forked from vitalif/vitastor
FSM is a dreadful unreadable thing, reimplement using gotos
parent
34451b6e44
commit
4afa95b0e3
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@ -83,6 +83,11 @@ void blockstore::handle_event(ring_data_t *data)
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{
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handle_stable_event(data, op);
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}
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else if ((op->flags & OP_TYPE_MASK) == OP_INTERNAL_FLUSH)
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{
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// Operation is not a blockstore_operation at all
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}
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}
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}
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11
blockstore.h
11
blockstore.h
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@ -33,8 +33,9 @@
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#define ST_J_WRITTEN 3
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#define ST_J_SYNCED 4
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#define ST_J_STABLE 5
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#define ST_J_MOVED 6
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#define ST_J_MOVE_SYNCED 7
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#define ST_J_MOVE_READ_SUBMITTED 6
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#define ST_J_MOVE_WRITE_SUBMITTED 7
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#define ST_J_MOVE_SYNCED 8
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#define ST_D_SUBMITTED 16
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#define ST_D_WRITTEN 17
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@ -183,6 +184,7 @@ public:
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#define OP_SYNC 3
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#define OP_STABLE 4
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#define OP_DELETE 5
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#define OP_INTERNAL_FLUSH 6
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#define OP_TYPE_MASK 0x7
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// Suspend operation until there are more free SQEs
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@ -196,9 +198,10 @@ public:
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struct blockstore_operation
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{
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std::function<void (blockstore_operation*)> callback;
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// flags contain operation type and possibly other flags
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uint32_t flags;
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uint64_t flags;
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// finish callback
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std::function<void (blockstore_operation*)> callback;
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// For reads, writes & deletes: oid is the requested object
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object_id oid;
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// For reads: version=0 -> last stable, version=UINT64_MAX -> last unstable, version=X -> specific version
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@ -156,154 +156,170 @@ void blockstore::handle_stable_event(ring_data_t *data, blockstore_operation *op
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}
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}
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struct offset_len
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struct copy_buffer_t
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{
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uint64_t offset, len;
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void *buf;
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};
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class journal_flusher_t
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{
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blockstore *bs;
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int state;
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int wait_state, wait_count;
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struct io_uring_sqe *sqe;
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struct ring_data_t *data;
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bool skip_copy;
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obj_ver_id cur;
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std::map<obj_ver_id, dirty_entry>::iterator dirty_it;
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std::vector<offset_len> v;
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std::vector<offset_len>::iterator it;
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uint64_t offset, len;
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std::vector<copy_buffer_t> v;
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std::vector<copy_buffer_t>::iterator it;
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uint64_t offset, len, submit_len, clean_loc;
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bool allocated;
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public:
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journal_flusher_t();
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journal_flusher_t(int flush_count);
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std::deque<obj_ver_id> flush_queue;
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void stabilize_object_loop();
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void loop();
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};
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#define F_NEXT_OBJ 0
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#define F_NEXT_VER 1
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#define F_FIND_POS 2
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#define F_SUBMIT_FULL 3
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#define F_SUBMIT_PART 4
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#define F_CUT_OFFSET 5
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#define F_FINISH_VER 6
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journal_flusher_t::journal_flusher_t()
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journal_flusher_t::journal_flusher_t(int flusher_count)
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{
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state = F_NEXT_OBJ;
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}
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// It would be prettier as a coroutine (maybe https://github.com/hnes/libaco ?)
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// Now it's a state machine
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void journal_flusher_t::stabilize_object_loop()
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void journal_flusher_t::loop()
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{
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begin:
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if (state == F_NEXT_OBJ)
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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 == 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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if (!flush_queue.size())
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return;
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cur = flush_queue.front();
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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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// Pick next object
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if (!flush_queue.size())
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return;
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while (1)
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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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allocated = false;
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skip_copy = false;
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do
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{
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cur = flush_queue.front();
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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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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_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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state = F_NEXT_VER;
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v.clear();
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break;
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}
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else if (flush_queue.size() == 0)
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return;
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}
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}
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if (state == F_NEXT_VER)
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{
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if (dirty_it->second.state == ST_J_STABLE)
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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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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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state = F_FIND_POS;
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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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state = F_NEXT_OBJ;
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}
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else if (IS_STABLE(dirty_it->second.state))
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{
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state = F_NEXT_OBJ;
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}
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else
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state = F_FINISH_VER;
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}
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if (state == F_FIND_POS)
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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+len)
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{
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state = F_SUBMIT_FULL;
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}
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else
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{
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if (it->offset > offset)
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state = F_SUBMIT_PART;
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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. We must allocate and zero it.
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clean_loc = allocator_find_free(bs->data_alloc);
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if (clean_loc == UINT64_MAX)
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{
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throw new std::runtime_error("No space on the data device while trying to flush journal");
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}
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// This is an interesting part. Flushing journal results in an allocation we don't know where to put O_o.
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allocator_set(bs->data_alloc, clean_loc, true);
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allocated = true;
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}
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else
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state = F_CUT_OFFSET;
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clean_loc = clean_it->second.location;
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}
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}
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if (state == F_SUBMIT_FULL)
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{
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struct io_uring_sqe *sqe = get_sqe();
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if (!sqe)
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return;
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struct ring_data_t *data = ((ring_data_t*)sqe->user_data);
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data->iov = (struct iovec){ malloc(len), len };
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data->op = op; // FIXME OOPS
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io_uring_prep_readv(
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sqe, journal_fd, &data->iov, 1, journal_offset + dirty_it->second.location + offset
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);
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op->pending_ops = 1;
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v.insert(it, (offset_len){ .offset = offset, .len = len });
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state = F_SUBMIT_FULL_WRITE;
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return;
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}
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if (state == F_SUBMIT_FULL_WRITE)
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{
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struct io_uring_sqe *sqe = get_sqe();
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if (!sqe)
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return;
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struct ring_data_t *data = ((ring_data_t*)sqe->user_data);
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}
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if (state == F_SUBMIT_PART)
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{
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if (!can_submit)
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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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return;
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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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wait_state = 5;
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resume_5:
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// Done, free all buffers
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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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free(it->buf);
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}
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v.clear();
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wait_state = 0;
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}
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}
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v.insert(it, (offset_len){ .offset = offset, .len = it->offset-offset });
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state = F_CUT_OFFSET;
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}
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if (state == F_CUT_OFFSET)
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{
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if (offset+len > it->offset+it->len)
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{
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len = offset+len - (it->offset+it->len);
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offset = it->offset+it->len;
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state = F_FIND_POS;
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}
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else
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state = F_FINISH_VER;
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}
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if (state == F_FINISH_VER)
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{
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dirty_it--;
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if (dirty_it == bs->dirty_db.begin() || dirty_it->first.oid != cur.oid)
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state = F_NEXT_OBJ;
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else
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state = F_NEXT_VER;
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}
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goto begin;
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}
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@ -66,7 +66,7 @@ int blockstore::dequeue_write(blockstore_operation *op)
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{
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// Big (redirect) write
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uint64_t loc = allocator_find_free(data_alloc);
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if (loc == (uint64_t)-1)
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if (loc == UINT64_MAX)
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{
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// no space
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op->retval = -ENOSPC;
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