Run parsing JSON into ResourceList on blocking pool.

chrome/browser/chromeos/drive/drive_api_service.cc

 // Copyright (c) 2012 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/drive/drive_api_service.h"
 
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/message_loop_proxy.h"
+#include "base/threading/sequenced_worker_pool.h"
 #include "base/values.h"
 #include "chrome/browser/google_apis/drive_api_operations.h"
 #include "chrome/browser/google_apis/drive_api_parser.h"
 #include "chrome/browser/google_apis/gdata_wapi_parser.h"
 #include "chrome/browser/google_apis/operation_runner.h"
 #include "chrome/browser/google_apis/time_util.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/net/url_util.h"
 #include "content/public/browser/browser_thread.h"
 
 using content::BrowserThread;
 
 namespace drive {
 
 namespace {
 
 // OAuth2 scopes for Drive API.
 const char kDriveScope[] = "https://www.googleapis.com/auth/drive";
 const char kDriveAppsReadonlyScope[] =
     "https://www.googleapis.com/auth/drive.apps.readonly";
 
-// Parses the JSON value into ResourceList and runs |callback|.
-void ParseResourceListAndRun(
+struct OnParseResourceListCompletedParams {
+  google_apis::GDataErrorCode error;
+  scoped_ptr<google_apis::ResourceList> resource_list;
+};
+
+void ParseResourceListOnBlockingPool(
+    scoped_ptr<base::Value> value,
+    OnParseResourceListCompletedParams* params) {
+  if (!value) {
+    // JSON value is not available.
+    return;
+  }
+
+  // Parse the value into ResourceList via ChangeList.
+  // If failed, set (i.e. overwrite) the error flag and return immediately.
+  scoped_ptr<google_apis::ChangeList> change_list(
+      google_apis::ChangeList::CreateFrom(*value));
+  if (!change_list) {
+    params->error = google_apis::GDATA_PARSE_ERROR;
+    return;
+  }
+
+  scoped_ptr<google_apis::ResourceList> resource_list =
+      google_apis::ResourceList::CreateFromChangeList(*change_list);
+  if (!resource_list) {
+    params->error = google_apis::GDATA_PARSE_ERROR;
+    return;
+  }
+
+  // Pass the result to the params, so that OnParseResourceListCompleted
+  // defined below can process it.
+  params->resource_list = resource_list.Pass();
+}
+
+// Callback invoked when the parsing of resource list is completed,
+// regardless whether it is succeeded or not.
+void OnParseResourceListCompleted(
+    const google_apis::GetResourceListCallback& callback,
+    OnParseResourceListCompletedParams* params) {
+  callback.Run(params->error, params->resource_list.Pass());
+}
+
+// Sends a task to parse the JSON value into ResourceList on blocking pool,
+// with a callback which is called when the task is done.
+void ParseResourceListOnBlockingPoolAndRun(
     const google_apis::GetResourceListCallback& callback,
     google_apis::GDataErrorCode error,
     scoped_ptr<base::Value> value) {
-  if (!value) {
-    callback.Run(error, scoped_ptr<google_apis::ResourceList>());
-    return;
-  }
+  OnParseResourceListCompletedParams* params =
+      new OnParseResourceListCompletedParams;
+  // The error is initialized here to the given |error|, but may be
+  // overwritten in ParseResourceListOnBlockingPool before used in
+  // OnParseResourceListCompleted.
+  params->error = error;
 
-  // TODO(satorux): Parse the JSON value on a blocking pool. crbug.com/165088
-  scoped_ptr<google_apis::ChangeList> change_list(
-      google_apis::ChangeList::CreateFrom(*value));
-  if (!change_list) {
-    callback.Run(google_apis::GDATA_PARSE_ERROR,
-                 scoped_ptr<google_apis::ResourceList>());
-    return;
-  }
-
-  // TODO(satorux): Do the conversion on a blocking pool too. crbug.com/165088
-  scoped_ptr<google_apis::ResourceList> resource_list =
-      google_apis::ResourceList::CreateFromChangeList(*change_list);
-  if (!resource_list) {
-    callback.Run(google_apis::GDATA_PARSE_ERROR,
-                 scoped_ptr<google_apis::ResourceList>());
-    return;
-  }
-
-  callback.Run(error, resource_list.Pass());
+  BrowserThread::GetBlockingPool()->PostTaskAndReply(
+      FROM_HERE,
+      base::Bind(&ParseResourceListOnBlockingPool,
+                 base::Passed(value.Pass()), params),

[kinaba, 2013/01/08 11:53:16]

You can use base::Passed(&value).

[hidehiko, 2013/01/08 13:57:00]

Good to know. Thank you!

+      base::Bind(&OnParseResourceListCompleted,
+                 callback, base::Owned(params)));
 }
 
 // Parses the JSON value to ResourceEntry runs |callback|.
 void ParseResourceEntryAndRun(
     const google_apis::GetResourceEntryCallback& callback,
     google_apis::GDataErrorCode error,
     scoped_ptr<base::Value> value) {
   DCHECK(!BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   if (!value) {
@@ skipping 141 matching lines @@
     const google_apis::GetResourceListCallback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!callback.is_null());
 
   runner_->StartOperationWithRetry(
       new google_apis::GetFilelistOperation(
           operation_registry(),
           url_request_context_getter_,
           url,
           search_query,
-          base::Bind(&ParseResourceListAndRun, callback)));
+          base::Bind(&ParseResourceListOnBlockingPoolAndRun, callback)));
 }
 
 void DriveAPIService::GetChangelist(
     const GURL& url,
     int64 start_changestamp,
     const google_apis::GetResourceListCallback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!callback.is_null());
 
   runner_->StartOperationWithRetry(
       new google_apis::GetChangelistOperation(
           operation_registry(),
           url_request_context_getter_,
           url,
           start_changestamp,
-          base::Bind(&ParseResourceListAndRun, callback)));
+          base::Bind(&ParseResourceListOnBlockingPoolAndRun, callback)));
 }
 
 void DriveAPIService::GetResourceEntry(
     const std::string& resource_id,
     const google_apis::GetResourceEntryCallback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!callback.is_null());
 
   runner_->StartOperationWithRetry(new google_apis::GetFileOperation(
       operation_registry(),
@@ skipping 182 matching lines @@
 
 void DriveAPIService::OnAuthenticationFailed(
     google_apis::GDataErrorCode error) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   FOR_EACH_OBSERVER(
       google_apis::DriveServiceObserver, observers_,
       OnAuthenticationFailed(error));
 }
 
 }  // namespace drive