Cache result of ls command.

src/navigate/CMakeLists.txt

@@ -9,6 +9,7 @@ add_executable(${PROJECT_NAME}
 	genericpath.cpp
 	dbsource.cpp
 	linereader.cpp
+	listdircontent.cpp
 )
 
 target_include_directories(${PROJECT_NAME}

src/navigate/listdircontent.cpp

@@ -0,0 +1,92 @@
+/* Copyright 2015, 2016, Michele Santullo
+ * This file is part of "dindexer".
+ *
+ * "dindexer" 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.
+ *
+ * "dindexer" 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 "dindexer".  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "listdircontent.hpp"
+#include "genericpath.hpp"
+#include "dbsource.hpp"
+#include "helpers/infix_iterator.hpp"
+#include <cassert>
+#include <utility>
+#include <boost/range/algorithm/copy.hpp>
+#include <sstream>
+#include <ciso646>
+#include <boost/lexical_cast.hpp>
+#include <algorithm>
+
+namespace din {
+	namespace {
+		template <typename V> std::vector<std::string> db_result_to_vec ( const V& parResult );
+		const std::size_t g_max_cached_lists = 4;
+
+		template <typename V>
+		std::vector<std::string> db_result_to_vec (const V& parResult) {
+			std::vector<std::string> result;
+			result.reserve(parResult.size());
+
+			for (const auto& row : parResult) {
+				std::ostringstream oss;
+				boost::copy(row, infix_ostream_iterator<std::string>(oss, "\t"));
+				result.push_back(oss.str());
+			}
+			return std::move(result);
+		}
+	} //unnamed namespace
+
+	ListDirContent::ListDirContent (DBSource* parDB) :
+		m_cache(g_max_cached_lists),
+		m_db(parDB)
+	{
+		assert(m_db);
+	}
+
+	auto ListDirContent::ls (const GenericPath& parDir) const -> const ListType& {
+		const auto curr_path = parDir.to_string();
+
+		//Check if requested item is already cached
+		auto it_found = std::find_if(m_cache.begin(), m_cache.end(), [&curr_path](const CachedItemType& itm) { return itm.first == curr_path; });
+		if (it_found != m_cache.end()) {
+			CachedItemType tmp;
+			std::swap(tmp, *it_found);
+			assert(it_found->first.empty());
+			assert(it_found->second.empty());
+			assert(tmp.first == curr_path);
+			m_cache.erase(it_found);
+			assert(m_cache.size() < g_max_cached_lists);
+			m_cache.push_back(std::move(tmp));
+			assert(not m_cache.empty());
+			assert(m_cache.back().first == curr_path);
+			return m_cache.back().second;
+		}
+
+		//Requested item is not cached, so we need to query the db now
+		if ("/" == curr_path) {
+			auto sets_ids = m_db->sets();
+			auto sets_info = m_db->set_details<SetDetail_ID, SetDetail_Desc, SetDetail_CreeationDate>(sets_ids);
+			m_cache.push_back(std::make_pair(curr_path, db_result_to_vec(sets_info)));
+		}
+		else {
+			const auto start_from = curr_path.find('/', 1);
+			auto path_prefix = boost::string_ref(curr_path).substr(start_from == curr_path.npos ? curr_path.size() : start_from + 1);
+			const auto set_id = boost::lexical_cast<uint32_t>(parDir[0]);
+			auto files_info = m_db->file_details<FileDetail_Path>(set_id, parDir.level(), path_prefix);
+			m_cache.push_back(std::make_pair(curr_path, db_result_to_vec(files_info)));
+		}
+		assert(not m_cache.empty());
+		assert(m_cache.back().first == curr_path);
+		return m_cache.back().second;
+	}
+} //namespace din

src/navigate/listdircontent.hpp

@@ -0,0 +1,44 @@
+/* Copyright 2015, 2016, Michele Santullo
+ * This file is part of "dindexer".
+ *
+ * "dindexer" 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.
+ *
+ * "dindexer" 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 "dindexer".  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef id5FCFB397A56A4D0D99AB6947A08E1075
+#define id5FCFB397A56A4D0D99AB6947A08E1075
+
+#include <boost/circular_buffer.hpp>
+#include <utility>
+#include <string>
+
+namespace din {
+	class GenericPath;
+	class DBSource;
+
+	class ListDirContent {
+		using ListType = std::vector<std::string>;
+		using CachedItemType = std::pair<std::string, ListType>;
+	public:
+		explicit ListDirContent ( DBSource* parDB );
+		~ListDirContent ( void ) noexcept = default;
+
+		const ListType& ls ( const GenericPath& parDir ) const;
+
+	private:
+		mutable boost::circular_buffer<CachedItemType> m_cache;
+		DBSource* m_db;
+	};
+} //namespace din
+
+#endif

src/navigate/main.cpp

@@ -21,23 +21,21 @@
 #include "genericpath.hpp"
 #include "dbsource.hpp"
 #include "dindexerConfig.h"
-#include "helpers/infix_iterator.hpp"
 #include "linereader.hpp"
+#include "listdircontent.hpp"
 #include <iostream>
 #include <ciso646>
 #include <string>
 #include <vector>
 #include <cassert>
 #include <boost/range/algorithm/copy.hpp>
-#include <boost/lexical_cast.hpp>
 
 namespace {
 	void do_navigation ( din::DBSource& parDB );
 
-	template <typename V> void print_db_result ( const V& parResult );
 	bool on_exit ( void );
 	void on_pwd ( const din::GenericPath& parDirMan );
-	void on_ls ( const din::GenericPath& parDirMan, din::DBSource& parDB );
+	void on_ls ( const din::ListDirContent& parLS, const din::GenericPath& parDirMan );
 } //unnamed namespace
 
 int main (int parArgc, char* parArgv[]) {
@@ -70,14 +68,6 @@ int main (int parArgc, char* parArgv[]) {
 }
 
 namespace {
-	template <typename V>
-	void print_db_result (const V& parResult) {
-		for (const auto& row : parResult) {
-			boost::copy(row, infix_ostream_iterator<std::string>(std::cout, "\t"));
-			std::cout << "\n";
-		}
-	}
-
 	bool on_exit() {
 		return true;
 	}
@@ -86,22 +76,9 @@ namespace {
 		std::cout << parDirMan.to_string() << '\n';
 	}
 
-	void on_ls (const din::GenericPath& parDirMan, din::DBSource& parDB) {
-		using namespace din;
-
-		const auto curr_path = parDirMan.to_string();
-		if ("/" == curr_path) {
-			auto sets_ids = parDB.sets();
-			auto sets_info = parDB.set_details<SetDetail_ID, SetDetail_Desc, SetDetail_CreeationDate>(sets_ids);
-			print_db_result(sets_info);
-		}
-		else {
-			const auto start_from = curr_path.find('/', 1);
-			auto path_prefix = boost::string_ref(curr_path).substr(start_from == curr_path.npos ? curr_path.size() : start_from + 1);
-			const auto set_id = boost::lexical_cast<uint32_t>(parDirMan[0]);
-			auto files_info = parDB.file_details<FileDetail_Path>(set_id, parDirMan.level(), path_prefix);
-			print_db_result(files_info);
-		}
+	void on_ls (const din::ListDirContent& parLS, const din::GenericPath& parDirMan) {
+		const auto& ls_result = parLS.ls(parDirMan);
+		boost::copy(ls_result, std::ostream_iterator<std::string>(std::cout, "\n"));
 	}
 
 	void do_navigation (din::DBSource& parDB) {
@@ -112,11 +89,12 @@ namespace {
 		std::string curr_line;
 		din::CommandProcessor proc;
 		din::GenericPath dir_man;
+		din::ListDirContent ls(&parDB);
 		proc.add_command("exit", &on_exit, 0);
 		proc.add_command("cd", std::function<void(const std::string&)>(std::bind(&din::GenericPath::push_piece, &dir_man, std::placeholders::_1)), 1);
 		proc.add_command("disconnect", std::function<void()>(std::bind(&din::DBSource::disconnect, &parDB)), 0);
 		proc.add_command("pwd", std::function<void()>(std::bind(&on_pwd, std::ref(dir_man))), 0);
-		proc.add_command("ls", std::function<void()>(std::bind(&on_ls, std::ref(dir_man), std::ref(parDB))), 0);
+		proc.add_command("ls", std::function<void()>(std::bind(on_ls, std::ref(ls), std::ref(dir_man))), 0);
 		do {
 			do {
 				curr_line = lines.read(prompt);