diff --git a/Signal/src/ViewControllers/ConversationView/ConversationViewController.m b/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
index 1744efb32..3eac90b3b 100644
--- a/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
+++ b/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
@@ -926,14 +926,10 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
             continue;
         }
 
-        [self.editingDatabaseConnection
-            asyncReadWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
-                [OWSIdentityManager.sharedManager setVerificationState:OWSVerificationStateDefault
-                                                           identityKey:identityKey
-                                                           recipientId:recipientId
-                                                 isUserInitiatedChange:YES
-                                                       protocolContext:transaction];
-            }];
+        [OWSIdentityManager.sharedManager setVerificationState:OWSVerificationStateDefault
+                                                   identityKey:identityKey
+                                                   recipientId:recipientId
+                                         isUserInitiatedChange:YES];
     }
 }
 
diff --git a/Signal/src/ViewControllers/DebugUI/DebugUISessionState.m b/Signal/src/ViewControllers/DebugUI/DebugUISessionState.m
index d21db0e81..4deb29891 100644
--- a/Signal/src/ViewControllers/DebugUI/DebugUISessionState.m
+++ b/Signal/src/ViewControllers/DebugUI/DebugUISessionState.m
@@ -99,20 +99,29 @@ NS_ASSUME_NONNULL_BEGIN
 #if DEBUG
 + (void)clearSessionAndIdentityStore
 {
-    [[TSStorageManager sharedManager] resetSessionStore];
-    [[OWSIdentityManager sharedManager] clearIdentityState];
+    [TSStorageManager.sharedManager.newDatabaseConnection
+        readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
+            [[TSStorageManager sharedManager] resetSessionStore:transaction];
+            [[OWSIdentityManager sharedManager] clearIdentityState:transaction];
+        }];
 }
 
 + (void)snapshotSessionAndIdentityStore
 {
-    [[TSStorageManager sharedManager] snapshotSessionStore];
-    [[OWSIdentityManager sharedManager] snapshotIdentityState];
+    [TSStorageManager.sharedManager.newDatabaseConnection
+        readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
+            [[TSStorageManager sharedManager] snapshotSessionStore:transaction];
+            [[OWSIdentityManager sharedManager] snapshotIdentityState:transaction];
+        }];
 }
 
 + (void)restoreSessionAndIdentityStore
 {
-    [[TSStorageManager sharedManager] restoreSessionStore];
-    [[OWSIdentityManager sharedManager] restoreIdentityState];
+    [TSStorageManager.sharedManager.newDatabaseConnection
+        readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
+            [[TSStorageManager sharedManager] restoreSessionStore:transaction];
+            [[OWSIdentityManager sharedManager] restoreIdentityState:transaction];
+        }];
 }
 #endif
 
diff --git a/Signal/src/ViewControllers/FingerprintViewScanController.m b/Signal/src/ViewControllers/FingerprintViewScanController.m
index 1503fbeee..cce0be4f5 100644
--- a/Signal/src/ViewControllers/FingerprintViewScanController.m
+++ b/Signal/src/ViewControllers/FingerprintViewScanController.m
@@ -200,15 +200,10 @@ NS_ASSUME_NONNULL_BEGIN
                                           @"Button that marks user as verified after a successful fingerprint scan.")
                                 style:UIAlertActionStyleDefault
                               handler:^(UIAlertAction *action) {
-                                  [TSStorageManager.sharedManager.newDatabaseConnection
-                                      asyncReadWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
-                                          [OWSIdentityManager.sharedManager
-                                               setVerificationState:OWSVerificationStateVerified
-                                                        identityKey:identityKey
-                                                        recipientId:recipientId
-                                              isUserInitiatedChange:YES
-                                                    protocolContext:transaction];
-                                      }];
+                                  [OWSIdentityManager.sharedManager setVerificationState:OWSVerificationStateVerified
+                                                                             identityKey:identityKey
+                                                                             recipientId:recipientId
+                                                                   isUserInitiatedChange:YES];
                                   [viewController dismissViewControllerAnimated:true completion:nil];
                               }]];
     UIAlertAction *dismissAction =
diff --git a/Signal/src/ViewControllers/ShowGroupMembersViewController.m b/Signal/src/ViewControllers/ShowGroupMembersViewController.m
index 04f024bf8..a4dcb74f1 100644
--- a/Signal/src/ViewControllers/ShowGroupMembersViewController.m
+++ b/Signal/src/ViewControllers/ShowGroupMembersViewController.m
@@ -251,14 +251,10 @@ NS_ASSUME_NONNULL_BEGIN
                 OWSFail(@"Missing identity key for: %@", recipientId);
                 continue;
             }
-            [TSStorageManager.sharedManager.newDatabaseConnection
-                asyncReadWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
-                    [identityManger setVerificationState:OWSVerificationStateDefault
-                                             identityKey:identityKey
-                                             recipientId:recipientId
-                                   isUserInitiatedChange:YES
-                                         protocolContext:transaction];
-                }];
+            [identityManger setVerificationState:OWSVerificationStateDefault
+                                     identityKey:identityKey
+                                     recipientId:recipientId
+                           isUserInitiatedChange:YES];
         }
     }
 
diff --git a/SignalServiceKit/src/Account/TSAccountManager.m b/SignalServiceKit/src/Account/TSAccountManager.m
index f0cd99ac6..344f161b9 100644
--- a/SignalServiceKit/src/Account/TSAccountManager.m
+++ b/SignalServiceKit/src/Account/TSAccountManager.m
@@ -104,9 +104,10 @@ NSString *const TSAccountManager_ServerSignalingKey = @"TSStorageServerSignaling
         _phoneNumberAwaitingVerification = nil;
         [self.dbConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *_Nonnull transaction) {
             [transaction removeAllObjectsInCollection:TSAccountManager_UserAccountCollection];
+
+            [[TSStorageManager sharedManager] resetSessionStore:transaction];
         }];
     }
-    [[TSStorageManager sharedManager] resetSessionStore];
 }
 
 + (BOOL)isRegistered
diff --git a/SignalServiceKit/src/Messages/OWSIdentityManager.h b/SignalServiceKit/src/Messages/OWSIdentityManager.h
index d79cf4c87..515710c8e 100644
--- a/SignalServiceKit/src/Messages/OWSIdentityManager.h
+++ b/SignalServiceKit/src/Messages/OWSIdentityManager.h
@@ -19,7 +19,7 @@ extern const NSUInteger kIdentityKeyLength;
 @class OWSRecipientIdentity;
 @class OWSSignalServiceProtosVerified;
 @class OWSStorage;
-@class OWSStorage;
+@class YapDatabaseReadWriteTransaction;
 
 // This class can be safely accessed and used from any thread.
 @interface OWSIdentityManager : NSObject <IdentityKeyStore>
@@ -44,6 +44,11 @@ extern const NSUInteger kIdentityKeyLength;
 - (OWSVerificationState)verificationStateForRecipientId:(NSString *)recipientId
                                             transaction:(YapDatabaseReadTransaction *)transaction;
 
+- (void)setVerificationState:(OWSVerificationState)verificationState
+                 identityKey:(NSData *)identityKey
+                 recipientId:(NSString *)recipientId
+       isUserInitiatedChange:(BOOL)isUserInitiatedChange;
+
 - (nullable OWSRecipientIdentity *)recipientIdentityForRecipientId:(NSString *)recipientId;
 
 /**
@@ -64,10 +69,10 @@ extern const NSUInteger kIdentityKeyLength;
 
 #if DEBUG
 // Clears everything except the local identity key.
-- (void)clearIdentityState;
+- (void)clearIdentityState:(YapDatabaseReadWriteTransaction *)transaction;
 
-- (void)snapshotIdentityState;
-- (void)restoreIdentityState;
+- (void)snapshotIdentityState:(YapDatabaseReadWriteTransaction *)transaction;
+- (void)restoreIdentityState:(YapDatabaseReadWriteTransaction *)transaction;
 #endif
 
 @end
diff --git a/SignalServiceKit/src/Messages/OWSIdentityManager.m b/SignalServiceKit/src/Messages/OWSIdentityManager.m
index 11492c9ab..d931cc6ff 100644
--- a/SignalServiceKit/src/Messages/OWSIdentityManager.m
+++ b/SignalServiceKit/src/Messages/OWSIdentityManager.m
@@ -23,7 +23,7 @@
 #import "TSStorageManager.h"
 #import "TextSecureKitEnv.h"
 #import "YapDatabaseConnection+OWS.h"
-#import "YapDatabaseReadTransaction+OWS.h"
+#import "YapDatabaseTransaction+OWS.h"
 #import <AxolotlKit/NSData+keyVersionByte.h>
 #import <Curve25519Kit/Curve25519.h>
 #import <YapDatabase/YapDatabase.h>
@@ -271,6 +271,23 @@ NSString *const kNSNotificationName_IdentityStateDidChange = @"kNSNotificationNa
     return NO;
 }
 
+- (void)setVerificationState:(OWSVerificationState)verificationState
+                 identityKey:(NSData *)identityKey
+                 recipientId:(NSString *)recipientId
+       isUserInitiatedChange:(BOOL)isUserInitiatedChange
+{
+    OWSAssert(identityKey.length == kStoredIdentityKeyLength);
+    OWSAssert(recipientId.length > 0);
+
+    [self.dbConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *_Nonnull transaction) {
+        [self setVerificationState:verificationState
+                       identityKey:identityKey
+                       recipientId:recipientId
+             isUserInitiatedChange:isUserInitiatedChange
+                       transaction:transaction];
+    }];
+}
+
 - (void)setVerificationState:(OWSVerificationState)verificationState
                  identityKey:(NSData *)identityKey
                  recipientId:(NSString *)recipientId
@@ -283,10 +300,27 @@ NSString *const kNSNotificationName_IdentityStateDidChange = @"kNSNotificationNa
 
     YapDatabaseReadWriteTransaction *transaction = protocolContext;
 
+    [self setVerificationState:verificationState
+                   identityKey:identityKey
+                   recipientId:recipientId
+         isUserInitiatedChange:isUserInitiatedChange
+                   transaction:transaction];
+}
+
+- (void)setVerificationState:(OWSVerificationState)verificationState
+                 identityKey:(NSData *)identityKey
+                 recipientId:(NSString *)recipientId
+       isUserInitiatedChange:(BOOL)isUserInitiatedChange
+                 transaction:(YapDatabaseReadWriteTransaction *)transaction
+{
+    OWSAssert(identityKey.length == kStoredIdentityKeyLength);
+    OWSAssert(recipientId.length > 0);
+    OWSAssert(transaction);
+
     // TODO: Remove all @synchronized
     // Ensure a remote identity exists for this key. We may be learning about
     // it for the first time.
-    [self saveRemoteIdentity:identityKey recipientId:recipientId protocolContext:protocolContext];
+    [self saveRemoteIdentity:identityKey recipientId:recipientId protocolContext:transaction];
 
     OWSRecipientIdentity *recipientIdentity =
         [OWSRecipientIdentity fetchObjectWithUniqueID:recipientId transaction:transaction];
@@ -845,23 +879,23 @@ NSString *const kNSNotificationName_IdentityStateDidChange = @"kNSNotificationNa
 #pragma mark - Debug
 
 #if DEBUG
-- (void)clearIdentityState
+- (void)clearIdentityState:(YapDatabaseReadWriteTransaction *)transaction
 {
-    [self.dbConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
-        NSMutableArray<NSString *> *identityKeysToRemove = [NSMutableArray new];
-        [transaction enumerateKeysInCollection:TSStorageManagerIdentityKeyStoreCollection
-                                    usingBlock:^(NSString *_Nonnull key, BOOL *_Nonnull stop) {
-                                        if ([key isEqualToString:TSStorageManagerIdentityKeyStoreIdentityKey]) {
-                                            // Don't delete our own key.
-                                            return;
-                                        }
-                                        [identityKeysToRemove addObject:key];
-                                    }];
-        for (NSString *key in identityKeysToRemove) {
-            [transaction removeObjectForKey:key inCollection:TSStorageManagerIdentityKeyStoreCollection];
-        }
-        [transaction removeAllObjectsInCollection:TSStorageManagerTrustedKeysCollection];
-    }];
+    OWSAssert(transaction);
+
+    NSMutableArray<NSString *> *identityKeysToRemove = [NSMutableArray new];
+    [transaction enumerateKeysInCollection:TSStorageManagerIdentityKeyStoreCollection
+                                usingBlock:^(NSString *_Nonnull key, BOOL *_Nonnull stop) {
+                                    if ([key isEqualToString:TSStorageManagerIdentityKeyStoreIdentityKey]) {
+                                        // Don't delete our own key.
+                                        return;
+                                    }
+                                    [identityKeysToRemove addObject:key];
+                                }];
+    for (NSString *key in identityKeysToRemove) {
+        [transaction removeObjectForKey:key inCollection:TSStorageManagerIdentityKeyStoreCollection];
+    }
+    [transaction removeAllObjectsInCollection:TSStorageManagerTrustedKeysCollection];
 }
 
 - (NSString *)identityKeySnapshotFilePath
@@ -878,20 +912,24 @@ NSString *const kNSNotificationName_IdentityStateDidChange = @"kNSNotificationNa
     return [dirPath stringByAppendingPathComponent:@".trusted-key-snapshot"];
 }
 
-- (void)snapshotIdentityState
+- (void)snapshotIdentityState:(YapDatabaseReadWriteTransaction *)transaction
 {
-    [self.dbConnection snapshotCollection:TSStorageManagerIdentityKeyStoreCollection
-                         snapshotFilePath:self.identityKeySnapshotFilePath];
-    [self.dbConnection snapshotCollection:TSStorageManagerTrustedKeysCollection
-                         snapshotFilePath:self.trustedKeySnapshotFilePath];
+    OWSAssert(transaction);
+
+    [transaction snapshotCollection:TSStorageManagerIdentityKeyStoreCollection
+                   snapshotFilePath:self.identityKeySnapshotFilePath];
+    [transaction snapshotCollection:TSStorageManagerTrustedKeysCollection
+                   snapshotFilePath:self.trustedKeySnapshotFilePath];
 }
 
-- (void)restoreIdentityState
+- (void)restoreIdentityState:(YapDatabaseReadWriteTransaction *)transaction
 {
-    [self.dbConnection restoreSnapshotOfCollection:TSStorageManagerIdentityKeyStoreCollection
-                                  snapshotFilePath:self.identityKeySnapshotFilePath];
-    [self.dbConnection restoreSnapshotOfCollection:TSStorageManagerTrustedKeysCollection
-                                  snapshotFilePath:self.trustedKeySnapshotFilePath];
+    OWSAssert(transaction);
+
+    [transaction restoreSnapshotOfCollection:TSStorageManagerIdentityKeyStoreCollection
+                            snapshotFilePath:self.identityKeySnapshotFilePath];
+    [transaction restoreSnapshotOfCollection:TSStorageManagerTrustedKeysCollection
+                            snapshotFilePath:self.trustedKeySnapshotFilePath];
 }
 
 #endif
diff --git a/SignalServiceKit/src/Storage/AxolotlStore/TSStorageManager+SessionStore.h b/SignalServiceKit/src/Storage/AxolotlStore/TSStorageManager+SessionStore.h
index f6847380e..bf92c4717 100644
--- a/SignalServiceKit/src/Storage/AxolotlStore/TSStorageManager+SessionStore.h
+++ b/SignalServiceKit/src/Storage/AxolotlStore/TSStorageManager+SessionStore.h
@@ -11,13 +11,15 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (void)archiveAllSessionsForContact:(NSString *)contactIdentifier protocolContext:(nullable id)protocolContext;
 
-#pragma mark - debug
+#pragma mark - Debug
+
+- (void)resetSessionStore:(YapDatabaseReadWriteTransaction *)transaction;
 
-- (void)resetSessionStore;
 #if DEBUG
-- (void)snapshotSessionStore;
-- (void)restoreSessionStore;
+- (void)snapshotSessionStore:(YapDatabaseReadWriteTransaction *)transaction;
+- (void)restoreSessionStore:(YapDatabaseReadWriteTransaction *)transaction;
 #endif
+
 - (void)printAllSessions;
 
 @end
diff --git a/SignalServiceKit/src/Storage/AxolotlStore/TSStorageManager+SessionStore.m b/SignalServiceKit/src/Storage/AxolotlStore/TSStorageManager+SessionStore.m
index 30fea09f2..d244bf8c1 100644
--- a/SignalServiceKit/src/Storage/AxolotlStore/TSStorageManager+SessionStore.m
+++ b/SignalServiceKit/src/Storage/AxolotlStore/TSStorageManager+SessionStore.m
@@ -5,6 +5,7 @@
 #import "OWSFileSystem.h"
 #import "TSStorageManager+SessionStore.h"
 #import "YapDatabaseConnection+OWS.h"
+#import "YapDatabaseTransaction+OWS.h"
 #import <AxolotlKit/SessionRecord.h>
 #import <YapDatabase/YapDatabase.h>
 
@@ -195,12 +196,13 @@ NSString *const kSessionStoreDBConnectionKey = @"kSessionStoreDBConnectionKey";
 
 #pragma mark - debug
 
-- (void)resetSessionStore
+- (void)resetSessionStore:(YapDatabaseReadWriteTransaction *)transaction
 {
+    OWSAssert(transaction);
+
     DDLogWarn(@"%@ resetting session store", self.logTag);
-    [self.sessionStoreDBConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *_Nonnull transaction) {
-        [transaction removeAllObjectsInCollection:TSStorageManagerSessionStoreCollection];
-    }];
+
+    [transaction removeAllObjectsInCollection:TSStorageManagerSessionStoreCollection];
 }
 
 - (void)printAllSessions
@@ -253,16 +255,19 @@ NSString *const kSessionStoreDBConnectionKey = @"kSessionStoreDBConnectionKey";
     return [dirPath stringByAppendingPathComponent:@".session-snapshot"];
 }
 
-- (void)snapshotSessionStore
+- (void)snapshotSessionStore:(YapDatabaseReadWriteTransaction *)transaction
 {
-    [self.sessionStoreDBConnection snapshotCollection:TSStorageManagerSessionStoreCollection
-                                     snapshotFilePath:self.snapshotFilePath];
+    OWSAssert(transaction);
+
+    [transaction snapshotCollection:TSStorageManagerSessionStoreCollection snapshotFilePath:self.snapshotFilePath];
 }
 
-- (void)restoreSessionStore
+- (void)restoreSessionStore:(YapDatabaseReadWriteTransaction *)transaction
 {
-    [self.sessionStoreDBConnection restoreSnapshotOfCollection:TSStorageManagerSessionStoreCollection
-                                              snapshotFilePath:self.snapshotFilePath];
+    OWSAssert(transaction);
+
+    [transaction restoreSnapshotOfCollection:TSStorageManagerSessionStoreCollection
+                            snapshotFilePath:self.snapshotFilePath];
 }
 #endif
 
diff --git a/SignalServiceKit/src/Storage/YapDatabaseConnection+OWS.h b/SignalServiceKit/src/Storage/YapDatabaseConnection+OWS.h
index 584be964c..4df5f5046 100644
--- a/SignalServiceKit/src/Storage/YapDatabaseConnection+OWS.h
+++ b/SignalServiceKit/src/Storage/YapDatabaseConnection+OWS.h
@@ -38,13 +38,6 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (void)purgeCollection:(NSString *)collection;
 
-#pragma mark - Debug
-
-#if DEBUG
-- (void)snapshotCollection:(NSString *)collection snapshotFilePath:(NSString *)snapshotFilePath;
-- (void)restoreSnapshotOfCollection:(NSString *)collection snapshotFilePath:(NSString *)snapshotFilePath;
-#endif
-
 @end
 
 NS_ASSUME_NONNULL_END
diff --git a/SignalServiceKit/src/Storage/YapDatabaseConnection+OWS.m b/SignalServiceKit/src/Storage/YapDatabaseConnection+OWS.m
index f1d672736..44d11aa68 100644
--- a/SignalServiceKit/src/Storage/YapDatabaseConnection+OWS.m
+++ b/SignalServiceKit/src/Storage/YapDatabaseConnection+OWS.m
@@ -168,47 +168,6 @@ NS_ASSUME_NONNULL_BEGIN
     [self setObject:@(value.timeIntervalSince1970) forKey:key inCollection:collection];
 }
 
-#pragma mark - Debug
-
-#if DEBUG
-- (void)snapshotCollection:(NSString *)collection snapshotFilePath:(NSString *)snapshotFilePath
-{
-    OWSAssert(collection.length > 0);
-    OWSAssert(snapshotFilePath.length > 0);
-
-    NSMutableDictionary<NSString *, id> *snapshot = [NSMutableDictionary new];
-    [self readWithBlock:^(YapDatabaseReadTransaction *_Nonnull transaction) {
-        [transaction
-            enumerateKeysAndObjectsInCollection:collection
-                                     usingBlock:^(NSString *_Nonnull key, id _Nonnull value, BOOL *_Nonnull stop) {
-                                         snapshot[key] = value;
-                                     }];
-    }];
-    NSData *_Nullable data = [NSKeyedArchiver archivedDataWithRootObject:snapshot];
-    OWSAssert(data);
-    BOOL success = [data writeToFile:snapshotFilePath atomically:YES];
-    OWSAssert(success);
-}
-
-- (void)restoreSnapshotOfCollection:(NSString *)collection snapshotFilePath:(NSString *)snapshotFilePath
-{
-    OWSAssert(collection.length > 0);
-    OWSAssert(snapshotFilePath.length > 0);
-
-    NSData *_Nullable data = [NSData dataWithContentsOfFile:snapshotFilePath];
-    OWSAssert(data);
-    NSMutableDictionary<NSString *, id> *_Nullable snapshot = [NSKeyedUnarchiver unarchiveObjectWithData:data];
-    OWSAssert(snapshot);
-
-    [self readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
-        [transaction removeAllObjectsInCollection:collection];
-        [snapshot enumerateKeysAndObjectsUsingBlock:^(NSString *_Nonnull key, id _Nonnull value, BOOL *_Nonnull stop) {
-            [transaction setObject:value forKey:key inCollection:collection];
-        }];
-    }];
-}
-#endif
-
 @end
 
 NS_ASSUME_NONNULL_END
diff --git a/SignalServiceKit/src/Storage/YapDatabaseReadTransaction+OWS.h b/SignalServiceKit/src/Storage/YapDatabaseTransaction+OWS.h
similarity index 79%
rename from SignalServiceKit/src/Storage/YapDatabaseReadTransaction+OWS.h
rename to SignalServiceKit/src/Storage/YapDatabaseTransaction+OWS.h
index 6ceaa4941..db9581683 100644
--- a/SignalServiceKit/src/Storage/YapDatabaseReadTransaction+OWS.h
+++ b/SignalServiceKit/src/Storage/YapDatabaseTransaction+OWS.h
@@ -25,4 +25,17 @@ NS_ASSUME_NONNULL_BEGIN
 
 @end
 
+#pragma mark -
+
+@interface YapDatabaseReadWriteTransaction (OWS)
+
+#pragma mark - Debug
+
+#if DEBUG
+- (void)snapshotCollection:(NSString *)collection snapshotFilePath:(NSString *)snapshotFilePath;
+- (void)restoreSnapshotOfCollection:(NSString *)collection snapshotFilePath:(NSString *)snapshotFilePath;
+#endif
+
+@end
+
 NS_ASSUME_NONNULL_END
diff --git a/SignalServiceKit/src/Storage/YapDatabaseReadTransaction+OWS.m b/SignalServiceKit/src/Storage/YapDatabaseTransaction+OWS.m
similarity index 68%
rename from SignalServiceKit/src/Storage/YapDatabaseReadTransaction+OWS.m
rename to SignalServiceKit/src/Storage/YapDatabaseTransaction+OWS.m
index 712a17832..63fdeeaaa 100644
--- a/SignalServiceKit/src/Storage/YapDatabaseReadTransaction+OWS.m
+++ b/SignalServiceKit/src/Storage/YapDatabaseTransaction+OWS.m
@@ -2,7 +2,7 @@
 //  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
-#import "YapDatabaseReadTransaction+OWS.h"
+#import "YapDatabaseTransaction+OWS.h"
 #import <AxolotlKit/PreKeyRecord.h>
 #import <AxolotlKit/SignedPrekeyRecord.h>
 #import <Curve25519Kit/Curve25519.h>
@@ -109,4 +109,46 @@ NS_ASSUME_NONNULL_BEGIN
 
 @end
 
+#pragma mark -
+
+@implementation YapDatabaseReadWriteTransaction (OWS)
+
+#pragma mark - Debug
+
+#if DEBUG
+- (void)snapshotCollection:(NSString *)collection snapshotFilePath:(NSString *)snapshotFilePath
+{
+    OWSAssert(collection.length > 0);
+    OWSAssert(snapshotFilePath.length > 0);
+
+    NSMutableDictionary<NSString *, id> *snapshot = [NSMutableDictionary new];
+    [self enumerateKeysAndObjectsInCollection:collection
+                                   usingBlock:^(NSString *_Nonnull key, id _Nonnull value, BOOL *_Nonnull stop) {
+                                       snapshot[key] = value;
+                                   }];
+    NSData *_Nullable data = [NSKeyedArchiver archivedDataWithRootObject:snapshot];
+    OWSAssert(data);
+    BOOL success = [data writeToFile:snapshotFilePath atomically:YES];
+    OWSAssert(success);
+}
+
+- (void)restoreSnapshotOfCollection:(NSString *)collection snapshotFilePath:(NSString *)snapshotFilePath
+{
+    OWSAssert(collection.length > 0);
+    OWSAssert(snapshotFilePath.length > 0);
+
+    NSData *_Nullable data = [NSData dataWithContentsOfFile:snapshotFilePath];
+    OWSAssert(data);
+    NSMutableDictionary<NSString *, id> *_Nullable snapshot = [NSKeyedUnarchiver unarchiveObjectWithData:data];
+    OWSAssert(snapshot);
+
+    [self removeAllObjectsInCollection:collection];
+    [snapshot enumerateKeysAndObjectsUsingBlock:^(NSString *_Nonnull key, id _Nonnull value, BOOL *_Nonnull stop) {
+        [self setObject:value forKey:key inCollection:collection];
+    }];
+}
+#endif
+
+@end
+
 NS_ASSUME_NONNULL_END
diff --git a/SignalServiceKit/src/Util/OWSBackgroundTask.m b/SignalServiceKit/src/Util/OWSBackgroundTask.m
index fbf45dca2..f571aec31 100644
--- a/SignalServiceKit/src/Util/OWSBackgroundTask.m
+++ b/SignalServiceKit/src/Util/OWSBackgroundTask.m
@@ -77,55 +77,63 @@
 - (void)startBackgroundTask
 {
     // beginBackgroundTaskWithExpirationHandler must be called on the main thread.
-    DispatchMainThreadSafe(^{
-        __weak typeof(self) weakSelf = self;
-        self.backgroundTaskId = [CurrentAppContext() beginBackgroundTaskWithExpirationHandler:^{
-            dispatch_async(dispatch_get_main_queue(), ^{
-                OWSBackgroundTask *strongSelf = weakSelf;
-                if (!strongSelf) {
-                    return;
-                }
-
-                // Make a local copy of completionBlock to ensure that it is called
-                // exactly once.
-                BackgroundTaskCompletionBlock _Nullable completionBlock = nil;
-
-                @synchronized(strongSelf)
-                {
-                    if (strongSelf.backgroundTaskId == UIBackgroundTaskInvalid) {
-                        return;
-                    }
-                    DDLogInfo(@"%@ %@ background task expired.", strongSelf.logTag, strongSelf.label);
-                    strongSelf.backgroundTaskId = UIBackgroundTaskInvalid;
-
-                    completionBlock = strongSelf.completionBlock;
-                    strongSelf.completionBlock = nil;
-                }
-
-                if (completionBlock) {
-                    completionBlock(BackgroundTaskState_Expired);
-                }
-            });
-        }];
-
-        // If a background task could not be begun, call the completion block.
-        if (self.backgroundTaskId == UIBackgroundTaskInvalid) {
-
-            DDLogInfo(@"%@ %@ background task could not be started.", self.logTag, self.label);
+    __weak typeof(self) weakSelf = self;
+    self.backgroundTaskId = [CurrentAppContext() beginBackgroundTaskWithExpirationHandler:^{
+        // Supposedly [UIApplication beginBackgroundTaskWithExpirationHandler]'s handler
+        // will always be called on the main thread, but in practice we've observed
+        // otherwise.  We use DispatchSyncMainThreadSafe() (note the sync) to ensure that
+        // this work is done on the main thread.
+        //
+        // See: https://developer.apple.com/documentation/uikit/uiapplication/1623031-beginbackgroundtaskwithexpiratio)
+        //
+        // Note the usage of OWSCAssert() to avoid capturing a reference to self.
+        OWSCAssert([NSThread isMainThread]);
+
+        DispatchSyncMainThreadSafe(^{
+            OWSBackgroundTask *strongSelf = weakSelf;
+            if (!strongSelf) {
+                return;
+            }
 
             // Make a local copy of completionBlock to ensure that it is called
             // exactly once.
-            BackgroundTaskCompletionBlock _Nullable completionBlock;
-            @synchronized(self)
+            BackgroundTaskCompletionBlock _Nullable completionBlock = nil;
+
+            @synchronized(strongSelf)
             {
-                completionBlock = self.completionBlock;
-                self.completionBlock = nil;
+                if (strongSelf.backgroundTaskId == UIBackgroundTaskInvalid) {
+                    return;
+                }
+                DDLogInfo(@"%@ %@ background task expired.", strongSelf.logTag, strongSelf.label);
+                strongSelf.backgroundTaskId = UIBackgroundTaskInvalid;
+
+                completionBlock = strongSelf.completionBlock;
+                strongSelf.completionBlock = nil;
             }
+
             if (completionBlock) {
-                completionBlock(BackgroundTaskState_CouldNotStart);
+                completionBlock(BackgroundTaskState_Expired);
             }
+        });
+    }];
+
+    // If a background task could not be begun, call the completion block.
+    if (self.backgroundTaskId == UIBackgroundTaskInvalid) {
+
+        DDLogInfo(@"%@ %@ background task could not be started.", self.logTag, self.label);
+
+        // Make a local copy of completionBlock to ensure that it is called
+        // exactly once.
+        BackgroundTaskCompletionBlock _Nullable completionBlock;
+        @synchronized(self)
+        {
+            completionBlock = self.completionBlock;
+            self.completionBlock = nil;
         }
-    });
+        if (completionBlock) {
+            completionBlock(BackgroundTaskState_CouldNotStart);
+        }
+    }
 }
 
 - (void)endBackgroundTask
diff --git a/SignalServiceKit/src/Util/Threading.h b/SignalServiceKit/src/Util/Threading.h
index 2173dd587..4aac9cec7 100644
--- a/SignalServiceKit/src/Util/Threading.h
+++ b/SignalServiceKit/src/Util/Threading.h
@@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 NS_ASSUME_NONNULL_BEGIN
@@ -7,8 +7,13 @@ NS_ASSUME_NONNULL_BEGIN
 typedef void (^SimpleBlock)(void);
 
 // The block is executed immediately if called from the
-// main thread; otherwise it is disptached async to the
+// main thread; otherwise it is dispatched async to the
 // main thread.
 void DispatchMainThreadSafe(SimpleBlock block);
 
+// The block is executed immediately if called from the
+// main thread; otherwise it is dispatched sync to the
+// main thread.
+void DispatchSyncMainThreadSafe(SimpleBlock block);
+
 NS_ASSUME_NONNULL_END
diff --git a/SignalServiceKit/src/Util/Threading.m b/SignalServiceKit/src/Util/Threading.m
index c37bc7429..72505e339 100644
--- a/SignalServiceKit/src/Util/Threading.m
+++ b/SignalServiceKit/src/Util/Threading.m
@@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 #import "Threading.h"
@@ -19,4 +19,17 @@ void DispatchMainThreadSafe(SimpleBlock block)
     }
 }
 
+void DispatchSyncMainThreadSafe(SimpleBlock block)
+{
+    OWSCAssert(block);
+
+    if ([NSThread isMainThread]) {
+        block();
+    } else {
+        dispatch_sync(dispatch_get_main_queue(), ^{
+            block();
+        });
+    }
+}
+
 NS_ASSUME_NONNULL_END