path: root/chrome/browser/chromeos/drive/directory_loader.cc

// Copyright 2014 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/directory_loader.h"

#include "base/callback.h"
#include "base/callback_helpers.h"
#include "base/metrics/histogram.h"
#include "base/strings/string_number_conversions.h"
#include "base/time/time.h"
#include "chrome/browser/chromeos/drive/change_list_loader.h"
#include "chrome/browser/chromeos/drive/change_list_loader_observer.h"
#include "chrome/browser/chromeos/drive/change_list_processor.h"
#include "chrome/browser/chromeos/drive/file_system_util.h"
#include "chrome/browser/chromeos/drive/job_scheduler.h"
#include "chrome/browser/chromeos/drive/resource_metadata.h"
#include "chrome/browser/drive/drive_api_util.h"
#include "chrome/browser/drive/drive_service_interface.h"
#include "chrome/browser/drive/event_logger.h"
#include "content/public/browser/browser_thread.h"
#include "google_apis/drive/drive_api_parser.h"
#include "url/gurl.h"

using content::BrowserThread;

namespace drive {
namespace internal {

namespace {

// Minimum changestamp gap required to start loading directory.
const int kMinimumChangestampGap = 50;

FileError CheckLocalState(ResourceMetadata* resource_metadata,
                          const google_apis::AboutResource& about_resource,
                          const std::string& local_id,
                          ResourceEntry* entry,
                          ResourceEntryVector* child_entries,
                          int64* local_changestamp) {
  // Fill My Drive resource ID.
  ResourceEntry mydrive;
  FileError error = resource_metadata->GetResourceEntryByPath(
      util::GetDriveMyDriveRootPath(), &mydrive);
  if (error != FILE_ERROR_OK)
    return error;

  if (mydrive.resource_id().empty()) {
    mydrive.set_resource_id(about_resource.root_folder_id());
    error = resource_metadata->RefreshEntry(mydrive);
    if (error != FILE_ERROR_OK)
      return error;
  }

  // Get entry.
  error = resource_metadata->GetResourceEntryById(local_id, entry);
  if (error != FILE_ERROR_OK)
    return error;

  // Get child entries.
  error = resource_metadata->ReadDirectoryById(local_id, child_entries);
  if (error != FILE_ERROR_OK)
    return error;

  // Get the local changestamp.
  *local_changestamp = resource_metadata->GetLargestChangestamp();
  return FILE_ERROR_OK;
}

FileError UpdateChangestamp(ResourceMetadata* resource_metadata,
                            const DirectoryFetchInfo& directory_fetch_info,
                            base::FilePath* directory_path) {
  // Update the directory changestamp.
  ResourceEntry directory;
  FileError error = resource_metadata->GetResourceEntryById(
      directory_fetch_info.local_id(), &directory);
  if (error != FILE_ERROR_OK)
    return error;

  if (!directory.file_info().is_directory())
    return FILE_ERROR_NOT_A_DIRECTORY;

  directory.mutable_directory_specific_info()->set_changestamp(
      directory_fetch_info.changestamp());
  error = resource_metadata->RefreshEntry(directory);
  if (error != FILE_ERROR_OK)
    return error;

  // Get the directory path.
  *directory_path = resource_metadata->GetFilePath(
      directory_fetch_info.local_id());
  return FILE_ERROR_OK;
}

}  // namespace

struct DirectoryLoader::ReadDirectoryCallbackState {
  ReadDirectoryCallback callback;
  std::set<std::string> sent_entry_names;
};

// Fetches the resource entries in the directory with |directory_resource_id|.
class DirectoryLoader::FeedFetcher {
 public:
  FeedFetcher(DirectoryLoader* loader,
              const DirectoryFetchInfo& directory_fetch_info,
              const std::string& root_folder_id)
      : loader_(loader),
        directory_fetch_info_(directory_fetch_info),
        root_folder_id_(root_folder_id),
        weak_ptr_factory_(this) {
  }

  ~FeedFetcher() {
  }

  void Run(const FileOperationCallback& callback) {
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
    DCHECK(!callback.is_null());
    DCHECK(!directory_fetch_info_.resource_id().empty());

    // Remember the time stamp for usage stats.
    start_time_ = base::TimeTicks::Now();

    // We use WAPI's GetResourceListInDirectory even if Drive API v2 is
    // enabled. This is the short term work around of the performance
    // regression.
    // TODO(hashimoto): Remove this. crbug.com/340931.

    std::string resource_id = directory_fetch_info_.resource_id();
    if (resource_id == root_folder_id_) {
      // GData WAPI doesn't accept the root directory id which is used in Drive
      // API v2. So it is necessary to translate it here.
      resource_id = util::kWapiRootDirectoryResourceId;
    }

    loader_->scheduler_->GetResourceListInDirectoryByWapi(
        resource_id,
        base::Bind(&FeedFetcher::OnResourceListFetched,
                   weak_ptr_factory_.GetWeakPtr(), callback));
  }

 private:
  void OnResourceListFetched(
      const FileOperationCallback& callback,
      google_apis::GDataErrorCode status,
      scoped_ptr<google_apis::ResourceList> resource_list) {
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
    DCHECK(!callback.is_null());

    FileError error = GDataToFileError(status);
    if (error != FILE_ERROR_OK) {
      callback.Run(error);
      return;
    }

    DCHECK(resource_list);
    scoped_ptr<ChangeList> change_list(new ChangeList(*resource_list));
    FixResourceIdInChangeList(change_list.get());

    GURL next_url;
    resource_list->GetNextFeedURL(&next_url);

    ResourceEntryVector* entries = new ResourceEntryVector;
    loader_->loader_controller_->ScheduleRun(base::Bind(
        base::IgnoreResult(
            &base::PostTaskAndReplyWithResult<FileError, FileError>),
        loader_->blocking_task_runner_,
        FROM_HERE,
        base::Bind(&ChangeListProcessor::RefreshDirectory,
                   loader_->resource_metadata_,
                   directory_fetch_info_,
                   base::Passed(&change_list),
                   entries),
        base::Bind(&FeedFetcher::OnDirectoryRefreshed,
                   weak_ptr_factory_.GetWeakPtr(),
                   callback,
                   next_url,
                   base::Owned(entries))));
  }

  void OnDirectoryRefreshed(
      const FileOperationCallback& callback,
      const GURL& next_url,
      const std::vector<ResourceEntry>* refreshed_entries,
      FileError error) {
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
    DCHECK(!callback.is_null());

    if (error != FILE_ERROR_OK) {
      callback.Run(error);
      return;
    }

    loader_->SendEntries(directory_fetch_info_.local_id(), *refreshed_entries,
                         true /*has_more*/);

    if (!next_url.is_empty()) {
      // There is the remaining result so fetch it.
      loader_->scheduler_->GetRemainingResourceList(
          next_url,
          base::Bind(&FeedFetcher::OnResourceListFetched,
                     weak_ptr_factory_.GetWeakPtr(), callback));
      return;
    }

    UMA_HISTOGRAM_TIMES("Drive.DirectoryFeedLoadTime",
                        base::TimeTicks::Now() - start_time_);

    // Note: The fetcher is managed by DirectoryLoader, and the instance
    // will be deleted in the callback. Do not touch the fields after this
    // invocation.
    callback.Run(FILE_ERROR_OK);
  }

  // Fixes resource IDs in |change_list| into the format that |drive_service_|
  // can understand. Note that |change_list| contains IDs in GData WAPI format
  // since currently we always use WAPI for fast fetch, regardless of the flag.
  void FixResourceIdInChangeList(ChangeList* change_list) {
    std::vector<ResourceEntry>* entries = change_list->mutable_entries();
    std::vector<std::string>* parent_resource_ids =
        change_list->mutable_parent_resource_ids();
    for (size_t i = 0; i < entries->size(); ++i) {
      ResourceEntry* entry = &(*entries)[i];
      if (entry->has_resource_id())
        entry->set_resource_id(FixResourceId(entry->resource_id()));

      (*parent_resource_ids)[i] = FixResourceId((*parent_resource_ids)[i]);
    }
  }

  std::string FixResourceId(const std::string& resource_id) {
    if (resource_id == util::kWapiRootDirectoryResourceId)
      return root_folder_id_;
    return loader_->drive_service_->GetResourceIdCanonicalizer().Run(
        resource_id);
  }

  DirectoryLoader* loader_;
  DirectoryFetchInfo directory_fetch_info_;
  std::string root_folder_id_;
  base::TimeTicks start_time_;
  base::WeakPtrFactory<FeedFetcher> weak_ptr_factory_;
  DISALLOW_COPY_AND_ASSIGN(FeedFetcher);
};

DirectoryLoader::DirectoryLoader(
    EventLogger* logger,
    base::SequencedTaskRunner* blocking_task_runner,
    ResourceMetadata* resource_metadata,
    JobScheduler* scheduler,
    DriveServiceInterface* drive_service,
    AboutResourceLoader* about_resource_loader,
    LoaderController* loader_controller)
    : logger_(logger),
      blocking_task_runner_(blocking_task_runner),
      resource_metadata_(resource_metadata),
      scheduler_(scheduler),
      drive_service_(drive_service),
      about_resource_loader_(about_resource_loader),
      loader_controller_(loader_controller),
      weak_ptr_factory_(this) {
}

DirectoryLoader::~DirectoryLoader() {
  STLDeleteElements(&fast_fetch_feed_fetcher_set_);
}

void DirectoryLoader::AddObserver(ChangeListLoaderObserver* observer) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  observers_.AddObserver(observer);
}

void DirectoryLoader::RemoveObserver(ChangeListLoaderObserver* observer) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  observers_.RemoveObserver(observer);
}

void DirectoryLoader::ReadDirectory(const base::FilePath& directory_path,
                                    const ReadDirectoryCallback& callback) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK(!callback.is_null());

  ResourceEntry* entry = new ResourceEntry;
  base::PostTaskAndReplyWithResult(
      blocking_task_runner_.get(),
      FROM_HERE,
      base::Bind(&ResourceMetadata::GetResourceEntryByPath,
                 base::Unretained(resource_metadata_),
                 directory_path,
                 entry),
      base::Bind(&DirectoryLoader::ReadDirectoryAfterGetEntry,
                 weak_ptr_factory_.GetWeakPtr(),
                 directory_path,
                 callback,
                 true,  // should_try_loading_parent
                 base::Owned(entry)));
}

void DirectoryLoader::ReadDirectoryAfterGetEntry(
    const base::FilePath& directory_path,
    const ReadDirectoryCallback& callback,
    bool should_try_loading_parent,
    const ResourceEntry* entry,
    FileError error) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK(!callback.is_null());

  if (error == FILE_ERROR_NOT_FOUND &&
      should_try_loading_parent &&
      util::GetDriveGrandRootPath().IsParent(directory_path)) {
    // This entry may be found after loading the parent.
    ReadDirectory(directory_path.DirName(),
                  base::Bind(&DirectoryLoader::ReadDirectoryAfterLoadParent,
                             weak_ptr_factory_.GetWeakPtr(),
                             directory_path,
                             callback));
    return;
  }
  if (error != FILE_ERROR_OK) {
    callback.Run(error, scoped_ptr<ResourceEntryVector>(), false /*has_more*/);
    return;
  }

  if (!entry->file_info().is_directory()) {
    callback.Run(FILE_ERROR_NOT_A_DIRECTORY,
                 scoped_ptr<ResourceEntryVector>(), false /*has_more*/);
    return;
  }

  DirectoryFetchInfo directory_fetch_info(
      entry->local_id(),
      entry->resource_id(),
      entry->directory_specific_info().changestamp());

  // Register the callback function to be called when it is loaded.
  const std::string& local_id = directory_fetch_info.local_id();
  ReadDirectoryCallbackState callback_state;
  callback_state.callback = callback;
  pending_load_callback_[local_id].push_back(callback_state);

  // If loading task for |local_id| is already running, do nothing.
  if (pending_load_callback_[local_id].size() > 1)
    return;

  // Note: To be precise, we need to call UpdateAboutResource() here. However,
  // - It is costly to do GetAboutResource HTTP request every time.
  // - The chance using an old value is small; it only happens when
  //   ReadDirectory is called during one GetAboutResource roundtrip time
  //   of a change list fetching.
  // - Even if the value is old, it just marks the directory as older. It may
  //   trigger one future unnecessary re-fetch, but it'll never lose data.
  about_resource_loader_->GetAboutResource(
      base::Bind(&DirectoryLoader::ReadDirectoryAfterGetAboutResource,
                 weak_ptr_factory_.GetWeakPtr(), local_id));
}

void DirectoryLoader::ReadDirectoryAfterLoadParent(
    const base::FilePath& directory_path,
    const ReadDirectoryCallback& callback,
    FileError error,
    scoped_ptr<ResourceEntryVector> entries,
    bool has_more) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK(!callback.is_null());

  if (has_more)
    return;

  if (error != FILE_ERROR_OK) {
    callback.Run(error, scoped_ptr<ResourceEntryVector>(), false /*has_more*/);
    return;
  }

  ResourceEntry* entry = new ResourceEntry;
  base::PostTaskAndReplyWithResult(
      blocking_task_runner_.get(),
      FROM_HERE,
      base::Bind(&ResourceMetadata::GetResourceEntryByPath,
                 base::Unretained(resource_metadata_),
                 directory_path,
                 entry),
      base::Bind(&DirectoryLoader::ReadDirectoryAfterGetEntry,
                 weak_ptr_factory_.GetWeakPtr(),
                 directory_path,
                 callback,
                 false,  // should_try_loading_parent
                 base::Owned(entry)));
}

void DirectoryLoader::ReadDirectoryAfterGetAboutResource(
    const std::string& local_id,
    google_apis::GDataErrorCode status,
    scoped_ptr<google_apis::AboutResource> about_resource) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  FileError error = GDataToFileError(status);
  if (error != FILE_ERROR_OK) {
    OnDirectoryLoadComplete(local_id, error);
    return;
  }

  DCHECK(about_resource);

  // Check the current status of local metadata, and start loading if needed.
  google_apis::AboutResource* about_resource_ptr = about_resource.get();
  ResourceEntry* entry = new ResourceEntry;
  ResourceEntryVector* child_entries = new ResourceEntryVector;
  int64* local_changestamp = new int64;
  base::PostTaskAndReplyWithResult(
      blocking_task_runner_,
      FROM_HERE,
      base::Bind(&CheckLocalState,
                 resource_metadata_,
                 *about_resource_ptr,
                 local_id,
                 entry,
                 child_entries,
                 local_changestamp),
      base::Bind(&DirectoryLoader::ReadDirectoryAfterCheckLocalState,
                 weak_ptr_factory_.GetWeakPtr(),
                 base::Passed(&about_resource),
                 local_id,
                 base::Owned(entry),
                 base::Owned(child_entries),
                 base::Owned(local_changestamp)));
}

void DirectoryLoader::ReadDirectoryAfterCheckLocalState(
    scoped_ptr<google_apis::AboutResource> about_resource,
    const std::string& local_id,
    const ResourceEntry* entry,
    const ResourceEntryVector* child_entries,
    const int64* local_changestamp,
    FileError error) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK(about_resource);

  if (error != FILE_ERROR_OK) {
    OnDirectoryLoadComplete(local_id, error);
    return;
  }
  // This entry does not exist on the server.
  if (entry->resource_id().empty()) {
    OnDirectoryLoadComplete(local_id, FILE_ERROR_OK);
    return;
  }

  int64 remote_changestamp = about_resource->largest_change_id();

  // Start loading the directory.
  int64 directory_changestamp = std::max(
      entry->directory_specific_info().changestamp(), *local_changestamp);

  DirectoryFetchInfo directory_fetch_info(
      local_id, entry->resource_id(), remote_changestamp);

  // We may not fetch from the server at all if the local metadata is new
  // enough, but we log this message here, so "Fast-fetch start" and
  // "Fast-fetch complete" always match.
  // TODO(satorux): Distinguish the "not fetching at all" case.
  logger_->Log(logging::LOG_INFO,
               "Fast-fetch start: %s; Server changestamp: %s",
               directory_fetch_info.ToString().c_str(),
               base::Int64ToString(remote_changestamp).c_str());

  // If the directory's changestamp is new enough, just schedule to run the
  // callback, as there is no need to fetch the directory.
  if (directory_changestamp + kMinimumChangestampGap > remote_changestamp) {
    OnDirectoryLoadComplete(local_id, FILE_ERROR_OK);
  } else {
    // Send locally found entries to callbacks.
    SendEntries(local_id, *child_entries, true /*has_more*/);
    // Start fetching the directory content, and mark it with the changestamp
    // |remote_changestamp|.
    LoadDirectoryFromServer(directory_fetch_info);
  }
}

void DirectoryLoader::OnDirectoryLoadComplete(const std::string& local_id,
                                              FileError error) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  logger_->Log(logging::LOG_INFO,
               "Fast-fetch complete: %s => %s",
               local_id.c_str(),
               FileErrorToString(error).c_str());

  ResourceEntryVector* entries = new ResourceEntryVector;
  base::PostTaskAndReplyWithResult(
      blocking_task_runner_.get(),
      FROM_HERE,
      base::Bind(&ResourceMetadata::ReadDirectoryById,
                 base::Unretained(resource_metadata_), local_id, entries),
      base::Bind(&DirectoryLoader::OnDirectoryLoadCompleteAfterRead,
                 weak_ptr_factory_.GetWeakPtr(),
                 local_id,
                 base::Owned(entries)));
}

void DirectoryLoader::OnDirectoryLoadCompleteAfterRead(
    const std::string& local_id,
    const ResourceEntryVector* entries,
    FileError error) {
  LoadCallbackMap::iterator it = pending_load_callback_.find(local_id);
  if (it != pending_load_callback_.end()) {
    DVLOG(1) << "Running callback for " << local_id;

    const bool kHasMore = false;
    if (error == FILE_ERROR_OK) {
      SendEntries(local_id, *entries, kHasMore);
    } else {
      for (size_t i = 0; i < it->second.size(); ++i) {
        const ReadDirectoryCallbackState& callback_state = it->second[i];
        callback_state.callback.Run(error, scoped_ptr<ResourceEntryVector>(),
                                    kHasMore);
      }
    }
    pending_load_callback_.erase(it);
  }
}

void DirectoryLoader::SendEntries(const std::string& local_id,
                                  const ResourceEntryVector& entries,
                                  bool has_more) {
  LoadCallbackMap::iterator it = pending_load_callback_.find(local_id);
  DCHECK(it != pending_load_callback_.end());

  for (size_t i = 0; i < it->second.size(); ++i) {
    ReadDirectoryCallbackState* callback_state = &it->second[i];

    // Filter out entries which were already sent.
    scoped_ptr<ResourceEntryVector> entries_to_send(new ResourceEntryVector);
    for (size_t i = 0; i < entries.size(); ++i) {
      const ResourceEntry& entry = entries[i];
      if (!callback_state->sent_entry_names.count(entry.base_name())) {
        callback_state->sent_entry_names.insert(entry.base_name());
        entries_to_send->push_back(entry);
      }
    }
    callback_state->callback.Run(FILE_ERROR_OK, entries_to_send.Pass(),
                                 has_more);
  }
}

void DirectoryLoader::LoadDirectoryFromServer(
    const DirectoryFetchInfo& directory_fetch_info) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK(!directory_fetch_info.empty());
  DCHECK(about_resource_loader_->cached_about_resource());
  DVLOG(1) << "Start loading directory: " << directory_fetch_info.ToString();

  FeedFetcher* fetcher = new FeedFetcher(
      this,
      directory_fetch_info,
      about_resource_loader_->cached_about_resource()->root_folder_id());
  fast_fetch_feed_fetcher_set_.insert(fetcher);
  fetcher->Run(
      base::Bind(&DirectoryLoader::LoadDirectoryFromServerAfterLoad,
                 weak_ptr_factory_.GetWeakPtr(),
                 directory_fetch_info,
                 fetcher));
}

void DirectoryLoader::LoadDirectoryFromServerAfterLoad(
    const DirectoryFetchInfo& directory_fetch_info,
    FeedFetcher* fetcher,
    FileError error) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK(!directory_fetch_info.empty());

  // Delete the fetcher.
  fast_fetch_feed_fetcher_set_.erase(fetcher);
  delete fetcher;

  if (error != FILE_ERROR_OK) {
    LOG(ERROR) << "Failed to load directory: "
               << directory_fetch_info.local_id()
               << ": " << FileErrorToString(error);
    OnDirectoryLoadComplete(directory_fetch_info.local_id(), error);
    return;
  }

  // Update changestamp and get the directory path.
  base::FilePath* directory_path = new base::FilePath;
  base::PostTaskAndReplyWithResult(
      blocking_task_runner_.get(),
      FROM_HERE,
      base::Bind(&UpdateChangestamp,
                 resource_metadata_,
                 directory_fetch_info,
                 directory_path),
      base::Bind(
          &DirectoryLoader::LoadDirectoryFromServerAfterUpdateChangestamp,
          weak_ptr_factory_.GetWeakPtr(),
          directory_fetch_info,
          base::Owned(directory_path)));
}

void DirectoryLoader::LoadDirectoryFromServerAfterUpdateChangestamp(
    const DirectoryFetchInfo& directory_fetch_info,
    const base::FilePath* directory_path,
    FileError error) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  DVLOG(1) << "Directory loaded: " << directory_fetch_info.ToString();
  OnDirectoryLoadComplete(directory_fetch_info.local_id(), error);

  // Also notify the observers.
  if (error == FILE_ERROR_OK && !directory_path->empty()) {
    FOR_EACH_OBSERVER(ChangeListLoaderObserver, observers_,
                      OnDirectoryChanged(*directory_path));
  }
}

}  // namespace internal
}  // namespace drive