chrome/browser/sync/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 "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
  15 using content::BrowserThread;
  16
  17 namespace browser_sync {
  18
  19 namespace {
  20
  21 // A simple callback to signal a waitable event after running a closure.
  22 void 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
  44 UIModelWorker::UIModelWorker(syncer::WorkerLoopDestructionObserver* observer)
  45     : syncer::ModelSafeWorker(observer) {
  46 }
  47
  48 void UIModelWorker::RegisterForLoopDestruction() {
  49   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  50   base::MessageLoop::current()->AddDestructionObserver(this);
  51   SetWorkingLoopToCurrent();
  52 }
  53
  54 syncer::SyncerError UIModelWorker::DoWorkAndWaitUntilDoneImpl(
  55     const syncer::WorkCallback& work) {
  56   syncer::SyncerError error_info;
  57   if (BrowserThread::CurrentlyOn(BrowserThread::UI)) {
  58     DLOG(WARNING) << "DoWorkAndWaitUntilDone called from "
  59       << "ui_loop_. Probably a nested invocation?";
  60     return work.Run();
  61   }
  62
  63   if (!BrowserThread::PostTask(
  64       BrowserThread::UI, FROM_HERE,
  65       base::Bind(&CallDoWorkAndSignalCallback,
  66                  work, work_done_or_stopped(), &error_info))) {
  67     DLOG(WARNING) << "Could not post work to UI loop.";
  68     error_info = syncer::CANNOT_DO_WORK;
  69     return error_info;
  70   }
  71   work_done_or_stopped()->Wait();
  72
  73   return error_info;
  74 }
  75
  76 syncer::ModelSafeGroup UIModelWorker::GetModelSafeGroup() {
  77   return syncer::GROUP_UI;
  78 }
  79
  80 UIModelWorker::~UIModelWorker() {
  81 }
  82
  83 }  // namespace browser_sync