[Sync] Refactor non-frontend DTC to handle new API properly.

chrome/browser/sync/glue/shared_change_processor.cc

+// Copyright (c) 2011 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/glue/shared_change_processor.h"
+
+#include "chrome/browser/sync/profile_sync_service.h"
+#include "chrome/browser/sync/api/sync_change.h"
+#include "chrome/browser/sync/glue/generic_change_processor.h"
+#include "content/browser/browser_thread.h"
+
+using base::AutoLock;
+
+namespace browser_sync {
+
+SharedChangeProcessor::SharedChangeProcessor()
+    : disconnected_(false) {
+  // We're always created on the UI thread.
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DetachFromThread();
+}
+
+SharedChangeProcessor::~SharedChangeProcessor() {
+  // We can either be deleted when the DTC is destroyed (on UI thread),
+  // or when the SyncableService stop's syncing (datatype thread).
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI) ||
+         CalledOnValidThread());
+  DetachFromThread();

[akalin, 2011/10/11 22:41:08]

DeleteSoon() the GCP here if necessary

[Nicolas Zea, 2011/10/12 04:24:19]

Not necessary. If we've been given a GC, we'll be released on the valid thread.
We're only released on the UI thread when we were not given a GC.

+}
+
+void SharedChangeProcessor::Connect(
+    GenericChangeProcessor* generic_change_processor) {
+  DCHECK(CalledOnValidThread());
+  DCHECK(generic_change_processor);
+  AutoLock lock(monitor_lock_);
+  if (disconnected_)
+    return;
+  generic_change_processor_.reset(generic_change_processor);
+}
+
+void SharedChangeProcessor::Disconnect() {
+  // May be called from any thread.
+  VLOG(1) << "Disconnecting change processor.";
+  AutoLock lock(monitor_lock_);
+  disconnected_ = true;
+}
+
+SyncError SharedChangeProcessor::GetSyncDataForType(
+    syncable::ModelType type,
+    SyncDataList* current_sync_data) {
+  DCHECK(CalledOnValidThread());
+  AutoLock lock(monitor_lock_);
+  if (disconnected_) {
+    SyncError error(FROM_HERE, "Change processor disconnected.", type);
+    return error;
+  }
+  return generic_change_processor_->GetSyncDataForType(type, current_sync_data);
+}
+
+SyncError SharedChangeProcessor::ProcessSyncChanges(
+    const tracked_objects::Location& from_here,
+    const SyncChangeList& list_of_changes) {
+  DCHECK(CalledOnValidThread());
+  AutoLock lock(monitor_lock_);
+  if (disconnected_) {
+    // The DTC that disconnects us must ensure it posts a StopSyncing task.
+    // If we reach this, it means it just hasn't executed yet.
+    syncable::ModelType type;

[akalin, 2011/10/11 22:41:08]

what should type be if list_of_changes is empty?  Maybe do nothing?

[Nicolas Zea, 2011/10/12 04:24:19]

UNSPECIFIED. I prefer returning an error even with that though, since the
SyncableService can then act on it immediately if necessary (by for example
stopping).

+    if (list_of_changes.size() > 0) {
+      type = list_of_changes[0].sync_data().GetDataType();
+    }
+    SyncError error(FROM_HERE, "Change processor disconnected.", type);
+    return error;
+  }
+  return generic_change_processor_->ProcessSyncChanges(
+      from_here, list_of_changes);
+}
+
+bool SharedChangeProcessor::SyncModelHasUserCreatedNodes(
+    syncable::ModelType type,
+    bool* has_nodes) {
+  DCHECK(CalledOnValidThread());
+  AutoLock lock(monitor_lock_);
+  if (disconnected_) {
+    LOG(ERROR) << "Change processor disconnected.";
+    return false;
+  }
+  return generic_change_processor_->SyncModelHasUserCreatedNodes(
+      type, has_nodes);
+}
+
+bool SharedChangeProcessor::CryptoReadyIfNecessary(syncable::ModelType type) {
+  DCHECK(CalledOnValidThread());
+  AutoLock lock(monitor_lock_);
+  if (disconnected_) {
+    LOG(ERROR) << "Change processor disconnected.";
+    return true;  // Otherwise we get into infinite spin waiting.
+  }
+  return generic_change_processor_->CryptoReadyIfNecessary(type);
+}
+
+void SharedChangeProcessor::ActivateDataType(
+    ProfileSyncService* sync_service,
+    syncable::ModelType model_type,
+    browser_sync::ModelSafeGroup model_safe_group) {
+  AutoLock lock(monitor_lock_);
+  if (disconnected_) {
+    LOG(ERROR) << "Change processor disconnected.";
+    return;
+  }
+  sync_service->ActivateDataType(
+      model_type, model_safe_group, generic_change_processor_.get());
+}
+
+}  // namespace browser_sync