components/sync_driver/glue/ui_model_worker.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "components/sync_driver/glue/ui_model_worker.h"
   6
   7 #include "base/bind.h"
   8 #include "base/bind_helpers.h"
   9 #include "base/message_loop/message_loop.h"
  10 #include "base/synchronization/waitable_event.h"
  11 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
  12 #include "base/threading/thread_restrictions.h"
  13
  14 namespace browser_sync {
  15
  16 namespace {
  17
  18 // A simple callback to signal a waitable event after running a closure.
  19 void CallDoWorkAndSignalCallback(const syncer::WorkCallback& work,
  20                                  base::WaitableEvent* work_done,
  21                                  syncer::SyncerError* error_info) {
  22   if (work.is_null()) {
  23     // This can happen during tests or cases where there are more than just the
  24     // default UIModelWorker in existence and it gets destroyed before
  25     // the main UI loop has terminated.  There is no easy way to assert the
  26     // loop is running / not running at the moment, so we just provide cancel
  27     // semantics here and short-circuit.
  28     // TODO(timsteele): Maybe we should have the message loop destruction
  29     // observer fire when the loop has ended, just a bit before it
  30     // actually gets destroyed.
  31     return;
  32   }
  33
  34   *error_info = work.Run();
  35
  36   work_done->Signal();  // Unblock the syncer thread that scheduled us.
  37 }
  38
  39 }  // namespace
  40
  41 UIModelWorker::UIModelWorker(
  42     const scoped_refptr<base::SingleThreadTaskRunner>& ui_thread,
  43     syncer::WorkerLoopDestructionObserver* observer)
  44     : syncer::ModelSafeWorker(observer), ui_thread_(ui_thread) {}
  45
  46 void UIModelWorker::RegisterForLoopDestruction() {
  47   CHECK(ui_thread_->BelongsToCurrentThread());
  48   SetWorkingLoopToCurrent();
  49 }
  50
  51 syncer::SyncerError UIModelWorker::DoWorkAndWaitUntilDoneImpl(
  52     const syncer::WorkCallback& work) {
  53   syncer::SyncerError error_info;
  54   if (ui_thread_->BelongsToCurrentThread()) {
  55     DLOG(WARNING) << "DoWorkAndWaitUntilDone called from "
  56                   << "ui_loop_. Probably a nested invocation?";
  57     return work.Run();
  58   }
  59
  60   if (!ui_thread_->PostTask(FROM_HERE,
  61                             base::Bind(&CallDoWorkAndSignalCallback, work,
  62                                        work_done_or_stopped(), &error_info))) {
  63     DLOG(WARNING) << "Could not post work to UI loop.";
  64     error_info = syncer::CANNOT_DO_WORK;
  65     return error_info;
  66   }
  67   work_done_or_stopped()->Wait();
  68
  69   return error_info;
  70 }
  71
  72 syncer::ModelSafeGroup UIModelWorker::GetModelSafeGroup() {
  73   return syncer::GROUP_UI;
  74 }
  75
  76 UIModelWorker::~UIModelWorker() {}
  77
  78 }  // namespace browser_sync