Cache policy control for image source

Summary: In the context of an app an image exists in three resolutions on the server: `thumb` (30px) `feed` (300px) `full` (900px). When looking at an individual item a user can come either from the feed, via a permalink or from other parts of the app. This allows a situation where the `feed` image might or might not already be loaded somewhere in the app. In the detail view I want to render `thumb` with a blur (to quickly display something), then the `feed` image if it exists to have something decent to display until `full` loads. However it is quite a waste to load the `feed` image if it isn't already in cache, and will slow down the time until `full` is loaded. It is possible to track the navigation from feed->detail and that the `feed` image has actually completed loading by the feed component however as component hierarchies grow this turns into quite a lot of prop passing and bad separation of concerns. NSURLRequests accepts a [Cache Policy](https://developer.apple.com/reference/fo Closes https://github.com/facebook/react-native/pull/10844 Differential Revision: D4425959 Pulled By: lacker fbshipit-source-id: 679835439c761a2fc894f56eb6d744c036cf0b49
2026-04-24 04:16:00 +08:00 · 2017-01-17 16:58:27 -08:00
parent a6844bdf75
commit 52d8851fc8
9 changed files with 206 additions and 2 deletions
--- a/IntegrationTests/ImageCachePolicyTest.js
+++ b/IntegrationTests/ImageCachePolicyTest.js
@@ -0,0 +1,115 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
+ */
+'use strict';
+
+var React = require('react');
+var ReactNative = require('react-native');
+var {
+  Image,
+  View,
+  Text,
+  StyleSheet,
+} = ReactNative;
+var { TestModule } = ReactNative.NativeModules;
+
+/*
+ * The reload and force-cache tests don't actually verify that the complete functionality.
+ *
+ * reload: Should have the server set a long cache header, then swap the image on next load
+ * with the test comparing the old image to the new image and making sure they are different.
+ *
+ * force-cache: Should do the above but set a no-cache header. The test should compare the first
+ * image with the new one and make sure they are the same.
+ */
+
+const TESTS = ['only-if-cached', 'default', 'reload', 'force-cache'];
+
+type Props = {}
+type State = {
+  'only-if-cached'?: boolean,
+  'default'?: boolean,
+  'reload'?: boolean,
+  'force-cache'?: boolean,
+}
+
+class ImageCachePolicyTest extends React.Component {
+  state = {}
+
+  shouldComponentUpdate(nextProps: Props, nextState: State) {
+    const results: Array<?boolean> = TESTS.map(x => nextState[x]);
+
+    if (!results.includes(undefined)) {
+      const result: boolean = results.reduce((x,y) => x === y === true, true)
+      TestModule.markTestPassed(result);
+    }
+
+    return false;
+  }
+
+  testComplete(name: string, pass: boolean) {
+    this.setState({[name]: pass});
+  }
+
+  render() {
+    return (
+      <View style={{flex: 1}}>
+        <Text>Hello</Text>
+      <Image
+        source={{
+              uri: 'https://facebook.github.io/react/img/logo_small_2x.png?cacheBust=notinCache' + Date.now(),
+              cache: 'only-if-cached'
+            }}
+        onLoad={() => this.testComplete('only-if-cached', false)}
+        onError={() => this.testComplete('only-if-cached', true)}
+        style={styles.base}
+      />
+        <Image
+          source={{
+              uri: 'https://facebook.github.io/react/img/logo_small_2x.png?cacheBust=notinCache' + Date.now(),
+              cache: 'default'
+            }}
+          onLoad={() => this.testComplete('default', true)}
+          onError={() => this.testComplete('default', false)}
+          style={styles.base}
+        />
+        <Image
+          source={{
+              uri: 'https://facebook.github.io/react/img/logo_small_2x.png?cacheBust=notinCache' + Date.now(),
+              cache: 'reload'
+            }}
+          onLoad={() => this.testComplete('reload', true)}
+          onError={() => this.testComplete('reload', false)}
+          style={styles.base}
+        />
+        <Image
+          source={{
+              uri: 'https://facebook.github.io/react/img/logo_small_2x.png?cacheBust=notinCache' + Date.now(),
+              cache: 'force-cache'
+            }}
+          onLoad={() => this.testComplete('force-cache', true)}
+          onError={() => this.testComplete('force-cache', false)}
+          style={styles.base}
+        />
+      </View>
+    );
+  }
+}
+
+const styles = StyleSheet.create({
+  base: {
+    width: 100,
+    height: 100,
+  },
+});
+
+ImageCachePolicyTest.displayName = 'ImageCachePolicyTest';
+
+module.exports = ImageCachePolicyTest;