241 lines
8.1 KiB
C++
241 lines
8.1 KiB
C++
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#include "blockstore.h"
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journal_flusher_t::journal_flusher_t(int flusher_count, blockstore *bs)
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{
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this->bs = bs;
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this->flusher_count = flusher_count;
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this->active_flushers = 0;
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co = new journal_flusher_co[flusher_count];
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for (int i = 0; i < flusher_count; i++)
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{
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co[i].bs = bs;
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co[i].wait_state = 0;
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co[i].flusher = this;
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}
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}
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journal_flusher_t::~journal_flusher_t()
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{
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delete[] co;
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}
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void journal_flusher_t::loop()
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{
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if (!active_flushers && !flush_queue.size())
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{
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return;
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}
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for (int i = 0; i < flusher_count; i++)
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{
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co[i].loop();
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}
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}
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void journal_flusher_co::loop()
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{
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// This is much better than implementing the whole function as an FSM
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// Maybe I should consider a coroutine library like https://github.com/hnes/libaco ...
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if (wait_state == 1)
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goto resume_1;
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else if (wait_state == 2)
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goto resume_2;
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else if (wait_state == 3)
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goto resume_3;
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else if (wait_state == 4)
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goto resume_4;
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else if (wait_state == 5)
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goto resume_5;
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else if (wait_state == 6)
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goto resume_6;
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else if (wait_state == 7)
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goto resume_7;
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if (!flusher->flush_queue.size())
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return;
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cur = flusher->flush_queue.front();
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flusher->flush_queue.pop_front();
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dirty_it = bs->dirty_db.find(cur);
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if (dirty_it != bs->dirty_db.end())
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{
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flusher->active_flushers++;
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v.clear();
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wait_count = 0;
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clean_loc = UINT64_MAX;
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skip_copy = false;
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do
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{
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if (dirty_it->second.state == ST_J_STABLE)
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{
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// First we submit all reads
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offset = dirty_it->second.offset;
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len = dirty_it->second.size;
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it = v.begin();
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while (1)
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{
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for (; it != v.end(); it++)
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if (it->offset >= offset)
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break;
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if (it == v.end() || it->offset > offset)
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{
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submit_len = it->offset >= offset+len ? len : it->offset-offset;
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resume_1:
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sqe = bs->get_sqe();
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if (!sqe)
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{
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// Can't submit read, ring is full
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wait_state = 1;
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return;
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}
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v.insert(it, (copy_buffer_t){ .offset = offset, .len = submit_len, .buf = memalign(512, submit_len) });
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data = ((ring_data_t*)sqe->user_data);
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data->iov = (struct iovec){ v.end()->buf, (size_t)submit_len };
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data->op = this;
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io_uring_prep_readv(
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sqe, bs->journal.fd, &data->iov, 1, bs->journal.offset + dirty_it->second.location + offset
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);
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wait_count++;
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}
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if (it == v.end() || it->offset+it->len >= offset+len)
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{
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break;
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}
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}
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// So subsequent stabilizers don't flush the entry again
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dirty_it->second.state = ST_J_MOVE_READ_SUBMITTED;
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}
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else if (dirty_it->second.state == ST_D_STABLE)
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{
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// Copy last STABLE entry metadata
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if (!skip_copy)
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{
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clean_loc = dirty_it->second.location;
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}
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skip_copy = true;
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}
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else if (IS_STABLE(dirty_it->second.state))
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{
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break;
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}
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dirty_it--;
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} while (dirty_it != bs->dirty_db.begin() && dirty_it->first.oid == cur.oid);
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if (clean_loc == UINT64_MAX)
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{
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// Find it in clean_db
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auto clean_it = bs->clean_db.find(cur.oid);
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if (clean_it == bs->clean_db.end())
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{
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// Object not present at all. This is a bug.
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throw new std::runtime_error("BUG: Object we are trying to flush not allocated on the data device");
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}
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else
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clean_loc = clean_it->second.location;
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}
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// Also we need to submit the metadata read. We do a read-modify-write for every operation.
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// But we must check if the same sector is already in memory.
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// Another option is to keep all raw metadata in memory all the time. Maybe I'll do it sometime...
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// And yet another option is to use LSM trees for metadata, but it sophisticates everything a lot,
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// so I'll avoid it as long as I can.
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meta_sector = (clean_loc / (512 / sizeof(clean_disk_entry))) * 512;
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meta_pos = (clean_loc % (512 / sizeof(clean_disk_entry)));
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meta_it = flusher->meta_sectors.find(meta_sector);
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if (meta_it == flusher->meta_sectors.end())
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{
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// Not in memory yet, read it
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meta_it = flusher->meta_sectors.emplace(meta_sector, (meta_sector_t){
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.offset = meta_sector,
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.len = 512,
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.state = 0, // 0 = not read yet
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.buf = memalign(512, 512),
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.usage_count = 1,
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}).first;
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resume_2:
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sqe = bs->get_sqe();
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if (!sqe)
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{
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wait_state = 2;
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return;
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}
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data = ((ring_data_t*)sqe->user_data);
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data->iov = (struct iovec){ meta_it->second.buf, 512 };
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data->op = this;
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io_uring_prep_writev(
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sqe, bs->meta_fd, &data->iov, 1, bs->meta_offset + meta_sector
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);
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wait_count++;
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}
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else
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meta_it->second.usage_count++;
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wait_state = 3;
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resume_3:
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// After reads complete we submit writes
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if (wait_count == 0)
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{
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for (it = v.begin(); it != v.end(); it++)
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{
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resume_4:
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sqe = bs->get_sqe();
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if (!sqe)
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{
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// Can't submit a write, ring is full
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wait_state = 4;
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return;
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}
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data = ((ring_data_t*)sqe->user_data);
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data->iov = (struct iovec){ it->buf, (size_t)it->len };
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data->op = this;
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io_uring_prep_writev(
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sqe, bs->data_fd, &data->iov, 1, bs->data_offset + clean_loc + it->offset
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);
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wait_count++;
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}
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// And a metadata write
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resume_5:
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if (meta_it->second.state == 0)
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{
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// metadata sector is still being read, wait for it
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wait_state = 5;
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return;
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}
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*((clean_disk_entry*)meta_it->second.buf + meta_pos) = {
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.oid = cur.oid,
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.version = cur.version,
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.flags = DISK_ENTRY_STABLE,
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};
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resume_6:
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sqe = bs->get_sqe();
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if (!sqe)
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{
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// Can't submit a write, ring is full
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wait_state = 6;
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return;
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}
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data = ((ring_data_t*)sqe->user_data);
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data->iov = (struct iovec){ meta_it->second.buf, 512 };
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data->op = this;
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io_uring_prep_writev(
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sqe, bs->meta_fd, &data->iov, 1, bs->meta_offset + meta_sector
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);
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wait_count++;
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wait_state = 7;
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resume_7:
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// Done, free all buffers
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if (wait_count == 0)
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{
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meta_it->second.usage_count--;
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if (meta_it->second.usage_count == 0)
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{
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free(meta_it->second.buf);
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flusher->meta_sectors.erase(meta_it);
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}
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for (it = v.begin(); it != v.end(); it++)
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{
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free(it->buf);
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}
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v.clear();
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wait_state = 0;
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flusher->active_flushers--;
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}
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// FIXME Now sync everything
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}
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}
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}
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