Register CrossProcessNotifier.

SignalServiceKit/src/Storage/TSDatabaseView.h

@@ -25,6 +25,8 @@ extern NSString *const TSSecondaryDevicesDatabaseViewExtensionName;
 // This method can be called from any thread.
 + (BOOL)hasPendingViewRegistrations;
 
++ (void)registerCrossProcessNotifier;
+
 // This method must be called _AFTER_ registerThreadInteractionsDatabaseView.
 + (void)registerThreadDatabaseView;
 

SignalServiceKit/src/Storage/TSDatabaseView.m

@@ -11,6 +11,7 @@
 #import "TSOutgoingMessage.h"
 #import "TSStorageManager.h"
 #import "TSThread.h"
+#import <YapDatabase/YapDatabaseCrossProcessNotification.h>
 #import <YapDatabase/YapDatabaseView.h>
 
 NSString *const kNSNotificationName_DatabaseViewRegistrationComplete =
@@ -88,6 +89,15 @@ NSString *const TSSecondaryDevicesDatabaseViewExtensionName = @"TSSecondaryDevic
     }
 }
 
++ (void)registerCrossProcessNotifier
+{
+    // I don't think the identifier and name of this extension matter for our purposes,
+    // so long as they don't conflict with any other extension names.
+    YapDatabaseExtension *extension =
+        [[YapDatabaseCrossProcessNotification alloc] initWithIdentifier:@"SignalCrossProcessNotifier"];
+    [[TSStorageManager sharedManager].database registerExtension:extension withName:@"SignalCrossProcessNotifier"];
+}
+
 + (void)registerMessageDatabaseViewWithName:(NSString *)viewName
                                viewGrouping:(YapDatabaseViewGrouping *)viewGrouping
                                     version:(NSString *)version

SignalServiceKit/src/Storage/TSStorageManager.m

@@ -310,6 +310,7 @@ void setDatabaseInitialized()
 - (void)setupDatabaseWithSafeBlockingMigrations:(void (^_Nonnull)())safeBlockingMigrationsBlock
 {
     // Synchronously register extensions which are essential for views.
+    [TSDatabaseView registerCrossProcessNotifier];
     [TSDatabaseView registerThreadInteractionsDatabaseView];
     [TSDatabaseView registerThreadDatabaseView];
     [TSDatabaseView registerUnreadDatabaseView];