blob: 5b159c7f9c33ce490eaa1817aa9a4931458bf14a [file] [log] [blame]
// Copyright (c) 2014 The Chromium OS 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 <base/basictypes.h>
#include <string>
namespace chromeos_metrics {
// PersistentIntegers is a named 64-bit integer value backed by a file.
// The in-memory value acts as a write-through cache of the file value.
// If the backing file doesn't exist or has bad content, the value is 0.
class PersistentInteger {
PersistentInteger(const std::string& name);
// Virtual only because of mock.
virtual ~PersistentInteger();
// Sets the value. This writes through to the backing file.
void Set(int64 v);
// Gets the value. May sync from backing file first.
int64 Get();
// Returns the name of the object.
std::string Name() { return name_; }
// Convenience function for Get() followed by Set(0).
int64 GetAndClear();
// Convenience function for v = Get, Set(v + x).
// Virtual only because of mock.
virtual void Add(int64 x);
// After calling with |testing| = true, changes some behavior for the purpose
// of testing. For instance: instances created while testing use the current
// directory for the backing files.
static void SetTestingMode(bool testing);
static const int kVersion = 1001;
// Writes |value_| to the backing file, creating it if necessary.
void Write();
// Reads the value from the backing file, stores it in |value_|, and returns
// true if the backing file is valid. Returns false otherwise, and creates
// a valid backing file as a side effect.
bool Read();
int64 value_;
int32 version_;
std::string name_;
std::string backing_file_name_;
bool synced_;
static bool testing_;