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         const uint8_t* data_byte_ptr = (uint8_t*)data;
 139         uint64_t remaining_samples = samples;
 140         uint64_t data_offset = 0;
 141
 142         do {
 143                 uint64_t copy_count = 0;
 144
 145                 if (remaining_samples <= unused_samples_) {
 146                         // All samples fit into the current chunk
 147                         copy_count = remaining_samples;
 148                 } else {
 149                         // Only a part of the samples fit, fill up current chunk
 150                         copy_count = unused_samples_;
 151                 }
 152
 153                 const uint8_t* dest = &(current_chunk_[used_samples_ * unit_size_]);
 154                 const uint8_t* src = &(data_byte_ptr[data_offset]);
 155                 memcpy((void*)dest, (void*)src, (copy_count * unit_size_));
 156
 157                 used_samples_ += copy_count;
 158                 unused_samples_ -= copy_count;
 159                 remaining_samples -= copy_count;
 160                 data_offset += (copy_count * unit_size_);
 161
 162                 if (unused_samples_ == 0) {
 163                         // If we're out of memory, this will throw std::bad_alloc
 164                         current_chunk_ = new uint8_t[chunk_size_];
 165                         data_chunks_.push_back(current_chunk_);
 166                         used_samples_ = 0;
 167                         unused_samples_ = chunk_size_ / unit_size_;
 168                 }
 169         } while (remaining_samples > 0);
 170
 171         sample_count_ += samples;
 172 }
 173
 174 uint8_t* Segment::get_raw_samples(uint64_t start, uint64_t count) const
 175 {
 176         assert(start < sample_count_);
 177         assert(start + count <= sample_count_);
 178         assert(count > 0);
 179
 180         lock_guard<recursive_mutex> lock(mutex_);
 181
 182         uint8_t* dest = new uint8_t[count * unit_size_];
 183         uint8_t* dest_ptr = dest;
 184
 185         uint64_t chunk_num = (start * unit_size_) / chunk_size_;
 186         uint64_t chunk_offs = (start * unit_size_) % chunk_size_;
 187
 188         while (count > 0) {
 189                 const uint8_t* chunk = data_chunks_[chunk_num];
 190
 191                 uint64_t copy_size = min(count * unit_size_,
 192                         chunk_size_ - chunk_offs);
 193
 194                 memcpy(dest_ptr, chunk + chunk_offs, copy_size);
 195
 196                 dest_ptr += copy_size;
 197                 count -= (copy_size / unit_size_);
 198
 199                 chunk_num++;
 200                 chunk_offs = 0;
 201         }
 202
 203         return dest;
 204 }
 205
 206 SegmentRawDataIterator* Segment::begin_raw_sample_iteration(uint64_t start)
 207 {
 208         SegmentRawDataIterator* it = new SegmentRawDataIterator;
 209
 210         assert(start < sample_count_);
 211
 212         iterator_count_++;
 213
 214         it->sample_index = start;
 215         it->chunk_num = (start * unit_size_) / chunk_size_;
 216         it->chunk_offs = (start * unit_size_) % chunk_size_;
 217         it->chunk = data_chunks_[it->chunk_num];
 218         it->value = it->chunk + it->chunk_offs;
 219
 220         return it;
 221 }
 222
 223 void Segment::continue_raw_sample_iteration(SegmentRawDataIterator* it, uint64_t increase)
 224 {
 225         // Fail gracefully if we are asked to deliver data we don't have
 226         if (it->sample_index > sample_count_)
 227                 return;
 228
 229         it->sample_index += increase;
 230         it->chunk_offs += (increase * unit_size_);
 231
 232         if (it->chunk_offs > (chunk_size_ - 1)) {
 233                 it->chunk_num++;
 234                 it->chunk_offs -= chunk_size_;
 235                 it->chunk = data_chunks_[it->chunk_num];
 236         }
 237
 238         it->value = it->chunk + it->chunk_offs;
 239 }
 240
 241 void Segment::end_raw_sample_iteration(SegmentRawDataIterator* it)
 242 {
 243         delete it;
 244
 245         iterator_count_--;
 246
 247         if ((iterator_count_ == 0) && mem_optimization_requested_) {
 248                 mem_optimization_requested_ = false;
 249                 free_unused_memory();
 250         }
 251 }
 252
 253 } // namespace data
 254 } // namespace pv