Refactored high priority service out of client service.

include/wsrep/high_priority_service.hpp

@@ -0,0 +1,99 @@
+//
+// Copyright (C) 2018 Codership Oy <info@codership.com>
+//
+
+/** @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
+
+namespace wsrep
+{
+    class ws_handle;
+    class ws_meta;
+    class const_buffer;
+    class transaction;
+    class high_priority_service
+    {
+    public:
+        virtual ~high_priority_service() { }
+
+        virtual int apply(const ws_handle&, const ws_meta&,
+                          const const_buffer&) = 0;
+        /**
+         * Start a new transaction
+         */
+        virtual int start_transaction(const wsrep::ws_handle&,
+                                      const wsrep::ws_meta&) = 0;
+
+        /**
+         * Adopt a transaction.
+         */
+        virtual void 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.
+         */
+        virtual int apply_write_set(const wsrep::const_buffer&) = 0;
+
+        /**
+         * Commit a transaction.
+         */
+        virtual int commit() = 0;
+
+        /**
+         * Roll back a transaction
+         */
+        virtual int rollback() = 0;
+
+        /**
+         * Apply a TOI operation.
+         *
+         * TOI operation is a standalone operation and should not
+         * be executed as a part of a transaction.
+         */
+        virtual int apply_toi(const wsrep::const_buffer&) = 0;
+
+        /**
+         * Actions to take after applying a write set was completed.
+         */
+        virtual void after_apply() = 0;
+
+        virtual void store_globals() = 0;
+        virtual void reset_globals() = 0;
+
+        virtual int log_dummy_write_set(const ws_handle&, const ws_meta&) = 0;
+
+        virtual bool is_replaying() const = 0;
+    private:
+    };
+
+    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_.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