This is the first version of the SR speedup feature for MariaDB 10.6.

Now all galera_sr tests succeed when SR speedup is disabled
and most galera_sr MTR tests succeed when SR speedup up is enabled.
The failing tests are listed in "skipped_tests" file.

The following MTR test suite run succeeds:

(cd mysql-test; ./mysql-test-run.pl --mysqld="--wsrep_SR_store=undolog"
                 --suite=galera_sr --skip-test-list=../skipped_tests --force)

include/wsrep/client_service.hpp

@@ -217,6 +217,14 @@ namespace wsrep
          * been enabled.
          */
         virtual void debug_crash(const char* crash_point) = 0;
+#ifdef WITH_WSREP_SR_SPEEDUP
+
+	/**
+	 * Return the binlog cache for the currently execution
+	 * transaction or a NULL pointer if no such cache exists.
+	 */
+	virtual void *get_binlog_cache() = 0;
+#endif /* WITH_WSREP_SR_SPEEDUP */
     };
 }