corp.", 
+    "11.5", 
+    "$23.58M", 
+    "n/a", 
+    "Finance", 
+    "Banks", 
+    "http://www.nasdaq.com/symbol/wvfc"
+  ], 
+  [
+    "WVVI", 
+    "Willamette Valley Vineyards, Inc.", 
+    "5.9499", 
+    "$28.93M", 
+    "n/a", 
+    "Consumer Non-Durables", 
+    "Beverages (Production/Distribution)", 
+    "http://www.nasdaq.com/symbol/wvvi"
+  ], 
+  [
+    "WWD", 
+    "Woodward, Inc.", 
+    "48.75", 
+    "$3.17B", 
+    "n/a", 
+    "Energy", 
+    "Industrial Machinery/Components", 
+    "http://www.nasdaq.com/symbol/wwd"
+  ], 
+  [
+    "WWWW", 
+    "Web.com Group, Inc.", 
+    "18.01", 
+    "$946.04M", 
+    "n/a", 
+    "Technology", 
+    "Computer Software: Prepackaged Software", 
+    "http://www.nasdaq.com/symbol/wwww"
+  ], 
+  [
+    "WYNN", 
+    "Wynn Resorts, Limited", 
+    "158.47", 
+    "$16.06B", 
+    "2002", 
+    "Consumer Services", 
+    "Hotels/Resorts", 
+    "http://www.nasdaq.com/symbol/wynn"
+  ], 
+  [
+    "XBKS", 
+    "Xenith Bankshares, Inc.", 
+    "6.4001", 
+    "$82.71M", 
+    "n/a", 
+    "Finance", 
+    "Major Banks", 
+    "http://www.nasdaq.com/symbol/xbks"
+  ], 
+  [
+    "XCRA", 
+    "Xcerra Corporation", 
+    "8.68", 
+    "$472.42M", 
+    "n/a", 
+    "Capital Goods", 
+    "Electrical Products", 
+    "http://www.nasdaq.com/symbol/xcra"
+  ], 
+  [
+    "XENE", 
+    "Xenon Pharmaceuticals Inc.", 
+    "19.38", 
+    "$274.83M", 
+    "2014", 
+    "Health Care", 
+    "Major Pharmaceuticals", 
+    "http://www.nasdaq.com/symbol/xene"
+  ], 
+  [
+    "XENT", 
+    "Intersect ENT, Inc.", 
+    "22.7", 
+    "$530.65M", 
+    "2014", 
+    "Health Care", 
+    "Medical/Dental Instruments", 
+    "http://www.nasdaq.com/symbol/xent"
+  ], 
+  [
+    "XGTI", 
+    "XG Technology, Inc", 
+    "0.49", 
+    "$12.26M", 
+    "2013", 
+    "Consumer Durables", 
+    "Telecommunications Equipment", 
+    "http://www.nasdaq.com/symbol/xgti"
+  ], 
+  [
+    "XGTIW", 
+    "XG Technology, Inc", 
+    "0.26", 
+    "n/a", 
+    "2013", 
+    "Consumer Durables", 
+    "Telecommunications Equipment", 
+    "http://www.nasdaq.com/symbol/xgtiw"
+  ], 
+  [
+    "XIV", 
+    "VelocityShares Daily Inverse VIX Short Term ETN", 
+    "31.285", 
+    "$485.35M", 
+    "n/a", 
+    "Finance", 
+    "Investment Bankers/Brokers/Service", 
+    "http://www.nasdaq.com/symbol/xiv"
+  ], 
+  [
+    "XLNX", 
+    "Xilinx, Inc.", 
+    "41.675", 
+    "$10.9B", 
+    "1990", 
+    "Technology", 
+    "Semiconductors", 
+    "http://www.nasdaq.com/symbol/xlnx"
+  ], 
+  [
+    "XLRN", 
+    "Acceleron Pharma Inc.", 
+    "39.98", 
+    "$1.29B", 
+    "2013", 
+    "Health Care", 
+    "Biotechnology: Biological Products (No Diagnostic Substances)", 
+    "http://www.nasdaq.com/symbol/xlrn"
+  ], 
+  [
+    "XNCR", 
+    "Xencor, Inc.", 
+    "15.06", 
+    "$473.52M", 
+    "2013", 
+    "Health Care", 
+    "Major Pharmaceuticals", 
+    "http://www.nasdaq.com/symbol/xncr"
+  ], 
+  [
+    "XNET", 
+    "Xunlei Limited", 
+    "7.25", 
+    "$471.36M", 
+    "2014", 
+    "Technology", 
+    "Computer Software: Prepackaged Software", 
+    "http://www.nasdaq.com/symbol/xnet"
+  ], 
+  [
+    "XNPT", 
+    "XenoPort, Inc.", 
+    "7.19", 
+    "$447.49M", 
+    "2005", 
+    "Health Care", 
+    "Major Pharmaceuticals", 
+    "http://www.nasdaq.com/symbol/xnpt"
+  ], 
+  [
+    "XOMA", 
+    "XOMA Corporation", 
+    "4.05", 
+    "$469.36M", 
+    "1986", 
+    "Health Care", 
+    "Major Pharmaceuticals", 
+    "http://www.nasdaq.com/symbol/xoma"
+  ], 
+  [
+    "XONE", 
+    "The ExOne Company", 
+    "16.32", 
+    "$235.71M", 
+    "2013", 
+    "Capital Goods", 
+    "Industrial Machinery/Components", 
+    "http://www.nasdaq.com/symbol/xone"
+  ], 
+  [
+    "XOOM", 
+    "Xoom Corporation", 
+    "16.43", 
+    "$631.69M", 
+    "2013", 
+    "Finance", 
+    "Investment Bankers/Brokers/Service", 
+    "http://www.nasdaq.com/symbol/xoom"
+  ], 
+  [
+    "XPLR", 
+    "Xplore Technologies Corp", 
+    "6.82", 
+    "$57.83M", 
+    "n/a", 
+    "Technology", 
+    "Computer Manufacturing", 
+    "http://www.nasdaq.com/symbol/xplr"
+  ], 
+  [
+    "XRAY", 
+    "DENTSPLY International Inc.", 
+    "52.53", 
+    "$7.43B", 
+    "1987", 
+    "Health Care", 
+    "Medical/Dental Instruments", 
+    "http://www.nasdaq.com/symbol/xray"
+  ], 
+  [
+    "XTLB", 
+    "XTL Biopharmaceuticals Ltd.", 
+    "2.21", 
+    "$25.73M", 
+    "n/a", 
+    "Health Care", 
+    "Major Pharmaceuticals", 
+    "http://www.nasdaq.com/symbol/xtlb"
+  ], 
+  [
+    "XXIA", 
+    "Ixia", 
+    "10.45", 
+    "$819.24M", 
+    "2000", 
+    "Capital Goods", 
+    "Electrical Products", 
+    "http://www.nasdaq.com/symbol/xxia"
+  ], 
+  [
+    "YDIV", 
+    "First Trust NASDAQ Technology Dividend Index Fund", 
+    "19.3412", 
+    "$12.57M", 
+    "n/a", 
+    "n/a", 
+    "n/a", 
+    "http://www.nasdaq.com/symbol/ydiv"
+  ], 
+  [
+    "YDLE", 
+    "Yodlee, Inc.", 
+    "13.01", 
+    "$380.3M", 
+    "2014", 
+    "Technology", 
+    "Computer Software: Prepackaged Software", 
+    "http://www.nasdaq.com/symbol/ydle"
+  ], 
+  [
+    "YHOO", 
+    "Yahoo! Inc.", 
+    "44.11", 
+    "$41.79B", 
+    "1996", 
+    "Technology", 
+    "EDP Services", 
+    "http://www.nasdaq.com/symbol/yhoo"
+  ], 
+  [
+    "YNDX", 
+    "Yandex N.V.", 
+    "17.01", 
+    "$5.41B", 
+    "2011", 
+    "Technology", 
+    "Computer Software: Programming, Data Processing", 
+    "http://www.nasdaq.com/symbol/yndx"
+  ], 
+  [
+    "YOD", 
+    "You On Demand Holdings, Inc.", 
+    "2.25", 
+    "$53.4M", 
+    "n/a", 
+    "Consumer Services", 
+    "Television Services", 
+    "http://www.nasdaq.com/symbol/yod"
+  ], 
+  [
+    "YORW", 
+    "The York Water Company", 
+    "23.07", 
+    "$295.51M", 
+    "n/a", 
+    "Public Utilities", 
+    "Water Supply", 
+    "http://www.nasdaq.com/symbol/yorw"
+  ], 
+  [
+    "YPRO", 
+    "AdvisorShares YieldPro ETF", 
+    "23.94", 
+    "$68.23M", 
+    "n/a", 
+    "n/a", 
+    "n/a", 
+    "http://www.nasdaq.com/symbol/ypro"
+  ], 
+  [
+    "YRCW", 
+    "YRC Worldwide, Inc.", 
+    "19.96", 
+    "$623.91M", 
+    "n/a", 
+    "Transportation", 
+    "Trucking Freight/Courier Services", 
+    "http://www.nasdaq.com/symbol/yrcw"
+  ], 
+  [
+    "YY", 
+    "YY Inc.", 
+    "61.82", 
+    "$3.5B", 
+    "2012", 
+    "Technology", 
+    "EDP Services", 
+    "http://www.nasdaq.com/symbol/yy"
+  ], 
+  [
+    "Z", 
+    "Zillow Group, Inc.", 
+    "125.42", 
+    "$5.12B", 
+    "2011", 
+    "Miscellaneous", 
+    "Business Services", 
+    "http://www.nasdaq.com/symbol/z"
+  ], 
+  [
+    "ZAGG", 
+    "ZAGG Inc", 
+    "6.51", 
+    "$197.48M", 
+    "n/a", 
+    "Consumer Services", 
+    "Other Specialty Stores", 
+    "http://www.nasdaq.com/symbol/zagg"
+  ], 
+  [
+    "ZAZA", 
+    "ZaZa Energy Corporation", 
+    "2.11", 
+    "$27.28M", 
+    "n/a", 
+    "Energy", 
+    "Oil & Gas Production", 
+    "http://www.nasdaq.com/symbol/zaza"
+  ], 
+  [
+    "ZBRA", 
+    "Zebra Technologies Corporation", 
+    "91", 
+    "$4.63B", 
+    "1991", 
+    "Technology", 
+    "Industrial Machinery/Components", 
+    "http://www.nasdaq.com/symbol/zbra"
+  ], 
+  [
+    "ZEUS", 
+    "Olympic Steel, Inc.", 
+    "16.35", 
+    "$179.56M", 
+    "1994", 
+    "Basic Industries", 
+    "Metal Fabrications", 
+    "http://www.nasdaq.com/symbol/zeus"
+  ], 
+  [
+    "ZFGN", 
+    "Zafgen, Inc.", 
+    "40.64", 
+    "$1.08B", 
+    "2014", 
+    "Health Care", 
+    "Major Pharmaceuticals", 
+    "http://www.nasdaq.com/symbol/zfgn"
+  ], 
+  [
+    "ZGNX", 
+    "Zogenix, Inc.", 
+    "1.55", 
+    "$237.21M", 
+    "2010", 
+    "Health Care", 
+    "Major Pharmaceuticals", 
+    "http://www.nasdaq.com/symbol/zgnx"
+  ], 
+  [
+    "ZHNE", 
+    "Zhone Technologies, Inc.", 
+    "1.54", 
+    "$50.05M", 
+    "n/a", 
+    "Public Utilities", 
+    "Telecommunications Equipment", 
+    "http://www.nasdaq.com/symbol/zhne"
+  ], 
+  [
+    "ZINC", 
+    "Horsehead Holding Corp.", 
+    "13.49", 
+    "$763.52M", 
+    "2007", 
+    "Capital Goods", 
+    "Metal Fabrications", 
+    "http://www.nasdaq.com/symbol/zinc"
+  ], 
+  [
+    "ZION", 
+    "Zions Bancorporation", 
+    "26.33", 
+    "$5.34B", 
+    "n/a", 
+    "Finance", 
+    "Major Banks", 
+    "http://www.nasdaq.com/symbol/zion"
+  ], 
+  [
+    "ZIONW", 
+    "Zions Bancorporation", 
+    "3.4", 
+    "n/a", 
+    "n/a", 
+    "Finance", 
+    "Major Banks", 
+    "http://www.nasdaq.com/symbol/zionw"
+  ], 
+  [
+    "ZIONZ", 
+    "Zions Bancorporation", 
+    "2.45", 
+    "n/a", 
+    "n/a", 
+    "Finance", 
+    "Major Banks", 
+    "http://www.nasdaq.com/symbol/zionz"
+  ], 
+  [
+    "ZIOP", 
+    "ZIOPHARM Oncology Inc", 
+    "9.56", 
+    "$1.11B", 
+    "n/a", 
+    "Health Care", 
+    "Medical Specialities", 
+    "http://www.nasdaq.com/symbol/ziop"
+  ], 
+  [
+    "ZIV", 
+    "VelocityShares Daily Inverse VIX Medium Term ETN", 
+    "41.1", 
+    "$37.81M", 
+    "n/a", 
+    "Finance", 
+    "Investment Bankers/Brokers/Service", 
+    "http://www.nasdaq.com/symbol/ziv"
+  ], 
+  [
+    "ZIXI", 
+    "Zix Corporation", 
+    "3.81", 
+    "$216.48M", 
+    "n/a", 
+    "Technology", 
+    "EDP Services", 
+    "http://www.nasdaq.com/symbol/zixi"
+  ], 
+  [
+    "ZLTQ", 
+    "ZELTIQ Aesthetics, Inc.", 
+    "34.23", 
+    "$1.3B", 
+    "2011", 
+    "Health Care", 
+    "Biotechnology: Electromedical & Electrotherapeutic Apparatus", 
+    "http://www.nasdaq.com/symbol/zltq"
+  ], 
+  [
+    "ZN", 
+    "Zion Oil & Gas Inc", 
+    "1.85", 
+    "$65.29M", 
+    "n/a", 
+    "Energy", 
+    "Oil & Gas Production", 
+    "http://www.nasdaq.com/symbol/zn"
+  ], 
+  [
+    "ZNGA", 
+    "Zynga Inc.", 
+    "2.32", 
+    "$2.09B", 
+    "2011", 
+    "Technology", 
+    "EDP Services", 
+    "http://www.nasdaq.com/symbol/znga"
+  ], 
+  [
+    "ZNWAA", 
+    "Zion Oil & Gas Inc", 
+    "n/a", 
+    "n/a", 
+    "n/a", 
+    "Energy", 
+    "Oil & Gas Production", 
+    "http://www.nasdaq.com/symbol/znwaa"
+  ], 
+  [
+    "ZSAN", 
+    "Zosano Pharma Corporation", 
+    "11.09", 
+    "$131.04M", 
+    "2015", 
+    "Health Care", 
+    "Major Pharmaceuticals", 
+    "http://www.nasdaq.com/symbol/zsan"
+  ], 
+  [
+    "ZSPH", 
+    "ZS Pharma, Inc.", 
+    "50.51", 
+    "$1.05B", 
+    "2014", 
+    "Health Care", 
+    "Major Pharmaceuticals", 
+    "http://www.nasdaq.com/symbol/zsph"
+  ], 
+  [
+    "ZU", 
+    "zulily, inc.", 
+    "14.4", 
+    "$1.8B", 
+    "2013", 
+    "Consumer Services", 
+    "Catalog/Specialty Distribution", 
+    "http://www.nasdaq.com/symbol/zu"
+  ], 
+  [
+    "ZUMZ", 
+    "Zumiez Inc.", 
+    "38.77", 
+    "$1.13B", 
+    "2005", 
+    "Consumer Services", 
+    "Clothing/Shoe/Accessory Stores", 
+    "http://www.nasdaq.com/symbol/zumz"
+  ]
+]

examples/stocks-fn/lib/stock_app.dart

@@ -34,18 +34,16 @@ class StocksApp extends App {
     ${typography.white.title};'''
   );
 
-  List<Stock> _sortedStocks = [];
+  StockDataFetcher _stockDataFetcher;
+  List<Stock> _stocks = [];
   bool _isSearching = false;
   bool _isShowingMenu = false;
   String _searchQuery;
 
   StocksApp() : super() {
-    fetchStockOracle().then((oracle) {
+    _stockDataFetcher = new StockDataFetcher((StockData data) {
       setState(() {
-        _sortedStocks = oracle.stocks;
-        trace('StocksApp::sortStocks', () {
-          _sortedStocks.sort((a, b) => a.symbol.compareTo(b.symbol));
-        });
+        data.appendTo(_stocks);
       });
     });
   }
@@ -155,7 +153,7 @@ class StocksApp extends App {
 
     return new Scaffold(
       actionBar: actionBar,
-      content: new Stocklist(stocks: _sortedStocks, query: _searchQuery),
+      content: new Stocklist(stocks: _stocks, query: _searchQuery),
       fab: new FloatingActionButton(
         content: new Icon(type: 'content/add_white', size: 24), level: 3),
       drawer: drawer,

examples/stocks-fn/lib/stock_data.dart

@@ -12,6 +12,8 @@ import 'package:sky/framework/net/fetch.dart';
 // "Symbol","Name","LastSale","MarketCap","IPOyear","Sector","industry","Summary Quote",
 // Data in stock_data.json
 
+final Random _rng = new Random();
+
 class Stock {
   String symbol;
   String name;
@@ -31,36 +33,41 @@ class Stock {
     symbol = fields[0];
     name = fields[1];
     marketCap = fields[4];
-    var rng = new Random();
-    percentChange = (rng.nextDouble() * 20) - 10;
+    percentChange = (_rng.nextDouble() * 20) - 10;
   }
 }
 
-class StockOracle {
-  List<Stock> stocks;
+class StockData {
+  List<List<String>> _data;
 
-  StockOracle(this.stocks);
+  StockData(this._data);
 
-  StockOracle.fromCompanyList(List<List<String>> list) {
-    stocks = list.map((fields) => new Stock.fromFields(fields)).toList();
+  void appendTo(List<Stock> stocks) {
+    for (List<String> fields in _data)
+      stocks.add(new Stock.fromFields(fields));
+  }
+}
+
+typedef void StockDataCallback(StockData data);
+const _kChunkCount = 30;
+
+class StockDataFetcher {
+  int _currentChunk = 0;
+  final StockDataCallback callback;
+
+  StockDataFetcher(this.callback) {
+    _fetchNextChunk();
   }
 
-  Stock lookupBySymbol(String symbol) {
-    this.stocks.forEach((stock) {
-      if (stock.symbol == symbol)
-        return stock;
+  void _fetchNextChunk() {
+    fetch('data/stock_data_${_currentChunk++}.json').then((Response response) {
+      String json = response.bodyAsString();
+      JsonDecoder decoder = new JsonDecoder();
+
+      callback(new StockData(decoder.convert(json)));
+
+      if (_currentChunk < _kChunkCount)
+        _fetchNextChunk();
     });
-    return null;
   }
 }
-
-Future<StockOracle> fetchStockOracle() async {
-  Response response = await fetch('lib/stock_data.json');
-
-  return trace('stocks::fetchStockOracle', () {
-    String json = response.bodyAsString();
-    JsonDecoder decoder = new JsonDecoder();
-    var companyList = decoder.convert(json);
-    return new StockOracle.fromCompanyList(companyList);
-  });
-}