1 // Copyright 2014 The Chromium Authors 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef COMPONENTS_METRICS_SERIALIZATION_SERIALIZATION_UTILS_H_ 6 #define COMPONENTS_METRICS_SERIALIZATION_SERIALIZATION_UTILS_H_ 7 8 #include <memory> 9 #include <string> 10 #include <vector> 11 12 namespace metrics { 13 14 class MetricSample; 15 16 // Metrics helpers to serialize and deserialize metrics collected by 17 // ChromeOS. 18 namespace SerializationUtils { 19 20 // If there are more than 100,000 messages in the file, discard the remaining 21 // messages to avoid running out of memory. 22 extern const int kMaxMessagesPerRead; 23 24 // Deserializes a sample passed as a string and return a sample. 25 // The return value will either be a scoped_ptr to a Metric sample (if the 26 // deserialization was successful) or a nullptr scoped_ptr. 27 std::unique_ptr<MetricSample> ParseSample(const std::string& sample); 28 29 // Reads all samples from a file and truncate the file when done. 30 void ReadAndTruncateMetricsFromFile( 31 const std::string& filename, 32 std::vector<std::unique_ptr<MetricSample>>* metrics); 33 34 // Serializes a sample and write it to filename. 35 // The format for the message is: 36 // message_size, serialized_message 37 // where 38 // * message_size is the total length of the message (message_size + 39 // serialized_message) on 4 bytes 40 // * serialized_message is the serialized version of sample (using ToString) 41 // 42 // NB: the file will never leave the device so message_size will be written 43 // with the architecture's endianness. 44 bool WriteMetricToFile(const MetricSample& sample, const std::string& filename); 45 46 // Maximum length of a serialized message 47 static const size_t kMessageMaxLength = 1024; 48 49 } // namespace SerializationUtils 50 } // namespace metrics 51 52 #endif // COMPONENTS_METRICS_SERIALIZATION_SERIALIZATION_UTILS_H_ 53