Allow IO operations in destructor of net::NetworkConfigWatcherMacThread

net/base/network_config_watcher_mac.cc

Index: net/base/network_config_watcher_mac.cc
diff --git a/net/base/network_config_watcher_mac.cc b/net/base/network_config_watcher_mac.cc
index afec17d91f4eeccaaf4a59cd27143174e65b5f74..5cc41b19f03c417bca3f096d3fab0ccd44263435 100644
--- a/net/base/network_config_watcher_mac.cc
+++ b/net/base/network_config_watcher_mac.cc
@@ -11,6 +11,7 @@
 #include "base/compiler_specific.h"
 #include "base/threading/thread.h"
 #include "base/mac/scoped_cftyperef.h"
+#include "base/threading/thread_restrictions.h"
 
 namespace net {
 
@@ -54,10 +55,18 @@ NetworkConfigWatcherMacThread::NetworkConfigWatcherMacThread(
       ALLOW_THIS_IN_INITIALIZER_LIST(method_factory_(this)) {}
 
 NetworkConfigWatcherMacThread::~NetworkConfigWatcherMacThread() {
+  // Allow IO because Stop() calls PlatformThread::Join(), which is a blocking
+  // operation. This is expected during shutdown.
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
+
   Stop();
 }
 
 void NetworkConfigWatcherMacThread::Init() {
+  // Disallow IO to make sure NetworkConfigWatcherMacThread's helper thread does
+  // not perform blocking operations.
+  base::ThreadRestrictions::SetIOAllowed(false);

[evanm, 2011/01/20 22:07:29]

Isn't this ok?  It's a helper thread, no?

[Raghu Simha, 2011/01/20 22:17:45]

Per email from willchan:

"Add a ScopedAllowIO in NetworkConfigWatcherMacThread's destructor. I don't
think that thread should be doing any blocking IO. In
NetworkConfigWatcherMacThread::Init(), we should probably do
base::ThreadRestrictions::SetIOAllowed(false), to make sure that
NetworkConfigWatcherMac's helper thread isn't blocking."

I'll defer to willchan's decision on whether this is necessary or not.

[willchan no longer on Chromium, 2011/01/20 22:47:10]

I think we should add it, because if we're going to join this thread in
non-shutdown situations, then we need to make sure the join is fast.

+
   // TODO(willchan): Look to see if there's a better signal for when it's ok to
   // initialize this, rather than just delaying it by a fixed time.
   const int kInitializationDelayMS = 1000;