From 440e2f0b71e33f74114cf87cf723093ae525ee52 Mon Sep 17 00:00:00 2001
From: Thomas Van Lenten <thomasvl@google.com>
Date: Thu, 4 Jun 2026 09:10:37 -0400
Subject: [PATCH] Avoid some more potential data race conditions.

Use `dispatch_once` instead of a `static BOOL` to guard the work.

While at it, remove one use of `@synchronized` to instead standardize on just
`dispatch_once`.
---
 Sources/Core/GTLRBase64.m        | 16 ++++++----------
 Sources/Core/GTLRRuntimeCommon.m |  7 +++----
 Sources/Core/GTLRUtilities.m     | 15 +++++++--------
 3 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/Sources/Core/GTLRBase64.m b/Sources/Core/GTLRBase64.m
index 989dd7048..1126ef5d4 100644
--- a/Sources/Core/GTLRBase64.m
+++ b/Sources/Core/GTLRBase64.m
@@ -119,24 +119,20 @@ static void CreateDecodingTable(const char *encodingTable,
 
 NSData *GTLRDecodeBase64(NSString *base64Str) {
   static char decodingTable[128];
-  static BOOL hasInited = NO;
-
-  if (!hasInited) {
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
     CreateDecodingTable(gStandardEncodingTable, sizeof(gStandardEncodingTable),
                         decodingTable);
-    hasInited = YES;
-  }
+  });
   return DecodeBase64StringCommon(base64Str, decodingTable, YES /* requirePadding */ );
 }
 
 NSData *GTLRDecodeWebSafeBase64(NSString *base64Str) {
   static char decodingTable[128];
-  static BOOL hasInited = NO;
-
-  if (!hasInited) {
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
     CreateDecodingTable(gWebSafeEncodingTable, sizeof(gWebSafeEncodingTable),
                         decodingTable);
-    hasInited = YES;
-  }
+  });
   return DecodeBase64StringCommon(base64Str, decodingTable, NO /* requirePadding */);
 }
diff --git a/Sources/Core/GTLRRuntimeCommon.m b/Sources/Core/GTLRRuntimeCommon.m
index b967083e5..b999776f0 100644
--- a/Sources/Core/GTLRRuntimeCommon.m
+++ b/Sources/Core/GTLRRuntimeCommon.m
@@ -484,11 +484,10 @@ typedef NS_ENUM(NSUInteger, GTLRPropertyType) {
     },
   };
 
-  static BOOL hasLookedUpClasses = NO;
-  if (!hasLookedUpClasses) {
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
     // Unfortunately, you can't put [NSString class] into the static structure,
     // so this lookup has to be done at runtime.
-    hasLookedUpClasses = YES;
     for (uint32_t idx = 0; idx < sizeof(kImplInfo)/sizeof(kImplInfo[0]); ++idx) {
       if (kImplInfo[idx].returnClassName) {
         kImplInfo[idx].returnClass = objc_getClass(kImplInfo[idx].returnClassName);
@@ -496,7 +495,7 @@ typedef NS_ENUM(NSUInteger, GTLRPropertyType) {
                    @"GTLRRuntimeCommon: class lookup failed: %s", kImplInfo[idx].returnClassName);
       }
     }
-  }
+  });
 
   const char *attr = property_getAttributes(prop);
 
diff --git a/Sources/Core/GTLRUtilities.m b/Sources/Core/GTLRUtilities.m
index efdf84aee..017844f13 100644
--- a/Sources/Core/GTLRUtilities.m
+++ b/Sources/Core/GTLRUtilities.m
@@ -85,14 +85,13 @@ BOOL GTLR_AreBoolsEqual(BOOL b1, BOOL b2) {
     if ([str rangeOfString:@"."].location != NSNotFound) {
       // This is a floating-point number.
       // Force the parser to use '.' as the decimal separator.
-      static NSLocale *usLocale = nil;
-      @synchronized([GTLRUtilities class]) {
-        if (usLocale == nil) {
-          usLocale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US"];
-        }
-        newNum = [NSDecimalNumber decimalNumberWithString:(NSString*)num
-                                                   locale:(id)usLocale];
-      }
+      static NSLocale *usLocale;
+      static dispatch_once_t onceToken;
+      dispatch_once(&onceToken, ^{
+        usLocale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US"];
+      });
+      newNum = [NSDecimalNumber decimalNumberWithString:(NSString*)num
+                                                 locale:(id)usLocale];
     } else {
       // NSDecimalNumber +decimalNumberWithString:locale:
       // does not correctly create an NSNumber for large values like