Updates from Wed Feb 18

- [reactnative] s/SpinnerIOS/ActivityIndicatorIOS/ | Dan Witte - [react-packager] Add a non-persistent mode for static builds | Amjad Masad - [React Native] Fix stored file rejection when initializing cache | Alex Akers - [React Native] Consolidate network requests in image downloader | Alex Akers - [React Native] Update RCTCache | Alex Akers - Converted all low-hanging RKBridgeModules in FBReactKit to RCTBridgeModules | Nick Lockwood
2025-01-12 02:24:23 +00:00 · 2015-02-18 17:51:14 -08:00 · 2015-02-18 17:51:14 -08:00 · c88a1cd9b8
commit c88a1cd9b8
parent 89db1a64aa
22 changed files with 430 additions and 272 deletions
--- a/Examples/Movies/SearchScreen.js
+++ b/Examples/Movies/SearchScreen.js
@ -9,7 +9,7 @@ var {
  ListView,
  ListViewDataSource,
  ScrollView,
-  SpinnerIOS,
+  ActivityIndicatorIOS,
  StyleSheet,
  Text,
  TextInput,
@ -215,7 +215,7 @@ var SearchScreen = React.createClass({
    if (!this.hasMore() || !this.state.isLoadingTail) {
      return <View style={styles.scrollSpinner} />;
    }
-    return <SpinnerIOS style={styles.scrollSpinner} />;
+    return <ActivityIndicatorIOS style={styles.scrollSpinner} />;
  },

  renderRow: function(movie: Object)  {
@ -290,7 +290,7 @@ var SearchBar = React.createClass({
          onFocus={this.props.onFocus}
          style={styles.searchBarInput}
        />
-        <SpinnerIOS
+        <ActivityIndicatorIOS
          animating={this.props.isLoading}
          style={styles.spinner}
        />
--- a/Examples/UIExplorer/ActivityIndicatorExample.js
+++ b/Examples/UIExplorer/ActivityIndicatorExample.js
@ -1,19 +1,19 @@
 /**
 * Copyright 2004-present Facebook. All Rights Reserved.
 *
- * @providesModule SpinnerExample
+ * @providesModule ActivityIndicatorExample
 */
 'use strict';

 var React = require('react-native');
 var {
-  SpinnerIOS,
+  ActivityIndicatorIOS,
  StyleSheet,
  TimerMixin,
  View,
 } = React;

-var ToggleAnimatingSpinner = React.createClass({
+var ToggleAnimatingActivityIndicator = React.createClass({
  mixins: [TimerMixin],

  getInitialState: function() {
@ -38,17 +38,17 @@ var ToggleAnimatingSpinner = React.createClass({

  render: function() {
    return (
-      <SpinnerIOS
+      <ActivityIndicatorIOS
        animating={this.state.animating}
        style={[styles.centering, {height: 80}]}
-        size={SpinnerIOS.size.large}
+        size={ActivityIndicatorIOS.size.large}
      />
    );
  }
 });

 exports.framework = 'React';
-exports.title = '<SpinnerIOS>';
+exports.title = '<ActivityIndicatorIOS>';
 exports.description = 'Animated loading indicators.';

 exports.examples = [
@ -56,7 +56,7 @@ exports.examples = [
    title: 'Default (small, white)',
    render: function() {
      return (
-        <SpinnerIOS
+        <ActivityIndicatorIOS
          style={[styles.centering, styles.gray, {height: 40}]}
          color="white"
          />
@ -68,10 +68,10 @@ exports.examples = [
    render: function() {
      return (
        <View>
-          <SpinnerIOS
+          <ActivityIndicatorIOS
            style={[styles.centering, {height: 40}]}
          />
-          <SpinnerIOS
+          <ActivityIndicatorIOS
            style={[styles.centering, {backgroundColor: '#eeeeee', height: 40}]}
          />
        </View>
@ -83,10 +83,10 @@ exports.examples = [
    render: function() {
      return (
        <View style={styles.horizontal}>
-          <SpinnerIOS color="#0000ff" />
-          <SpinnerIOS color="#aa00aa" />
-          <SpinnerIOS color="#aa3300" />
-          <SpinnerIOS color="#00aa00" />
+          <ActivityIndicatorIOS color="#0000ff" />
+          <ActivityIndicatorIOS color="#aa00aa" />
+          <ActivityIndicatorIOS color="#aa3300" />
+          <ActivityIndicatorIOS color="#00aa00" />
        </View>
      );
    }
@ -95,10 +95,10 @@ exports.examples = [
    title: 'Large',
    render: function() {
      return (
-        <SpinnerIOS
+        <ActivityIndicatorIOS
          style={[styles.centering, styles.gray, {height: 80}]}
          color="white"
-          size={SpinnerIOS.size.large}
+          size={ActivityIndicatorIOS.size.large}
        />
      );
    }
@ -108,20 +108,20 @@ exports.examples = [
    render: function() {
      return (
        <View style={styles.horizontal}>
-          <SpinnerIOS
-            size={SpinnerIOS.size.large}
+          <ActivityIndicatorIOS
+            size={ActivityIndicatorIOS.size.large}
            color="#0000ff"
          />
-          <SpinnerIOS
-            size={SpinnerIOS.size.large}
+          <ActivityIndicatorIOS
+            size={ActivityIndicatorIOS.size.large}
            color="#aa00aa"
          />
-          <SpinnerIOS
-            size={SpinnerIOS.size.large}
+          <ActivityIndicatorIOS
+            size={ActivityIndicatorIOS.size.large}
            color="#aa3300"
          />
-          <SpinnerIOS
-            size={SpinnerIOS.size.large}
+          <ActivityIndicatorIOS
+            size={ActivityIndicatorIOS.size.large}
            color="#00aa00"
          />
        </View>
@ -131,7 +131,7 @@ exports.examples = [
  {
    title: 'Start/stop',
    render: function() {
-      return <ToggleAnimatingSpinner />;
+      return <ToggleAnimatingActivityIndicator />;
    }
  },
 ];
--- a/Examples/UIExplorer/UIExplorerList.js
+++ b/Examples/UIExplorer/UIExplorerList.js
@ -29,7 +29,7 @@ var EXAMPLES = [
  require('./StatusBarIOSExample'),
  require('./PointerEventsExample'),
  require('./TouchableExample'),
-  require('./SpinnerExample'),
+  require('./ActivityIndicatorExample'),
  require('./ScrollViewExample'),
 ];

--- a/Libraries/Components/ActivityIndicatorIOS/ActivityIndicatorIOS.ios.js
+++ b/Libraries/Components/ActivityIndicatorIOS/ActivityIndicatorIOS.ios.js
@ -1,7 +1,7 @@
 /**
 * Copyright 2004-present Facebook. All Rights Reserved.
 *
- * @providesModule SpinnerIOS
+ * @providesModule ActivityIndicatorIOS
 */
 'use strict';

@ -25,7 +25,7 @@ var SpinnerSize = keyMirror({

 var GRAY = '#999999';

-var SpinnerIOS = React.createClass({
+var ActivityIndicatorIOS = React.createClass({
  mixins: [NativeMethodsMixin],

  propTypes: {
@ -39,8 +39,8 @@ var SpinnerIOS = React.createClass({
    color: PropTypes.string,
    /**
     * The size of the spinner, must be one of:
-     * - SpinnerIOS.size.large
-     * - SpinnerIOS.size.small (default)
+     * - ActivityIndicatorIOS.size.large
+     * - ActivityIndicatorIOS.size.small (default)
     */
    size: PropTypes.oneOf([SpinnerSize.large, SpinnerSize.small]),
  },
@ -101,4 +101,4 @@ var UIActivityIndicatorView = createReactIOSNativeComponentClass({
  uiViewClassName: 'UIActivityIndicatorView',
 });

-module.exports = SpinnerIOS;
+module.exports = ActivityIndicatorIOS;
--- a/Libraries/react-native/react-native-interface.js
+++ b/Libraries/react-native/react-native-interface.js
@ -11,7 +11,7 @@ declare module "react-native" {
  declare var NavigatorItemIOS: ReactClass<any, any, any>;
  declare var PixelRatio: ReactClass<any, any, any>;
  declare var ScrollView: ReactClass<any, any, any>;
-  declare var SpinnerIOS: ReactClass<any, any, any>;
+  declare var ActivityIndicatorIOS: ReactClass<any, any, any>;
  declare var StyleSheet: ReactClass<any, any, any>;
  declare var Text: ReactClass<any, any, any>;
  declare var TextInput: ReactClass<any, any, any>;
--- a/Libraries/react-native/react-native.js
+++ b/Libraries/react-native/react-native.js
@ -16,7 +16,7 @@ var ReactNative = {
  NavigatorIOS: require('NavigatorIOS'),
  PixelRatio: require('PixelRatio'),
  ScrollView: require('ScrollView'),
-  SpinnerIOS: require('SpinnerIOS'),
+  ActivityIndicatorIOS: require('ActivityIndicatorIOS'),
  StatusBarIOS: require('StatusBarIOS'),
  StyleSheet: require('StyleSheet'),
  Text: require('Text'),
--- a/ReactKit/Base/RCTBridge.m
+++ b/ReactKit/Base/RCTBridge.m
@ -235,8 +235,9 @@ static NSDictionary *RCTRemoteModulesConfig()
    RCTRemoteModulesByID = [[NSMutableDictionary alloc] init];
    
    remoteModules = [[NSMutableDictionary alloc] init];
-    [RCTExportedMethodsByModule() enumerateKeysAndObjectsUsingBlock:^(NSString *moduleName, NSArray *rawMethods, BOOL *stop) {
-      
+    [RCTBridgeModuleClasses() enumerateKeysAndObjectsUsingBlock:^(NSString *moduleName, Class moduleClass, BOOL *stop) {
+
+      NSArray *rawMethods = RCTExportedMethodsByModule()[moduleName];
      NSMutableDictionary *methods = [NSMutableDictionary dictionaryWithCapacity:rawMethods.count];
      [rawMethods enumerateObjectsUsingBlock:^(RCTModuleMethod *method, NSUInteger methodID, BOOL *stop) {
        methods[method.JSMethodName] = @{
@ -249,13 +250,15 @@ static NSDictionary *RCTRemoteModulesConfig()
        @"moduleID": @(remoteModules.count),
        @"methods": methods
      };
-      
-      Class cls = RCTBridgeModuleClasses()[moduleName];
-      if (RCTClassOverridesClassMethod(cls, @selector(constantsToExport))) {
-        module = [module mutableCopy];
-        ((NSMutableDictionary *)module)[@"constants"] = [cls constantsToExport];
+
+      if (RCTClassOverridesClassMethod(moduleClass, @selector(constantsToExport))) {
+        NSDictionary *constants = [moduleClass constantsToExport];
+        if (constants.count) {
+          module = [module mutableCopy];
+          ((NSMutableDictionary *)module)[@"constants"] = constants;
+        }
      }
-      remoteModules[moduleName] = module;
+      remoteModules[moduleName] = [module copy];
      
      // Add module lookup
      RCTRemoteModulesByID[module[@"moduleID"]] = moduleName;
@ -303,13 +306,13 @@ static NSDictionary *RCTLocalModulesConfig()
    // Add globally used methods
    [JSMethods addObjectsFromArray:@[
      @"Bundler.runApplication",
+      @"RCTDeviceEventEmitter.emit",
      @"RCTEventEmitter.receiveEvent",
      @"RCTEventEmitter.receiveTouches",
    ]];
    
    //  NOTE: these methods are currently unused in the OSS project
    //  @"Dimensions.set",
-    //  @"RCTDeviceEventEmitter.emit",
    //  @"RCTNativeAppEventEmitter.emit",
    //  @"ReactIOS.unmountComponentAtNodeAndRemoveContainer",
    
@ -376,10 +379,15 @@ static id<RCTJavaScriptExecutor> _latestJSExecutor;
    _moduleInstances = [[NSMutableDictionary alloc] init];
    [RCTBridgeModuleClasses() enumerateKeysAndObjectsUsingBlock:^(NSString *moduleName, Class moduleClass, BOOL *stop) {
      if (_moduleInstances[moduleName] == nil) {
+        id<RCTBridgeModule> moduleInstance;
        if ([moduleClass instancesRespondToSelector:@selector(initWithBridge:)]) {
-          _moduleInstances[moduleName] = [[moduleClass alloc] initWithBridge:self];
+          moduleInstance = [[moduleClass alloc] initWithBridge:self];
        } else {
-          _moduleInstances[moduleName] = [[moduleClass alloc] init];
+          moduleInstance = [[moduleClass alloc] init];
+        }
+        if (moduleInstance) {
+          // If nil, the module doesn't support auto-instantiation
+          _moduleInstances[moduleName] = moduleInstance;
        }
      }
    }];
@ -522,7 +530,7 @@ static id<RCTJavaScriptExecutor> _latestJSExecutor;
  }
  
  if (![buffer isKindOfClass:[NSArray class]]) {
-    RCTLogMustFix(@"Buffer must be an instance of NSArray, got %@", NSStringFromClass([buffer class]));
+    RCTLogError(@"Buffer must be an instance of NSArray, got %@", NSStringFromClass([buffer class]));
    return;
  }
  
@ -530,14 +538,14 @@ static id<RCTJavaScriptExecutor> _latestJSExecutor;
  NSUInteger bufferRowCount = [requestsArray count];
  NSUInteger expectedFieldsCount = RCTBridgeFieldResponseReturnValues + 1;
  if (bufferRowCount != expectedFieldsCount) {
-    RCTLogMustFix(@"Must pass all fields to buffer - expected %zd, saw %zd", expectedFieldsCount, bufferRowCount);
+    RCTLogError(@"Must pass all fields to buffer - expected %zd, saw %zd", expectedFieldsCount, bufferRowCount);
    return;
  }
  
  for (NSUInteger fieldIndex = RCTBridgeFieldRequestModuleIDs; fieldIndex <= RCTBridgeFieldParamss; fieldIndex++) {
    id field = [requestsArray objectAtIndex:fieldIndex];
    if (![field isKindOfClass:[NSArray class]]) {
-      RCTLogMustFix(@"Field at index %zd in buffer must be an instance of NSArray, got %@", fieldIndex, NSStringFromClass([field class]));
+      RCTLogError(@"Field at index %zd in buffer must be an instance of NSArray, got %@", fieldIndex, NSStringFromClass([field class]));
      return;
    }
  }
@ -549,7 +557,7 @@ static id<RCTJavaScriptExecutor> _latestJSExecutor;
  NSUInteger numRequests = [moduleIDs count];
  BOOL allSame = numRequests == [methodIDs count] && numRequests == [paramsArrays count];
  if (!allSame) {
-    RCTLogMustFix(@"Invalid data message - all must be length: %zd", numRequests);
+    RCTLogError(@"Invalid data message - all must be length: %zd", numRequests);
    return;
  }
  
@ -578,30 +586,30 @@ static id<RCTJavaScriptExecutor> _latestJSExecutor;
                      params:(NSArray *)params
 {
  if (![params isKindOfClass:[NSArray class]]) {
-    RCTLogMustFix(@"Invalid module/method/params tuple for request #%zd", i);
+    RCTLogError(@"Invalid module/method/params tuple for request #%zd", i);
    return NO;
  }
  
  NSString *moduleName = RCTRemoteModulesByID[moduleID];
  if (!moduleName) {
-    RCTLogMustFix(@"Unknown moduleID: %@", moduleID);
+    RCTLogError(@"Unknown moduleID: %@", moduleID);
    return NO;
  }
  
  NSArray *methods = RCTExportedMethodsByModule()[moduleName];
  if (methodID >= methods.count) {
-    RCTLogMustFix(@"Unknown methodID: %zd for module: %@", methodID, moduleName);
+    RCTLogError(@"Unknown methodID: %zd for module: %@", methodID, moduleName);
    return NO;
  }
  
  RCTModuleMethod *method = methods[methodID];
  NSUInteger methodArity = method.arity;
  if (params.count != methodArity) {
-    RCTLogMustFix(@"Expected %tu arguments but got %tu invoking %@.%@",
-                  methodArity,
-                  params.count,
-                  moduleName,
-                  method.JSMethodName);
+    RCTLogError(@"Expected %tu arguments but got %tu invoking %@.%@",
+                methodArity,
+                params.count,
+                moduleName,
+                method.JSMethodName);
    return NO;
  }
  
@ -663,13 +671,13 @@ static id<RCTJavaScriptExecutor> _latestJSExecutor;
          // TODO: it seems like an error if the param doesn't respond
          // so we should probably surface that error rather than failing silently
 #define CASE(_value, _type, _selector)                           \
-case _value:                                             \
-if ([param respondsToSelector:@selector(_selector)]) { \
-_type value = [param _selector];                     \
-[invocation setArgument:&value atIndex:argIdx];      \
-shouldSet = NO;                                      \
-}                                                      \
-break;
+        case _value:                                             \
+          if ([param respondsToSelector:@selector(_selector)]) { \
+            _type value = [param _selector];                     \
+            [invocation setArgument:&value atIndex:argIdx];      \
+            shouldSet = NO;                                      \
+          }                                                      \
+          break;
          
          CASE('c', char, charValue)
          CASE('C', unsigned char, unsignedCharValue)
@ -698,7 +706,7 @@ break;
      [invocation invoke];
    }
    @catch (NSException *exception) {
-      RCTLogMustFix(@"Exception thrown while invoking %@ on target %@ with params %@: %@", method.JSMethodName, target, params, exception);
+      RCTLogError(@"Exception thrown while invoking %@ on target %@ with params %@: %@", method.JSMethodName, target, params, exception);
    }
  });
  
--- a/ReactKit/Base/RCTCache.m
+++ b/ReactKit/Base/RCTCache.m
@ -5,21 +5,90 @@
 #import <UIKit/UIKit.h>
 #import <sys/xattr.h>

-static NSString *const CacheSubdirectoryName = @"ReactKit";
-static NSString *const KeyExtendedAttributeName = @"com.facebook.ReactKit.RCTCacheManager.Key";
-static dispatch_queue_t Queue;
+static NSString *const RCTCacheSubdirectoryName = @"ReactKit";
+static NSString *const RCTKeyExtendedAttributeName = @"com.facebook.ReactKit.RCTCacheManager.Key";
+static NSMapTable *RCTLivingCachesByName;
+
+static NSError *RCTPOSIXError(int errorNumber)
+{
+  NSDictionary *userInfo = @{
+    NSLocalizedDescriptionKey: @(strerror(errorNumber))
+  };
+  return [NSError errorWithDomain:NSPOSIXErrorDomain code:errorNumber userInfo:userInfo];
+}
+
+static NSString *RCTGetExtendedAttribute(NSURL *fileURL, NSString *key, NSError **error)
+{
+  const char *path = fileURL.fileSystemRepresentation;
+  ssize_t length = getxattr(path, key.UTF8String, NULL, 0, 0, 0);
+  if (length <= 0) {
+    if (error) *error = RCTPOSIXError(errno);
+    return nil;
+  }
+
+  char *buffer = malloc(length);
+  length = getxattr(path, key.UTF8String, buffer, length, 0, 0);
+  if (length > 0) {
+    return [[NSString alloc] initWithBytesNoCopy:buffer length:length encoding:NSUTF8StringEncoding freeWhenDone:YES];
+  }
+
+  free(buffer);
+  if (error) *error = RCTPOSIXError(errno);
+  return nil;
+}
+
+static BOOL RCTSetExtendedAttribute(NSURL *fileURL, NSString *key, NSString *value, NSError **error)
+{
+  const char *path = fileURL.fileSystemRepresentation;
+
+  int result;
+  if (value) {
+    const char *valueUTF8String = value.UTF8String;
+    result = setxattr(path, key.UTF8String, valueUTF8String, strlen(valueUTF8String), 0, 0);
+  } else {
+    result = removexattr(path, key.UTF8String, 0);
+  }
+
+  if (result) {
+    if (error) *error = RCTPOSIXError(errno);
+    return NO;
+  }
+
+  return YES;
+}

 #pragma mark - Cache Record -

@interface RCTCacheRecord : NSObject

-@property (nonatomic, copy) NSUUID *UUID;
+@property (readonly) NSUUID *UUID;
+@property (readonly, weak) dispatch_queue_t queue;
@property (nonatomic, copy) NSData *data;

@end

@implementation RCTCacheRecord

+- (instancetype)initWithUUID:(NSUUID *)UUID
+{
+  if ((self = [super init])) {
+    _UUID = [UUID copy];
+  }
+  return self;
+}
+
+- (void)enqueueBlock:(dispatch_block_t)block
+{
+  dispatch_queue_t queue = _queue;
+  if (!queue) {
+    NSString *queueName = [NSString stringWithFormat:@"com.facebook.ReactKit.RCTCache.%@", _UUID.UUIDString];
+    queue = dispatch_queue_create(queueName.UTF8String, DISPATCH_QUEUE_SERIAL);
+    _queue = queue;
+  }
+
+  dispatch_async(queue, block);
+}
+
@end

 #pragma mark - Cache
@ -35,9 +104,10 @@ static dispatch_queue_t Queue;
 + (void)initialize
 {
  if (self == [RCTCache class]) {
-    Queue = dispatch_queue_create("com.facebook.ReactKit.RCTCache", DISPATCH_QUEUE_SERIAL);
+    RCTLivingCachesByName = [NSMapTable strongToWeakObjectsMapTable];
  }
 }
+
 - (instancetype)init
 {
  return [self initWithName:@"default"];
@ -46,46 +116,39 @@ static dispatch_queue_t Queue;
 - (instancetype)initWithName:(NSString *)name
 {
  NSParameterAssert(name.length < NAME_MAX);
+  RCTCache *cachedCache = [RCTLivingCachesByName objectForKey:name];
+  if (cachedCache) {
+    self = cachedCache;
+    return self;
+  }
+
  if ((self = [super init])) {
    _name = [name copy];
    _fileManager = [[NSFileManager alloc] init];
    _storage = [NSMutableDictionary dictionary];

    NSURL *cacheDirectoryURL = [[_fileManager URLsForDirectory:NSCachesDirectory inDomains:NSUserDomainMask] lastObject];
-    cacheDirectoryURL = [cacheDirectoryURL URLByAppendingPathComponent:CacheSubdirectoryName isDirectory:YES];
+    cacheDirectoryURL = [cacheDirectoryURL URLByAppendingPathComponent:RCTCacheSubdirectoryName isDirectory:YES];
    _cacheDirectoryURL = [cacheDirectoryURL URLByAppendingPathComponent:name isDirectory:YES];
    [_fileManager createDirectoryAtURL:_cacheDirectoryURL withIntermediateDirectories:YES attributes:nil error:NULL];

    NSArray *fileURLs = [_fileManager contentsOfDirectoryAtURL:_cacheDirectoryURL includingPropertiesForKeys:nil options:NSDirectoryEnumerationSkipsHiddenFiles error:NULL];
    for (NSURL *fileURL in fileURLs) {
-      NSUUID *uuid = [[NSUUID alloc] initWithUUIDString:fileURL.lastPathComponent];
-      if (!uuid) continue;
+      NSUUID *UUID = [[NSUUID alloc] initWithUUIDString:fileURL.lastPathComponent];
+      if (!UUID) continue;

-      NSString *key = [self keyOfItemAtURL:fileURL error:NULL];
+      NSString *key = RCTGetExtendedAttribute(fileURL, RCTKeyExtendedAttributeName, NULL);
      if (!key) {
        [_fileManager removeItemAtURL:fileURL error:NULL];
        continue;
      }

-      RCTCacheRecord *record = [[RCTCacheRecord alloc] init];
-      record.UUID = uuid;
-      _storage[key] = record;
+      _storage[key] = [[RCTCacheRecord alloc] initWithUUID:UUID];
    }
  }
  return self;
 }

- (void)runOnQueue:(dispatch_block_t)block
-{
-  UIBackgroundTaskIdentifier identifier = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil];
-  dispatch_async(Queue, ^{
-    if (block) block();
-    if (identifier != UIBackgroundTaskInvalid) {
-      [[UIApplication sharedApplication] endBackgroundTask:identifier];
-    }
-  });
-}
-
 - (BOOL)hasDataForKey:(NSString *)key
 {
  return _storage[key] != nil;
@ -95,115 +158,67 @@ static dispatch_queue_t Queue;
 {
  NSParameterAssert(key.length > 0);
  NSParameterAssert(completionHandler != nil);
-  [self runOnQueue:^{
-    RCTCacheRecord *record = _storage[key];
-    if (record && !record.data) {
+  RCTCacheRecord *record = _storage[key];
+  if (!record) {
+    completionHandler(nil);
+    return;
+  }
+
+  [record enqueueBlock:^{
+    if (!record.data) {
      record.data = [NSData dataWithContentsOfURL:[_cacheDirectoryURL URLByAppendingPathComponent:record.UUID.UUIDString]];
    }
-
-    dispatch_async(dispatch_get_main_queue(), ^{
-      completionHandler(record.data);
-    });
+    completionHandler(record.data);
  }];
 }

 - (void)setData:(NSData *)data forKey:(NSString *)key
 {
  NSParameterAssert(key.length > 0);
-  [self runOnQueue:^{
-    RCTCacheRecord *record = _storage[key];
+  RCTCacheRecord *record = _storage[key];
+  if (!record) {
+    if (!data) return;
+
+    record = [[RCTCacheRecord alloc] initWithUUID:[NSUUID UUID]];
+    _storage[key] = record;
+  }
+
+  NSURL *fileURL = [_cacheDirectoryURL URLByAppendingPathComponent:record.UUID.UUIDString];
+
+  UIBackgroundTaskIdentifier identifier = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil];
+  [record enqueueBlock:^{
    if (data) {
-      if (!record) {
-        record = [[RCTCacheRecord alloc] init];
-        record.UUID = [NSUUID UUID];
-        _storage[key] = record;
-      }
-
-      record.data = data;
-
-      NSURL *fileURL = [_cacheDirectoryURL URLByAppendingPathComponent:record.UUID.UUIDString];
      [data writeToURL:fileURL options:NSDataWritingAtomic error:NULL];
-    } else if (record) {
-      [_storage removeObjectForKey:key];
-
-      NSURL *fileURL = [_cacheDirectoryURL URLByAppendingPathComponent:record.UUID.UUIDString];
+      RCTSetExtendedAttribute(fileURL, RCTKeyExtendedAttributeName, key, NULL);
+    } else {
      [_fileManager removeItemAtURL:fileURL error:NULL];
    }
+
+    if (identifier != UIBackgroundTaskInvalid) {
+      [[UIApplication sharedApplication] endBackgroundTask:identifier];
+    }
  }];
 }

 - (void)removeAllData
 {
-  [self runOnQueue:^{
-    [_storage removeAllObjects];
+  UIBackgroundTaskIdentifier identifier = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil];
+  dispatch_group_t group = dispatch_group_create();

-    NSDirectoryEnumerator *enumerator = [_fileManager enumeratorAtURL:_cacheDirectoryURL includingPropertiesForKeys:nil options:NSDirectoryEnumerationSkipsHiddenFiles errorHandler:nil];
-    for (NSURL *fileURL in enumerator) {
+  [_storage enumerateKeysAndObjectsUsingBlock:^(NSString *key, RCTCacheRecord *record, BOOL *stop) {
+    NSURL *fileURL = [_cacheDirectoryURL URLByAppendingPathComponent:record.UUID.UUIDString];
+    dispatch_group_async(group, record.queue, ^{
      [_fileManager removeItemAtURL:fileURL error:NULL];
-    }
+    });
  }];
-}

-#pragma mark - Extended Attributes
-
- (NSError *)errorWithPOSIXErrorNumber:(int)errorNumber
-{
-  NSDictionary *userInfo = @{
-    NSLocalizedDescriptionKey: @(strerror(errorNumber))
-  };
-  return [NSError errorWithDomain:NSPOSIXErrorDomain code:errorNumber userInfo:userInfo];
-}
-
- (BOOL)setAttribute:(NSString *)key value:(NSString *)value ofItemAtURL:(NSURL *)fileURL error:(NSError **)error
-{
-  const char *path = fileURL.fileSystemRepresentation;
-
-  int result;
-  if (value) {
-    const char *valueUTF8String = value.UTF8String;
-    result = setxattr(path, key.UTF8String, valueUTF8String, strlen(valueUTF8String), 0, 0);
-  } else {
-    result = removexattr(path, key.UTF8String, 0);
+  if (identifier != UIBackgroundTaskInvalid) {
+    dispatch_group_notify(group, dispatch_get_main_queue(), ^{
+      [[UIApplication sharedApplication] endBackgroundTask:identifier];
+    });
  }

-  if (result) {
-    if (error) *error = [self errorWithPOSIXErrorNumber:errno];
-    return NO;
-  }
-
-  return YES;
-}
-
- (NSString *)attribute:(NSString *)key ofItemAtURL:(NSURL *)fileURL error:(NSError **)error
-{
-  const char *path = fileURL.fileSystemRepresentation;
-  const ssize_t length = getxattr(path, key.UTF8String, NULL, 0, 0, 0);
-  if (length <= 0) {
-    if (error) *error = [self errorWithPOSIXErrorNumber:errno];
-    return nil;
-  }
-
-  char *buffer = malloc(length);
-  ssize_t result = getxattr(path, key.UTF8String, buffer, length, 0, 0);
-  if (result == 0) {
-    return [[NSString alloc] initWithBytesNoCopy:buffer length:length encoding:NSUTF8StringEncoding freeWhenDone:YES];
-  }
-
-  free(buffer);
-  if (error) *error = [self errorWithPOSIXErrorNumber:errno];
-  return nil;
-}
-
-#pragma mark - Extended Attributes - Key
-
- (NSString *)keyOfItemAtURL:(NSURL *)fileURL error:(NSError **)error
-{
-  return [self attribute:KeyExtendedAttributeName ofItemAtURL:fileURL error:error];
-}
-
- (BOOL)setKey:(NSString *)key ofItemAtURL:(NSURL *)fileURL error:(NSError **)error
-{
-  return [self setAttribute:KeyExtendedAttributeName value:key ofItemAtURL:fileURL error:error];
+  [_storage removeAllObjects];
 }

@end
--- a/ReactKit/Base/RCTEventDispatcher.h
+++ b/ReactKit/Base/RCTEventDispatcher.h
@ -21,27 +21,36 @@ typedef NS_ENUM(NSInteger, RCTScrollEventType) {
  RCTScrollEventTypeEndAnimation,
 };

+/**
+ * This class wraps the -[RCTBridge enqueueJSCall:args:] method, and
+ * provides some convenience methods for generating event calls.
+ */
@interface RCTEventDispatcher : NSObject

 - (instancetype)initWithBridge:(RCTBridge *)bridge;

 /**
- * Send a named event. For most purposes, use the an
- * event type of RCTEventTypeDefault, the other types
- * are used internally by the React framework.
+ * Send a device or application event that does not relate to a specific
+ * view, e.g. rotation, location, keyboard show/hide, background/awake, etc.
 */
- (void)sendEventWithName:(NSString *)name body:(NSDictionary *)body;
+- (void)sendDeviceEventWithName:(NSString *)name body:(NSDictionary *)body;

 /**
- * Send text events
+ * Send a user input event. The body dictionary must contain a "target"
+ * parameter, representing the react tag of the view sending the event
+ */
+- (void)sendInputEventWithName:(NSString *)name body:(NSDictionary *)body;
+
+/**
+ * Send a text input/focus event.
 */
 - (void)sendTextEventWithType:(RCTTextEventType)type
                     reactTag:(NSNumber *)reactTag
                         text:(NSString *)text;

 /**
- * Send scroll events
- * (You can send a fake scroll event by passing nil for scrollView)
+ * Send a scroll event.
+ * (You can send a fake scroll event by passing nil for scrollView).
 */
 - (void)sendScrollEventWithType:(RCTScrollEventType)type
                       reactTag:(NSNumber *)reactTag
--- a/ReactKit/Base/RCTEventDispatcher.m
+++ b/ReactKit/Base/RCTEventDispatcher.m
@ -4,7 +4,6 @@

 #import "RCTAssert.h"
 #import "RCTBridge.h"
-#import "UIView+ReactKit.h"

@implementation RCTEventDispatcher
 {
@ -19,7 +18,14 @@
  return self;
 }

- (void)sendEventWithName:(NSString *)name body:(NSDictionary *)body
+- (void)sendDeviceEventWithName:(NSString *)name body:(NSDictionary *)body
+{
+  [_bridge enqueueJSCall:@"RCTDeviceEventEmitter.emit"
+                    args:body ? @[name, body] : @[name]];
+}
+
+
+- (void)sendInputEventWithName:(NSString *)name body:(NSDictionary *)body
 {
  RCTAssert([body[@"target"] isKindOfClass:[NSNumber class]],
            @"Event body dictionary must include a 'target' property containing a react tag");
@ -40,7 +46,7 @@
    @"topEndEditing",
  };
  
-  [self sendEventWithName:events[type] body:@{
+  [self sendInputEventWithName:events[type] body:@{
    @"text": text,
    @"target": reactTag
  }];
@ -91,7 +97,7 @@
    body = mutableBody;
  }
  
-  [self sendEventWithName:events[type] body:body];
+  [self sendInputEventWithName:events[type] body:body];
 }

@end
--- a/ReactKit/Base/RCTImageDownloader.m
+++ b/ReactKit/Base/RCTImageDownloader.m
@ -7,9 +7,12 @@

 // TODO: something a bit more sophisticated

+typedef void (^RCTCachedDataDownloadBlock)(BOOL cached, NSData *data, NSError *error);
+
@implementation RCTImageDownloader
 {
  RCTCache *_cache;
+  NSMutableDictionary *_pendingBlocks;
 }

 + (instancetype)sharedInstance
@ -27,6 +30,7 @@
 {
  if ((self = [super init])) {
    _cache = [[RCTCache alloc] initWithName:@"RCTImageDownloader"];
+    _pendingBlocks = [NSMutableDictionary dictionary];
  }
  return self;
 }
@ -36,8 +40,7 @@
  return url.absoluteString;
 }

- (id)_downloadDataForURL:(NSURL *)url
-                    block:(RCTDataDownloadBlock)block
+- (id)_downloadDataForURL:(NSURL *)url block:(RCTCachedDataDownloadBlock)block
 {
  NSString *cacheKey = [self cacheKeyForURL:url];

@ -45,36 +48,58 @@
  __block NSURLSessionDataTask *task = nil;
  dispatch_block_t cancel = ^{
    cancelled = YES;
+
+    NSMutableArray *pendingBlocks = _pendingBlocks[cacheKey];
+    [pendingBlocks removeObject:block];
+
    if (task) {
      [task cancel];
      task = nil;
    }
  };

-  if ([_cache hasDataForKey:cacheKey]) {
-    [_cache fetchDataForKey:cacheKey completionHandler:^(NSData *data) {
-      if (cancelled) return;
-      block(data, nil);
-    }];
+  NSMutableArray *pendingBlocks = _pendingBlocks[cacheKey];
+  if (pendingBlocks) {
+    [pendingBlocks addObject:block];
  } else {
-    task = [[NSURLSession sharedSession] dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
-      block(data, error);
-    }];
+    _pendingBlocks[cacheKey] = [NSMutableArray arrayWithObject:block];

-    [task resume];
+    __weak RCTImageDownloader *weakSelf = self;
+    RCTCachedDataDownloadBlock runBlocks = ^(BOOL cached, NSData *data, NSError *error) {
+      RCTImageDownloader *strongSelf = weakSelf;
+      NSArray *blocks = strongSelf->_pendingBlocks[cacheKey];
+      [strongSelf->_pendingBlocks removeObjectForKey:cacheKey];
+
+      for (RCTCachedDataDownloadBlock block in blocks) {
+        block(cached, data, error);
+      }
+    };
+
+    if ([_cache hasDataForKey:cacheKey]) {
+      [_cache fetchDataForKey:cacheKey completionHandler:^(NSData *data) {
+        if (!cancelled) runBlocks(YES, data, nil);
+      }];
+    } else {
+      task = [[NSURLSession sharedSession] dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
+        if (!cancelled) runBlocks(NO, data, error);
+      }];
+
+      [task resume];
+    }
  }

  return [cancel copy];
 }

- (id)downloadDataForURL:(NSURL *)url
-                   block:(RCTDataDownloadBlock)block
+- (id)downloadDataForURL:(NSURL *)url block:(RCTDataDownloadBlock)block
 {
  NSString *cacheKey = [self cacheKeyForURL:url];
  __weak RCTImageDownloader *weakSelf = self;
-  return [self _downloadDataForURL:url block:^(NSData *data, NSError *error) {
-    RCTImageDownloader *strongSelf = weakSelf;
-    [strongSelf->_cache setData:data forKey:cacheKey];
+  return [self _downloadDataForURL:url block:^(BOOL cached, NSData *data, NSError *error) {
+    if (!cached) {
+      RCTImageDownloader *strongSelf = weakSelf;
+      [strongSelf->_cache setData:data forKey:cacheKey];
+    }

    dispatch_async(dispatch_get_main_queue(), ^{
      block(data, error);
@ -82,52 +107,51 @@
  }];
 }

- (id)downloadImageForURL:(NSURL *)url
-                     size:(CGSize)size
-                    scale:(CGFloat)scale
-                    block:(RCTImageDownloadBlock)block
+- (id)downloadImageForURL:(NSURL *)url size:(CGSize)size scale:(CGFloat)scale block:(RCTImageDownloadBlock)block
 {
  NSString *cacheKey = [self cacheKeyForURL:url];
  __weak RCTImageDownloader *weakSelf = self;
-  return [self _downloadDataForURL:url block:^(NSData *data, NSError *error) {
-    if (data) {
-      UIImage *image = [UIImage imageWithData:data scale:scale];
-
-      if (image) {
-        CGSize imageSize = size;
-        if (CGSizeEqualToSize(imageSize, CGSizeZero)) {
-          imageSize = image.size;
-        }
-
-        CGFloat imageScale = scale;
-        if (imageScale == 0 || imageScale > image.scale) {
-          imageScale = image.scale;
-        }
-
-        UIGraphicsBeginImageContextWithOptions(imageSize, NO, imageScale);
-        [image drawInRect:(CGRect){{0, 0}, imageSize}];
-        image = UIGraphicsGetImageFromCurrentImageContext();
-        UIGraphicsEndImageContext();
-
-        RCTImageDownloader *strongSelf = weakSelf;
-        [strongSelf->_cache setData:UIImagePNGRepresentation(image) forKey:cacheKey];
-      }
-
-      dispatch_async(dispatch_get_main_queue(), ^{
-        block(image, nil);
-      });
-    } else {
-      dispatch_async(dispatch_get_main_queue(), ^{
+  return [self _downloadDataForURL:url block:^(BOOL cached, NSData *data, NSError *error) {
+    if (!data) {
+      return dispatch_async(dispatch_get_main_queue(), ^{
        block(nil, error);
      });
    }
+
+    UIImage *image = [UIImage imageWithData:data scale:scale];
+
+    if (image) {
+      CGSize imageSize = size;
+      if (CGSizeEqualToSize(imageSize, CGSizeZero)) {
+        imageSize = image.size;
+      }
+
+      CGFloat imageScale = scale;
+      if (imageScale == 0 || imageScale > image.scale) {
+        imageScale = image.scale;
+      }
+
+      UIGraphicsBeginImageContextWithOptions(imageSize, NO, imageScale);
+      [image drawInRect:(CGRect){{0, 0}, imageSize}];
+      image = UIGraphicsGetImageFromCurrentImageContext();
+      UIGraphicsEndImageContext();
+
+      if (!cached) {
+        RCTImageDownloader *strongSelf = weakSelf;
+        [strongSelf->_cache setData:UIImagePNGRepresentation(image) forKey:cacheKey];
+      }
+    }
+
+    dispatch_async(dispatch_get_main_queue(), ^{
+      block(image, nil);
+    });
  }];
 }

 - (void)cancelDownload:(id)downloadToken
 {
  if (downloadToken) {
-    dispatch_block_t block = downloadToken;
+    dispatch_block_t block = (id)downloadToken;
    block();
  }
 }
--- a/ReactKit/Modules/RCTUIManager.m
+++ b/ReactKit/Modules/RCTUIManager.m
@ -677,7 +677,10 @@ static void RCTSetShadowViewProps(NSDictionary *props, RCTShadowView *shadowView
    RCTLogWarn(@"No manager class found for view with module name \"%@\"", moduleName);
    manager = [[RCTViewManager alloc] init];
  }
-  
+
+  // Register manager
+  _viewManagerRegistry[reactTag] = manager;
+
  // Generate default view, used for resetting default props
  if (!_defaultShadowViews[moduleName]) {
    _defaultShadowViews[moduleName] = [manager shadowView];
@ -691,10 +694,7 @@ static void RCTSetShadowViewProps(NSDictionary *props, RCTShadowView *shadowView
  
  [self addUIBlock:^(RCTUIManager *uiManager, RCTSparseArray *viewRegistry){
    RCTCAssertMainThread();
-    
-    // Register manager
-    uiManager->_viewManagerRegistry[reactTag] = manager;
-    
+
    // Generate default view, used for resetting default props
    if (!uiManager->_defaultViews[moduleName]) {
      // Note the default is setup after the props are read for the first time ever
--- a/ReactKit/Views/RCTNavigator.m
+++ b/ReactKit/Views/RCTNavigator.m
@ -324,7 +324,7 @@ NSInteger kNeverProgressed = -10000;
      return;
    }
    _mostRecentProgress = nextProgress;
-    [_eventDispatcher sendEventWithName:@"topNavigationProgress" body:@{
+    [_eventDispatcher sendInputEventWithName:@"topNavigationProgress" body:@{
      @"fromIndex": @(_currentlyTransitioningFrom),
      @"toIndex": @(_currentlyTransitioningTo),
      @"progress": @(nextProgress),
@ -447,7 +447,7 @@ NSInteger kNeverProgressed = -10000;

 - (void)handleTopOfStackChanged
 {
-  [_eventDispatcher sendEventWithName:@"topNavigateBack" body:@{
+  [_eventDispatcher sendInputEventWithName:@"topNavigateBack" body:@{
    @"target":self.reactTag,
    @"stackLength":@(_navigationController.viewControllers.count)
  }];
--- a/ReactKit/Views/RCTWrapperViewController.m
+++ b/ReactKit/Views/RCTWrapperViewController.m
@ -96,7 +96,7 @@

 - (void)rightButtonTapped
 {
-  [_eventDispatcher sendEventWithName:@"topNavRightButtonTap" body:@{@"target":_navItem.reactTag}];
+  [_eventDispatcher sendInputEventWithName:@"topNavRightButtonTap" body:@{@"target":_navItem.reactTag}];
 }

 - (void)didMoveToParentViewController:(UIViewController *)parent
--- a/packager/react-packager/index.js
+++ b/packager/react-packager/index.js
@ -10,10 +10,30 @@ exports.middleware = function(options) {

 exports.buildPackageFromUrl = function(options, reqUrl) {
  Activity.disable();
+  // Don't start the filewatcher or the cache.
+  if (options.nonPersistent == null) {
+    options.nonPersistent = true;
+  }
+
  var server = new Server(options);
  return server.buildPackageFromUrl(reqUrl)
    .then(function(p) {
-      server.kill();
+      server.end();
      return p;
    });
 };
+
+exports.getDependencies = function(options, main) {
+  Activity.disable();
+  // Don't start the filewatcher or the cache.
+  if (options.nonPersistent == null) {
+    options.nonPersistent = true;
+  }
+
+  var server = new Server(options);
+  return server.getDependencies(main)
+    .then(function(r) {
+      server.end();
+      return r.dependencies;
+    });
+};
--- a/packager/react-packager/src/DependencyResolver/haste/tests/HasteDependencyResolver-test.js
+++ b/packager/react-packager/src/DependencyResolver/haste/tests/HasteDependencyResolver-test.js
@ -55,6 +55,25 @@ describe('HasteDependencyResolver', function() {
              isPolyfill: true,
              dependencies: ['polyfills/prelude.js', 'polyfills/require.js']
            },
+            { id: 'polyfills/console.js',
+              isPolyfill: true,
+              path: 'polyfills/console.js',
+              dependencies: [
+                'polyfills/prelude.js',
+                'polyfills/require.js',
+                'polyfills/polyfills.js'
+              ],
+            },
+            { id: 'polyfills/error-guard.js',
+              isPolyfill: true,
+              path: 'polyfills/error-guard.js',
+              dependencies: [
+                'polyfills/prelude.js',
+                'polyfills/require.js',
+                'polyfills/polyfills.js',
+                'polyfills/console.js'
+              ],
+            },
            module
          ]);
        });
@ -97,11 +116,35 @@ describe('HasteDependencyResolver', function() {
              isPolyfill: true,
              dependencies: ['polyfills/prelude.js', 'polyfills/require.js']
            },
+            { id: 'polyfills/console.js',
+              isPolyfill: true,
+              path: 'polyfills/console.js',
+              dependencies: [
+                'polyfills/prelude.js',
+                'polyfills/require.js',
+                'polyfills/polyfills.js'
+              ],
+            },
+            { id: 'polyfills/error-guard.js',
+              isPolyfill: true,
+              path: 'polyfills/error-guard.js',
+              dependencies: [
+                'polyfills/prelude.js',
+                'polyfills/require.js',
+                'polyfills/polyfills.js',
+                'polyfills/console.js'
+              ],
+            },
            { path: 'some module',
              id: 'some module',
              isPolyfill: true,
-              dependencies: [ 'polyfills/prelude.js', 'polyfills/require.js',
-                'polyfills/polyfills.js']
+              dependencies: [
+                'polyfills/prelude.js',
+                'polyfills/require.js',
+                'polyfills/polyfills.js',
+                'polyfills/console.js',
+                'polyfills/error-guard.js',
+              ]
            },
            module
          ]);
--- a/packager/react-packager/src/DependencyResolver/haste/index.js
+++ b/packager/react-packager/src/DependencyResolver/haste/index.js
@ -19,7 +19,10 @@ var DEFINE_MODULE_REPLACE_RE = /_moduleName_|_code_|_deps_/g;
 var REL_REQUIRE_STMT = /require\(['"]([\.\/0-9A-Z_$\-]*)['"]\)/gi;

 function HasteDependencyResolver(config) {
-  this._fileWatcher = new FileWatcher(config.projectRoots);
+  this._fileWatcher = config.nonPersistent
+    ? FileWatcher.createDummyWatcher()
+    : new FileWatcher(config.projectRoots);
+
  this._depGraph = new DependencyGraph({
    roots: config.projectRoots,
    ignoreFilePath: function(filepath) {
@ -97,7 +100,6 @@ HasteDependencyResolver.prototype.wrapModule = function(module, code) {
    }
  }

-
  var relativizedCode =
    code.replace(REL_REQUIRE_STMT, function(codeMatch, depName) {
      var dep = resolvedDeps[depName];
@ -117,7 +119,6 @@ HasteDependencyResolver.prototype.wrapModule = function(module, code) {
  });
 };

-
 HasteDependencyResolver.prototype.end = function() {
  return this._fileWatcher.end();
 };
--- a/packager/react-packager/src/FileWatcher/index.js
+++ b/packager/react-packager/src/FileWatcher/index.js
@ -76,3 +76,11 @@ function createWatcher(root) {
    });
  });
 }
+
+FileWatcher.createDummyWatcher = function() {
+  var ev = new EventEmitter();
+  ev.end = function() {
+    return q();
+  };
+  return ev;
+};
--- a/packager/react-packager/src/JSTransformer/tests/Transformer-test.js
+++ b/packager/react-packager/src/JSTransformer/tests/Transformer-test.js
@ -6,6 +6,10 @@ jest
  .dontMock('os')
  .dontMock('../index');

+var OPTIONS = {
+  transformModulePath: '/foo/bar'
+};
+
 describe('Transformer', function() {
  var Transformer;
  var workers;
@ -32,7 +36,7 @@ describe('Transformer', function() {
      callback(null, 'content');
    });

-    return new Transformer({}).loadFileAndTransform([], 'file', {})
+    return new Transformer(OPTIONS).loadFileAndTransform([], 'file', {})
      .then(function(data) {
        expect(data).toEqual({
          code: 'transformed',
@ -55,7 +59,7 @@ describe('Transformer', function() {
      callback(null, {error: esprimaError});
    });

-    return new Transformer({}).loadFileAndTransform([], 'foo-file.js', {})
+    return new Transformer(OPTIONS).loadFileAndTransform([], 'foo-file.js', {})
      .catch(function(error) {
        expect(error.type).toEqual('TransformError');
        expect(error.snippet).toEqual([
--- a/packager/react-packager/src/JSTransformer/index.js
+++ b/packager/react-packager/src/JSTransformer/index.js
@ -14,15 +14,21 @@ module.exports = Transformer;
 Transformer.TransformError = TransformError;

 function Transformer(projectConfig) {
-  this._cache = new Cache(projectConfig);
-  this._workers = workerFarm(
-    {autoStart: true},
-    projectConfig.transformModulePath
-  );
+  this._cache = projectConfig.nonPersistent
+    ? new DummyCache() : new Cache(projectConfig);
+
+  if (projectConfig.transformModulePath == null) {
+    this._failedToStart = q.Promise.reject(new Error('No transfrom module'));
+  } else {
+    this._workers = workerFarm(
+      {autoStart: true},
+      projectConfig.transformModulePath
+    );
+  }
 }

 Transformer.prototype.kill = function() {
-  workerFarm.end(this._workers);
+  this._workers && workerFarm.end(this._workers);
  return this._cache.end();
 };

@ -37,6 +43,10 @@ Transformer.prototype.loadFileAndTransform = function(
  filePath,
  options
 ) {
+  if (this._failedToStart) {
+    return this._failedToStart;
+  }
+
  var workers = this._workers;
  return this._cache.get(filePath, function() {
    return readFile(filePath)
@ -93,3 +103,10 @@ function formatEsprimaError(err, filename, source) {
  error.description = err.description;
  return error;
 }
+
+function DummyCache() {}
+DummyCache.prototype.get = function(filePath, loaderCb) {
+  return loaderCb();
+};
+DummyCache.prototype.end =
+DummyCache.prototype.invalidate = function(){};
--- a/packager/react-packager/src/Packager/index.js
+++ b/packager/react-packager/src/Packager/index.js
@ -34,15 +34,7 @@ var DEFAULT_CONFIG = {
   */
  polyfillModuleNames: [],

-  /**
-   * DEPRECATED
-   *
-   * A string of code to be appended to the top of a package.
-   *
-   * TODO: THIS RUINS SOURCE MAPS. THIS OPTION SHOULD BE REMOVED ONCE WE GET
-   *       config.polyfillModuleNames WORKING!
-   */
-  runtimeCode: ''
+  nonPersistent: false,
 };

 function Packager(projectConfig) {
@ -72,7 +64,7 @@ Packager.prototype.package = function(main, runModule, sourceMapUrl) {
  var findEventId = Activity.startEvent('find dependencies');
  var transformEventId;

-  return this._resolver.getDependencies(main)
+  return this.getDependencies(main)
    .then(function(result) {
      Activity.endEvent(findEventId);
      transformEventId = Activity.startEvent('transform');
@ -98,10 +90,14 @@ Packager.prototype.package = function(main, runModule, sourceMapUrl) {
    });
 };

-Packager.prototype.invalidateFile = function(filePath){
+Packager.prototype.invalidateFile = function(filePath) {
  this._transformer.invalidateFile(filePath);
 }

+Packager.prototype.getDependencies = function(main) {
+  return this._resolver.getDependencies(main);
+};
+
 Packager.prototype._transformModule = function(module) {
  var resolver = this._resolver;
  return this._transformer.loadFileAndTransform(
--- a/packager/react-packager/src/Server/index.js
+++ b/packager/react-packager/src/Server/index.js
@ -18,10 +18,13 @@ function Server(options) {
    cacheVersion: options.cacheVersion,
    resetCache: options.resetCache,
    dev: options.dev,
-    transformModulePath: options.transformModulePath
+    transformModulePath: options.transformModulePath,
+    nonPersistent: options.nonPersistent,
  });

-  this._fileWatcher = new FileWatcher(options.projectRoots);
+  this._fileWatcher = options.nonPersistent
+    ? FileWatcher.createDummyWatcher()
+    : new FileWatcher(options.projectRoots);

  var onFileChange = this._onFileChange.bind(this);
  this._fileWatcher.on('all', onFileChange);
@ -48,7 +51,7 @@ Server.prototype._rebuildPackages = function(filepath) {
  });
 };

-Server.prototype.kill = function() {
+Server.prototype.end = function() {
  q.all([
    this._fileWatcher.end(),
    this._packager.kill(),
@ -68,6 +71,10 @@ Server.prototype.buildPackageFromUrl = function(reqUrl) {
  return this._buildPackage(options);
 };

+Server.prototype.getDependencies = function(main) {
+  return this._packager.getDependencies(main);
+};
+
 Server.prototype._processDebugRequest = function(reqUrl, res) {
  var ret = '<!doctype html>';
  var pathname = url.parse(reqUrl).pathname;