Method FindFilesToPrune

src/node/blockstorage.cpp:139–196

}

void BlockManager::FindFilesToPrune(std::set<int>& setFilesToPrune, uint64_t nPruneAfterHeight, int chain_tip_height, int prune_height, bool is_ibd)
{
    LOCK2(cs_main, cs_LastBlockFile);
    if (chain_tip_height < 0 || nPruneTarget == 0) {
        return;
    }
    if ((uint64_t)chain_tip_height <= nPruneAfterHeight) {
        return;
    }

    unsigned int nLastBlockWeCanPrune{(unsigned)std::min(prune_height, chain_tip_height - static_cast<int>(MIN_BLOCKS_TO_KEEP))};
    uint64_t nCurrentUsage = CalculateCurrentUsage();
    // We don't check to prune until after we've allocated new space for files
    // So we should leave a buffer under our target to account for another allocation
    // before the next pruning.
    uint64_t nBuffer = BLOCKFILE_CHUNK_SIZE + UNDOFILE_CHUNK_SIZE;
    uint64_t nBytesToPrune;
    int count = 0;

    if (nCurrentUsage + nBuffer >= nPruneTarget) {
        // On a prune event, the chainstate DB is flushed.
        // To avoid excessive prune events negating the benefit of high dbcache
        // values, we should not prune too rapidly.
        // So when pruning in IBD, increase the buffer a bit to avoid a re-prune too soon.
        if (is_ibd) {
            // Since this is only relevant during IBD, we use a fixed 10%
            nBuffer += nPruneTarget / 10;
        }

        for (int fileNumber = 0; fileNumber < m_last_blockfile; fileNumber++) {
            nBytesToPrune = m_blockfile_info[fileNumber].nSize + m_blockfile_info[fileNumber].nUndoSize;

            if (m_blockfile_info[fileNumber].nSize == 0) {
                continue;
            }

            if (nCurrentUsage + nBuffer < nPruneTarget) { // are we below our target?
                break;
            }

            // don't prune files that could have a block within MIN_BLOCKS_TO_KEEP of the main chain's tip but keep scanning
            if (m_blockfile_info[fileNumber].nHeightLast > nLastBlockWeCanPrune) {
                continue;
            }

            PruneOneBlockFile(fileNumber);
            // Queue up the files for removal
            setFilesToPrune.insert(fileNumber);
            nCurrentUsage -= nBytesToPrune;
            count++;
        }
    }

    LogPrint(BCLog::PRUNE, "Prune: target=%dMiB actual=%dMiB diff=%dMiB max_prune_height=%d removed %d blk/rev pairs\n",
           nPruneTarget/1024/1024, nCurrentUsage/1024/1024,
           ((int64_t)nPruneTarget - (int64_t)nCurrentUsage)/1024/1024,
           nLastBlockWeCanPrune, count);
}