Simplified distributed block storage with strong consistency, like in Ceph
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157 lines
5.2 KiB

#include "blockstore.h"
int blockstore::fulfill_read_push(blockstore_operation *op, uint64_t &fulfilled, uint32_t item_start,
uint32_t item_state, uint64_t item_version, uint64_t item_location, uint32_t cur_start, uint32_t cur_end)
{
if (cur_end > cur_start)
{
if (IS_IN_FLIGHT(item_state))
{
// Pause until it's written somewhere
op->wait_for = WAIT_IN_FLIGHT;
op->wait_detail = item_version;
return 0;
}
else if (item_state == ST_DEL_WRITTEN || item_state == ST_DEL_SYNCED || item_state == ST_DEL_MOVED)
{
// item is unallocated - return zeroes
memset(op->buf + cur_start - op->offset, 0, cur_end - cur_start);
return 1;
}
BS_SUBMIT_GET_SQE(sqe, data);
data->iov = (struct iovec){
op->buf + cur_start - op->offset,
cur_end - cur_start
};
op->read_vec[cur_start] = data->iov;
io_uring_prep_readv(
sqe,
IS_JOURNAL(item_state) ? journal.fd : data_fd,
&data->iov, 1,
(IS_JOURNAL(item_state) ? journal.offset : data_offset) + item_location + cur_start - item_start
);
data->op = op;
fulfilled += cur_end-cur_start;
}
return 1;
}
int blockstore::fulfill_read(blockstore_operation *read_op, uint64_t &fulfilled, uint32_t item_start, uint32_t item_end,
uint32_t item_state, uint64_t item_version, uint64_t item_location)
{
uint32_t cur_start = item_start;
if (cur_start < read_op->offset + read_op->len && item_end > read_op->offset)
{
cur_start = cur_start < read_op->offset ? read_op->offset : cur_start;
item_end = item_end > read_op->offset + read_op->len ? read_op->offset + read_op->len : item_end;
auto fulfill_near = read_op->read_vec.lower_bound(cur_start);
if (fulfill_near != read_op->read_vec.begin())
{
fulfill_near--;
if (fulfill_near->first + fulfill_near->second.iov_len <= cur_start)
{
fulfill_near++;
}
}
while (fulfill_near != read_op->read_vec.end() && fulfill_near->first < item_end)
{
if (!fulfill_read_push(read_op, fulfilled, item_start, item_state, item_version, item_location, cur_start, fulfill_near->first))
{
return 0;
}
cur_start = fulfill_near->first + fulfill_near->second.iov_len;
fulfill_near++;
}
if (!fulfill_read_push(read_op, fulfilled, item_start, item_state, item_version, item_location, cur_start, item_end))
{
return 0;
}
}
return 1;
}
int blockstore::dequeue_read(blockstore_operation *read_op)
{
auto clean_it = clean_db.find(read_op->oid);
auto dirty_it = dirty_db.upper_bound((obj_ver_id){
.oid = read_op->oid,
.version = UINT64_MAX,
});
dirty_it--;
bool clean_found = clean_it != clean_db.end();
bool dirty_found = (dirty_it != dirty_db.end() && dirty_it->first.oid == read_op->oid);
if (!clean_found && !dirty_found)
{
// region is not allocated - return zeroes
memset(read_op->buf, 0, read_op->len);
read_op->retval = read_op->len;
read_op->callback(read_op);
return 1;
}
uint64_t fulfilled = 0;
if (dirty_found)
{
while (dirty_it->first.oid == read_op->oid)
{
dirty_entry& dirty = dirty_it->second;
bool version_ok = read_op->version >= dirty_it->first.version;
if (IS_STABLE(dirty.state))
{
if (!version_ok && read_op->version != 0)
read_op->version = dirty_it->first.version;
version_ok = true;
}
if (version_ok)
{
if (!fulfill_read(read_op, fulfilled, dirty.offset, dirty.offset + dirty.size,
dirty.state, dirty_it->first.version, dirty.location))
{
// need to wait. undo added requests, don't dequeue op
read_op->read_vec.clear();
return 0;
}
}
if (fulfilled == read_op->len)
{
break;
}
dirty_it--;
}
}
if (clean_it != clean_db.end())
{
if (!fulfill_read(read_op, fulfilled, 0, block_size, ST_CURRENT, 0, clean_it->second.location))
{
// need to wait. undo added requests, don't dequeue op
read_op->read_vec.clear();
return 0;
}
}
if (!read_op->read_vec.size())
{
// region is not allocated - return zeroes
memset(read_op->buf, 0, read_op->len);
read_op->retval = read_op->len;
read_op->callback(read_op);
return 1;
}
read_op->retval = 0;
read_op->pending_ops = read_op->read_vec.size();
return 1;
}
void blockstore::handle_read_event(ring_data_t *data, blockstore_operation *op)
{
op->pending_ops--;
if (data->res < 0)
{
// read error
op->retval = data->res;
}
if (op->pending_ops == 0)
{
if (op->retval == 0)
op->retval = op->len;
op->callback(op);
}
}