00001 /* 00002 * Copyright 2016 The Cartographer Authors 00003 * 00004 * Licensed under the Apache License, Version 2.0 (the "License"); 00005 * you may not use this file except in compliance with the License. 00006 * You may obtain a copy of the License at 00007 * 00008 * http://www.apache.org/licenses/LICENSE-2.0 00009 * 00010 * Unless required by applicable law or agreed to in writing, software 00011 * distributed under the License is distributed on an "AS IS" BASIS, 00012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00013 * See the License for the specific language governing permissions and 00014 * limitations under the License. 00015 */ 00016 00017 #ifndef CARTOGRAPHER_COMMON_FIXED_RATIO_SAMPLER_H_ 00018 #define CARTOGRAPHER_COMMON_FIXED_RATIO_SAMPLER_H_ 00019 00020 #include <string> 00021 00022 #include "cartographer/common/port.h" 00023 00024 namespace cartographer { 00025 namespace common { 00026 00027 // Signals when a sample should be taken from a stream of data to select a 00028 // uniformly distributed fraction of the data. 00029 class FixedRatioSampler { 00030 public: 00031 explicit FixedRatioSampler(double ratio); 00032 ~FixedRatioSampler(); 00033 00034 FixedRatioSampler(const FixedRatioSampler&) = delete; 00035 FixedRatioSampler& operator=(const FixedRatioSampler&) = delete; 00036 00037 // Returns true if this pulse should result in an sample. 00038 bool Pulse(); 00039 00040 // Returns a debug string describing the current ratio of samples to pulses. 00041 std::string DebugString(); 00042 00043 private: 00044 // Sampling occurs if the proportion of samples to pulses drops below this 00045 // number. 00046 const double ratio_; 00047 00048 int64 num_pulses_ = 0; 00049 int64 num_samples_ = 0; 00050 }; 00051 00052 } // namespace common 00053 } // namespace cartographer 00054 00055 #endif // CARTOGRAPHER_COMMON_FIXED_RATIO_SAMPLER_H_