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Convert ImageDownloader to async await.

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This commit is contained in:
Brent Simmons 2024-04-17 20:51:06 -07:00
parent f0be57b77c
commit 280a59ffa3
1 changed files with 39 additions and 63 deletions
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102
Images/Sources/Images/ImageDownloader.swift
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@ -17,24 +17,19 @@ public extension Notification.Name {
static let ImageDidBecomeAvailable = Notification.Name("ImageDidBecomeAvailableNotification") // UserInfoKey.url
}
public final class ImageDownloader {
@MainActor public final class ImageDownloader {
public static let imageURLKey = "url"
private var log = OSLog(subsystem: Bundle.main.bundleIdentifier!, category: "ImageDownloader")
private let folder: String
private var diskCache: BinaryDiskCache
private let queue: DispatchQueue
private let diskCache: BinaryDiskCache
private var imageCache = [String: Data]() // url: image
private var urlsInProgress = Set<String>()
private var badURLs = Set<String>() // That return a 404 or whatever. Just skip them in the future.
public init(folder: String) {
self.folder = folder
self.diskCache = BinaryDiskCache(folder: folder)
self.queue = DispatchQueue(label: "ImageDownloader serial queue - \(folder)")
}
@discardableResult
@ -59,90 +54,71 @@ private extension ImageDownloader {
func findImage(_ url: String) {
guard !urlsInProgress.contains(url) && !badURLs.contains(url) else {
return
}
urlsInProgress.insert(url)
Task { @MainActor in
readFromDisk(url) { (image) in
if let image = image {
self.cacheImage(url, image)
self.urlsInProgress.remove(url)
guard !urlsInProgress.contains(url) && !badURLs.contains(url) else {
return
}
self.downloadImage(url) { (image) in
urlsInProgress.insert(url)
if let image = image {
self.cacheImage(url, image)
}
self.urlsInProgress.remove(url)
if let imageData = await readFromDisk(url) {
cacheImage(url, imageData)
} else if let imageData = await downloadImage(url) {
cacheImage(url, imageData)
}
urlsInProgress.remove(url)
}
}
func readFromDisk(_ url: String, _ completion: @escaping (Data?) -> Void) {
func readFromDisk(_ url: String) async -> Data? {
queue.async {
if let data = self.diskCache[self.diskKey(url)], !data.isEmpty {
DispatchQueue.main.async {
completion(data)
}
return
}
DispatchQueue.main.async {
completion(nil)
}
guard let data = await self.diskCache[Self.diskKey(url)], !data.isEmpty else {
return nil
}
return data
}
func downloadImage(_ url: String, _ completion: @escaping (Data?) -> Void) {
func downloadImage(_ url: String) async -> Data? {
guard let imageURL = URL(string: url) else {
completion(nil)
return
return nil
}
Task { @MainActor in
downloadUsingCache(imageURL) { (data, response, error) in
if let data = data, !data.isEmpty, let response = response, response.statusIsOK, error == nil {
self.saveToDisk(url, data)
completion(data)
return
}
if let response = response as? HTTPURLResponse, response.statusCode >= HTTPResponseCode.badRequest && response.statusCode <= HTTPResponseCode.notAcceptable {
self.badURLs.insert(url)
}
if let error = error {
os_log(.info, log: self.log, "Error downloading image at %@: %@.", url, error.localizedDescription)
}
completion(nil)
do {
let downloadData = try await downloadUsingCache(imageURL)
if let data = downloadData.data, !data.isEmpty, let response = downloadData.response, response.statusIsOK {
try await saveToDisk(url, data)
return data
}
if let response = downloadData.response as? HTTPURLResponse, response.statusCode >= HTTPResponseCode.badRequest && response.statusCode <= HTTPResponseCode.notAcceptable {
badURLs.insert(url)
}
} catch {
os_log(.info, log: self.log, "Error downloading image at %@: %@.", url, error.localizedDescription)
}
return nil
}
func saveToDisk(_ url: String, _ data: Data) {
func saveToDisk(_ url: String, _ data: Data) async throws {
queue.async {
self.diskCache[self.diskKey(url)] = data
}
let key = Self.diskKey(url)
try await diskCache.setData(data, forKey: key)
}
func diskKey(_ url: String) -> String {
static func diskKey(_ url: String) -> String {
return url.md5String
url.md5String
}
func postImageDidBecomeAvailableNotification(_ url: String) {
DispatchQueue.main.async {
NotificationCenter.default.post(name: .ImageDidBecomeAvailable, object: self, userInfo: [Self.imageURLKey: url])
}
NotificationCenter.default.post(name: .ImageDidBecomeAvailable, object: self, userInfo: [Self.imageURLKey: url])
}
}