Lazy attachment restores.

Signal.xcodeproj/project.pbxproj

@@ -205,6 +205,7 @@
 		34D1F0C01F8EC1760066283D /* MessageRecipientStatusUtils.swift in Sources */ = {isa = PBXBuildFile; fileRef = 34D1F0BF1F8EC1760066283D /* MessageRecipientStatusUtils.swift */; };
 		34D2CCD4206294B900CB1A14 /* OWSScreenLock.swift in Sources */ = {isa = PBXBuildFile; fileRef = 34D2CCD3206294B900CB1A14 /* OWSScreenLock.swift */; };
 		34D2CCDA2062E7D000CB1A14 /* OWSScreenLockUI.m in Sources */ = {isa = PBXBuildFile; fileRef = 34D2CCD92062E7D000CB1A14 /* OWSScreenLockUI.m */; };
+		34D2CCD220618B3000CB1A14 /* OWSBackupLazyRestoreJob.swift in Sources */ = {isa = PBXBuildFile; fileRef = 34D2CCD120618B2F00CB1A14 /* OWSBackupLazyRestoreJob.swift */; };
 		34D5CCA91EAE3D30005515DB /* AvatarViewHelper.m in Sources */ = {isa = PBXBuildFile; fileRef = 34D5CCA81EAE3D30005515DB /* AvatarViewHelper.m */; };
 		34D8C0271ED3673300188D7C /* DebugUIMessages.m in Sources */ = {isa = PBXBuildFile; fileRef = 34D8C0241ED3673300188D7C /* DebugUIMessages.m */; };
 		34D8C0281ED3673300188D7C /* DebugUITableViewController.m in Sources */ = {isa = PBXBuildFile; fileRef = 34D8C0261ED3673300188D7C /* DebugUITableViewController.m */; };
@@ -812,6 +813,7 @@
 		34D2CCD3206294B900CB1A14 /* OWSScreenLock.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = OWSScreenLock.swift; sourceTree = "<group>"; };
 		34D2CCD82062E7D000CB1A14 /* OWSScreenLockUI.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = OWSScreenLockUI.h; sourceTree = "<group>"; };
 		34D2CCD92062E7D000CB1A14 /* OWSScreenLockUI.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = OWSScreenLockUI.m; sourceTree = "<group>"; };
+		34D2CCD120618B2F00CB1A14 /* OWSBackupLazyRestoreJob.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = OWSBackupLazyRestoreJob.swift; sourceTree = "<group>"; };
 		34D5CCA71EAE3D30005515DB /* AvatarViewHelper.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = AvatarViewHelper.h; sourceTree = "<group>"; };
 		34D5CCA81EAE3D30005515DB /* AvatarViewHelper.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = AvatarViewHelper.m; sourceTree = "<group>"; };
 		34D8C0231ED3673300188D7C /* DebugUIMessages.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = DebugUIMessages.h; sourceTree = "<group>"; };
@@ -1974,6 +1976,7 @@
 				34D2CCD3206294B900CB1A14 /* OWSScreenLock.swift */,
 				34D2CCD82062E7D000CB1A14 /* OWSScreenLockUI.h */,
 				34D2CCD92062E7D000CB1A14 /* OWSScreenLockUI.m */,
+				34D2CCD120618B2F00CB1A14 /* OWSBackupLazyRestoreJob.swift */,
 				4579431C1E7C8CE9008ED0C0 /* Pastelog.h */,
 				4579431D1E7C8CE9008ED0C0 /* Pastelog.m */,
 				450DF2041E0D74AC003D14BE /* Platform.swift */,
@@ -3143,6 +3146,7 @@
 				458DE9D91DEE7B360071BB03 /* OWSWebRTCDataProtos.pb.m in Sources */,
 				76EB063C18170B33006006FC /* NumberUtil.m in Sources */,
 				451166C01FD86B98000739BA /* AccountManager.swift in Sources */,
+				34D2CCD220618B3000CB1A14 /* OWSBackupLazyRestoreJob.swift in Sources */,
 				3430FE181F7751D4000EC51B /* GiphyAPI.swift in Sources */,
 				34A55F3720485465002CC6DE /* OWS2FARegistrationViewController.m in Sources */,
 				340FC8AD204DAC8D007AEB0F /* OWSLinkedDevicesTableViewController.m in Sources */,

Signal/src/AppDelegate.m

@@ -418,8 +418,8 @@ static NSString *const kURLHostVerifyPrefix             = @"verify";
     // Every time we change or add a database view in such a way that
     // might cause a delay on launch, we need to bump this constant.
     //
-    // We upgraded YapDatabase in v2.20.0 and need to regenerate all database views.
-    NSString *kLastVersionWithDatabaseViewChange = @"2.20.0";
+    // We added a database view in v2.23.0.
+    NSString *kLastVersionWithDatabaseViewChange = @"2.23.0";
     BOOL mayNeedUpgrade = ([TSAccountManager isRegistered] && lastLaunchedAppVersion
         && (!lastCompletedLaunchAppVersion ||
                [VersionMigrations isVersion:lastCompletedLaunchAppVersion
@@ -1134,6 +1134,8 @@ static NSString *const kURLHostVerifyPrefix             = @"verify";
     [self ensureRootViewController];
 
     [OWSBackup.sharedManager setup];
+
+    [OWSBackupLazyRestoreJob run];
 }
 
 - (void)registrationStateDidChange

Signal/src/Signal-Bridging-Header.h

@@ -19,6 +19,8 @@
 #import "NotificationsManager.h"
 #import "OWSAnyTouchGestureRecognizer.h"
 #import "OWSAudioPlayer.h"
+#import "OWSBackup.h"
+#import "OWSBackupIO.h"
 #import "OWSBezierPathView.h"
 #import "OWSCallNotificationsAdaptee.h"
 #import "OWSDatabaseMigration.h"

Signal/src/util/OWSBackup.h

@@ -20,13 +20,15 @@ typedef NS_ENUM(NSUInteger, OWSBackupState) {
     OWSBackupState_Succeeded,
 };
 
+@class OWSBackupIO;
+@class TSAttachmentStream;
 @class TSThread;
 
 @interface OWSBackup : NSObject
 
 - (instancetype)init NS_UNAVAILABLE;
 
-+ (instancetype)sharedManager;
++ (instancetype)sharedManager NS_SWIFT_NAME(shared());
 
 - (void)setup;
 
@@ -71,6 +73,16 @@ typedef NS_ENUM(NSUInteger, OWSBackupState) {
 - (void)logBackupRecords;
 - (void)clearAllCloudKitRecords;
 
+#pragma mark - Lazy Restore
+
+- (NSArray<TSAttachmentStream *> *)attachmentsForLazyRestore;
+
+- (NSArray<NSString *> *)attachmentIdsForLazyRestore;
+
+- (void)lazyRestoreAttachment:(TSAttachmentStream *)attachment
+                     backupIO:(OWSBackupIO *)backupIO
+                   completion:(OWSBackupBoolBlock)completion;
+
 @end
 
 NS_ASSUME_NONNULL_END

Signal/src/util/OWSBackup.m

@@ -4,6 +4,7 @@
 
 #import "OWSBackup.h"
 #import "OWSBackupExportJob.h"
+#import "OWSBackupIO.h"
 #import "OWSBackupImportJob.h"
 #import "Signal-Swift.h"
 #import <Curve25519Kit/Randomness.h>
@@ -483,6 +484,149 @@ NS_ASSUME_NONNULL_BEGIN
         }];
 }
 
+#pragma mark - Lazy Restore
+
+- (NSArray<TSAttachmentStream *> *)attachmentsForLazyRestore
+{
+    NSMutableArray<TSAttachmentStream *> *attachments = [NSMutableArray new];
+    [self.dbConnection readWithBlock:^(YapDatabaseReadTransaction *transaction) {
+        id ext = [transaction ext:TSMessageDatabaseViewExtensionName];
+        if (!ext) {
+            OWSProdLogAndFail(@"%@ Could not load database view.", self.logTag);
+            return;
+        }
+
+        [ext enumerateKeysAndObjectsInGroup:TSLazyRestoreAttachmentsGroup
+                                 usingBlock:^(
+                                     NSString *collection, NSString *key, id object, NSUInteger index, BOOL *stop) {
+                                     if (![object isKindOfClass:[TSAttachmentStream class]]) {
+                                         OWSProdLogAndFail(@"%@ Unexpected object: %@ in collection:%@",
+                                             self.logTag,
+                                             [object class],
+                                             collection);
+                                         return;
+                                     }
+                                     [attachments addObject:object];
+                                 }];
+    }];
+    return attachments;
+}
+
+- (NSArray<NSString *> *)attachmentIdsForLazyRestore
+{
+    NSMutableArray<NSString *> *attachmentIds = [NSMutableArray new];
+    [self.dbConnection readWithBlock:^(YapDatabaseReadTransaction *transaction) {
+        id ext = [transaction ext:TSMessageDatabaseViewExtensionName];
+        if (!ext) {
+            OWSProdLogAndFail(@"%@ Could not load database view.", self.logTag);
+            return;
+        }
+
+        [ext enumerateKeysInGroup:TSLazyRestoreAttachmentsGroup
+                       usingBlock:^(NSString *collection, NSString *key, NSUInteger index, BOOL *stop) {
+                           [attachmentIds addObject:key];
+                       }];
+    }];
+    return attachmentIds;
+}
+
+- (void)lazyRestoreAttachment:(TSAttachmentStream *)attachment
+                     backupIO:(OWSBackupIO *)backupIO
+                   completion:(OWSBackupBoolBlock)completion
+{
+    OWSAssert(attachment);
+    OWSAssert(backupIO);
+    OWSAssert(completion);
+
+    NSString *_Nullable attachmentFilePath = [attachment filePath];
+    if (attachmentFilePath.length < 1) {
+        DDLogError(@"%@ Attachment has invalid file path.", self.logTag);
+        return completion(NO);
+    }
+    if ([NSFileManager.defaultManager fileExistsAtPath:attachmentFilePath]) {
+        DDLogError(@"%@ Attachment already has file.", self.logTag);
+        return completion(NO);
+    }
+
+    NSString *_Nullable recordName = attachment.backupRestoreRecordName;
+    NSData *_Nullable encryptionKey = attachment.backupRestoreEncryptionKey;
+    if (recordName.length < 1 || encryptionKey.length < 1) {
+        return completion(NO);
+    }
+
+    // Use a predictable file path so that multiple "import backup" attempts
+    // will leverage successful file downloads from previous attempts.
+    //
+    // TODO: This will also require imports using a predictable jobTempDirPath.
+    NSString *_Nullable tempFilePath = [backupIO createTempFile];
+    if (!tempFilePath) {
+        return completion(NO);
+    }
+
+    [OWSBackupAPI downloadFileFromCloudWithRecordName:recordName
+        toFileUrl:[NSURL fileURLWithPath:tempFilePath]
+        success:^{
+            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+                [self lazyRestoreAttachment:attachment
+                                   backupIO:backupIO
+                          encryptedFilePath:tempFilePath
+                              encryptionKey:encryptionKey
+                                 completion:completion];
+            });
+        }
+        failure:^(NSError *error) {
+            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+                completion(NO);
+            });
+        }];
+}
+
+- (void)lazyRestoreAttachment:(TSAttachmentStream *)attachment
+                     backupIO:(OWSBackupIO *)backupIO
+            encryptedFilePath:(NSString *)encryptedFilePath
+                encryptionKey:(NSData *)encryptionKey
+                   completion:(OWSBackupBoolBlock)completion
+{
+    OWSAssert(attachment);
+    OWSAssert(backupIO);
+    OWSAssert(encryptedFilePath.length > 0);
+    OWSAssert(encryptionKey.length > 0);
+    OWSAssert(completion);
+
+    NSData *_Nullable data = [NSData dataWithContentsOfFile:encryptedFilePath];
+    if (!data) {
+        DDLogError(@"%@ Could not load encrypted file.", self.logTag);
+        return completion(NO);
+    }
+
+    NSString *_Nullable decryptedFilePath = [backupIO createTempFile];
+    if (!decryptedFilePath) {
+        return completion(NO);
+    }
+
+    if (![backupIO decryptFileAsFile:encryptedFilePath dstFilePath:decryptedFilePath encryptionKey:encryptionKey]) {
+        DDLogError(@"%@ Could not load decrypt file.", self.logTag);
+        return completion(NO);
+    }
+
+    NSString *_Nullable attachmentFilePath = [attachment filePath];
+    if (attachmentFilePath.length < 1) {
+        DDLogError(@"%@ Attachment has invalid file path.", self.logTag);
+        return completion(NO);
+    }
+    NSError *error;
+    BOOL success =
+        [NSFileManager.defaultManager moveItemAtPath:decryptedFilePath toPath:attachmentFilePath error:&error];
+    if (!success || error) {
+        DDLogError(@"%@ Attachment file could not be restored: %@.", self.logTag, error);
+        return completion(NO);
+    }
+
+    [attachment updateWithBackupRestoreComplete];
+
+    completion(YES);
+}
+
 #pragma mark - Notifications
 
 - (void)postDidChangeNotification

Signal/src/util/OWSBackupAPI.swift

@@ -6,6 +6,15 @@ import Foundation
 import SignalServiceKit
 import CloudKit
 
+// We don't worry about atomic writes.  Each backup export
+// will diff against last successful backup.
+//
+// Note that all of our CloudKit records are immutable.
+// "Persistent" records are only uploaded once.
+// "Ephemeral" records are always uploaded to a new record name.
+//
+// TODO: We could store known encryption ids locally to
+// facilitate "resume" of failed backup exports.
 @objc public class OWSBackupAPI: NSObject {
 
     // If we change the record types, we need to ensure indices

Signal/src/util/OWSBackupIO.h

@@ -20,6 +20,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (instancetype)initWithJobTempDirPath:(NSString *)jobTempDirPath;
 
+- (nullable NSString *)createTempFile;
+
 #pragma mark - Encrypt
 
 - (nullable OWSBackupEncryptedItem *)encryptFileAsTempFile:(NSString *)srcFilePath;

Signal/src/util/OWSBackupIO.m

@@ -44,6 +44,16 @@ static const compression_algorithm SignalCompressionAlgorithm = COMPRESSION_LZMA
     return self;
 }
 
+- (nullable NSString *)createTempFile
+{
+    NSString *filePath = [self.jobTempDirPath stringByAppendingPathComponent:[NSUUID UUID].UUIDString];
+    if (![OWSFileSystem ensureFileExists:filePath]) {
+        OWSProdLogAndFail(@"%@ could not create temp file.", self.logTag);
+        return nil;
+    }
+    return filePath;
+}
+
 #pragma mark - Encrypt
 
 - (nullable OWSBackupEncryptedItem *)encryptFileAsTempFile:(NSString *)srcFilePath
@@ -92,7 +102,10 @@ static const compression_algorithm SignalCompressionAlgorithm = COMPRESSION_LZMA
         // TODO: Encrypt the data using key;
         NSData *encryptedData = unencryptedData;
 
-        NSString *dstFilePath = [self.jobTempDirPath stringByAppendingPathComponent:[NSUUID UUID].UUIDString];
+        NSString *_Nullable dstFilePath = [self createTempFile];
+        if (!dstFilePath) {
+            return nil;
+        }
         NSError *error;
         BOOL success = [encryptedData writeToFile:dstFilePath options:NSDataWritingAtomic error:&error];
         if (!success || error) {

Signal/src/util/OWSBackupJob.m

@@ -86,16 +86,12 @@ NSString *const kOWSBackup_KeychainService = @"kOWSBackup_KeychainService";
     // might want to use a predictable directory so that repeated
     // import attempts can reuse downloads from previous attempts.
     NSString *temporaryDirectory = NSTemporaryDirectory();
-    self.jobTempDirPath = [temporaryDirectory stringByAppendingString:[NSUUID UUID].UUIDString];
+    self.jobTempDirPath = [temporaryDirectory stringByAppendingPathComponent:[NSUUID UUID].UUIDString];
 
     if (![OWSFileSystem ensureDirectoryExists:self.jobTempDirPath]) {
         OWSProdLogAndFail(@"%@ Could not create jobTempDirPath.", self.logTag);
         return NO;
     }
-    if (![OWSFileSystem protectFileOrFolderAtPath:self.jobTempDirPath]) {
-        OWSProdLogAndFail(@"%@ Could not protect jobTempDirPath.", self.logTag);
-        return NO;
-    }
     return YES;
 }
 

Signal/src/util/OWSBackupLazyRestoreJob.swift

@@ -0,0 +1,90 @@
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
+
+import Foundation
+import PromiseKit
+import SignalServiceKit
+
+@objc
+public class OWSBackupLazyRestoreJob: NSObject {
+
+    let TAG = "[OWSBackupLazyRestoreJob]"
+
+    let primaryStorage: OWSPrimaryStorage
+
+    private var jobTempDirPath: String?
+
+    deinit {
+        if let jobTempDirPath = self.jobTempDirPath {
+            DispatchQueue.global().async {
+                OWSFileSystem.deleteFile(jobTempDirPath)
+            }
+        }
+    }
+
+    @objc
+    public class func run() {
+        OWSBackupLazyRestoreJob().run()
+    }
+
+    public override init() {
+        self.primaryStorage = OWSPrimaryStorage.shared()
+    }
+
+    private func run() {
+        AssertIsOnMainThread()
+
+        DispatchQueue.global().async {
+            self.restoreAttachments()
+        }
+    }
+
+    private func restoreAttachments() {
+        let temporaryDirectory = NSTemporaryDirectory()
+        let jobTempDirPath = (temporaryDirectory as NSString).appendingPathComponent(NSUUID().uuidString)
+        //            let jobTempDirPath = temporaryDirectory.appendingPathComponent(UUID().uuidString)
+
+        guard OWSFileSystem.ensureDirectoryExists(jobTempDirPath) else {
+            Logger.error("\(TAG) could not create temp directory.")
+            return
+        }
+
+        self.jobTempDirPath = jobTempDirPath
+
+        let backupIO = OWSBackupIO(jobTempDirPath: jobTempDirPath)
+
+        let attachmentIds = OWSBackup.shared().attachmentIdsForLazyRestore()
+        self.tryToRestoreNextAttachment(attachmentIds: attachmentIds, backupIO: backupIO)
+    }
+
+    private func tryToRestoreNextAttachment(attachmentIds: [String], backupIO: OWSBackupIO) {
+        var attachmentIdsCopy = attachmentIds
+        guard let attachmentId = attachmentIdsCopy.last else {
+            // This job is done.
+            Logger.verbose("\(TAG) job is done.")
+            return
+        }
+        attachmentIdsCopy.removeLast()
+        guard let attachment = TSAttachmentStream.fetch(uniqueId: attachmentId) else {
+            Logger.warn("\(TAG) could not load attachment.")
+            // Not necessarily an error.
+            // The attachment might have been deleted since the job began.
+            // Continue trying to restore the other attachments.
+            tryToRestoreNextAttachment(attachmentIds: attachmentIds, backupIO: backupIO)
+            return
+        }
+        OWSBackup.shared().lazyRestoreAttachment(attachment,
+                                                 backupIO: backupIO,
+                                                 completion: { (success) in
+                                                    if success {
+                                                        Logger.info("\(self.TAG) restored attachment.")
+                                                    } else {
+                                                        Logger.warn("\(self.TAG) could not restore attachment.")
+                                                    }
+                                                // Continue trying to restore the other attachments.
+                                                self.tryToRestoreNextAttachment(attachmentIds: attachmentIdsCopy, backupIO: backupIO)
+        })
+
+    }
+}

SignalServiceKit/src/Messages/Attachments/TSAttachmentStream.h

@@ -34,6 +34,11 @@ NS_ASSUME_NONNULL_BEGIN
 
 @property (nonatomic, readonly) NSDate *creationTimestamp;
 
+// Optional properties.  Set only for attachments which
+// need "lazy backup restore."
+@property (nonatomic, readonly, nullable) NSString *backupRestoreRecordName;
+@property (nonatomic, readonly, nullable) NSData *backupRestoreEncryptionKey;
+
 #if TARGET_OS_IPHONE
 - (nullable UIImage *)image;
 - (nullable UIImage *)thumbnailImage;
@@ -62,6 +67,13 @@ NS_ASSUME_NONNULL_BEGIN
 
 + (nullable NSError *)migrateToSharedData;
 
+#pragma mark - Update With... Methods
+
+// Marks attachment as needing "lazy backup restore."
+- (void)updateWithBackupRestoreRecordName:(NSString *)recordName encryptionKey:(NSData *)encryptionKey;
+// Marks attachment as having completed "lazy backup restore."
+- (void)updateWithBackupRestoreComplete;
+
 @end
 
 NS_ASSUME_NONNULL_END

SignalServiceKit/src/Messages/Attachments/TSAttachmentStream.m

@@ -26,6 +26,9 @@ NS_ASSUME_NONNULL_BEGIN
 // This property should only be accessed on the main thread.
 @property (nullable, nonatomic) NSNumber *cachedAudioDurationSeconds;
 
+@property (nonatomic, nullable) NSString *backupRestoreRecordName;
+@property (nonatomic, nullable) NSData *backupRestoreEncryptionKey;
+
 @end
 
 #pragma mark -
@@ -610,6 +613,33 @@ NS_ASSUME_NONNULL_BEGIN
     return audioDurationSeconds;
 }
 
+#pragma mark - Update With... Methods
+
+- (void)updateWithBackupRestoreRecordName:(NSString *)recordName encryptionKey:(NSData *)encryptionKey
+{
+    OWSAssert(recordName.length > 0);
+    OWSAssert(encryptionKey.length > 0);
+
+    [self.dbReadWriteConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
+        [self applyChangeToSelfAndLatestCopy:transaction
+                                 changeBlock:^(TSAttachmentStream *attachment) {
+                                     [attachment setBackupRestoreRecordName:recordName];
+                                     [attachment setBackupRestoreEncryptionKey:encryptionKey];
+                                 }];
+    }];
+}
+
+- (void)updateWithBackupRestoreComplete
+{
+    [self.dbReadWriteConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
+        [self applyChangeToSelfAndLatestCopy:transaction
+                                 changeBlock:^(TSAttachmentStream *attachment) {
+                                     [attachment setBackupRestoreRecordName:nil];
+                                     [attachment setBackupRestoreEncryptionKey:nil];
+                                 }];
+    }];
+}
+
 @end
 
 NS_ASSUME_NONNULL_END

SignalServiceKit/src/Storage/OWSPrimaryStorage.m

@@ -57,6 +57,7 @@ void runAsyncRegistrationsForStorage(OWSStorage *storage)
     [OWSFailedMessagesJob asyncRegisterDatabaseExtensionsWithPrimaryStorage:storage];
     [OWSFailedAttachmentDownloadsJob asyncRegisterDatabaseExtensionsWithPrimaryStorage:storage];
     [OWSMediaGalleryFinder asyncRegisterDatabaseExtensionsWithPrimaryStorage:storage];
+    [TSDatabaseView asyncRegisterLazyRestoreAttachmentsDatabaseView:storage];
 }
 
 #pragma mark -

SignalServiceKit/src/Storage/TSDatabaseView.h

@@ -17,6 +17,9 @@ extern NSString *const TSUnreadDatabaseViewExtensionName;
 
 extern NSString *const TSSecondaryDevicesDatabaseViewExtensionName;
 
+extern NSString *const TSLazyRestoreAttachmentsGroup;
+extern NSString *const TSLazyRestoreAttachmentsDatabaseViewExtensionName;
+
 @interface TSDatabaseView : NSObject
 
 - (instancetype)init NS_UNAVAILABLE;
@@ -55,4 +58,6 @@ extern NSString *const TSSecondaryDevicesDatabaseViewExtensionName;
 
 + (void)asyncRegisterSecondaryDevicesDatabaseView:(OWSStorage *)storage;
 
++ (void)asyncRegisterLazyRestoreAttachmentsDatabaseView:(OWSStorage *)storage;
+
 @end

SignalServiceKit/src/Storage/TSDatabaseView.m

@@ -5,6 +5,8 @@
 #import "TSDatabaseView.h"
 #import "OWSDevice.h"
 #import "OWSReadTracking.h"
+#import "TSAttachment.h"
+#import "TSAttachmentStream.h"
 #import "TSIncomingMessage.h"
 #import "TSInvalidIdentityKeyErrorMessage.h"
 #import "TSOutgoingMessage.h"
@@ -28,6 +30,9 @@ NSString *const TSUnreadDatabaseViewExtensionName = @"TSUnreadDatabaseViewExtens
 NSString *const TSUnseenDatabaseViewExtensionName = @"TSUnseenDatabaseViewExtensionName";
 NSString *const TSThreadSpecialMessagesDatabaseViewExtensionName = @"TSThreadSpecialMessagesDatabaseViewExtensionName";
 NSString *const TSSecondaryDevicesDatabaseViewExtensionName = @"TSSecondaryDevicesDatabaseViewExtensionName";
+NSString *const TSLazyRestoreAttachmentsDatabaseViewExtensionName
+    = @"TSLazyRestoreAttachmentsDatabaseViewExtensionName";
+NSString *const TSLazyRestoreAttachmentsGroup = @"TSLazyRestoreAttachmentsGroup";
 
 @interface OWSStorage (TSDatabaseView)
 
@@ -295,30 +300,26 @@ NSString *const TSSecondaryDevicesDatabaseViewExtensionName = @"TSSecondaryDevic
 
 + (void)asyncRegisterSecondaryDevicesDatabaseView:(OWSStorage *)storage
 {
-    YapDatabaseViewGrouping *viewGrouping =
-        [YapDatabaseViewGrouping withObjectBlock:^NSString *_Nullable(YapDatabaseReadTransaction *_Nonnull transaction,
-            NSString *_Nonnull collection,
-            NSString *_Nonnull key,
-            id _Nonnull object) {
-            if ([object isKindOfClass:[OWSDevice class]]) {
-                OWSDevice *device = (OWSDevice *)object;
-                if (![device isPrimaryDevice]) {
-                    return TSSecondaryDevicesGroup;
-                }
+    YapDatabaseViewGrouping *viewGrouping = [YapDatabaseViewGrouping withObjectBlock:^NSString *_Nullable(
+        YapDatabaseReadTransaction *transaction, NSString *collection, NSString *key, id object) {
+        if ([object isKindOfClass:[OWSDevice class]]) {
+            OWSDevice *device = (OWSDevice *)object;
+            if (![device isPrimaryDevice]) {
+                return TSSecondaryDevicesGroup;
             }
-            return nil;
-        }];
+        }
+        return nil;
+    }];
 
     YapDatabaseViewSorting *viewSorting =
-        [YapDatabaseViewSorting withObjectBlock:^NSComparisonResult(YapDatabaseReadTransaction *_Nonnull transaction,
-            NSString *_Nonnull group,
-            NSString *_Nonnull collection1,
-            NSString *_Nonnull key1,
-            id _Nonnull object1,
-            NSString *_Nonnull collection2,
-            NSString *_Nonnull key2,
-            id _Nonnull object2) {
-
+        [YapDatabaseViewSorting withObjectBlock:^NSComparisonResult(YapDatabaseReadTransaction *transaction,
+            NSString *group,
+            NSString *collection1,
+            NSString *key1,
+            id object1,
+            NSString *collection2,
+            NSString *key2,
+            id object2) {
             if ([object1 isKindOfClass:[OWSDevice class]] && [object2 isKindOfClass:[OWSDevice class]]) {
                 OWSDevice *device1 = (OWSDevice *)object1;
                 OWSDevice *device2 = (OWSDevice *)object2;
@@ -341,6 +342,58 @@ NSString *const TSSecondaryDevicesDatabaseViewExtensionName = @"TSSecondaryDevic
     [storage asyncRegisterExtension:view withName:TSSecondaryDevicesDatabaseViewExtensionName];
 }
 
++ (void)asyncRegisterLazyRestoreAttachmentsDatabaseView:(OWSStorage *)storage
+{
+    YapDatabaseViewGrouping *viewGrouping = [YapDatabaseViewGrouping withObjectBlock:^NSString *_Nullable(
+        YapDatabaseReadTransaction *transaction, NSString *collection, NSString *key, id object) {
+        if (![object isKindOfClass:[TSAttachment class]]) {
+            OWSProdLogAndFail(@"%@ Unexpected entity %@ in collection: %@", self.logTag, [object class], collection);
+            return nil;
+        }
+        if (![object isKindOfClass:[TSAttachmentStream class]]) {
+            return nil;
+        }
+        TSAttachmentStream *attachmentStream = (TSAttachmentStream *)object;
+        if (attachmentStream.backupRestoreRecordName.length > 0
+            && attachmentStream.backupRestoreEncryptionKey.length > 0) {
+            return TSLazyRestoreAttachmentsGroup;
+        } else {
+            return nil;
+        }
+    }];
+
+    YapDatabaseViewSorting *viewSorting = [YapDatabaseViewSorting withObjectBlock:^NSComparisonResult(
+        YapDatabaseReadTransaction *transaction,
+        NSString *group,
+        NSString *collection1,
+        NSString *key1,
+        id object1,
+        NSString *collection2,
+        NSString *key2,
+        id object2) {
+        if (![object1 isKindOfClass:[TSAttachment class]]) {
+            OWSProdLogAndFail(@"%@ Unexpected entity %@ in collection: %@", self.logTag, [object1 class], collection1);
+            return NSOrderedSame;
+        }
+        if (![object2 isKindOfClass:[TSAttachment class]]) {
+            OWSProdLogAndFail(@"%@ Unexpected entity %@ in collection: %@", self.logTag, [object2 class], collection2);
+            return NSOrderedSame;
+        }
+
+        TSAttachmentStream *attachmentStream1 = (TSAttachmentStream *)object1;
+        TSAttachmentStream *attachmentStream2 = (TSAttachmentStream *)object2;
+        return [attachmentStream2.creationTimestamp compare:attachmentStream1.creationTimestamp];
+    }];
+
+    YapDatabaseViewOptions *options = [YapDatabaseViewOptions new];
+    options.isPersistent = YES;
+    options.allowedCollections =
+        [[YapWhitelistBlacklist alloc] initWithWhitelist:[NSSet setWithObject:[TSAttachment collection]]];
+    YapDatabaseView *view =
+        [[YapDatabaseAutoView alloc] initWithGrouping:viewGrouping sorting:viewSorting versionTag:@"1" options:options];
+    [storage asyncRegisterExtension:view withName:TSLazyRestoreAttachmentsDatabaseViewExtensionName];
+}
+
 + (id)unseenDatabaseViewExtension:(YapDatabaseReadTransaction *)transaction
 {
     OWSAssert(transaction);

SignalServiceKit/src/Util/OWSFileSystem.h

@@ -28,6 +28,8 @@ NS_ASSUME_NONNULL_BEGIN
 // Returns NO IFF the directory does not exist and could not be created.
 + (BOOL)ensureDirectoryExists:(NSString *)dirPath;
 
++ (BOOL)ensureFileExists:(NSString *)filePath;
+
 + (BOOL)deleteFile:(NSString *)filePath;
 
 + (BOOL)deleteFileIfExists:(NSString *)filePath;

SignalServiceKit/src/Util/OWSFileSystem.m

@@ -227,6 +227,21 @@ NS_ASSUME_NONNULL_BEGIN
     }
 }
 
++ (BOOL)ensureFileExists:(NSString *)filePath
+{
+    BOOL exists = [[NSFileManager defaultManager] fileExistsAtPath:filePath];
+    if (exists) {
+        return [self protectFileOrFolderAtPath:filePath];
+    } else {
+        BOOL success = [[NSFileManager defaultManager] createFileAtPath:filePath contents:nil attributes:nil];
+        if (!success) {
+            OWSFail(@"%@ Failed to create file.", self.logTag);
+            return NO;
+        }
+        return [self protectFileOrFolderAtPath:filePath];
+    }
+}
+
 + (BOOL)deleteFile:(NSString *)filePath
 {
     NSError *error;