From d7d293ee4fd15649222143ca3bcaeeb9f43014e9 Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt@redhat.com>
Date: Tue, 10 Jun 2014 16:38:20 +0100
Subject: [PATCH] thin_delta now works

---
 thin-provisioning/thin_delta.cc | 153 ++++++++++++++++++++++++++++++--
 1 file changed, 148 insertions(+), 5 deletions(-)

diff --git a/thin-provisioning/thin_delta.cc b/thin-provisioning/thin_delta.cc
index bbd1ec2..c12c084 100644
--- a/thin-provisioning/thin_delta.cc
+++ b/thin-provisioning/thin_delta.cc
@@ -6,7 +6,15 @@
 
 #include "version.h"
 
+#include "persistent-data/data-structures/btree_damage_visitor.h"
+#include "persistent-data/run.h"
+#include "persistent-data/space-maps/core.h"
+#include "persistent-data/file_utils.h"
+#include "thin-provisioning/superblock.h"
+#include "thin-provisioning/mapping_tree.h"
+
 using namespace std;
+using namespace thin_provisioning;
 
 //----------------------------------------------------------------
 
@@ -30,9 +38,9 @@ namespace {
 			exit(1);
 		}
 
-		unsigned parse_snap(string const &str) {
+		uint64_t parse_snap(string const &str) {
 			try {
-				return boost::lexical_cast<unsigned>(str);
+				return boost::lexical_cast<uint64_t>(str);
 
 			} catch (...) {
 				ostringstream out;
@@ -49,9 +57,143 @@ namespace {
 
 	struct flags {
 		boost::optional<string> dev;
-		boost::optional<unsigned> snap1;
-		boost::optional<unsigned> snap2;
+		boost::optional<uint64_t> snap1;
+		boost::optional<uint64_t> snap2;
 	};
+
+	//--------------------------------
+
+	block_manager<>::ptr
+	open_bm(string const &path) {
+		block_address nr_blocks = get_nr_blocks(path);
+		block_io<>::mode m = block_io<>::READ_ONLY;
+		return block_manager<>::ptr(new block_manager<>(path, nr_blocks, 1, m));
+	}
+
+	transaction_manager::ptr
+	open_tm(block_manager<>::ptr bm) {
+		space_map::ptr sm(new core_map(bm->get_nr_blocks()));
+		sm->inc(superblock_detail::SUPERBLOCK_LOCATION);
+		transaction_manager::ptr tm(new transaction_manager(bm, sm));
+		return tm;
+	}
+
+	//--------------------------------
+
+	class delta_visitor {
+	public:
+		delta_visitor(single_mapping_tree const &origin)
+		: origin_(origin) {
+			reset_range();
+		}
+
+		// This is slow, but easy to write.  Faster would be to
+		// iterate both trees simultaneously.
+		void visit(btree_path const &path, mapping_tree_detail::block_time const &bt) {
+			single_mapping_tree::key k = {path[0]};
+			boost::optional<mapping_tree_detail::block_time> origin_bt = origin_.lookup(k);
+			if (!origin_bt || origin_bt->block_ != bt.block_)
+				emit(path[0], bt.block_);
+		}
+
+	private:
+		void reset_range() {
+			obegin_ = oend_ = 0;
+			dbegin_ = dend_ = 0;
+		}
+
+		void emit(uint64_t oblock, uint64_t dblock) {
+			if (obegin_ == oend_) {
+				// We're starting a new range
+				obegin_ = oblock;
+				oend_ = obegin_;
+
+				dbegin_ = dblock;
+				dend_ = dbegin_;
+
+			} else {
+				if (oblock != oend_ || dblock != dend_) {
+					// Emit the current range ...
+					if (oend_ - obegin_ > 1) {
+						cout << "<range_mapping origin_begin=\"" << obegin_ << "\""
+						     << " data_begin=\"" << dbegin_ << "\""
+						     << " length=\"" << oend_ - obegin_ << "\"/>" << endl;
+					} else {
+						cout << "<single_mapping origin_block=\"" << obegin_ << "\""
+						     << " data_block=\"" << dbegin_ << "\"/>" << endl;
+					}
+
+					obegin_ = oblock;
+					oend_ = obegin_;
+
+					dbegin_ = dblock;
+					dend_ = dbegin_;
+				}
+			}
+
+			oend_++;
+			dend_++;
+		}
+
+		uint64_t obegin_, oend_;
+		uint64_t dbegin_, dend_;
+
+		single_mapping_tree const &origin_;
+	};
+
+	class damage_visitor {
+	public:
+		virtual void visit(btree_path const &path, btree_detail::damage const &d) {
+			throw std::runtime_error("damage in mapping tree, please run thin_check");
+		}
+	};
+
+	void delta_(application &app, flags const &fs) {
+		block_manager<>::ptr bm = open_bm(*fs.dev);
+		transaction_manager::ptr tm = open_tm(bm);
+
+		superblock_detail::superblock sb = read_superblock(bm);
+
+		dev_tree dtree(tm, sb.data_mapping_root_,
+			       mapping_tree_detail::mtree_traits::ref_counter(tm));
+
+		dev_tree::key k = {*fs.snap1};
+		boost::optional<uint64_t> snap1_root = dtree.lookup(k);
+
+		if (!snap1_root) {
+			ostringstream out;
+			out << "Unable to find mapping tree for snap1 (" << *fs.snap1 << ")";
+			app.die(out.str());
+		}
+
+		single_mapping_tree snap1(tm, *snap1_root, mapping_tree_detail::block_traits::ref_counter(tm->get_sm()));
+
+		k[0] = *fs.snap2;
+		boost::optional<uint64_t> snap2_root = dtree.lookup(k);
+
+		if (!snap2_root) {
+			ostringstream out;
+			out << "Unable to find mapping tree for snap2 (" << *fs.snap2 << ")";
+			app.die(out.str());
+		}
+
+		single_mapping_tree snap2(tm, *snap2_root, mapping_tree_detail::block_traits::ref_counter(tm->get_sm()));
+
+		delta_visitor delta_v(snap1);
+		damage_visitor damage_v;
+		btree_visit_values(snap2, delta_v, damage_v);
+	}
+
+	int delta(application &app, flags const &fs) {
+		try {
+			delta_(app, fs);
+		} catch (exception const &e) {
+			app.die(e.what());
+			return 1; // never get here
+		}
+
+		return 0;
+	}
 }
 
 //----------------------------------------------------------------
@@ -70,6 +212,7 @@ int main(int argc, char **argv)
 		{ "version", no_argument, NULL, 'V' },
 		{ "snap1", required_argument, NULL, 1 },
 		{ "snap2", required_argument, NULL, 2 },
+		{ "metadata-snap", optional_argument, NULL, 3 },
 	};
 
 	while ((c = getopt_long(argc, argv, shortopts, longopts, NULL)) != -1) {
@@ -107,7 +250,7 @@ int main(int argc, char **argv)
 	if (!fs.snap2)
 		app.die("--snap2 not specified.");
 
-	return 0;
+	return delta(app, fs);
 }
 
 //----------------------------------------------------------------