Base: Add a handle verifier to ScopedHandle.

base/win/scoped_handle.h

Index: base/win/scoped_handle.h
===================================================================
--- base/win/scoped_handle.h	(revision 139138)
+++ base/win/scoped_handle.h	(working copy)
@@ -8,7 +8,9 @@
 
 #include <windows.h>
 
+#include "base/base_export.h"
 #include "base/basictypes.h"
+#include "base/location.h"
 #include "base/logging.h"
 
 namespace base {
@@ -21,7 +23,7 @@
 //     and INVALID_HANDLE_VALUE (-1) for Win32 handles.
 //   - Receive() method allows to receive a handle value from a function that
 //     takes a raw handle pointer only.
-template <class Traits>
+template <class Traits, class Verifier>
 class GenericScopedHandle {
  public:
   typedef typename Traits::Handle Handle;
@@ -46,6 +48,8 @@
 
       if (Traits::IsHandleValid(handle)) {
         handle_ = handle;
+        Verifier::StartTracking(handle, this,
+                                tracked_objects::GetProgramCounter());
       }
     }
   }
@@ -60,6 +64,10 @@
 
   Handle* Receive() {
     DCHECK(!Traits::IsHandleValid(handle_)) << "Handle must be NULL";
+
+    // We cannot track this case :(. Just tell the verifier about it.

[alexeypa (please no reviews), 2012/05/30 20:19:30]

This is one of the most common ways of initializing GenericScopedHandle objects.

[rvargas (doing something else), 2012/05/30 21:39:01]

That is both unfortunate and surprising (given that this method was added three
months ago). I'm all ears if you have ideas for tracking this (short of removing
the method and changing callers to use a temp).

+    Verifier::StartTracking(INVALID_HANDLE_VALUE, this,
+                            tracked_objects::GetProgramCounter());
     return &handle_;
   }
 
@@ -67,6 +75,7 @@
   Handle Take() {
     Handle temp = handle_;
     handle_ = Traits::NullHandle();
+    Verifier::StopTracking(temp, this, tracked_objects::GetProgramCounter());
     return temp;
   }
 
@@ -76,6 +85,8 @@
       if (!Traits::CloseHandle(handle_)) {
         CHECK(false);
       }
+      Verifier::StopTracking(handle_, this,
+                             tracked_objects::GetProgramCounter());
       handle_ = Traits::NullHandle();
     }
   }
@@ -110,8 +121,32 @@
   DISALLOW_IMPLICIT_CONSTRUCTORS(HandleTraits);
 };
 
-typedef GenericScopedHandle<HandleTraits> ScopedHandle;
+// Do-nothing verifier.
+class DummyVerifierTraits {
+ public:
+  typedef HANDLE Handle;
 
+  static void StartTracking(HANDLE handle, const void* owner, const void* pc) {}
+  static void StopTracking(HANDLE handle, const void* owner, const void* pc) {}
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(DummyVerifierTraits);
+};
+
+// Performs actual run-time tracking.
+class BASE_EXPORT VerifierTraits {
+ public:
+  typedef HANDLE Handle;
+
+  static void StartTracking(HANDLE handle, const void* owner, const void* pc);
+  static void StopTracking(HANDLE handle, const void* owner, const void* pc);
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(VerifierTraits);
+};
+
+typedef GenericScopedHandle<HandleTraits, DummyVerifierTraits> ScopedHandle;
+
 }  // namespace win
 }  // namespace base