97 lines
2.7 KiB
C++
97 lines
2.7 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "persistent_integer.h"
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#include <fcntl.h>
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#include <base/logging.h>
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#include <base/posix/eintr_wrapper.h>
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#include "constants.h"
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namespace chromeos_metrics {
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PersistentInteger::PersistentInteger(const std::string& name,
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const base::FilePath& directory)
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: value_(0),
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version_(kVersion),
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name_(name),
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backing_file_path_(directory.Append(name_)),
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synced_(false) {}
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PersistentInteger::~PersistentInteger() {}
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void PersistentInteger::Set(int64_t value) {
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value_ = value;
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Write();
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}
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int64_t PersistentInteger::Get() {
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// If not synced, then read. If the read fails, it's a good idea to write.
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if (!synced_ && !Read())
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Write();
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return value_;
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}
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int64_t PersistentInteger::GetAndClear() {
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int64_t v = Get();
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Set(0);
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return v;
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}
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void PersistentInteger::Add(int64_t x) {
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Set(Get() + x);
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}
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void PersistentInteger::Write() {
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int fd = HANDLE_EINTR(open(backing_file_path_.value().c_str(),
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O_WRONLY | O_CREAT | O_TRUNC,
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S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH));
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PCHECK(fd >= 0) << "cannot open " << backing_file_path_.value()
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<< " for writing";
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PCHECK((HANDLE_EINTR(write(fd, &version_, sizeof(version_))) ==
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sizeof(version_)) &&
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(HANDLE_EINTR(write(fd, &value_, sizeof(value_))) ==
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sizeof(value_)))
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<< "cannot write to " << backing_file_path_.value();
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close(fd);
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synced_ = true;
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}
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bool PersistentInteger::Read() {
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int fd = HANDLE_EINTR(open(backing_file_path_.value().c_str(), O_RDONLY));
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if (fd < 0) {
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PLOG(WARNING) << "cannot open " << backing_file_path_.value()
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<< " for reading";
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return false;
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}
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int32_t version;
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int64_t value;
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bool read_succeeded = false;
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if (HANDLE_EINTR(read(fd, &version, sizeof(version))) == sizeof(version) &&
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version == version_ &&
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HANDLE_EINTR(read(fd, &value, sizeof(value))) == sizeof(value)) {
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value_ = value;
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read_succeeded = true;
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synced_ = true;
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}
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close(fd);
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return read_succeeded;
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}
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} // namespace chromeos_metrics
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