sync: Change progress marker checking in tests

chrome/browser/sync/test/integration/quiesce_status_change_checker.cc

Index: chrome/browser/sync/test/integration/quiesce_status_change_checker.cc
diff --git a/chrome/browser/sync/test/integration/quiesce_status_change_checker.cc b/chrome/browser/sync/test/integration/quiesce_status_change_checker.cc
new file mode 100644
index 0000000000000000000000000000000000000000..92b8654ec65e275c779aa2aa430c56de225dc30c
--- /dev/null
+++ b/chrome/browser/sync/test/integration/quiesce_status_change_checker.cc
@@ -0,0 +1,223 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/sync/test/integration/quiesce_status_change_checker.h"
+
+#include "base/format_macros.h"
+#include "base/scoped_observer.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/stringprintf.h"
+#include "chrome/browser/sync/profile_sync_service.h"
+#include "chrome/browser/sync/test/integration/profile_sync_service_harness.h"
+#include "sync/internal_api/public/sessions/sync_session_snapshot.h"
+
+namespace {
+
+// Returns true if this service is disabled.
+bool IsSyncDisabled(ProfileSyncService* service) {
+  return !service->setup_in_progress() && !service->HasSyncSetupCompleted();
+}
+
+// Returns true if these services have matching progress markers.
+bool ProgressMarkersMatch(const ProfileSyncService* service1,
+                          const ProfileSyncService* service2) {
+  const syncer::ModelTypeSet common_types =
+      Intersection(service1->GetActiveDataTypes(),
+                   service2->GetActiveDataTypes());
+
+  const syncer::sessions::SyncSessionSnapshot& snap1 =
+      service1->GetLastSessionSnapshot();
+  const syncer::sessions::SyncSessionSnapshot& snap2 =
+      service2->GetLastSessionSnapshot();
+
+  for (syncer::ModelTypeSet::Iterator type_it = common_types.First();
+       type_it.Good(); type_it.Inc()) {
+    // Look up the progress markers.  Fail if either one is missing.
+    syncer::ProgressMarkerMap::const_iterator pm_it1 =
+        snap1.download_progress_markers().find(type_it.Get());
+    if (pm_it1 == snap1.download_progress_markers().end()) {
+      return false;
+    }
+
+    syncer::ProgressMarkerMap::const_iterator pm_it2 =
+        snap2.download_progress_markers().find(type_it.Get());
+    if (pm_it2 == snap2.download_progress_markers().end()) {
+      return false;
+    }
+
+    // Fail if any of them don't match.
+    if (pm_it1->second != pm_it2->second) {
+      return false;
+    }
+  }
+  return true;
+}
+
+}  // namespace
+
+// A helper class to keep an eye on a particular ProfileSyncService's
+// "HasLatestProgressMarkers()" state.
+//
+// This is a work-around for the HasLatestProgressMarkers check's inherent
+// flakiness.  It's not safe to check that condition whenever we want.  The
+// safest time to check it is when the ProfileSyncService emits an
+// OnStateChanged() event.  This class waits for those events and updates its
+// cached HasLatestProgressMarkers state every time that event occurs.
+//
+// See the comments in UpdatedProgressMarkerChecker for more details.
+//
+// The long-term plan is to deprecate this hack by replacing all its usees with
+// more reliable status checkers.
+class ProgressMarkerWatcher : public ProfileSyncServiceObserver {
+ public:
+  ProgressMarkerWatcher(
+      ProfileSyncService* service,
+      QuiesceStatusChangeChecker* quiesce_checker);
+  virtual ~ProgressMarkerWatcher();
+  virtual void OnStateChanged() OVERRIDE;
+
+  bool HasLatestProgressMarkers();
+  bool IsSyncDisabled();
+
+ private:
+  void UpdateHasLatestProgressMarkers();
+
+  ProfileSyncService* service_;
+  QuiesceStatusChangeChecker* quiesce_checker_;
+  ScopedObserver<ProfileSyncService, ProgressMarkerWatcher> scoped_observer_;
+  bool probably_has_latest_progress_markers_;
+};
+
+ProgressMarkerWatcher::ProgressMarkerWatcher(
+    ProfileSyncService* service,
+    QuiesceStatusChangeChecker* quiesce_checker)
+  : service_(service),
+    quiesce_checker_(quiesce_checker),
+    scoped_observer_(this),
+    probably_has_latest_progress_markers_(false) {
+  scoped_observer_.Add(service);
+  UpdateHasLatestProgressMarkers();
+}
+
+ProgressMarkerWatcher::~ProgressMarkerWatcher() { }
+
+void ProgressMarkerWatcher::OnStateChanged() {
+  UpdateHasLatestProgressMarkers();
+  quiesce_checker_->OnServiceStateChanged(service_);
+}
+
+void ProgressMarkerWatcher::UpdateHasLatestProgressMarkers() {
+  if (IsSyncDisabled()) {
+    probably_has_latest_progress_markers_ = false;
+    return;
+  }
+
+  // This is the same progress marker check as used by the
+  // UpdatedProgressMarkerChecker.  It has the samed drawbacks and potential for
+  // flakiness.  See the comment in
+  // UpdatedProgressMarkerChecker::IsExitConditionSatisfied() for more
+  // information.
+  //
+  // The QuiesceStatusChangeChecker attempts to work around the limitations of
+  // this progress marker checking method.  It tries to update the progress
+  // marker status only in the OnStateChanged() callback, where the snapshot is
+  // freshest.
+  //
+  // It also checks the progress marker status when it is first initialized, and
+  // that's where it's most likely that we could return a false positive.  We
+  // need to check these service at startup, since not every service is
+  // guaranteed to generate OnStateChanged() events while we're waiting for
+  // quiescence.
+  const syncer::sessions::SyncSessionSnapshot& snap =
+      service_->GetLastSessionSnapshot();
+  probably_has_latest_progress_markers_ =
+      snap.model_neutral_state().num_successful_commits == 0 &&
+      !service_->HasUnsyncedItems();
+}
+
+bool ProgressMarkerWatcher::HasLatestProgressMarkers() {
+  return probably_has_latest_progress_markers_;
+}
+
+bool ProgressMarkerWatcher::IsSyncDisabled() {
+  return ::IsSyncDisabled(service_);
+}
+
+QuiesceStatusChangeChecker::QuiesceStatusChangeChecker(
+    std::vector<ProfileSyncService*> services)
+  : services_(services), harness_(NULL) {
+  DCHECK_LE(1U, services_.size());
+  for (size_t i = 0; i < services_.size(); ++i) {
+    observers_.push_back(new ProgressMarkerWatcher(services[i], this));
+  }
+}
+
+QuiesceStatusChangeChecker::~QuiesceStatusChangeChecker() {}
+
+bool QuiesceStatusChangeChecker::IsExitConditionSatisfied() {
+  // Check that all progress markers are up to date.
+  for (ScopedVector<ProgressMarkerWatcher>::const_iterator it =
+       observers_.begin(); it != observers_.end(); ++it) {
+    if ((*it)->IsSyncDisabled()) {
+      continue;  // Skip disabled services.
+    }
+
+    if (!(*it)->HasLatestProgressMarkers()) {
+      VLOG(1) << "Not quiesced: Progress markers are old.";
+      return false;
+    }
+  }
+
+  std::vector<ProfileSyncService*> enabled_services;
+  for (std::vector<ProfileSyncService*>::const_iterator it = services_.begin();
+       it != services_.end(); ++it) {
+    if (!IsSyncDisabled(*it)) {
+      enabled_services.push_back(*it);
+    }
+  }
+
+  // Return true if we have nothing to compare against.
+  if (enabled_services.size() <= 1) {
+    return true;
+  }
+
+  std::vector<ProfileSyncService*>::const_iterator it1 =
+      enabled_services.begin();
+  std::vector<ProfileSyncService*>::const_iterator it2 =
+      enabled_services.begin();
+  it2++;
+
+  while (it2 != enabled_services.end()) {
+    // Return false if there is a progress marker mismatch.
+    if (!ProgressMarkersMatch(*it1, *it2)) {
+      VLOG(1) << "Not quiesced: Progress marker mismatch.";
+      return false;
+    }
+    it1++;
+    it2++;
+  }
+
+  return true;
+}
+
+std::string QuiesceStatusChangeChecker::GetDebugMessage() const {
+  return base::StringPrintf("Waiting for quiescence of %" PRIuS " clients",
+                            services_.size());
+}
+
+
+void QuiesceStatusChangeChecker::InitObserver(
+    ProfileSyncServiceHarness* harness) {
+  harness_ = harness;
+}
+
+void QuiesceStatusChangeChecker::UninitObserver(
+    ProfileSyncServiceHarness* harness) {
+  harness_ = NULL;
+}
+
+void QuiesceStatusChangeChecker::OnServiceStateChanged(
+    ProfileSyncService* service) {
+  harness_->OnStateChanged();
+}