metricsd/serialization/serialization_utils.h

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef METRICS_SERIALIZATION_SERIALIZATION_UTILS_H_
#define METRICS_SERIALIZATION_SERIALIZATION_UTILS_H_

#include <string>

#include "base/memory/scoped_ptr.h"
#include "base/memory/scoped_vector.h"

namespace metrics {

class MetricSample;

// Metrics helpers to serialize and deserialize metrics collected by
// ChromeOS.
namespace SerializationUtils {

// Deserializes a sample passed as a string and return a sample.
// The return value will either be a scoped_ptr to a Metric sample (if the
// deserialization was successful) or a NULL scoped_ptr.
scoped_ptr<MetricSample> ParseSample(const std::string& sample);

// Reads all samples from a file. The file contents remain unchanged.
void ReadMetricsFromFile(const std::string& filename,
                         ScopedVector<MetricSample>* metrics);

// Reads all samples from a file and truncates the file when done.
void ReadAndTruncateMetricsFromFile(const std::string& filename,
                                    ScopedVector<MetricSample>* metrics);

// Serializes a sample and write it to filename.
// The format for the message is:
//  message_size, serialized_message
// where
//  * message_size is the total length of the message (message_size +
//    serialized_message) on 4 bytes
//  * serialized_message is the serialized version of sample (using ToString)
//
//  NB: the file will never leave the device so message_size will be written
//  with the architecture's endianness.
bool WriteMetricToFile(const MetricSample& sample, const std::string& filename);

// Maximum length of a serialized message
static const int kMessageMaxLength = 1024;

}  // namespace SerializationUtils
}  // namespace metrics

#endif  // METRICS_SERIALIZATION_SERIALIZATION_UTILS_H_