Defer ARC file system operations while ARC is booting.

chrome/browser/chromeos/arc/fileapi/arc_deferred_file_system_operation_runner.cc

+// Copyright 2017 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/chromeos/arc/fileapi/arc_deferred_file_system_operation_runner.h"
+
+#include "base/bind.h"
+#include "base/optional.h"
+#include "components/arc/arc_bridge_service.h"
+#include "content/public/browser/browser_thread.h"
+#include "url/gurl.h"
+
+using content::BrowserThread;
+
+namespace arc {
+
+ArcDeferredFileSystemOperationRunner::ArcDeferredFileSystemOperationRunner(
+    ArcBridgeService* bridge_service)
+    : ArcDeferredFileSystemOperationRunner(bridge_service, true) {}
+
+ArcDeferredFileSystemOperationRunner::ArcDeferredFileSystemOperationRunner(
+    ArcBridgeService* bridge_service,
+    bool observe_events)
+    : ArcFileSystemOperationRunner(bridge_service),
+      observe_events_(observe_events),
+      weak_ptr_factory_(this) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  if (observe_events_) {
+    ArcSessionManager::Get()->AddObserver(this);
+    arc_bridge_service()->file_system()->AddObserver(this);
+    OnStateChanged();
+  }
+}
+
+ArcDeferredFileSystemOperationRunner::~ArcDeferredFileSystemOperationRunner() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  if (observe_events_) {
+    ArcSessionManager::Get()->RemoveObserver(this);
+    arc_bridge_service()->file_system()->RemoveObserver(this);
+  }
+  // On destruction, deferred operations are discarded.
+}
+
+void ArcDeferredFileSystemOperationRunner::GetFileSize(
+    const GURL& url,
+    const GetFileSizeCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  if (should_defer_) {
+    deferred_operations_.emplace_back(
+        base::Bind(&ArcDeferredFileSystemOperationRunner::GetFileSize,
+                   weak_ptr_factory_.GetWeakPtr(), url, callback));
+    return;
+  }
+  auto* file_system_instance = ARC_GET_INSTANCE_FOR_METHOD(
+      arc_bridge_service()->file_system(), GetFileSize);
+  if (!file_system_instance) {
+    callback.Run(-1);

[hashimoto, 2017/01/23 08:28:42]

Could you run the callback asynchronously here, using
base::ThreadTaskRunnerHandle::Get()->PostTask()? (the same goes for other
methods)
With this code, callback is run immediately (instead of run asynchronously) only
when file_system_instance is not available, and
this may result in subtle bugs which are difficult to reproduce.

[Shuhei Takahashi, 2017/01/23 09:17:51]

Done.

+    return;
+  }
+  file_system_instance->GetFileSize(url.spec(), callback);
+}
+
+void ArcDeferredFileSystemOperationRunner::OpenFileToRead(
+    const GURL& url,
+    const OpenFileToReadCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  if (should_defer_) {
+    deferred_operations_.emplace_back(
+        base::Bind(&ArcDeferredFileSystemOperationRunner::OpenFileToRead,
+                   weak_ptr_factory_.GetWeakPtr(), url, callback));
+    return;
+  }
+  auto* file_system_instance = ARC_GET_INSTANCE_FOR_METHOD(
+      arc_bridge_service()->file_system(), OpenFileToRead);
+  if (!file_system_instance) {
+    callback.Run(mojo::ScopedHandle());
+    return;
+  }
+  file_system_instance->OpenFileToRead(url.spec(), callback);
+}
+
+void ArcDeferredFileSystemOperationRunner::GetDocument(
+    const std::string& authority,
+    const std::string& document_id,
+    const GetDocumentCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  if (should_defer_) {
+    deferred_operations_.emplace_back(base::Bind(
+        &ArcDeferredFileSystemOperationRunner::GetDocument,
+        weak_ptr_factory_.GetWeakPtr(), authority, document_id, callback));
+    return;
+  }
+  auto* file_system_instance = ARC_GET_INSTANCE_FOR_METHOD(
+      arc_bridge_service()->file_system(), GetDocument);
+  if (!file_system_instance) {
+    callback.Run(mojom::DocumentPtr());
+    return;
+  }
+  file_system_instance->GetDocument(authority, document_id, callback);
+}
+
+void ArcDeferredFileSystemOperationRunner::GetChildDocuments(
+    const std::string& authority,
+    const std::string& parent_document_id,
+    const GetChildDocumentsCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  if (should_defer_) {
+    deferred_operations_.emplace_back(
+        base::Bind(&ArcDeferredFileSystemOperationRunner::GetChildDocuments,
+                   weak_ptr_factory_.GetWeakPtr(), authority,
+                   parent_document_id, callback));
+    return;
+  }
+  auto* file_system_instance = ARC_GET_INSTANCE_FOR_METHOD(
+      arc_bridge_service()->file_system(), GetChildDocuments);
+  if (!file_system_instance) {
+    callback.Run(base::nullopt);
+    return;
+  }
+  file_system_instance->GetChildDocuments(authority, parent_document_id,
+                                          callback);
+}
+
+void ArcDeferredFileSystemOperationRunner::OnArcOptInChanged(bool enabled) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  OnStateChanged();
+}
+
+void ArcDeferredFileSystemOperationRunner::OnInstanceReady() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  OnStateChanged();
+}
+
+void ArcDeferredFileSystemOperationRunner::OnInstanceClosed() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  OnStateChanged();
+}
+
+void ArcDeferredFileSystemOperationRunner::OnStateChanged() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  SetShouldDefer(ArcSessionManager::Get()->IsArcEnabled() &&
+                 !arc_bridge_service()->file_system()->has_instance());
+}
+
+void ArcDeferredFileSystemOperationRunner::SetShouldDefer(bool should_defer) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  should_defer_ = should_defer;
+
+  if (should_defer_)
+    return;
+
+  // Run deferred operations.
+  std::vector<base::Closure> deferred_operations;
+  deferred_operations.swap(deferred_operations_);
+  for (const base::Closure& operation : deferred_operations) {
+    operation.Run();
+  }
+
+  // No deferred operations should be left at this point.
+  DCHECK(deferred_operations_.empty());
+}
+
+}  // namespace arc