contacts: Add contacts::ContactDatabase.

chrome/browser/chromeos/contacts/contact_database.h

+// 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.
+
+#ifndef CHROME_BROWSER_CHROMEOS_CONTACTS_CONTACT_DATABASE_H_
+#define CHROME_BROWSER_CHROMEOS_CONTACTS_CONTACT_DATABASE_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/compiler_specific.h"
+#include "base/file_path.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
+#include "base/memory/weak_ptr.h"
+#include "base/synchronization/condition_variable.h"
+#include "base/synchronization/lock.h"
+
+namespace leveldb {
+class DB;
+}
+
+namespace contacts {
+
+class Contact;
+typedef std::vector<const Contact*> ContactPointers;
+
+// Interface for classes providing persistent storage of Contact objects.
+class ContactDatabaseInterface {
+ public:
+  // The parameter is true on success and false on failure.
+  typedef base::Callback<void(bool)> InitCallback;

[satorux1, 2012/07/30 17:15:07]

Having a parameter name would make it a bit more informative.

typedef base::Callback<void(bool success)> InitCallback;

[Daniel Erat, 2012/07/30 22:12:09]

Thanks, didn't know that this works!  Done.

+
+  // The parameter is true on success and false on failure.
+  typedef base::Callback<void(bool)> SaveCallback;
+
+  // The first parameter is true on success and false on failure.
+  typedef base::Callback<void(bool, scoped_ptr<ScopedVector<Contact> >)>
+      LoadCallback;
+
+  ContactDatabaseInterface() {}
+
+  // Destruction blocks until all outstanding file operations are complete.
+  virtual ~ContactDatabaseInterface() {}
+
+  // Asynchronously initializes the object.  |callback| will be invoked on the
+  // UI thread when complete.
+  virtual void Init(const FilePath& database_dir, InitCallback callback) = 0;
+
+  // Asynchronously saves |contacts| to the database.  If |is_full_update| is
+  // true, all existing contacts in the database not present in |contacts| will
+  // be removed.  |callback| will be invoked on the UI thread when complete.
+  // The caller must not make changes to the underlying passed-in Contact
+  // objects until the callback has been invoked.
+  virtual void SaveContacts(scoped_ptr<ContactPointers> contacts,
+                            bool is_full_update,
+                            SaveCallback callback) = 0;
+
+  // Asynchronously loads all contacts from the database and invokes |callback|
+  // when complete.
+  virtual void LoadContacts(LoadCallback callback) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ContactDatabaseInterface);
+};
+
+class ContactDatabase : public ContactDatabaseInterface,
+                        public base::SupportsWeakPtr<ContactDatabase> {
+ public:
+  ContactDatabase();
+  virtual ~ContactDatabase();
+
+  // ContactDatabaseInterface implementation.
+  virtual void Init(const FilePath& database_dir,
+                    InitCallback callback) OVERRIDE;
+  virtual void SaveContacts(scoped_ptr<ContactPointers> contacts,
+                            bool is_full_update,
+                            SaveCallback callback) OVERRIDE;
+  virtual void LoadContacts(LoadCallback callback) OVERRIDE;
+
+ private:
+  // Initializes the database in |database_dir| and posts |callback| on the UI
+  // thread with the result.
+  void InitOnFileThread(const FilePath& database_dir, InitCallback callback);
+
+  // Helper method called by InitOnFileThread().  Returns true on success.
+  bool InitInternal(const FilePath& database_dir);
+
+  // Saves |contacts| to disk and invokes |callback| on the UI thread when
+  // complete.
+  void SaveContactsOnFileThread(scoped_ptr<ContactPointers> contacts,
+                                bool is_full_update,
+                                SaveCallback callback);
+
+  // Loads contacts from disk and passes them to |callback| on the UI thread
+  // when complete.
+  void LoadContactsOnFileThread(LoadCallback callback);
+
+  // Helper method called by LoadContactsOnFileThread().  Returns true on
+  // success.
+  bool LoadContactsInternal(ScopedVector<Contact>* contacts);
+
+  // Increments or decrements |num_outstanding_file_operations_|.
+  void IncrementOutstandingFileOperations();
+  void DecrementOutstandingFileOperations();
+
+  scoped_ptr<leveldb::DB> db_;
+
+  // Protects |num_outstanding_file_operations_|.
+  base::Lock lock_;
+
+  // Signals on |lock_| when a file operation completes.
+  base::ConditionVariable condition_variable_;

[satorux1, 2012/07/30 17:15:07]

I'm very wary of Lock and friends. Can you go without them?

Here's some background:

In GDataFileSystem, Lock and WaitableEvent were used, and these were a source of
super nasty issues, so we decided to get rid of them and it took a huge amount
of work. Once these are gone, everyone was happy.

[Daniel Erat, 2012/07/30 22:12:09]

Done.

+
+  // Number of pending or in-progress operations on the file thread.
+  int num_outstanding_file_operations_;
+
+  DISALLOW_COPY_AND_ASSIGN(ContactDatabase);
+};
+
+}  // namespace contacts
+
+#endif  // CHROME_BROWSER_CHROMEOS_CONTACTS_CONTACT_DATABASE_H_