From bfb5fac879a325f0b25726e9143b14379c6a09d3 Mon Sep 17 00:00:00 2001
From: Matthew Chen <charlesmchen@gmail.com>
Date: Fri, 15 Sep 2017 10:16:52 -0400
Subject: [PATCH] Make "database view registration complete" check thread-safe.

// FREEBIE
---
 SignalServiceKit/src/Storage/TSDatabaseView.h |  1 +
 SignalServiceKit/src/Storage/TSDatabaseView.m | 23 ++++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/SignalServiceKit/src/Storage/TSDatabaseView.h b/SignalServiceKit/src/Storage/TSDatabaseView.h
index 921b36ede..505696b43 100644
--- a/SignalServiceKit/src/Storage/TSDatabaseView.h
+++ b/SignalServiceKit/src/Storage/TSDatabaseView.h
@@ -23,6 +23,7 @@ extern NSString *const TSSecondaryDevicesDatabaseViewExtensionName;
 
 - (instancetype)init NS_UNAVAILABLE;
 
+// This method can be called from any thread.
 + (BOOL)hasPendingViewRegistrations;
 
 // This method must be called _AFTER_ registerThreadInteractionsDatabaseView.
diff --git a/SignalServiceKit/src/Storage/TSDatabaseView.m b/SignalServiceKit/src/Storage/TSDatabaseView.m
index 35ed412d5..5ef98df25 100644
--- a/SignalServiceKit/src/Storage/TSDatabaseView.m
+++ b/SignalServiceKit/src/Storage/TSDatabaseView.m
@@ -64,13 +64,29 @@ NSString *const TSSecondaryDevicesDatabaseViewExtensionName = @"TSSecondaryDevic
     return self;
 }
 
-+ (BOOL)hasPendingViewRegistrations
+- (BOOL)hasPendingViewRegistrations
 {
-    OWSAssert([NSThread isMainThread]);
+    @synchronized(self)
+    {
+        return !self.areAllAsyncRegistrationsComplete;
+    }
+}
 
++ (BOOL)hasPendingViewRegistrations
+{
     return ![TSDatabaseView sharedInstance].areAllAsyncRegistrationsComplete;
 }
 
+- (void)setAreAllAsyncRegistrationsComplete
+{
+    @synchronized(self)
+    {
+        OWSAssert(!self.areAllAsyncRegistrationsComplete);
+
+        self.areAllAsyncRegistrationsComplete = YES;
+    }
+}
+
 + (void)registerMessageDatabaseViewWithName:(NSString *)viewName
                                viewGrouping:(YapDatabaseViewGrouping *)viewGrouping
                                     version:(NSString *)version
@@ -423,8 +439,9 @@ NSString *const TSSecondaryDevicesDatabaseViewExtensionName = @"TSSecondaryDevic
     // All async registrations are complete when writes are unblocked.
     [[TSStorageManager sharedManager].newDatabaseConnection
         asyncReadWriteWithBlock:^(YapDatabaseReadWriteTransaction *_Nonnull transaction) {
+            [TSDatabaseView.sharedInstance setAreAllAsyncRegistrationsComplete];
+
             dispatch_async(dispatch_get_main_queue(), ^{
-                TSDatabaseView.sharedInstance.areAllAsyncRegistrationsComplete = YES;
                 [[NSNotificationCenter defaultCenter]
                     postNotificationName:kNSNotificationName_DatabaseViewRegistrationComplete
                                   object:nil