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// 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 "persistent_integer.h"
#include <fcntl.h>
#include <base/logging.h>
#include <base/posix/eintr_wrapper.h>
#include "constants.h"
#include "metrics/metrics_library.h"
namespace chromeos_metrics {
// Static class member instantiation.
bool PersistentInteger::testing_ = false;
PersistentInteger::PersistentInteger(const std::string& name) :
value_(0),
version_(kVersion),
name_(name),
synced_(false) {
if (testing_) {
backing_file_name_ = name_;
} else {
backing_file_name_ = metrics::kMetricsDirectory + name_;
}
}
PersistentInteger::~PersistentInteger() {}
void PersistentInteger::Set(int64_t value) {
value_ = value;
Write();
}
int64_t PersistentInteger::Get() {
// If not synced, then read. If the read fails, it's a good idea to write.
if (!synced_ && !Read())
Write();
return value_;
}
int64_t PersistentInteger::GetAndClear() {
int64_t v = Get();
Set(0);
return v;
}
void PersistentInteger::Add(int64_t x) {
Set(Get() + x);
}
void PersistentInteger::Write() {
int fd = HANDLE_EINTR(open(backing_file_name_.c_str(),
O_WRONLY | O_CREAT | O_TRUNC,
S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH));
PCHECK(fd >= 0) << "cannot open " << backing_file_name_ << " for writing";
PCHECK((HANDLE_EINTR(write(fd, &version_, sizeof(version_))) ==
sizeof(version_)) &&
(HANDLE_EINTR(write(fd, &value_, sizeof(value_))) ==
sizeof(value_)))
<< "cannot write to " << backing_file_name_;
close(fd);
synced_ = true;
}
bool PersistentInteger::Read() {
int fd = HANDLE_EINTR(open(backing_file_name_.c_str(), O_RDONLY));
if (fd < 0) {
PLOG(WARNING) << "cannot open " << backing_file_name_ << " for reading";
return false;
}
int32_t version;
int64_t value;
bool read_succeeded = false;
if (HANDLE_EINTR(read(fd, &version, sizeof(version))) == sizeof(version) &&
version == version_ &&
HANDLE_EINTR(read(fd, &value, sizeof(value))) == sizeof(value)) {
value_ = value;
read_succeeded = true;
synced_ = true;
}
close(fd);
return read_succeeded;
}
void PersistentInteger::SetTestingMode(bool testing) {
testing_ = testing;
}
} // namespace chromeos_metrics
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