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Image caching improvements #129

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94e84a6
Add an optional cache key
davidminor Aug 23, 2019
969ac06
Avoid repeat downloads
davidminor Aug 23, 2019
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40 changes: 29 additions & 11 deletions src/CacheManager.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -15,20 +15,34 @@ export class CacheEntry {

options: DownloadOptions;

constructor(uri: string, options: DownloadOptions) {
cacheKey: string;

downloadPromise: Promise<string | undefined> | undefined;

constructor(uri: string, options: DownloadOptions, cacheKey: string) {
this.uri = uri;
this.options = options;
this.cacheKey = cacheKey;
}

async getPath(): Promise<string | undefined> {
const { uri, options } = this;
const { path, exists, tmpPath } = await getCacheEntry(uri);
const { cacheKey } = this;
const { path, exists, tmpPath } = await getCacheEntry(cacheKey);
if (exists) {
return path;
}
if (!this.downloadPromise) {
this.downloadPromise = this.download(path, tmpPath);
}
return this.downloadPromise;
}

private async download(path: string, tmpPath: string): Promise<string | undefined> {
const { uri, options } = this;
const result = await FileSystem.createDownloadResumable(uri, tmpPath, options).downloadAsync();
// If the image download failed, we don't cache anything
if (result && result.status !== 200) {
this.downloadPromise = undefined;
return undefined;
}
await FileSystem.moveAsync({ from: tmpPath, to: path });
Expand All @@ -39,11 +53,11 @@ export class CacheEntry {
export default class CacheManager {
static entries: { [uri: string]: CacheEntry } = {};

static get(uri: string, options: DownloadOptions): CacheEntry {
if (!CacheManager.entries[uri]) {
CacheManager.entries[uri] = new CacheEntry(uri, options);
static get(uri: string, options: DownloadOptions, cacheKey: string): CacheEntry {
if (!CacheManager.entries[cacheKey]) {
CacheManager.entries[cacheKey] = new CacheEntry(uri, options, cacheKey);
}
return CacheManager.entries[uri];
return CacheManager.entries[cacheKey];
}

static async clearCache(): Promise<void> {
Expand All @@ -60,11 +74,15 @@ export default class CacheManager {
}
}

const getCacheEntry = async (uri: string): Promise<{ exists: boolean; path: string; tmpPath: string }> => {
const filename = uri.substring(uri.lastIndexOf("/"), uri.indexOf("?") === -1 ? uri.length : uri.indexOf("?"));
const getCacheEntry = async (cacheKey: string): Promise<{ exists: boolean; path: string; tmpPath: string }> => {
const filename = cacheKey.substring(
cacheKey.lastIndexOf("/"),
cacheKey.indexOf("?") === -1 ? cacheKey.length : cacheKey.indexOf("?")
);
const ext = filename.indexOf(".") === -1 ? ".jpg" : filename.substring(filename.lastIndexOf("."));
const path = `${BASE_DIR}${SHA1(uri)}${ext}`;
const tmpPath = `${BASE_DIR}${SHA1(uri)}-${_.uniqueId()}${ext}`;
const sha = SHA1(cacheKey);
const path = `${BASE_DIR}${sha}${ext}`;
const tmpPath = `${BASE_DIR}${sha}-${_.uniqueId()}${ext}`;
// TODO: maybe we don't have to do this every time
try {
await FileSystem.makeDirectoryAsync(BASE_DIR);
Expand Down
5 changes: 3 additions & 2 deletions src/Image.tsx
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Expand Up @@ -22,6 +22,7 @@ interface ImageProps {
preview?: ImageSourcePropType;
options?: DownloadOptions;
uri: string;
cacheKey?: string;
transitionDuration?: number;
tint?: "dark" | "light";
}
Expand Down Expand Up @@ -66,9 +67,9 @@ export default class Image extends React.Component<ImageProps, ImageState> {
this.mounted = false;
}

async load({ uri, options = {} }: ImageProps): Promise<void> {
async load({ uri, options = {}, cacheKey }: ImageProps): Promise<void> {
if (uri) {
const path = await CacheManager.get(uri, options).getPath();
const path = await CacheManager.get(uri, options, cacheKey || uri).getPath();
if (this.mounted) {
this.setState({ uri: path });
}
Expand Down