Move a bunch of code from the old to new TLS interface.

Review URL: http://codereview.chromium.org/1660

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@1982 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 27 insertions, 31 deletions

diff --git a/base/message_loop.cc b/base/message_loop.cc
index e90f0b2..3abf0c8 100644
--- a/base/message_loop.cc
+++ b/base/message_loop.cc
@@ -7,17 +7,16 @@
 #include <algorithm>
 
 #include "base/compiler_specific.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/message_pump_default.h"
 #include "base/string_util.h"
-#include "base/thread_local_storage.h"
+#include "base/thread_local.h"
 
-// a TLS index to the message loop for the current thread
-// Note that if we start doing complex stuff in other static initializers
-// this could cause problems.
-// TODO(evanm): this shouldn't rely on static initialization.
-// static
-TLSSlot MessageLoop::tls_index_;
+// A lazily created thread local storage for quick access to a thread's message
+// loop, if one exists.  This should be safe and free of static constructors.
+static base::LazyInstance<base::ThreadLocalPointer<MessageLoop> > lazy_tls_ptr(
+    base::LINKER_INITIALIZED);
 
 //------------------------------------------------------------------------------
 
@@ -55,14 +54,22 @@ static LPTOP_LEVEL_EXCEPTION_FILTER GetTopSEHFilter() {
 
 //------------------------------------------------------------------------------
 
+// static
+MessageLoop* MessageLoop::current() {
+  // TODO(darin): sadly, we cannot enable this yet since people call us even
+  // when they have no intention of using us.
+  //DCHECK(loop) << "Ouch, did you forget to initialize me?";
+  return lazy_tls_ptr.Pointer()->Get();
+}
+
 MessageLoop::MessageLoop(Type type)
     : type_(type),
       nestable_tasks_allowed_(true),
       exception_restoration_(false),
       state_(NULL),
       next_sequence_num_(0) {
-  DCHECK(!tls_index_.Get()) << "should only have one message loop per thread";
-  tls_index_.Set(this);
+  DCHECK(!current()) << "should only have one message loop per thread";
+  lazy_tls_ptr.Pointer()->Set(this);
 
   // TODO(darin): Choose the pump based on the requested type.
 #if defined(OS_WIN)
@@ -83,6 +90,9 @@ MessageLoop::~MessageLoop() {
   FOR_EACH_OBSERVER(DestructionObserver, destruction_observers_,
                     WillDestroyCurrentMessageLoop());
 
+  // OK, now make it so that no one can find us.
+  lazy_tls_ptr.Pointer()->Set(NULL);
+
   DCHECK(!state_);
 
   // Clean up any unprocessed tasks, but take care: deleting a task could
diff --git a/base/message_loop.h b/base/message_loop.h
index f4511f8..a65a2e8 100644
--- a/base/message_loop.h
+++ b/base/message_loop.h
@@ -16,7 +16,6 @@
 #include "base/ref_counted.h"
 #include "base/task.h"
 #include "base/timer.h"
-#include "base/thread_local_storage.h"
 
 #if defined(OS_WIN)
 // We need this to declare base::MessagePumpWin::Dispatcher, which we should
@@ -201,13 +200,7 @@ class MessageLoop : public base::MessagePump::Delegate {
   const std::string& thread_name() const { return thread_name_; }
 
   // Returns the MessageLoop object for the current thread, or null if none.
-  static MessageLoop* current() {
-    MessageLoop* loop = static_cast<MessageLoop*>(tls_index_.Get());
-    // TODO(darin): sadly, we cannot enable this yet since people call us even
-    // when they have no intention of using us.
-    //DCHECK(loop) << "Ouch, did you forget to initialize me?";
-    return loop;
-  }
+  static MessageLoop* current();
 
   // Enables or disables the recursive task processing. This happens in the case
   // of recursive message loops. Some unwanted message loop may occurs when
@@ -347,7 +340,6 @@ class MessageLoop : public base::MessagePump::Delegate {
   // If message_histogram_ is NULL, this is a no-op.
   void HistogramEvent(int event);
 
-  static TLSSlot tls_index_;
   static const LinearHistogram::DescriptionPair event_descriptions_[];
   static bool enable_histogrammer_;
 
diff --git a/base/thread.cc b/base/thread.cc
index 4f68546..fd076a4 100644
--- a/base/thread.cc
+++ b/base/thread.cc
@@ -4,7 +4,7 @@
 
 #include "base/thread.h"
 
-#include "base/singleton.h"
+#include "base/lazy_instance.h"
 #include "base/string_util.h"
 #include "base/thread_local.h"
 #include "base/waitable_event.h"
@@ -44,29 +44,25 @@ Thread::~Thread() {
   Stop();
 }
 
+namespace {
+
 // We use this thread-local variable to record whether or not a thread exited
 // because its Stop method was called.  This allows us to catch cases where
 // MessageLoop::Quit() is called directly, which is unexpected when using a
 // Thread to setup and run a MessageLoop.
-namespace {
-
-// Use a differentiating type to make sure we don't share our boolean we any
-// other Singleton<ThreadLocalBoolean>'s.
-struct ThreadExitedDummyDiffType { };
-typedef Singleton<ThreadLocalBoolean,
-                  DefaultSingletonTraits<ThreadLocalBoolean>,
-                  ThreadExitedDummyDiffType> ThreadExitedSingleton;
+base::LazyInstance<base::ThreadLocalBoolean> lazy_tls_bool(
+    base::LINKER_INITIALIZED);
 
 }  // namespace
 
 void Thread::SetThreadWasQuitProperly(bool flag) {
-  ThreadExitedSingleton::get()->Set(flag);
+  lazy_tls_bool.Pointer()->Set(flag);
 }
 
 bool Thread::GetThreadWasQuitProperly() {
   bool quit_properly = true;
 #ifndef NDEBUG
-  quit_properly = ThreadExitedSingleton::get()->Get();
+  quit_properly = lazy_tls_bool.Pointer()->Get();
 #endif
   return quit_properly;
 }
diff --git a/base/thread.h b/base/thread.h
index 8d08ade..93ba037 100644
--- a/base/thread.h
+++ b/base/thread.h
@@ -136,8 +136,6 @@ class Thread : PlatformThread::Delegate {
   // The name of the thread.  Used for debugging purposes.
   std::string name_;
 
-  static TLSSlot tls_index_;
-
   friend class ThreadQuitTask;
 
   DISALLOW_COPY_AND_ASSIGN(Thread);