[net] Ensure aborted HostResolverImpl::Jobs release slots in the dispatcher.

net/base/host_resolver_impl.cc

Index: net/base/host_resolver_impl.cc
diff --git a/net/base/host_resolver_impl.cc b/net/base/host_resolver_impl.cc
index 1e4d757af05ed2d6934e28ae95bafdffc1b125bb..1982b440afa65c814c868280348bf6d4ee2a14fa 100644
--- a/net/base/host_resolver_impl.cc
+++ b/net/base/host_resolver_impl.cc
@@ -1572,8 +1572,10 @@ void HostResolverImpl::CancelRequest(RequestHandle req_handle) {
     // that Request could not have been cancelled, so job->num_active_requests()
     // could not be 0. Therefore, we are not in Job::CompleteRequests().
     RemoveJob(job);
-    if (job->is_running())
+    if (job->is_running()) {

[cbentzel, 2012/03/02 19:46:49]

I asked over email - but is there a chance that a job is not |is_running()| but
is still treated like a non-queued job by the dispatcher? That would leak slots
as well.

+      dispatcher_.OnJobFinished();
       job->Abort();

[cbentzel, 2012/03/02 20:02:40]

FYI: I don't think the Abort is needed here. ~Job appears to be doing all the
cleanup that is needed since there are no requests and associated callbacks tied
to this job.

[szym, 2012/03/02 20:05:43]

The cleaning up is now in a few places: Job::~Job, Job::CancelRequest,
HostResolverImpl::CancelRequest. Right now, ~Job is only supposed to take care
of the case when HostResolverImpl is destroyed. I'll refactor this in the next
CL.

+    }
     delete job;
   }
 }
@@ -1709,7 +1711,6 @@ HostResolverImpl::Key HostResolverImpl::GetEffectiveKeyForRequest(
 }
 
 void HostResolverImpl::AbortAllInProgressJobs() {
-  base::WeakPtr<HostResolverImpl> self = AsWeakPtr();
   // In Abort, a Request callback could spawn new Jobs with matching keys, so
   // first collect and remove all running jobs from |jobs_|.
   std::vector<Job*> jobs_to_abort;
@@ -1724,10 +1725,16 @@ void HostResolverImpl::AbortAllInProgressJobs() {
     }
   }
 
+  // Check if no dispatcher slots leaked out.
+  DCHECK_EQ(dispatcher_.num_running_jobs(), jobs_to_abort.size());
+
+  // Life check to bail once |this| is deleted.
+  base::WeakPtr<HostResolverImpl> self = AsWeakPtr();
+
   // Then Abort them and dispatch new Jobs.
-  for (size_t i = 0; i < jobs_to_abort.size(); ++i) {
-    jobs_to_abort[i]->Abort();
+  for (size_t i = 0; self && i < jobs_to_abort.size(); ++i) {
     dispatcher_.OnJobFinished();
+    jobs_to_abort[i]->Abort();
   }
   STLDeleteElements(&jobs_to_abort);
 }