Make progress on FaviconDownloader.

Evergreen.xcodeproj/project.pbxproj

@@ -21,7 +21,7 @@
 		846E77411F6EF6A100A165E2 /* Database.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 846E77211F6EF5D100A165E2 /* Database.framework */; };
 		846E77421F6EF6A100A165E2 /* Database.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 846E77211F6EF5D100A165E2 /* Database.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
 		84702AA41FA27AC0006B8943 /* MarkReadOrUnreadCommand.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84702AA31FA27AC0006B8943 /* MarkReadOrUnreadCommand.swift */; };
-		848F6AE51FC29CFB002D422E /* FaviconCache.swift in Sources */ = {isa = PBXBuildFile; fileRef = 848F6AE41FC29CFA002D422E /* FaviconCache.swift */; };
+		848F6AE51FC29CFB002D422E /* FaviconDownloader.swift in Sources */ = {isa = PBXBuildFile; fileRef = 848F6AE41FC29CFA002D422E /* FaviconDownloader.swift */; };
 		849A97431ED9EAA9007D329B /* AddFolderWindowController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 849A97421ED9EAA9007D329B /* AddFolderWindowController.swift */; };
 		849A97531ED9EAC0007D329B /* AddFeedController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 849A97511ED9EAC0007D329B /* AddFeedController.swift */; };
 		849A97541ED9EAC0007D329B /* AddFeedWindowController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 849A97521ED9EAC0007D329B /* AddFeedWindowController.swift */; };
@@ -409,7 +409,7 @@
 		846E77161F6EF5D000A165E2 /* Database.xcodeproj */ = {isa = PBXFileReference; lastKnownFileType = "wrapper.pb-project"; name = Database.xcodeproj; path = Frameworks/Database/Database.xcodeproj; sourceTree = "<group>"; };
 		846E77301F6EF5D600A165E2 /* Account.xcodeproj */ = {isa = PBXFileReference; lastKnownFileType = "wrapper.pb-project"; name = Account.xcodeproj; path = Frameworks/Account/Account.xcodeproj; sourceTree = "<group>"; };
 		84702AA31FA27AC0006B8943 /* MarkReadOrUnreadCommand.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MarkReadOrUnreadCommand.swift; sourceTree = "<group>"; };
-		848F6AE41FC29CFA002D422E /* FaviconCache.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = FaviconCache.swift; sourceTree = "<group>"; };
+		848F6AE41FC29CFA002D422E /* FaviconDownloader.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = FaviconDownloader.swift; sourceTree = "<group>"; };
 		849A97421ED9EAA9007D329B /* AddFolderWindowController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AddFolderWindowController.swift; sourceTree = "<group>"; };
 		849A97511ED9EAC0007D329B /* AddFeedController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = AddFeedController.swift; path = AddFeed/AddFeedController.swift; sourceTree = "<group>"; };
 		849A97521ED9EAC0007D329B /* AddFeedWindowController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = AddFeedWindowController.swift; path = AddFeed/AddFeedWindowController.swift; sourceTree = "<group>"; };
@@ -578,7 +578,7 @@
 		848F6AE31FC29CFA002D422E /* Favicons */ = {
 			isa = PBXGroup;
 			children = (
-				848F6AE41FC29CFA002D422E /* FaviconCache.swift */,
+				848F6AE41FC29CFA002D422E /* FaviconDownloader.swift */,
 			);
 			name = Favicons;
 			path = Evergreen/Favicons;
@@ -1319,7 +1319,7 @@
 				849A97791ED9EC04007D329B /* TimelineStringUtilities.swift in Sources */,
 				84F204CE1FAACB660076E152 /* FeedListViewController.swift in Sources */,
 				845EE7B11FC2366500854A1F /* StarredFeedDelegate.swift in Sources */,
-				848F6AE51FC29CFB002D422E /* FaviconCache.swift in Sources */,
+				848F6AE51FC29CFB002D422E /* FaviconDownloader.swift in Sources */,
 				849A97981ED9EFAA007D329B /* Node-Extensions.swift in Sources */,
 				849A97531ED9EAC0007D329B /* AddFeedController.swift in Sources */,
 				849A97831ED9EC63007D329B /* StatusBarView.swift in Sources */,

Evergreen/Favicons/FaviconCache.swift

@@ -1,25 +0,0 @@
-//
-//  FaviconCache.swift
-//  Evergreen
-//
-//  Created by Brent Simmons on 11/19/17.
-//  Copyright © 2017 Ranchero Software. All rights reserved.
-//
-
-import AppKit
-import Data
-
-extension Notification.Name {
-
-	static let FaviconDidDownload = Notification.Name("FaviconDidDownloadNotification")
-}
-
-final class FaviconCache {
-
-	// MARK: - API
-
-	func favicon(for feed: Feed) -> NSImage? {
-
-		return nil
-	}
-}

Evergreen/Favicons/FaviconDownloader.swift

@@ -0,0 +1,145 @@
+//
+//  FaviconDownloader.swift
+//  Evergreen
+//
+//  Created by Brent Simmons on 11/19/17.
+//  Copyright © 2017 Ranchero Software. All rights reserved.
+//
+
+import AppKit
+import Data
+import RSCore
+import RSWeb
+
+extension Notification.Name {
+
+	static let FaviconDidBecomeAvailable = Notification.Name("FaviconDidBecomeAvailableNotification") // userInfo keys: homePageURL, faviconURL, image
+}
+
+final class FaviconDownloader {
+
+	private var cache = ThreadSafeCache<NSImage>() // faviconURL: NSImage
+	private var faviconURLCache = ThreadSafeCache<String>() // homePageURL: faviconURL
+	private let folder: String
+	private var urlsBeingDownloaded = Set<String>()
+	private let binaryCache: RSBinaryCache
+	private var badImages = Set<String>() // keys for images on disk that NSImage can’t handle
+	private let queue: DispatchQueue
+
+	public struct UserInfoKey {
+		static let homePageURL = "homePageURL"
+		static let faviconURL = "faviconURL"
+		static let image = "image" // NSImage
+	}
+
+	init(folder: String) {
+
+		self.folder = folder
+		self.binaryCache = RSBinaryCache(folder: folder)
+		self.queue = DispatchQueue(label: "FaviconCache serial queue - \(folder)")
+	}
+
+	// MARK: - API
+
+	func favicon(for feed: Feed) -> NSImage? {
+
+		assert(Thread.isMainThread)
+
+		if let faviconURL = faviconURL(for: feed) {
+
+			if let cachedFavicon = cache[faviconURL] {
+				return cachedFavicon
+			}
+			if shouldDownloadFaviconURL(faviconURL) {
+				downloadFavicon(faviconURL)
+				return nil
+			}
+		}
+
+		return nil
+	}
+}
+
+private extension FaviconDownloader {
+
+	func shouldDownloadFaviconURL(_ faviconURL: String) -> Bool {
+
+		return !urlsBeingDownloaded.contains(faviconURL)
+	}
+
+	func downloadFavicon(_ faviconURL: String) {
+
+		guard let url = URL(string: faviconURL) else {
+			return
+		}
+
+		urlsBeingDownloaded.insert(faviconURL)
+
+		download(url) { (data, response, error) in
+
+			self.urlsBeingDownloaded.remove(faviconURL)
+			if let data = data {
+				self.queue.async {
+					let _ = NSImage(data: data)
+				}
+			}
+		}
+	}
+
+	func faviconURL(for feed: Feed) -> String? {
+
+		if let faviconURL = feed.faviconURL {
+			return faviconURL
+		}
+
+		if let homePageURL = feed.homePageURL {
+			return faviconURLCache[homePageURL]
+		}
+		return nil
+	}
+
+	func readFaviconFromDisk(_ faviconURL: String, _ callback: @escaping (NSImage?) -> Void) {
+
+		queue.async {
+			let image = self.tryToInstantiateNSImageFromDisk(faviconURL)
+			DispatchQueue.main.async {
+				callback(image)
+			}
+		}
+	}
+
+	func tryToInstantiateNSImageFromDisk(_ faviconURL: String) -> NSImage? {
+
+		// Call on serial queue.
+
+		if badImages.contains(faviconURL) {
+			return nil
+		}
+
+		let key = keyFor(faviconURL)
+		var data: Data?
+
+		do {
+			data = try binaryCache.binaryData(forKey: key)
+		}
+		catch {
+			return nil
+		}
+
+		if data == nil {
+			return nil
+		}
+
+		guard let image = NSImage(data: data!) else {
+			badImages.insert(faviconURL)
+			return nil
+		}
+
+		return image
+	}
+
+	func keyFor(_ faviconURL: String) -> String {
+
+		return (faviconURL as NSString).rs_md5Hash()
+	}
+}