Second try at splitting WebDataService (minus ownership changes)

chrome/browser/webdata/web_database_service.cc

Index: chrome/browser/webdata/web_database_service.cc
diff --git a/chrome/browser/webdata/web_database_service.cc b/chrome/browser/webdata/web_database_service.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a120f023169b27a3518219d7685dc099b52e705b
--- /dev/null
+++ b/chrome/browser/webdata/web_database_service.cc
@@ -0,0 +1,268 @@
+// Copyright 2013 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/webdata/web_database_service.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "chrome/browser/api/webdata/web_data_results.h"
+#include "chrome/browser/api/webdata/web_data_service_consumer.h"
+#include "chrome/browser/webdata/web_data_request_manager.h"
+#include "chrome/browser/webdata/web_data_service.h"
+// TODO(caitkp): Remove this autofill dependency.
+#include "components/autofill/browser/autofill_country.h"
+
+using base::Bind;
+using base::FilePath;
+using content::BrowserThread;
+
+
+////////////////////////////////////////////////////////////////////////////////
+//
+// WebDatabaseServiceInternal implementation.
+//
+////////////////////////////////////////////////////////////////////////////////
+
+// Refcounted to allow asynchronous destruction on the DB thread.
+class WebDatabaseServiceInternal
+    : public base::RefCountedThreadSafe<WebDatabaseServiceInternal,
+                                        BrowserThread::DeleteOnDBThread> {
+ public:
+

[dhollowa, 2013/03/15 18:56:21]

nit: Remove empty line.

[Cait (Slow), 2013/03/15 20:43:59]

Done.

+  explicit WebDatabaseServiceInternal(const FilePath& path);
+
+  // Initializes the database and notifies caller via callback when complete.

[dhollowa, 2013/03/15 18:56:21]

Please mention that callback is called synchronously on DB thread.

[Cait (Slow), 2013/03/15 20:43:59]

Done.

+  void InitDatabaseWithCallback(
+      const WebDatabaseService::InitCallback& callback);
+
+  // Opens the database file from the profile path, if an init has not yet been

[dhollowa, 2013/03/15 18:56:21]

Remove comma in "path, if".

[Cait (Slow), 2013/03/15 20:43:59]

Done.

+  // attempted. Separated from the constructor to ease construction/destruction
+  // of this object on one thread but database access on the DB thread. Returns
+  // the status of the database.
+  sql::InitStatus LoadDatabaseIfNecessary();
+
+  // Shuts down database. |should_reinit| tells us whether or not it should be
+  // possible to re-initialize the DB after the shutdown.
+  void ShutdownDatabase(bool should_reinit);
+
+  // Task wrappers to run database tasks.
+  void DBWriteTaskWrapper(
+      const WebDatabaseService::WriteTask& task,
+      scoped_ptr<WebDataRequest> request);
+  void DBReadTaskWrapper(
+      const WebDatabaseService::ReadTask& task,
+      scoped_ptr<WebDataRequest> request);
+
+  const scoped_refptr<WebDataRequestManager>& request_manager() {
+    return request_manager_; }

[dhollowa, 2013/03/15 18:56:21]

} on new line

[Cait (Slow), 2013/03/15 20:43:59]

Done.

+
+  WebDatabase* database() {return db_.get();}

[dhollowa, 2013/03/15 18:56:21]

nit: space after { and before }

[Cait (Slow), 2013/03/15 20:43:59]

Done.

+
+ private:
+  friend struct BrowserThread::DeleteOnThread<BrowserThread::DB>;
+  friend class base::DeleteHelper<WebDatabaseServiceInternal>;
+
+  virtual ~WebDatabaseServiceInternal();
+
+  // Commit the current transaction.
+  void Commit();
+
+  // Path to database file.
+  FilePath db_path_;
+
+  scoped_ptr<WebDatabase> db_;
+
+  // Keeps track of all pending requests made to the db.
+  scoped_refptr<WebDataRequestManager> request_manager_;
+
+  // State of database initialization. Used to prevent the executing of tasks
+  // before the db is ready.
+  sql::InitStatus init_status_;
+
+  // True if an attempt has been made to load the database (even if the attempt
+  // fails), used to avoid continually trying to reinit if the db init fails.
+  bool init_complete_;
+
+  // The application locale.  The locale is needed for some database migrations,
+  // and must be read on the UI thread.  It's cached here so that we can pass it
+  // to the migration code on the DB thread.
+  const std::string app_locale_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebDatabaseServiceInternal);
+};
+
+////////////////////////////////////////////////////////////////////////////////
+//
+// WebDatabaseServiceInternal implementation.
+//
+////////////////////////////////////////////////////////////////////////////////
+
+WebDatabaseServiceInternal::WebDatabaseServiceInternal(const FilePath& path)
+    : db_path_(path),
+      request_manager_(new WebDataRequestManager()),
+      init_status_(sql::INIT_FAILURE),
+      init_complete_(false),
+      app_locale_(AutofillCountry::ApplicationLocale()) {
+  db_.reset(NULL);

[dhollowa, 2013/03/15 18:56:21]

Not needed.

[Cait (Slow), 2013/03/15 20:43:59]

Done.

+}
+
+void WebDatabaseServiceInternal::InitDatabaseWithCallback(
+    const WebDatabaseService::InitCallback& callback) {
+  if (!callback.is_null()) {
+    callback.Run(LoadDatabaseIfNecessary());
+  }
+}
+
+sql::InitStatus WebDatabaseServiceInternal::LoadDatabaseIfNecessary() {
+  if (init_complete_ || db_path_.empty()) {
+    return init_status_;
+  }
+  init_complete_ = true;
+  db_.reset(new WebDatabase());
+  init_status_ = db_->Init(db_path_, app_locale_);
+  if (init_status_ != sql::INIT_OK) {
+    LOG(ERROR) << "Cannot initialize the web database: " << init_status_;
+    db_.reset(NULL);
+    return init_status_;
+  }
+
+  db_->BeginTransaction();
+  return init_status_;
+}
+
+void WebDatabaseServiceInternal::ShutdownDatabase(bool should_reinit) {
+  if (db_.get() && init_status_ == sql::INIT_OK)
+    db_->CommitTransaction();
+  db_.reset(NULL);
+  init_complete_ = !should_reinit; // Setting init_complete_ to true will ensure
+  // that the init sequence is not re-run.
+
+  init_status_ = sql::INIT_FAILURE;
+}
+
+void WebDatabaseServiceInternal::DBWriteTaskWrapper(
+    const WebDatabaseService::WriteTask& task,
+    scoped_ptr<WebDataRequest> request) {
+  LoadDatabaseIfNecessary();
+  if (db_.get() && init_status_ == sql::INIT_OK && !request->IsCancelled()) {
+    WebDatabase::State state = task.Run(db_.get());
+    if (state == WebDatabase::COMMIT_NEEDED)
+      Commit();
+  }
+  request_manager_->RequestCompleted(request.Pass());
+}
+
+void WebDatabaseServiceInternal::DBReadTaskWrapper(
+    const WebDatabaseService::ReadTask& task,
+    scoped_ptr<WebDataRequest> request) {
+  LoadDatabaseIfNecessary();
+  if (db_.get() && init_status_ == sql::INIT_OK && !request->IsCancelled()) {
+    request->SetResult(task.Run(db_.get()).Pass());
+  }
+  request_manager_->RequestCompleted(request.Pass());
+}
+
+WebDatabaseServiceInternal::~WebDatabaseServiceInternal() {
+  ShutdownDatabase(false);
+}
+
+void WebDatabaseServiceInternal::Commit() {
+  if (db_.get() && init_status_ == sql::INIT_OK) {
+      db_->CommitTransaction();
+      db_->BeginTransaction();
+  } else {
+    NOTREACHED() << "Commit scheduled after Shutdown()";
+  }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+WebDatabaseService::WebDatabaseService(const base::FilePath& path)
+    : path_(path) {
+  // WebDatabaseService should be instantiated on UI thread.
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  // WebDatabaseService requires DB thread if instantiated.
+  DCHECK(BrowserThread::IsWellKnownThread(BrowserThread::DB));
+}
+
+WebDatabaseService::~WebDatabaseService() {
+  wdbs_internal_ = NULL;

[dhollowa, 2013/03/15 18:56:21]

Not needed.

[Cait (Slow), 2013/03/15 20:43:59]

Done.

+}
+
+void WebDatabaseService::LoadDatabase(const InitCallback& callback) {
+  if (!wdbs_internal_) {

[dhollowa, 2013/03/15 18:56:21]

nit: No need for {}

[Cait (Slow), 2013/03/15 20:43:59]

Done.

+    wdbs_internal_ = new WebDatabaseServiceInternal(path_);
+  }
+  BrowserThread::PostTask(
+      BrowserThread::DB,
+      FROM_HERE,
+      Bind(&WebDatabaseServiceInternal::InitDatabaseWithCallback,
+           wdbs_internal_, callback));
+}
+
+void WebDatabaseService::UnloadDatabase() {
+  if (wdbs_internal_) {

[dhollowa, 2013/03/15 18:56:21]

Please change to the form:
  if (!wdbs_internal_)
    return;
  ... the rest ...

[Cait (Slow), 2013/03/15 20:43:59]

Done.

+    BrowserThread::PostTask(BrowserThread::DB, FROM_HERE,
+        Bind(&WebDatabaseServiceInternal::ShutdownDatabase,
+             wdbs_internal_, true));
+  }
+}
+
+void WebDatabaseService::ShutdownDatabase() {
+  if (wdbs_internal_) {

[dhollowa, 2013/03/15 18:56:21]

Please change to the form:
  if (!wdbs_internal_)
    return;
  ... the rest ...

[Cait (Slow), 2013/03/15 20:43:59]

Done.

+    BrowserThread::PostTask(BrowserThread::DB, FROM_HERE,
+        Bind(&WebDatabaseServiceInternal::ShutdownDatabase,
+             wdbs_internal_, false));
+  }
+}
+
+WebDatabase* WebDatabaseService::GetDatabase() const {

[dhollowa, 2013/03/15 18:56:21]

Consider changing these exceptional methods to *OnDB, eg. GetDatabaseOnDB.

[Cait (Slow), 2013/03/15 20:43:59]

Done. Changed WebDatabaseService method names. Will change WebDataService in a
later CL as it touches serveral files.

+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+  if (wdbs_internal_)

[dhollowa, 2013/03/15 18:56:21]

Please change to the form:
  if (!wdbs_internal_)
    return;
  ... the rest ...

[Cait (Slow), 2013/03/15 20:43:59]

Done.

+    return wdbs_internal_->database();
+  return NULL;
+}
+
+void WebDatabaseService::ScheduleDBTask(
+      const tracked_objects::Location& from_here,
+      const WriteTask& task) {
+  if (!wdbs_internal_) {
+    NOTREACHED() << "Task scheduled after Shutdown()";
+    return;
+  }
+
+  scoped_ptr<WebDataRequest> request(
+      new WebDataRequest(NULL, wdbs_internal_->request_manager()));
+
+  BrowserThread::PostTask(BrowserThread::DB, from_here,
+      Bind(&WebDatabaseServiceInternal::DBWriteTaskWrapper, wdbs_internal_,
+           task, base::Passed(&request)));
+}
+
+WebDataService::Handle WebDatabaseService::ScheduleDBTaskWithResult(
+      const tracked_objects::Location& from_here,
+      const ReadTask& task,
+      WebDataServiceConsumer* consumer) {
+  DCHECK(consumer);
+  WebDataService::Handle handle = 0;
+
+  if (!wdbs_internal_) {
+    NOTREACHED() << "Task scheduled after Shutdown()";
+    return handle;
+  }
+
+  scoped_ptr<WebDataRequest> request(
+      new WebDataRequest(consumer, wdbs_internal_->request_manager()));
+  handle = request->GetHandle();
+
+  BrowserThread::PostTask(BrowserThread::DB, from_here,
+      Bind(&WebDatabaseServiceInternal::DBReadTaskWrapper, wdbs_internal_,
+           task, base::Passed(&request)));
+
+  return handle;
+}
+
+void WebDatabaseService::CancelRequest(WebDataServiceBase::Handle h) {
+  if (wdbs_internal_)

[dhollowa, 2013/03/15 18:56:21]

Please change to the form:
  if (!wdbs_internal_)
    return;
  ... the rest ...

[Cait (Slow), 2013/03/15 20:43:59]

Done.

+    wdbs_internal_->request_manager()->CancelRequest(h);
+}