Fix up race between NSThread setName and pthread_getname on the thread. (#213)

1 files changed, 24 insertions, 3 deletions

diff --git a/Foundation/GTMNSThread+BlocksTest.m b/Foundation/GTMNSThread+BlocksTest.m
index b7e0cdb..e051de9 100644
--- a/Foundation/GTMNSThread+BlocksTest.m
+++ b/Foundation/GTMNSThread+BlocksTest.m
@@ -316,12 +316,33 @@ static const int kThreadMethoduSleep = 10000;
 - (void)testPThreadName {
   NSString *testName = @"InigoMontoya";
   [workerThread_ setName:testName];
+  // There is actually a race between setting the thread name in NSThread and it
+  // being visible in the thread itself. A thread's name can only be set from
+  // inside the thread (pthread_setname) so we are assuming that NSThread has
+  // some internal wiring to kick the runloop and update the value for the
+  // thread on the thread itself.
+  // If we run our "check" block too soon, we will check the value on the
+  // thread before it's been set.
+  // Therefore we loop over it with some sleep to give the thread a chance
+  // to update it's internals.
   [workerThread_ gtm_performWaitingUntilDone:YES block:^{
     XCTAssertEqualObjects([workerThread_ name], testName);
-    char threadName[100];
-    pthread_getname_np(pthread_self(), threadName, 100);
-    XCTAssertEqualObjects([NSString stringWithUTF8String:threadName], testName);
   }];
+  __block BOOL finished = NO;
+  for (int i = 0; i < 100; i++) {
+    [workerThread_ gtm_performWaitingUntilDone:YES block:^{
+      char threadName[100];
+      pthread_getname_np(pthread_self(), threadName, 100);
+      NSString *nsThreadName = [NSString stringWithUTF8String:threadName];
+      finished = ([testName compare:nsThreadName] == NSOrderedSame);
+    }];
+    if (finished) {
+      break;
+    } else {
+      usleep(kThreadMethoduSleep);
+    }
+  }
+  XCTAssertTrue(finished, @"pthread name did not change to %@", testName);
 }
 
 @end