pv/data/segment.cpp

   1 /*
   2  * This file is part of the PulseView project.
   3  *
   4  * Copyright (C) 2017 Soeren Apel <soeren@apelpie.net>
   5  * Copyright (C) 2012 Joel Holdsworth <joel@airwebreathe.org.uk>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include "segment.hpp"
  22
  23 #include <cassert>
  24 #include <cstdlib>
  25 #include <cstring>
  26
  27 using std::lock_guard;
  28 using std::min;
  29 using std::recursive_mutex;
  30
  31 namespace pv {
  32 namespace data {
  33
  34 const uint64_t Segment::MaxChunkSize = 10*1024*1024;  /* 10MiB */
  35
  36 Segment::Segment(uint64_t samplerate, unsigned int unit_size) :
  37         sample_count_(0),
  38         start_time_(0),
  39         samplerate_(samplerate),
  40         unit_size_(unit_size),
  41         iterator_count_(0),
  42         mem_optimization_requested_(false)
  43 {
  44         lock_guard<recursive_mutex> lock(mutex_);
  45         assert(unit_size_ > 0);
  46
  47         // Determine the number of samples we can fit in one chunk
  48         // without exceeding MaxChunkSize
  49         chunk_size_ = min(MaxChunkSize, (MaxChunkSize / unit_size_) * unit_size_);
  50
  51         // Create the initial chunk
  52         current_chunk_ = new uint8_t[chunk_size_];
  53         data_chunks_.push_back(current_chunk_);
  54         used_samples_ = 0;
  55         unused_samples_ = chunk_size_ / unit_size_;
  56 }
  57
  58 Segment::~Segment()
  59 {
  60         lock_guard<recursive_mutex> lock(mutex_);
  61
  62         for (uint8_t* chunk : data_chunks_)
  63                 delete[] chunk;
  64 }
  65
  66 uint64_t Segment::get_sample_count() const
  67 {
  68         lock_guard<recursive_mutex> lock(mutex_);
  69         return sample_count_;
  70 }
  71
  72 const pv::util::Timestamp& Segment::start_time() const
  73 {
  74         return start_time_;
  75 }
  76
  77 double Segment::samplerate() const
  78 {
  79         return samplerate_;
  80 }
  81
  82 void Segment::set_samplerate(double samplerate)
  83 {
  84         samplerate_ = samplerate;
  85 }
  86
  87 unsigned int Segment::unit_size() const
  88 {
  89         return unit_size_;
  90 }
  91
  92 void Segment::free_unused_memory()
  93 {
  94         lock_guard<recursive_mutex> lock(mutex_);
  95
  96         // Do not mess with the data chunks if we have iterators pointing at them
  97         if (iterator_count_ > 0) {
  98                 mem_optimization_requested_ = true;
  99                 return;
 100         }
 101
 102         // No more data will come in, so re-create the last chunk accordingly
 103         uint8_t* resized_chunk = new uint8_t[used_samples_ * unit_size_];
 104         memcpy(resized_chunk, current_chunk_, used_samples_ * unit_size_);
 105
 106         delete[] current_chunk_;
 107         current_chunk_ = resized_chunk;
 108
 109         data_chunks_.pop_back();
 110         data_chunks_.push_back(resized_chunk);
 111 }
 112
 113 void Segment::append_single_sample(void *data)
 114 {
 115         lock_guard<recursive_mutex> lock(mutex_);
 116
 117         // There will always be space for at least one sample in
 118         // the current chunk, so we do not need to test for space
 119
 120         memcpy(current_chunk_ + (used_samples_ * unit_size_), data, unit_size_);
 121         used_samples_++;
 122         unused_samples_--;
 123
 124         if (unused_samples_ == 0) {
 125                 current_chunk_ = new uint8_t[chunk_size_];
 126                 data_chunks_.push_back(current_chunk_);
 127                 used_samples_ = 0;
 128                 unused_samples_ = chunk_size_ / unit_size_;
 129         }
 130
 131         sample_count_++;
 132 }
 133
 134 void Segment::append_samples(void* data, uint64_t samples)
 135 {
 136         lock_guard<recursive_mutex> lock(mutex_);
 137
 138         if (unused_samples_ >= samples) {
 139                 // All samples fit into the current chunk
 140                 memcpy(current_chunk_ + (used_samples_ * unit_size_),
 141                         data, (samples * unit_size_));
 142                 used_samples_ += samples;
 143                 unused_samples_ -= samples;
 144         } else {
 145                 // Only a part of the samples fit, split data up between chunks
 146                 memcpy(current_chunk_ + (used_samples_ * unit_size_),
 147                         data, (unused_samples_ * unit_size_));
 148                 const uint64_t remaining_samples = samples - unused_samples_;
 149
 150                 // If we're out of memory, this will throw std::bad_alloc
 151                 current_chunk_ = new uint8_t[chunk_size_];
 152                 data_chunks_.push_back(current_chunk_);
 153                 memcpy(current_chunk_, (uint8_t*)data + (unused_samples_ * unit_size_),
 154                         (remaining_samples * unit_size_));
 155
 156                 used_samples_ = remaining_samples;
 157                 unused_samples_ = (chunk_size_ / unit_size_) - remaining_samples;
 158         }
 159
 160         if (unused_samples_ == 0) {
 161                 // If we're out of memory, this will throw std::bad_alloc
 162                 current_chunk_ = new uint8_t[chunk_size_];
 163                 data_chunks_.push_back(current_chunk_);
 164                 used_samples_ = 0;
 165                 unused_samples_ = chunk_size_ / unit_size_;
 166         }
 167
 168         sample_count_ += samples;
 169 }
 170
 171 uint8_t* Segment::get_raw_samples(uint64_t start, uint64_t count) const
 172 {
 173         assert(start < sample_count_);
 174         assert(start + count <= sample_count_);
 175         assert(count > 0);
 176
 177         lock_guard<recursive_mutex> lock(mutex_);
 178
 179         uint8_t* dest = new uint8_t[count * unit_size_];
 180         uint8_t* dest_ptr = dest;
 181
 182         uint64_t chunk_num = (start * unit_size_) / chunk_size_;
 183         uint64_t chunk_offs = (start * unit_size_) % chunk_size_;
 184
 185         while (count > 0) {
 186                 const uint8_t* chunk = data_chunks_[chunk_num];
 187
 188                 uint64_t copy_size = min(count * unit_size_,
 189                         chunk_size_ - chunk_offs);
 190
 191                 memcpy(dest_ptr, chunk + chunk_offs, copy_size);
 192
 193                 dest_ptr += copy_size;
 194                 count -= (copy_size / unit_size_);
 195
 196                 chunk_num++;
 197                 chunk_offs = 0;
 198         }
 199
 200         return dest;
 201 }
 202
 203 SegmentRawDataIterator* Segment::begin_raw_sample_iteration(uint64_t start)
 204 {
 205         SegmentRawDataIterator* it = new SegmentRawDataIterator;
 206
 207         assert(start < sample_count_);
 208
 209         iterator_count_++;
 210
 211         it->sample_index = start;
 212         it->chunk_num = (start * unit_size_) / chunk_size_;
 213         it->chunk_offs = (start * unit_size_) % chunk_size_;
 214         it->chunk = data_chunks_[it->chunk_num];
 215         it->value = it->chunk + it->chunk_offs;
 216
 217         return it;
 218 }
 219
 220 void Segment::continue_raw_sample_iteration(SegmentRawDataIterator* it, uint64_t increase)
 221 {
 222         lock_guard<recursive_mutex> lock(mutex_);
 223
 224         // Fail gracefully if we are asked to deliver data we don't have
 225         if (it->sample_index > sample_count_)
 226                 return;
 227
 228         it->sample_index += increase;
 229         it->chunk_offs += (increase * unit_size_);
 230
 231         if (it->chunk_offs > (chunk_size_ - 1)) {
 232                 it->chunk_num++;
 233                 it->chunk_offs -= chunk_size_;
 234                 it->chunk = data_chunks_[it->chunk_num];
 235         }
 236
 237         it->value = it->chunk + it->chunk_offs;
 238 }
 239
 240 void Segment::end_raw_sample_iteration(SegmentRawDataIterator* it)
 241 {
 242         delete it;
 243
 244         iterator_count_--;
 245
 246         if ((iterator_count_ == 0) && mem_optimization_requested_) {
 247                 mem_optimization_requested_ = false;
 248                 free_unused_memory();
 249         }
 250 }
 251
 252 } // namespace data
 253 } // namespace pv