[space-maps/noop] Add the noops space map

Used when we know we're npt modifying the metadata.

persistent-data/space-maps/noop.h

@@ -0,0 +1,103 @@
+// Copyright (C) 2019 Red Hat, Inc. All rights reserved.
+//
+// This file is part of the thin-provisioning-tools source.
+//
+// thin-provisioning-tools 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 3 of
+// the License, or (at your option) any later version.
+//
+// thin-provisioning-tools 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 thin-provisioning-tools.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+#ifndef NOOP_MAP_H
+#define NOOP_MAP_H
+
+#include "persistent-data/space_map.h"
+
+//----------------------------------------------------------------
+
+namespace persistent_data {
+	class noop_map : public checked_space_map {
+	public:
+		typedef boost::shared_ptr<noop_map> ptr;
+
+		block_address get_nr_blocks() const {
+			fail();
+			return 0;
+		}
+
+		block_address get_nr_free() const {
+			fail();
+			return 0;
+		}
+
+		ref_t get_count(block_address b) const {
+			fail();
+			return 0;
+		}
+
+		void set_count(block_address b, ref_t c) {
+			fail();
+		}
+
+		void commit() {
+			fail();
+		}
+
+		void inc(block_address b) {
+			fail();
+		}
+
+		void dec(block_address b) {
+			fail();
+		}
+
+		maybe_block find_free(span_iterator &it) {
+			fail();
+			return 0;
+		}
+
+		bool count_possibly_greater_than_one(block_address b) const {
+			fail();
+			return false;
+		}
+
+		void extend(block_address extra_blocks) {
+			fail();
+		}
+
+		void count_metadata(block_counter &bc) const {
+			fail();
+		}
+
+		size_t root_size() const {
+			fail();
+			return 0;
+		}
+
+		virtual void copy_root(void *dest, size_t len) const {
+			fail();
+		}
+
+		checked_space_map::ptr clone() const {
+			return ptr(new noop_map());
+		}
+
+	private:
+		void fail() const {
+			throw std::runtime_error("noop space map used");
+		}
+	};
+}
+
+//----------------------------------------------------------------
+
+#endif
+