This patch removes log_position from streaming_context. The
log_position was meant for keeping track of the database specific
position corresponding to the changes that have been already
replicated by a streaming transaction. In reality, things may be more
complex in the DBMS side and a size_t may be unsufficient to keep
track of the progress of a streaming transaction. For example, in
MariaDB, it may be necessary to keep track of positions in both
transaction and statement caches. Suggesting that the responsibility
of tracking these position(s) should be delegated to client_service.
The log_position was also used to do sanity checks in
streaming_step(). Those sanity checks are preserved by simply keeping
track of the number of bytes that were certified by the streaming
transaction.
This patch implments replaying for prepared XA transactions.
Replay may happen in the following cases:
1) The transaction is BF aborted in prepared state and is idle. In
that case, the transaction is handed over to rollbacker for replay.
2) The transaction is BF aborted while executing the
commit (i.e. before or after successful certification). In
which case the transaction replays itself from fragment storage.
3) The transaction is BF aborted while certifying its commit
fragment. This case is handled like replay for streaming transactions,
where the provider is directly involved and re-delivers the last
fragment.
Remove methods `is_xa()`, `is_xa_prepare()`, and `xid()` from
client_service interface. Instead, transactions are explicitly
assigned their xid, through at start of XA.
* Add method `restore_prepared_transaction` to `client_state` class
which restores a transaction state from storage given its xid.
* Add method `commit_or_rollback_by_xid` to terminate prepared XA
transactions by xid.
* Make sure that transactions in prepared state are not rolled back
when their master fails/partitions away.
Moved the check for transaction state before certification step
into separate method abort_or_interrupted() which will check the state
and adjust state and client_state error status accordingly.
Moved the check for abort_or_interrupted() to happen before
the state is changed to certifying and write set data is appended.
This makes the check atomic and reduces the probability of race
conditions. After this check we rely on provider side transaction
state management and error reporting until the certification step
is over.
Change to public API: Pass client_state mutex wrappend in unique_lock
object to client_service::interrupted() call. This way the DBMS side
has a control to the lock object in case it needs to unlock it
temporarily. The underlying mutex will always be locked when the lock
object is passed via interrupted() call.
Other: Allow server_state change from donor to connected. This may
happen if the joiner crashes during SST and the provider reports
it before the DBMS side SST mechanism detects the error.
* Check fragment removal error code in prepare phase. It is possible
that the transaction gets BF aborted during fragment removal.
* Mark fragment certified in certify_fragment() even if the provider
returns cert failed error. With current wsrep-API error codes
it may not be possible to distinquish certification failure
and BF abort during fragment replication. This may also be a
provider bug. As a result rollback fragment may sometimes be
replicated when it would not be necessary.
quite useful as there might not be enough information for it
after the statement has been processed. Better to handle retrying
on DBMS side. Also removed after_statement_result enumeration and
return plain int from after_statement().
