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/*
* Copyright (C) 2018 Codership Oy <info@codership.com>
*
* This file is part of wsrep-lib.
*
* Wsrep-lib is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* Wsrep-lib is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with wsrep-lib. If not, see <https://www.gnu.org/licenses/>.
*/
/** @file client_service.hpp
*
* This file will define a `callback` abstract interface for a
* DBMS client session service. The interface will define methods
* which will be called by the wsrep-lib.
*/
#ifndef WSREP_CLIENT_SERVICE_HPP
#define WSREP_CLIENT_SERVICE_HPP
#include "buffer.hpp"
#include "provider.hpp"
#include "mutex.hpp"
#include "lock.hpp"
namespace wsrep
{
class client_service
{
public:
client_service() { }
virtual ~client_service() { }
/**
* Return true if the current transaction has been interrupted
* by the DBMS. The lock which is passed to interrupted call
* will always have underlying mutex locked.
*
* @param lock Lock object grabbed by the client_state
*/
virtual bool interrupted(wsrep::unique_lock<wsrep::mutex>& lock) const = 0;
/**
* Reset possible global or thread local parameters associated
* to the thread.
*/
virtual void reset_globals() = 0;
/**
* Store possible global or thread local parameters associated
* to the thread.
*/
virtual void store_globals() = 0;
/**
* Set up a data for replication.
*/
virtual int prepare_data_for_replication() = 0;
/**
* Clean up after transcation has been terminated.
*/
virtual void cleanup_transaction() = 0;
//
// Streaming
//
/**
* Return true if current statement is allowed for streaming,
* otherwise false.
*/
virtual bool statement_allowed_for_streaming() const = 0;
/**
* Return the total number of bytes generated by the transaction
* context.
*/
virtual size_t bytes_generated() const = 0;
/**
* Prepare a buffer containing data for the next fragment to replicate.
* The caller may set log_position to record the database specific
* position corresponding to changes contained in the buffer.
* When the call returns, the log_position will be available to read
* from streaming_context::log_position().
*
* @return Zero in case of success, non-zero on failure.
* If there is no data to replicate, the method shall return
* zero and leave the buffer empty.
*/
virtual int prepare_fragment_for_replication(wsrep::mutable_buffer& buffer,
size_t& log_position) = 0;
/**
* Remove fragments from the storage within current transaction.
* Fragment removal will be committed once the current transaction
* commits.
*
* @return Zero in case of success, non-zero on failure.
*/
virtual int remove_fragments() = 0;
//
// Rollback
//
/**
* Perform brute force rollback.
*
* This method may be called from two contexts, either from
* client state methods when the BF abort condition is detected,
* or from the background rollbacker thread. The task for this
* method is to release all reasources held by the client
* after BF abort so that the high priority thread can continue
* applying.
*/
virtual int bf_rollback() = 0;
//
// Interface to global server state
//
/**
* Forcefully shut down the DBMS process or replication system.
* This may be called in situations where
* the process may encounter a situation where data integrity
* may not be guaranteed or other unrecoverable condition is
* encontered.
*/
virtual void emergency_shutdown() = 0;
// Replaying
/**
* Notify that the client will replay.
*
* @todo This should not be visible to DBMS level, should be
* handled internally by wsrep-lib.
*/
virtual void will_replay() = 0;
/**
* Signal that replay is done.
*/
virtual void signal_replayed() = 0;
/**
* Replay the current transaction. The implementation must put
* the caller Client Context into applying mode and call
* client_state::replay().
*
* @todo This should not be visible to DBMS level, should be
* handled internally by wsrep-lib.
*/
virtual enum wsrep::provider::status replay() = 0;
/**
* Replay the current transaction. This is used for replaying
* prepared XA transactions, which are BF aborted but not
* while orderding commit / rollback.
*/
virtual enum wsrep::provider::status replay_unordered() = 0;
/**
* Wait until all replaying transactions have been finished
* replaying.
*
* @todo This should not be visible to DBMS level, should be
* handled internally by wsrep-lib.
*/
virtual void wait_for_replayers(wsrep::unique_lock<wsrep::mutex>&) = 0;
//
// XA
//
/**
* Send a commit by xid
*/
virtual enum wsrep::provider::status commit_by_xid() = 0;
/**
* Returns true if the client has an ongoing XA transaction.
* This method is used to determine when to cleanup the
* corresponding wsrep-lib transaction object.
* This method should return false when the XA transaction
* is over, and the wsrep-lib transaction object can be
* cleaned up.
*/
virtual bool is_explicit_xa() = 0;
/**
* Returns true if the currently executing command is
* a rollback for XA. This is used to avoid setting a
* a deadlock error rollback as it may be unexpected
* by the DBMS.
*/
virtual bool is_xa_rollback() = 0;
//
// Debug interface
//
/**
* Enter debug sync point.
*
* @params sync_point Name of the debug sync point.
*/
virtual void debug_sync(const char* sync_point) = 0;
/**
* Forcefully kill the process if the crash_point has
* been enabled.
*/
virtual void debug_crash(const char* crash_point) = 0;
};
}
#endif // WSREP_CLIENT_SERVICE_HPP
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