pfp: profile pic image cache

So we don't have to download 60MB of profile pics every time we load the
app..

Changelog-Added: Added profile picture cache
Signed-off-by: William Casarin <jb55@jb55.com>

damus/Models/HomeModel.swift

@@ -509,7 +509,8 @@ func process_metadata_event(image_cache: ImageCache, profiles: Profiles, ev: Nos
     let picture = tprof.profile.picture ?? robohash(ev.pubkey)
     if let url = URL(string: picture) {
         Task<UIImage?, Never>.init(priority: .background) {
-            let res = await load_image(cache: image_cache, from: url)
+            let pfp_key = pfp_cache_key(url: url)
+            let res = await image_cache.lookup_or_load_image(key: pfp_key, url: url)
             DispatchQueue.main.async {
                 notify(.profile_updated, ProfileUpdate(pubkey: ev.pubkey, profile: profile))
             }

damus/Util/ImageCache.swift

@@ -7,7 +7,7 @@
 
 import Foundation
 import SwiftUI
-import Combine
+import UIKit
 
 enum ImageProcessingStatus {
     case processing
@@ -30,27 +30,27 @@ class ImageCache {
         state[key] = new_state
     }
     
-    lazy var cache: NSCache<AnyObject, UIImage> = {
-        let cache = NSCache<AnyObject, UIImage>()
+    lazy var cache: NSCache<NSString, UIImage> = {
+        let cache = NSCache<NSString, UIImage>()
         cache.totalCostLimit = 1024 * 1024 * 100 // 100MB
         return cache
     }()
     
     // simple polling until I can figure out a better way to do this
-    func wait_for_image(_ url: URL) async {
+    func wait_for_image(_ key: String) async {
         while true {
             let why_would_this_happen: ()? = try? await Task.sleep(nanoseconds: 100_000_000) // 100ms
             if why_would_this_happen == nil {
                 return
             }
-            if get_state(url.absoluteString) == .done {
+            if get_state(key) == .done {
                 return
             }
         }
     }
     
-    func lookup_sync(for url: URL) -> UIImage? {
-        let status = get_state(url.absoluteString)
+    func lookup_sync(key: String) -> UIImage? {
+        let status = get_state(key)
         
         switch status {
         case .done:
@@ -61,61 +61,115 @@ class ImageCache {
             return nil
         }
         
-        if let decoded = cache.object(forKey: url as AnyObject) {
+        if let decoded = cache.object(forKey: NSString(string: key)) {
             return decoded
         }
             
         return nil
     }
     
-    func lookup(for url: URL) async -> UIImage? {
-        let status = get_state(url.absoluteString)
+    func lookup_or_load_image(key: String, url: URL?) async -> UIImage? {
+        if let img = await lookup(key: key) {
+            return img
+        }
+        
+        guard let url = url else {
+            return nil
+        }
+
+        return await load_image(cache: self, from: url, key: key)
+    }
+    
+    func get_cache_url(key: String, suffix: String, ext: String = "png") -> URL? {
+        let urls = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)
+        
+        guard let root = urls.first else {
+            return nil
+        }
+        
+        return root.appendingPathComponent("\(key)\(suffix).\(ext)")
+    }
+    
+    private func lookup_file_cache(key: String, suffix: String = "_pfp") -> UIImage? {
+        guard let img_file = get_cache_url(key: key, suffix: suffix) else {
+            return nil
+        }
+        
+        guard let img = UIImage(contentsOfFile: img_file.path) else {
+            //print("failed to load \(key)\(suffix).png from file cache")
+            return nil
+        }
+        
+        save_to_memory_cache(key: key, img: img)
+
+        print("loaded \(key)\(suffix).png from file cache")
+        
+        return img
+    }
+    
+    func lookup(key: String) async -> UIImage? {
+        let status = get_state(key)
         
         switch status {
         case .done:
             break
         case .processing:
-            await wait_for_image(url)
+            await wait_for_image(key)
         case .none:
-            return nil
+            return lookup_file_cache(key: key)
         }
         
-        if let decoded = cache.object(forKey: url as AnyObject) {
+        if let decoded = cache.object(forKey: NSString(string: key)) {
             return decoded
         }
             
         return nil
     }
     
-    func remove(for url: URL) {
+    func remove(key: String) {
         lock.lock(); defer { lock.unlock() }
-        cache.removeObject(forKey: url as AnyObject)
+        cache.removeObject(forKey: NSString(string: key))
     }
     
-    func insert(_ image: UIImage, for url: URL) async -> UIImage? {
+    func insert(_ image: UIImage, key: String) async -> UIImage? {
         let scale = await UIScreen.main.scale
         let size = CGSize(width: PFP_SIZE * scale, height: PFP_SIZE * scale)
         
-        let key = url.absoluteString
-        
         set_state(key, new_state: .processing)
         
         let decoded_image = await image.byPreparingThumbnail(ofSize: size)
         
-        lock.lock()
-        cache.setObject(decoded_image ?? UIImage(), forKey: url as AnyObject)
-        state[key] = .done
-        lock.unlock()
+        save_to_memory_cache(key: key, img: decoded_image ?? UIImage())
+        if let img = decoded_image {
+            if !save_to_file_cache(key: key, img: img) {
+                print("failed saving \(key) pfp to file cache")
+            }
+        }
         
         return decoded_image
     }
-}
-
-func load_image(cache: ImageCache, from url: URL) async -> UIImage? {
-    if let image = await cache.lookup(for: url) {
-        return image
+    
+    func save_to_file_cache(key: String, img: UIImage, suffix: String = "_pfp") -> Bool {
+        guard let url = get_cache_url(key: key, suffix: suffix) else {
+            return false
+        }
+        
+        guard let data = img.pngData() else {
+            return false
+        }
+        
+        return (try? data.write(to: url)) != nil
     }
     
+    func save_to_memory_cache(key: String, img: UIImage) {
+        lock.lock()
+        cache.setObject(img, forKey: NSString(string: key))
+        state[key] = .done
+        lock.unlock()
+    }
+}
+
+func load_image(cache: ImageCache, from url: URL, key: String) async -> UIImage? {
     guard let (data, _) = try? await URLSession.shared.data(from: url) else {
         return nil
     }
@@ -124,5 +178,18 @@ func load_image(cache: ImageCache, from url: URL) async -> UIImage? {
         return nil
     }
     
-    return await cache.insert(img, for: url)
+    return await cache.insert(img, key: key)
+}
+
+
+func hashed_hexstring(_ str: String) -> String {
+    guard let data = str.data(using: .utf8) else {
+        return str
+    }
+    
+    return hex_encode(sha256(data))
+}
+    
+func pfp_cache_key(url: URL) -> String {
+    return hashed_hexstring(url.absoluteString)
 }

damus/Views/ProfilePicView.swift

@@ -53,8 +53,8 @@ struct ProfilePicView: View {
             .padding(2)
     }
     
-    func ProfilePic(_ url: URL) -> some View {
-        return Group {
+    var MainContent: some View {
+        Group {
             if let img = self.img {
                 img
                     .resizable()
@@ -66,27 +66,23 @@ struct ProfilePicView: View {
                 Placeholder
             }
         }
-        .task {
-            let ui_img = await load_image(cache: image_cache, from: url)
-            if let ui_img = ui_img {
-                self.img = Image(uiImage: ui_img)
-            }
-        }
-    }
-    
-    var MainContent: some View {
-        Group {
-            let picture = picture ?? profiles.lookup(id: pubkey)?.picture ?? robohash(pubkey)
-            if let pic_url = URL(string: picture) {
-                ProfilePic(pic_url)
-            } else {
-                Placeholder
-            }
-        }
     }
     
     var body: some View {
         MainContent
+            .task {
+                let pic = picture ?? profiles.lookup(id: pubkey)?.picture ?? robohash(pubkey)
+                guard let url = URL(string: pic) else {
+                    return
+                }
+                let pfp_key = pfp_cache_key(url: url)
+                let ui_img = await image_cache.lookup_or_load_image(key: pfp_key, url: url)
+                
+                if let ui_img = ui_img {
+                    self.img = Image(uiImage: ui_img)
+                    return
+                }
+            }
             .onReceive(handle_notify(.profile_updated)) { notif in
                 let updated = notif.object as! ProfileUpdate
 
@@ -96,7 +92,8 @@ struct ProfilePicView: View {
                 
                 if let pic = updated.profile.picture {
                     if let url = URL(string: pic) {
-                        if let ui_img = image_cache.lookup_sync(for: url) {
+                        let pfp_key = pfp_cache_key(url: url)
+                        if let ui_img = image_cache.lookup_sync(key: pfp_key) {
                             self.img = Image(uiImage: ui_img)
                         }
                     }