| 1329 | // --------------------------------------------------------------------------- |
| 1330 | |
| 1331 | size_t NetworkFile::read(void *buffer, size_t sizeBytes) { |
| 1332 | |
| 1333 | if (sizeBytes == 0) |
| 1334 | return 0; |
| 1335 | |
| 1336 | auto iterOffset = m_pos; |
| 1337 | while (sizeBytes) { |
| 1338 | const auto chunkIdxToDownload = iterOffset / DOWNLOAD_CHUNK_SIZE; |
| 1339 | const auto offsetToDownload = chunkIdxToDownload * DOWNLOAD_CHUNK_SIZE; |
| 1340 | std::vector<unsigned char> region; |
| 1341 | auto pChunk = gNetworkChunkCache.get(m_ctx, m_url, chunkIdxToDownload); |
| 1342 | if (pChunk != nullptr) { |
| 1343 | region = *pChunk; |
| 1344 | } else { |
| 1345 | if (offsetToDownload == m_lastDownloadedOffset) { |
| 1346 | // In case of consecutive reads (of small size), we use a |
| 1347 | // heuristic that we will read the file sequentially, so |
| 1348 | // we double the requested size to decrease the number of |
| 1349 | // client/server roundtrips. |
| 1350 | if (m_nBlocksToDownload < 100) |
| 1351 | m_nBlocksToDownload *= 2; |
| 1352 | } else { |
| 1353 | // Random reads. Cancel the above heuristics. |
| 1354 | m_nBlocksToDownload = 1; |
| 1355 | } |
| 1356 | |
| 1357 | // Ensure that we will request at least the number of blocks |
| 1358 | // to satisfy the remaining buffer size to read. |
| 1359 | const auto endOffsetToDownload = |
| 1360 | ((iterOffset + sizeBytes + DOWNLOAD_CHUNK_SIZE - 1) / |
| 1361 | DOWNLOAD_CHUNK_SIZE) * |
| 1362 | DOWNLOAD_CHUNK_SIZE; |
| 1363 | const auto nMinBlocksToDownload = static_cast<size_t>( |
| 1364 | (endOffsetToDownload - offsetToDownload) / DOWNLOAD_CHUNK_SIZE); |
| 1365 | if (m_nBlocksToDownload < nMinBlocksToDownload) |
| 1366 | m_nBlocksToDownload = nMinBlocksToDownload; |
| 1367 | |
| 1368 | // Avoid reading already cached data. |
| 1369 | // Note: this might get evicted if concurrent reads are done, but |
| 1370 | // this should not cause bugs. Just missed optimization. |
| 1371 | for (size_t i = 1; i < m_nBlocksToDownload; i++) { |
| 1372 | if (gNetworkChunkCache.get(m_ctx, m_url, |
| 1373 | chunkIdxToDownload + i) != nullptr) { |
| 1374 | m_nBlocksToDownload = i; |
| 1375 | break; |
| 1376 | } |
| 1377 | } |
| 1378 | |
| 1379 | if (m_nBlocksToDownload > MAX_CHUNKS) |
| 1380 | m_nBlocksToDownload = MAX_CHUNKS; |
| 1381 | |
| 1382 | region.resize(m_nBlocksToDownload * DOWNLOAD_CHUNK_SIZE); |
| 1383 | size_t nRead = 0; |
| 1384 | std::string errorBuffer; |
| 1385 | errorBuffer.resize(1024); |
| 1386 | if (!m_handle) { |
| 1387 | m_handle = m_ctx->networking.open( |
| 1388 | m_ctx, m_url.c_str(), offsetToDownload, |
nothing calls this directly
no test coverage detected