vitastor/blockstore_journal.cpp

#include "blockstore.h"

blockstore_journal_check_t::blockstore_journal_check_t(blockstore *bs)
{
    this->bs = bs;
    sectors_required = 0;
    next_pos = bs->journal.next_free;
    next_sector = bs->journal.cur_sector;
    next_in_pos = bs->journal.in_sector_pos;
    right_dir = next_pos >= bs->journal.used_start;
}

// Check if we can write <required> entries of <size> bytes and <data_after> data bytes after them to the journal
int blockstore_journal_check_t::check_available(blockstore_operation *op, int required, int size, int data_after)
{
    while (1)
    {
        int fits = (512 - next_in_pos) / size;
        if (fits > 0)
        {
            required -= fits;
            next_in_pos += fits * size;
            sectors_required++;
        }
        if (required <= 0)
        {
            break;
        }
        next_pos = next_pos+512;
        if (next_pos >= bs->journal.len)
        {
            next_pos = 512;
            right_dir = false;
        }
        next_in_pos = 0;
        if (bs->journal.sector_info[next_sector].usage_count > 0)
        {
            next_sector = ((next_sector + 1) % bs->journal.sector_count);
        }
        if (bs->journal.sector_info[next_sector].usage_count > 0)
        {
            // No memory buffer available. Wait for it.
            op->wait_for = WAIT_JOURNAL_BUFFER;
            return 0;
        }
    }
    if (data_after > 0)
    {
        next_pos = next_pos + data_after;
        if (next_pos > bs->journal.len)
        {
            next_pos = 512 + data_after;
            right_dir = false;
        }
    }
    if (!right_dir && next_pos >= bs->journal.used_start-512)
    {
        // No space in the journal. Wait until used_start changes.
        op->wait_for = WAIT_JOURNAL;
        op->wait_detail = bs->journal.used_start;
        return 0;
    }
    return 1;
}

journal_entry* prefill_single_journal_entry(journal_t & journal, uint16_t type, uint32_t size)
{
    if (512 - journal.in_sector_pos < size)
    {
        // Move to the next journal sector
        if (journal.sector_info[journal.cur_sector].usage_count > 0)
        {
            // Also select next sector buffer in memory
            journal.cur_sector = ((journal.cur_sector + 1) % journal.sector_count);
        }
        journal.sector_info[journal.cur_sector].offset = journal.next_free;
        journal.in_sector_pos = 0;
        journal.next_free = (journal.next_free+512) < journal.len ? journal.next_free + 512 : 512;
        memset(journal.inmemory
            ? journal.buffer + journal.sector_info[journal.cur_sector].offset
            : journal.sector_buf + 512*journal.cur_sector, 0, 512);
    }
    journal_entry *je = (struct journal_entry*)(
        (journal.inmemory
            ? journal.buffer + journal.sector_info[journal.cur_sector].offset
            : journal.sector_buf + 512*journal.cur_sector) + journal.in_sector_pos
    );
    journal.in_sector_pos += size;
    je->magic = JOURNAL_MAGIC;
    je->type = type;
    je->size = size;
    je->crc32_prev = journal.crc32_last;
    return je;
}

void prepare_journal_sector_write(journal_t & journal, io_uring_sqe *sqe, std::function<void(ring_data_t*)> cb)
{
    journal.sector_info[journal.cur_sector].usage_count++;
    ring_data_t *data = ((ring_data_t*)sqe->user_data);
    data->iov = (struct iovec){
        (journal.inmemory
            ? journal.buffer + journal.sector_info[journal.cur_sector].offset
            : journal.sector_buf + 512*journal.cur_sector),
        512
    };
    data->callback = cb;
    my_uring_prep_writev(
        sqe, journal.fd, &data->iov, 1, journal.offset + journal.sector_info[journal.cur_sector].offset
    );
}

journal_t::~journal_t()
{
    if (sector_buf)
        free(sector_buf);
    if (sector_info)
        free(sector_info);
    if (buffer)
        free(buffer);
    sector_buf = NULL;
    sector_info = NULL;
    buffer = NULL;
}