Refactor BaseTimer to avoid spamming the MessageLoop with orphaned tasks.

This change maintains the same API promises*, but instead of orphaning tasks when they are stopped, the BaseTimer_Helper class holds on to the task until either (1) it expires or (2) the user requests a delay that would arrive earlier than the pending task. If the user requests a longer delay than the pending task, a followup task will be posted when the pending task fires to span the remaining time.

* The one change of usage is related to threading. The threading requirements are now more strict. It is not allowed to destruct a timer on a different thread than the one used to post tasks. A thread ID DCHECK is now in place that will help catch misuse. Some existing instances are changed as part of this CL.

A side effect of this change is that the BaseTimer and DelayTimer are simplified to use features of BaseTimer_Helper (which is now called Timer).

As suggested in timer.h, I ran the disabled TimerTest tests from linux, and they pass consistently. I also added some new tests to verify correct run states.

BUG=117451,103667,119714,119750

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=128412

Reverted: http://src.chromium.org/viewvc/chrome?view=rev&revision=128506

Review URL: https://chromiumcodereview.appspot.com/9655006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@128993 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 5 insertions, 4 deletions

diff --git a/net/disk_cache/backend_impl.cc b/net/disk_cache/backend_impl.cc
index aa232c3..1f08b15 100644
--- a/net/disk_cache/backend_impl.cc
+++ b/net/disk_cache/backend_impl.cc
@@ -423,8 +423,9 @@ int BackendImpl::SyncInit() {
     trace_object_ = TraceObject::GetTraceObject();
     // Create a recurrent timer of 30 secs.
     int timer_delay = unit_test_ ? 1000 : 30000;
-    timer_.Start(FROM_HERE, TimeDelta::FromMilliseconds(timer_delay), this,
-                 &BackendImpl::OnStatsTimer);
+    timer_.reset(new base::RepeatingTimer<BackendImpl>());
+    timer_->Start(FROM_HERE, TimeDelta::FromMilliseconds(timer_delay), this,
+                  &BackendImpl::OnStatsTimer);
   }
 
   init_ = true;
@@ -497,7 +498,7 @@ int BackendImpl::SyncInit() {
 void BackendImpl::CleanupCache() {
   Trace("Backend Cleanup");
   eviction_.Stop();
-  timer_.Stop();
+  timer_.reset();
 
   if (init_) {
     stats_.Store();
diff --git a/net/disk_cache/backend_impl.h b/net/disk_cache/backend_impl.h
index e2fb6ef..663f7fc 100644
--- a/net/disk_cache/backend_impl.h
+++ b/net/disk_cache/backend_impl.h
@@ -383,7 +383,7 @@ class NET_EXPORT_PRIVATE BackendImpl : public Backend {
   net::NetLog* net_log_;
 
   Stats stats_;  // Usage statistics.
-  base::RepeatingTimer<BackendImpl> timer_;  // Usage timer.
+  scoped_ptr<base::RepeatingTimer<BackendImpl> > timer_;  // Usage timer.
   base::WaitableEvent done_;  // Signals the end of background work.
   scoped_refptr<TraceObject> trace_object_;  // Initializes internal tracing.
   base::WeakPtrFactory<BackendImpl> ptr_factory_;