[thin_rmap] rmap_visitor

thin-provisioning/rmap_visitor.cc

@@ -0,0 +1,103 @@
+#include "thin-provisioning/rmap_visitor.h"
+
+#include <iostream>
+
+using namespace thin_provisioning;
+
+//----------------------------------------------------------------
+
+rmap_visitor::rmap_visitor()
+{
+}
+
+void
+rmap_visitor::add_data_region(region const &r)
+{
+	regions_.push_back(r);
+}
+
+void
+rmap_visitor::visit(btree_path const &path,
+		    mapping_tree_detail::block_time const &bt)
+{
+	if (in_regions(bt.block_)) {
+		uint32_t thin_dev = path[0];
+		block_address thin_block = path[1];
+
+		visit_block(thin_dev, thin_block, bt.block_);
+	}
+}
+
+void
+rmap_visitor::complete()
+{
+	if (current_rmap_)
+		push_current();
+}
+
+vector<rmap_visitor::rmap_region> const &
+rmap_visitor::get_rmap() const
+{
+	return rmap_;
+}
+
+// Slow, but I suspect we wont run with many regions.
+bool
+rmap_visitor::in_regions(block_address b) const
+{
+	for (region const &r : regions_)
+		if (r.contains(b))
+			return true;
+
+	return false;
+}
+
+bool
+rmap_visitor::adjacent_block(rmap_region const &rr,
+			     uint32_t thin_dev, block_address thin_block,
+			     block_address data_block) const
+{
+	block_address run_length = rr.data_end - rr.data_begin;
+
+	return (rr.thin_dev == thin_dev) &&
+		(data_block == rr.data_end) &&
+		(thin_block == rr.thin_begin + run_length);
+}
+
+void
+rmap_visitor::insert_new_region(uint32_t thin_dev, block_address thin_block,
+				block_address data_block)
+{
+	rmap_region rr;
+	rr.data_begin = data_block;
+	rr.data_end = data_block + 1;
+	rr.thin_dev = thin_dev;
+	rr.thin_begin = thin_block;
+
+	current_rmap_ = rr;
+}
+
+void
+rmap_visitor::push_current()
+{
+	rmap_.push_back(*current_rmap_);
+	current_rmap_ = boost::optional<rmap_region>();
+}
+
+void
+rmap_visitor::visit_block(uint32_t thin_dev, block_address thin_block,
+			  block_address data_block)
+{
+	if (current_rmap_) {
+		if (adjacent_block(*current_rmap_, thin_dev, thin_block, data_block))
+			current_rmap_->data_end++;
+		else {
+			push_current();
+			insert_new_region(thin_dev, thin_block, data_block);
+		}
+
+	} else
+		insert_new_region(thin_dev, thin_block, data_block);
+}
+
+//----------------------------------------------------------------

thin-provisioning/rmap_visitor.h

@@ -0,0 +1,68 @@
+#ifndef THIN_RMAP_VISITOR_H
+#define THIN_RMAP_VISITOR_H
+
+#include "persistent-data/range.h"
+#include "thin-provisioning/mapping_tree.h"
+
+//----------------------------------------------------------------
+
+namespace thin_provisioning {
+	// This value visitor (see btree_damage_visitor.h) produces a
+	// reverse mapping for parts of the data device.
+	//
+	// i) Use add_data_region() to specify which areas of the data device you're interested in.
+	// ii) visit the mapping tree
+	// iii) call complete()
+	// iv) get the rmaps with get_rmap();
+	class rmap_visitor {
+	public:
+		typedef range<block_address> region;
+
+		rmap_visitor();
+
+		// Specify which regions of the data device you want the rmap for.
+		void add_data_region(region const &r);
+		void visit(btree_path const &path, mapping_tree_detail::block_time const &bt);
+
+		struct rmap_region {
+			// FIXME: surely we don't need to provide this for
+			// a POD structure?
+			bool operator ==(rmap_region const &rhs) const {
+				return ((data_begin == rhs.data_begin) &&
+					(data_end == rhs.data_end) &&
+					(thin_dev == rhs.thin_dev) &&
+					(thin_begin == rhs.thin_begin));
+			}
+
+			block_address data_begin;
+		        block_address data_end;
+
+			uint32_t thin_dev;
+			block_address thin_begin;
+		};
+
+		void complete();
+		vector<rmap_region> const &get_rmap() const;
+
+	private:
+		bool in_regions(block_address b) const;
+		bool adjacent_block(rmap_region const &rr,
+				    uint32_t thin_dev, block_address thin_block,
+				    block_address data_block) const;
+		void insert_new_region(uint32_t thin_dev, block_address thin_block,
+				       block_address data_block);
+		void push_current();
+
+		void visit_block(uint32_t thin_dev, block_address thin_block,
+				 block_address data_block);
+
+		vector<region> regions_;
+
+		boost::optional<rmap_region> current_rmap_;
+		vector<rmap_region> rmap_;
+	};
+}
+
+//----------------------------------------------------------------
+
+#endif