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 "chrome/browser/sync/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#include "content/public/browser/browser_thread.h"
14
15using content::BrowserThread;
16
17namespace browser_sync {
18
19namespace {
20
21// A simple callback to signal a waitable event after running a closure.
22void CallDoWorkAndSignalCallback(const syncer::WorkCallback& work,
23                                 base::WaitableEvent* work_done,
24                                 syncer::SyncerError* error_info) {
25  if (work.is_null()) {
26    // This can happen during tests or cases where there are more than just the
27    // default UIModelWorker in existence and it gets destroyed before
28    // the main UI loop has terminated.  There is no easy way to assert the
29    // loop is running / not running at the moment, so we just provide cancel
30    // semantics here and short-circuit.
31    // TODO(timsteele): Maybe we should have the message loop destruction
32    // observer fire when the loop has ended, just a bit before it
33    // actually gets destroyed.
34    return;
35  }
36
37  *error_info = work.Run();
38
39  work_done->Signal();  // Unblock the syncer thread that scheduled us.
40}
41
42}  // namespace
43
44UIModelWorker::UIModelWorker(syncer::WorkerLoopDestructionObserver* observer)
45    : syncer::ModelSafeWorker(observer) {
46}
47
48void UIModelWorker::RegisterForLoopDestruction() {
49  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
50  SetWorkingLoopToCurrent();
51}
52
53syncer::SyncerError UIModelWorker::DoWorkAndWaitUntilDoneImpl(
54    const syncer::WorkCallback& work) {
55  syncer::SyncerError error_info;
56  if (BrowserThread::CurrentlyOn(BrowserThread::UI)) {
57    DLOG(WARNING) << "DoWorkAndWaitUntilDone called from "
58      << "ui_loop_. Probably a nested invocation?";
59    return work.Run();
60  }
61
62  if (!BrowserThread::PostTask(
63      BrowserThread::UI, FROM_HERE,
64      base::Bind(&CallDoWorkAndSignalCallback,
65                 work, work_done_or_stopped(), &error_info))) {
66    DLOG(WARNING) << "Could not post work to UI loop.";
67    error_info = syncer::CANNOT_DO_WORK;
68    return error_info;
69  }
70  work_done_or_stopped()->Wait();
71
72  return error_info;
73}
74
75syncer::ModelSafeGroup UIModelWorker::GetModelSafeGroup() {
76  return syncer::GROUP_UI;
77}
78
79UIModelWorker::~UIModelWorker() {
80}
81
82}  // namespace browser_sync
83