@@ -12,6 +12,7 @@ import SwiftFoundation
1212#else
1313import Foundation
1414#endif
15+ import SQLite3
1516
1617/*!
1718 @enum URLCache.StoragePolicy
@@ -128,6 +129,26 @@ open class CachedURLResponse : NSObject, NSSecureCoding, NSCopying {
128129
129130open class URLCache : NSObject {
130131
132+ private static let sharedSyncQ = DispatchQueue ( label: " org.swift.URLCache.sharedSyncQ " )
133+
134+ private static var sharedCache : URLCache ? {
135+ willSet {
136+ URLCache . sharedCache? . syncQ. sync {
137+ URLCache . sharedCache? . _databaseClient? . close ( )
138+ URLCache . sharedCache? . flushDatabase ( )
139+ }
140+ }
141+ didSet {
142+ URLCache . sharedCache? . syncQ. sync {
143+ URLCache . sharedCache? . setupCacheDatabaseIfNotExist ( )
144+ }
145+ }
146+ }
147+
148+ private let syncQ = DispatchQueue ( label: " org.swift.URLCache.syncQ " )
149+ private let _baseDiskPath : String ?
150+ private var _databaseClient : _CacheSQLiteClient ?
151+
131152 /*!
132153 @method sharedURLCache
133154 @abstract Returns the shared URLCache instance.
@@ -147,10 +168,22 @@ open class URLCache : NSObject {
147168 */
148169 open class var shared : URLCache {
149170 get {
150- NSUnimplemented ( )
171+ return sharedSyncQ. sync {
172+ if let cache = sharedCache {
173+ return cache
174+ } else {
175+ let fourMegaByte = 4 * 1024 * 1024
176+ let twentyMegaByte = 20 * 1024 * 1024
177+ let cacheDirectoryPath = FileManager . default. urls ( for: . cachesDirectory, in: . userDomainMask) . first? . path ?? " \( NSHomeDirectory ( ) ) /Library/Caches/ "
178+ let path = " \( cacheDirectoryPath) \( Bundle . main. bundleIdentifier ?? UUID ( ) . uuidString) "
179+ let cache = URLCache ( memoryCapacity: fourMegaByte, diskCapacity: twentyMegaByte, diskPath: path)
180+ sharedCache = cache
181+ return cache
182+ }
183+ }
151184 }
152185 set {
153- NSUnimplemented ( )
186+ sharedSyncQ . sync { sharedCache = newValue }
154187 }
155188 }
156189
@@ -167,7 +200,13 @@ open class URLCache : NSObject {
167200 @result an initialized URLCache, with the given capacity, backed
168201 by disk.
169202 */
170- public init ( memoryCapacity: Int , diskCapacity: Int , diskPath path: String ? ) { NSUnimplemented ( ) }
203+ public init ( memoryCapacity: Int , diskCapacity: Int , diskPath path: String ? ) {
204+ self . memoryCapacity = memoryCapacity
205+ self . diskCapacity = diskCapacity
206+ self . _baseDiskPath = path
207+
208+ super. init ( )
209+ }
171210
172211 /*!
173212 @method cachedResponseForRequest:
@@ -249,10 +288,132 @@ open class URLCache : NSObject {
249288 @result the current usage of the on-disk cache of the receiver.
250289 */
251290 open var currentDiskUsage : Int { NSUnimplemented ( ) }
291+
292+ private func flushDatabase( ) {
293+ guard let path = _baseDiskPath else { return }
294+
295+ do {
296+ let dbPath = path. appending ( " /Cache.db " )
297+ try FileManager . default. removeItem ( atPath: dbPath)
298+ } catch {
299+ fatalError ( " Unable to flush database for URLCache: \( error. localizedDescription) " )
300+ }
301+ }
302+
252303}
253304
254305extension URLCache {
255306 public func storeCachedResponse( _ cachedResponse: CachedURLResponse , for dataTask: URLSessionDataTask ) { NSUnimplemented ( ) }
256307 public func getCachedResponse( for dataTask: URLSessionDataTask , completionHandler: ( CachedURLResponse ? ) -> Void ) { NSUnimplemented ( ) }
257308 public func removeCachedResponse( for dataTask: URLSessionDataTask ) { NSUnimplemented ( ) }
258309}
310+
311+ extension URLCache {
312+
313+ private func setupCacheDatabaseIfNotExist( ) {
314+ guard let path = _baseDiskPath else { return }
315+
316+ if !FileManager. default. fileExists ( atPath: path) {
317+ do {
318+ try FileManager . default. createDirectory ( atPath: path, withIntermediateDirectories: true )
319+ } catch {
320+ fatalError ( " Unable to create directories for URLCache: \( error. localizedDescription) " )
321+ }
322+ }
323+
324+ // Close the currently opened database connection(if any), before creating/replacing the db file
325+ _databaseClient? . close ( )
326+
327+ let dbPath = path. appending ( " /Cache.db " )
328+ if !FileManager. default. createFile ( atPath: dbPath, contents: nil , attributes: nil ) {
329+ fatalError ( " Unable to setup database for URLCache " )
330+ }
331+
332+ _databaseClient = _CacheSQLiteClient ( databasePath: dbPath)
333+ if _databaseClient == nil {
334+ _databaseClient? . close ( )
335+ flushDatabase ( )
336+ fatalError ( " Unable to setup database for URLCache " )
337+ }
338+
339+ if !createTables( ) {
340+ _databaseClient? . close ( )
341+ flushDatabase ( )
342+ fatalError ( " Unable to setup database for URLCache: Tables not created " )
343+ }
344+
345+ if !createIndicesForTables( ) {
346+ _databaseClient? . close ( )
347+ flushDatabase ( )
348+ fatalError ( " Unable to setup database for URLCache: Indices not created for tables " )
349+ }
350+ }
351+
352+ private func createTables( ) -> Bool {
353+ guard _databaseClient != nil else {
354+ fatalError ( " Cannot create table before database setup " )
355+ }
356+
357+ let tableSQLs = [
358+ " CREATE TABLE cfurl_cache_response(entry_ID INTEGER PRIMARY KEY, version INTEGER, hash_value VARCHAR, storage_policy INTEGER, request_key VARCHAR, time_stamp DATETIME, partition VARCHAR) " ,
359+ " CREATE TABLE cfurl_cache_receiver_data(entry_ID INTEGER PRIMARY KEY, isDataOnFS INTEGER, receiver_data BLOB) " ,
360+ " CREATE TABLE cfurl_cache_blob_data(entry_ID INTEGER PRIMARY KEY, response_object BLOB, request_object BLOB, proto_props BLOB, user_info BLOB) " ,
361+ " CREATE TABLE cfurl_cache_schema_version(schema_version INTEGER) "
362+ ]
363+
364+ for sql in tableSQLs {
365+ if let isSuccess = _databaseClient? . execute ( sql: sql) , !isSuccess {
366+ return false
367+ }
368+ }
369+
370+ return true
371+ }
372+
373+ private func createIndicesForTables( ) -> Bool {
374+ guard _databaseClient != nil else {
375+ fatalError ( " Cannot create table before database setup " )
376+ }
377+
378+ let indicesSQLs = [
379+ " CREATE INDEX proto_props_index ON cfurl_cache_blob_data(entry_ID) " ,
380+ " CREATE INDEX receiver_data_index ON cfurl_cache_receiver_data(entry_ID) " ,
381+ " CREATE INDEX request_key_index ON cfurl_cache_response(request_key) " ,
382+ " CREATE INDEX time_stamp_index ON cfurl_cache_response(time_stamp) "
383+ ]
384+
385+ for sql in indicesSQLs {
386+ if let isSuccess = _databaseClient? . execute ( sql: sql) , !isSuccess {
387+ return false
388+ }
389+ }
390+
391+ return true
392+ }
393+
394+ }
395+
396+ fileprivate struct _CacheSQLiteClient {
397+
398+ private var database : OpaquePointer ?
399+
400+ init ? ( databasePath: String ) {
401+ if sqlite3_open_v2 ( databasePath, & database, SQLITE_OPEN_CREATE | SQLITE_OPEN_READWRITE, nil ) != SQLITE_OK {
402+ return nil
403+ }
404+ }
405+
406+ func execute( sql: String ) -> Bool {
407+ guard let db = database else { return false }
408+
409+ return sqlite3_exec ( db, sql, nil , nil , nil ) == SQLITE_OK
410+ }
411+
412+ mutating func close( ) {
413+ guard let db = database else { return }
414+
415+ sqlite3_close_v2 ( db)
416+ database = nil
417+ }
418+
419+ }
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