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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 high_priority_service.hpp
+ *
+ * Interface for services for applying high priority transactions.
+ */
+#ifndef WSREP_HIGH_PRIORITY_SERVICE_HPP
+#define WSREP_HIGH_PRIORITY_SERVICE_HPP
+
+#include "xid.hpp"
+#include "server_state.hpp"
+
+namespace wsrep
+{
+ class ws_handle;
+ class ws_meta;
+ class const_buffer;
+ class transaction;
+ class high_priority_service
+ {
+ public:
+ high_priority_service(wsrep::server_state& server_state)
+ : server_state_(server_state)
+ , must_exit_() { }
+ virtual ~high_priority_service() { }
+
+ int apply(const ws_handle& ws_handle, const ws_meta& ws_meta,
+ const const_buffer& data)
+ {
+ return server_state_.on_apply(*this, ws_handle, ws_meta, data);
+ }
+ /**
+ * Start a new transaction
+ */
+ virtual int start_transaction(const wsrep::ws_handle&,
+ const wsrep::ws_meta&) = 0;
+
+ /**
+ * Start the next fragment of current transaction
+ */
+ virtual int next_fragment(const wsrep::ws_meta&) = 0;
+
+ /**
+ * Return transaction object associated to high priority
+ * service state.
+ */
+ virtual const wsrep::transaction& transaction() const = 0;
+
+ /**
+ * Adopt a transaction.
+ */
+ virtual int adopt_transaction(const wsrep::transaction&) = 0;
+
+ /**
+ * Apply a write set.
+ *
+ * A write set applying happens always
+ * as a part of the transaction. The caller must start a
+ * new transaction before applying a write set and must
+ * either commit to make changes persistent or roll back.
+ *
+ * @params ws_meta Write set meta data
+ * @params ws Write set buffer
+ * @params err Buffer to store error data
+ */
+ virtual int apply_write_set(const wsrep::ws_meta& ws_meta,
+ const wsrep::const_buffer& ws,
+ wsrep::mutable_buffer& err) = 0;
+
+ /**
+ * Append a fragment into fragment storage. This will be
+ * called after a non-committing fragment belonging to
+ * streaming transaction has been applied. The call will
+ * not be done within an open transaction, the implementation
+ * must start a new transaction and commit.
+ *
+ * Note that the call is not done from streaming transaction
+ * context, but from applier context.
+ */
+ virtual int append_fragment_and_commit(
+ const wsrep::ws_handle& ws_handle,
+ const wsrep::ws_meta& ws_meta,
+ const wsrep::const_buffer& data,
+ const wsrep::xid& xid) = 0;
+
+ /**
+ * Remove fragments belonging to streaming transaction.
+ * This method will be called within the streaming transaction
+ * before commit. The implementation must not commit the
+ * whole transaction. The call will be done from streaming
+ * transaction context.
+ *
+ * @param ws_meta Write set meta data for commit fragment.
+ *
+ * @return Zero on success, non-zero on failure.
+ */
+ virtual int remove_fragments(const wsrep::ws_meta& ws_meta) = 0;
+
+ /**
+ * Commit a transaction.
+ * An implementation must call
+ * wsrep::client_state::prepare_for_ordering() to set
+ * the ws_handle and ws_meta before the commit if the
+ * commit process will go through client state commit
+ * processing. Otherwise the implementation must release
+ * commit order explicitly via provider.
+ *
+ * @param ws_handle Write set handle
+ * @param ws_meta Write set meta
+ *
+ * @return Zero in case of success, non-zero in case of failure
+ */
+ virtual int commit(const wsrep::ws_handle& ws_handle,
+ const wsrep::ws_meta& ws_meta) = 0;
+ /**
+ * Roll back a transaction
+ *
+ * An implementation must call
+ * wsrep::client_state::prepare_for_ordering() to set
+ * the ws_handle and ws_meta before the rollback if
+ * the rollback process will go through client state
+ * rollback processing. Otherwise the implementation
+ * must release commit order explicitly via provider.
+ *
+ * @param ws_handle Write set handle
+ * @param ws_meta Write set meta
+ *
+ * @return Zero in case of success, non-zero in case of failure
+ */
+ virtual int rollback(const wsrep::ws_handle& ws_handle,
+ const wsrep::ws_meta& ws_meta) = 0;
+
+ /**
+ * Apply a TOI operation.
+ *
+ * TOI operation is a standalone operation and should not
+ * be executed as a part of a transaction.
+ *
+ * @params ws_meta Write set meta data
+ * @params ws Write set buffer
+ * @params err Buffer to store error data
+ */
+ virtual int apply_toi(const wsrep::ws_meta& ws_meta,
+ const wsrep::const_buffer& ws,
+ wsrep::mutable_buffer& err) = 0;
+
+ /**
+ * Apply NBO begin event.
+ *
+ * The responsibility of the implementation is to start
+ * an asynchronous process which will complete the operation.
+ * The call is done under total order isolation, and the
+ * isolation is released by the caller after the method
+ * returns. It is a responsibility of the asynchronous process
+ * to complete the second phase of NBO.
+ *
+ * @param ws_meta Write set meta data.
+ * @param data Buffer containing the command to execute.
+ * @params err Buffer to store error data
+ *
+ * @return Zero in case of success, non-zero if the asynchronous
+ * process could not be started.
+ */
+ virtual int apply_nbo_begin(const wsrep::ws_meta& ws_meta,
+ const wsrep::const_buffer& data,
+ wsrep::mutable_buffer& err) = 0;
+
+ /**
+ * Actions to take after applying a write set was completed.
+ */
+ virtual void after_apply() = 0;
+
+ /**
+ * Store global execution context for high priority service.
+ */
+ virtual void store_globals() = 0;
+
+ /**
+ * Reset global execution context for high priority service.
+ */
+ virtual void reset_globals() = 0;
+
+ /**
+ * Switch exection context to context of orig_hps.
+ *
+ * @param orig_hps Original high priority service.
+ */
+ virtual void switch_execution_context(
+ wsrep::high_priority_service& orig_hps) = 0;
+
+ /**
+ * Log a dummy write set which is either SR transaction fragment
+ * or roll back fragment. The implementation must release
+ * commit order inside the call.
+ *
+ * @params ws_handle Write set handle
+ * @params ws_meta Write set meta data
+ * @params err Optional applying error data buffer, may be modified
+ *
+ * @return Zero in case of success, non-zero on failure
+ */
+ virtual int log_dummy_write_set(const ws_handle& ws_handle,
+ const ws_meta& ws_meta,
+ wsrep::mutable_buffer& err) = 0;
+
+ /**
+ * Adopt (store) apply error description for further reporting
+ * to provider, source buffer may be modified.
+ */
+ virtual void adopt_apply_error(wsrep::mutable_buffer& err) = 0;
+
+ virtual bool is_replaying() const = 0;
+
+ bool must_exit() const { return must_exit_; }
+
+ /**
+ * Debug facility to crash the server at given point.
+ */
+ virtual void debug_crash(const char* crash_point) = 0;
+
+ protected:
+ wsrep::server_state& server_state_;
+ bool must_exit_;
+ };
+
+ class high_priority_switch
+ {
+ public:
+ high_priority_switch(high_priority_service& orig_service,
+ high_priority_service& current_service)
+ : orig_service_(orig_service)
+ , current_service_(current_service)
+ {
+ orig_service_.reset_globals();
+ current_service_.switch_execution_context(orig_service_);
+ current_service_.store_globals();
+ }
+ ~high_priority_switch()
+ {
+ current_service_.reset_globals();
+ orig_service_.store_globals();
+ }
+ private:
+ high_priority_service& orig_service_;
+ high_priority_service& current_service_;
+ };
+}
+
+#endif // WSREP_HIGH_PRIORITY_SERVICE_HPP