Additional DCHECK for InFlightIO::InvokeCallback.

I'm interested in InFlightIO::io_list_, which is of type
std::set<scoped_refptr<BackgroundIO> >, so it holds refs to the
underlying objects.

On the primary/callback thread, the erase call in
InFlightIO::InvokeCallback can delete the operation if the list holds
the last reference.  This typically can't happen because the pending
tasks hold a reference to the operation; this is good: it means that
operations are deleted/newed on the background thread, I believe.

This DCHECK() is useful for when you make changes that can delete an
operation in the primary thread, like we found with some of the posix
races in http://codereview.chromium.org/9702059/

Question: for debugging I like the use of scoped_refptr<BackgroundIO>;
but since we never want to delete here, wouldn't a set<BackgroundIO*>
on non-debug builds be more in line with our use?

BUG=None


Review URL: http://codereview.chromium.org/9758002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@128593 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 1 insertions, 0 deletions

diff --git a/net/disk_cache/in_flight_io.cc b/net/disk_cache/in_flight_io.cc
index 636cb4f..86c2dcc 100644
--- a/net/disk_cache/in_flight_io.cc
+++ b/net/disk_cache/in_flight_io.cc
@@ -91,6 +91,7 @@ void InFlightIO::InvokeCallback(BackgroundIO* operation, bool cancel_task) {
   // Make sure that we remove the operation from the list before invoking the
   // callback (so that a subsequent cancel does not invoke the callback again).
   DCHECK(io_list_.find(operation) != io_list_.end());
+  DCHECK(!operation->HasOneRef());
   io_list_.erase(make_scoped_refptr(operation));
   OnOperationComplete(operation, cancel_task);
 }