[cache] cache_metadata_size

caching/cache_metadata_size.cc

@@ -0,0 +1,156 @@
+#include "version.h"
+
+#include <boost/lexical_cast.hpp>
+#include <boost/optional.hpp>
+#include <iostream>
+#include <getopt.h>
+#include <stdint.h>
+#include <stdexcept>
+
+using namespace boost;
+using namespace std;
+
+//----------------------------------------------------------------
+
+namespace {
+	struct flags {
+		flags()
+			: max_hint_width(4) {
+		}
+
+		optional<uint64_t> device_size;
+		optional<uint32_t> block_size;
+		optional<uint64_t> nr_blocks;
+		uint32_t max_hint_width;
+	};
+
+	void usage(ostream &out, string const &cmd) {
+		out << "Usage: " << cmd << " [options]" << endl
+		    << "Options:" << endl
+		    << "  {-h|--help}" << endl
+		    << "  {-V|--version}" << endl
+		    << "  {--block-size <sectors>}" << endl
+		    << "  {--device-size <sectors>}" << endl
+		    << "  {--nr-blocks <natural>}" << endl << endl
+		    << "These all relate to the size of the fast device (eg, SSD), rather" << endl
+		    << "than the whole cached device." << endl;
+	}
+
+	enum parse_result {
+		FINISH,
+		CONTINUE
+	};
+
+	parse_result parse_command_line(string const &prog_name, int argc, char **argv, flags &fs) {
+
+		int c;
+		char const short_opts[] = "hV";
+		option const long_opts[] = {
+			{ "block-size", required_argument, NULL, 0 },
+			{ "device-size", required_argument, NULL, 1 },
+			{ "nr-blocks", required_argument, NULL, 2 },
+			{ "max-hint-width", required_argument, NULL, 3 },
+			{ "help", no_argument, NULL, 'h' },
+			{ "version", no_argument, NULL, 'V' },
+			{ NULL, no_argument, NULL, 0 }
+		};
+
+		while ((c = getopt_long(argc, argv, short_opts, long_opts, NULL)) != -1) {
+			switch (c) {
+			case 0:
+				fs.block_size = lexical_cast<uint32_t>(optarg);
+				break;
+
+			case 1:
+				fs.device_size = lexical_cast<uint64_t>(optarg);
+				break;
+
+			case 2:
+				fs.nr_blocks = lexical_cast<uint64_t>(optarg);
+				break;
+
+			case 3:
+				fs.max_hint_width = lexical_cast<uint32_t>(optarg);
+
+			case 'h':
+				usage(cout, prog_name);
+				return FINISH;
+				break;
+
+			case 'V':
+				cout << THIN_PROVISIONING_TOOLS_VERSION << endl;
+				return FINISH;
+				break;
+
+			default:
+				usage(cerr, prog_name);
+				throw runtime_error("Invalid command line");
+				break;
+			}
+		}
+
+		return CONTINUE;
+	}
+
+	void expand_flags(flags &fs) {
+		if (!fs.device_size && !fs.nr_blocks)
+			throw runtime_error("Please specify either --device-size and --block-size, or --nr-blocks.");
+
+		if (fs.device_size && !fs.block_size)
+			throw runtime_error("If you specify --device-size you must also give --block-size.");
+
+		if (fs.block_size && !fs.device_size)
+			throw runtime_error("If you specify --block-size you must also give --device-size.");
+
+		if (fs.device_size && fs.block_size) {
+			uint64_t nr_blocks = *fs.device_size / *fs.block_size;
+			if (fs.nr_blocks) {
+				if (nr_blocks != *fs.nr_blocks)
+					throw runtime_error(
+						"Contradictory arguments given, --nr-blocks doesn't match the --device-size and --block-size.");
+			} else
+				fs.nr_blocks = nr_blocks;
+		}
+	}
+
+	uint64_t meg(uint64_t n) {
+		return n * 2048;
+	}
+
+	uint64_t calc_size(flags const &fs) {
+		uint64_t const SECTOR_SIZE = 512;
+		uint64_t const TRANSACTION_OVERHEAD = meg(4);
+		uint64_t const BYTES_PER_BLOCK = 16;
+		uint64_t const HINT_OVERHEAD_PER_BLOCK = 8;
+
+		uint64_t mapping_size = (*fs.nr_blocks * BYTES_PER_BLOCK) / SECTOR_SIZE;
+		uint64_t hint_size = (*fs.nr_blocks * (fs.max_hint_width + HINT_OVERHEAD_PER_BLOCK)) / SECTOR_SIZE;
+		return TRANSACTION_OVERHEAD + mapping_size + hint_size;
+	}
+}
+
+int main(int argc, char **argv)
+{
+	flags fs;
+
+	try {
+		switch (parse_command_line(argv[0], argc, argv, fs)) {
+		case FINISH:
+			return 0;
+
+		case CONTINUE:
+			break;
+		}
+
+		expand_flags(fs);
+		cout << calc_size(fs) << " sectors" << endl;
+
+	} catch (std::exception const &e) {
+		cerr << e.what();
+		return 1;
+	}
+
+	return 0;
+}
+
+//----------------------------------------------------------------