Optimization - Get rid of the vector that held the unique_ptr.

Use the replies list directly. I can't see any significant
performance improvement yet, but there is something else I want to
try starting from this point.

.gitignore

@@ -1 +1,4 @@
 tags
+.ycm_extra_conf.py
+__pycache__/
+compile_commands.json

CMakeLists.txt

@@ -22,6 +22,7 @@ add_library(${PROJECT_NAME} SHARED
 	src/async_connection.cpp
 	src/incredis.cpp
 	src/incredis_batch.cpp
+	src/reply_list.cpp
 )
 
 target_include_directories(${PROJECT_NAME} SYSTEM

include/incredis/batch.hpp

@@ -20,8 +20,9 @@
 
 #include "reply.hpp"
 #include "arg_to_bin_safe.hpp"
-#include <vector>
+#include "sized_range.hpp"
 #include <memory>
+#include <forward_list>
 
 namespace redis {
 	class Command;
@@ -31,12 +32,15 @@ namespace redis {
 	class Batch {
 		friend class Command;
 	public:
+		using ConstReplies = SizedRange<std::forward_list<Reply>::const_iterator>;
+		using Replies = SizedRange<std::forward_list<Reply>::iterator>;
+
 		Batch ( Batch&& parOther );
 		Batch ( const Batch& ) = delete;
 		~Batch ( void ) noexcept;
 
-		const std::vector<Reply>& replies ( void );
-		std::vector<Reply>& replies_nonconst ( void );
+		ConstReplies replies ( void ) const;
+		Replies replies_nonconst ( void );
 		bool replies_requested ( void ) const;
 		void throw_if_failed ( void );
 
@@ -54,8 +58,6 @@ namespace redis {
 		explicit Batch ( AsyncConnection* parConn, ThreadContext& parThreadContext );
 		void run_pvt ( int parArgc, const char** parArgv, std::size_t* parLengths );
 
-		std::vector<std::unique_ptr<Reply>> m_futures;
-		std::vector<Reply> m_replies;
 		std::unique_ptr<LocalData> m_local_data;
 		AsyncConnection* m_async_conn;
 	};

include/incredis/incredis_batch.hpp

@@ -27,6 +27,8 @@
 namespace redis {
 	class IncRedisBatch {
 	public:
+		using ConstReplies = Batch::ConstReplies;
+
 		enum ZADD_Mode {
 			ZADD_XX_UpdateOnly,
 			ZADD_NX_AlwaysAdd,
@@ -46,7 +48,7 @@ namespace redis {
 
 		void reset ( void );
 		void throw_if_failed ( void );
-		const std::vector<Reply>& replies ( void ) { return m_batch.replies(); }
+		ConstReplies replies ( void ) { return m_batch.replies(); }
 		Batch& batch ( void ) { return m_batch; }
 		const Batch& batch ( void ) const { return m_batch; }
 

include/incredis/sized_range.hpp

@@ -0,0 +1,56 @@
+/* Copyright 2016, Michele Santullo
+ * This file is part of "incredis".
+ *
+ * "incredis" 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.
+ *
+ * "incredis" 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 "incredis".  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef idC3909E193A3C4DBEB9B646A4F5ED3518
+#define idC3909E193A3C4DBEB9B646A4F5ED3518
+
+#include <boost/range/iterator_range_core.hpp>
+#include <cstddef>
+#include <cassert>
+#include <ciso646>
+
+namespace redis {
+	template <typename I>
+	class SizedRange : public boost::iterator_range<I> {
+	public:
+		SizedRange ( I parBegin, I parEnd, std::size_t parSize ) :
+			boost::iterator_range<I>(parBegin, parEnd),
+			m_size(parSize)
+		{
+		}
+
+		template <typename R>
+		SizedRange ( R& parRange, std::size_t parSize ) :
+			boost::iterator_range<I>(parRange),
+			m_size(parSize)
+		{
+		}
+
+		~SizedRange ( void ) noexcept = default;
+
+		std::size_t size ( void ) const { return m_size; }
+		bool empty ( void ) const { return static_cast<bool>(0 == m_size); }
+
+		typename I::reference front ( void ) { assert(not empty()); return *this->begin(); }
+		const typename I::reference front ( void ) const { assert(not empty()); return *this->begin(); }
+
+	private:
+		std::size_t m_size;
+	};
+} //namespace redis
+
+#endif

src/batch.cpp

@@ -18,6 +18,7 @@
 #include "batch.hpp"
 #include "async_connection.hpp"
 #include "thread_context.hpp"
+#include "reply_list.hpp"
 #include <hiredis/hiredis.h>
 #include <hiredis/async.h>
 #include <cassert>
@@ -41,13 +42,13 @@ namespace redis {
 			HiredisCallbackData ( std::atomic_size_t& parPendingFutures, std::atomic_size_t& parLocalPendingFutures, std::condition_variable& parSendCmdCond, std::condition_variable& parLocalCmdsCond ) :
 				pending_futures(parPendingFutures),
 				local_pending_futures(parLocalPendingFutures),
-				reply_ptr(nullptr),
+				reply_ptr(),
 				send_command_condition(parSendCmdCond),
 				local_commands_condition(parLocalCmdsCond)
 			{
 			}
 
-			Reply* reply_ptr;
+			ReplyList::ReplyPtr reply_ptr;
 			std::atomic_size_t& pending_futures;
 			std::atomic_size_t& local_pending_futures;
 			std::condition_variable& send_command_condition;
@@ -92,7 +93,6 @@ namespace redis {
 
 			if (parReply) {
 				auto reply = make_redis_reply_type(static_cast<redisReply*>(parReply));
-				assert(data->reply_ptr);
 				*data->reply_ptr = std::move(reply);
 			}
 			else {
@@ -108,7 +108,8 @@ namespace redis {
 			delete data;
 		}
 
-		int array_throw_if_failed (int parErrCount, int parMaxReportedErrors, const std::vector<Reply>& parReplies, std::ostream& parStream) {
+		template <typename R>
+		int array_throw_if_failed (int parErrCount, int parMaxReportedErrors, const R& parReplies, std::ostream& parStream) {
 			int err_count = 0;
 			for (const auto& rep : parReplies) {
 				if (rep.which() == RedisVariantType_Error) {
@@ -135,6 +136,7 @@ namespace redis {
 		{
 		}
 
+		ReplyList replies;
 		std::condition_variable free_cmd_slot;
 		std::condition_variable no_more_pending_futures;
 		std::mutex futures_mutex;
@@ -146,8 +148,6 @@ namespace redis {
 	Batch::Batch (Batch&&) = default;
 
 	Batch::Batch (AsyncConnection* parConn, ThreadContext& parThreadContext) :
-		m_futures(),
-		m_replies(),
 		m_local_data(new LocalData(parThreadContext)),
 		m_async_conn(parConn)
 	{
@@ -161,7 +161,6 @@ namespace redis {
 	}
 
 	void Batch::run_pvt (int parArgc, const char** parArgv, std::size_t* parLengths) {
-		assert(not replies_requested());
 		assert(parArgc >= 1);
 		assert(parArgv);
 		assert(parLengths); //This /could/ be null, but I don't see why it should
@@ -185,9 +184,7 @@ namespace redis {
 		std::cout << " emplace_back(future)... ";
 #endif
 
-		std::unique_ptr<Reply> new_reply(new Reply);
-		data->reply_ptr = new_reply.get();
-		m_futures.emplace_back(std::move(new_reply));
+		data->reply_ptr = m_local_data->replies.add();
 		{
 			std::lock_guard<std::mutex> lock(m_async_conn->event_mutex());
 			const int command_added = redisAsyncCommandArgv(m_async_conn->connection(), &hiredis_run_callback, data, parArgc, parArgv, parLengths);
@@ -202,28 +199,22 @@ namespace redis {
 	}
 
 	bool Batch::replies_requested() const {
-		return not m_replies.empty();
+		return static_cast<bool>(0 == m_local_data->local_pending_futures);
 	}
 
-	const std::vector<Reply>& Batch::replies() {
-		return replies_nonconst();
-	}
-
-	std::vector<Reply>& Batch::replies_nonconst() {
+	auto Batch::replies() const -> ConstReplies {
 		if (not replies_requested()) {
 			if (m_local_data->local_pending_futures > 0) {
 				std::unique_lock<std::mutex> u_lock(m_local_data->pending_futures_mutex);
 				m_local_data->no_more_pending_futures.wait(u_lock, [this]() { return m_local_data->local_pending_futures == 0; });
 			}
-
-			m_replies.reserve(m_futures.size());
-			for (auto& itm : m_futures) {
-				m_replies.emplace_back(std::move(*itm));
-			}
-
-			auto empty_vec = std::move(m_futures);
 		}
-		return m_replies;
+		return ConstReplies(m_local_data->replies.begin(), m_local_data->replies.end(), m_local_data->replies.size());
+	}
+
+	auto Batch::replies_nonconst() -> Replies {
+		replies();
+		return Replies(m_local_data->replies.begin(), m_local_data->replies.end(), m_local_data->replies.size());
 	}
 
 	void Batch::throw_if_failed() {
@@ -233,7 +224,7 @@ namespace redis {
 		oss << "Error in reply: ";
 		const int err_count = array_throw_if_failed(0, max_reported_errors, replies(), oss);
 		if (err_count) {
-			oss << " (showing " << err_count << '/' << max_reported_errors << " errors on " << replies().size() << " total replies)";
+			oss << " (showing " << err_count << '/' << max_reported_errors << " errors on " << m_local_data->replies.size() << " total replies)";
 			throw std::runtime_error(oss.str());
 		}
 	}
@@ -248,8 +239,7 @@ namespace redis {
 
 		assert(m_local_data);
 		assert(0 == m_local_data->local_pending_futures);
-		m_futures.clear();
-		m_replies.clear();
+		m_local_data->replies.clear();
 	}
 
 	RedisError::RedisError (const char* parMessage, std::size_t parLength) :

src/reply_list.cpp

@@ -0,0 +1,58 @@
+/* Copyright 2016, Michele Santullo
+ * This file is part of "incredis".
+ *
+ * "incredis" 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.
+ *
+ * "incredis" 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 "incredis".  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "reply_list.hpp"
+#include "reply.hpp"
+
+namespace redis {
+	ReplyList::ReplyList() :
+		m_replies(),
+		m_next_iterator(m_replies.before_begin()),
+		m_size(0)
+	{
+	}
+
+	ReplyList::~ReplyList() noexcept = default;
+
+	auto ReplyList::add() -> ReplyPtr {
+		m_next_iterator = m_replies.emplace_after(m_next_iterator);
+		++m_size;
+		return m_next_iterator;
+	}
+
+	std::size_t ReplyList::size() const {
+		return m_size;
+	}
+
+	bool ReplyList::empty() const {
+		return static_cast<bool>(0 == m_size);
+	}
+
+	std::forward_list<Reply>::iterator ReplyList::begin() {
+		return m_replies.begin();
+	}
+
+	std::forward_list<Reply>::iterator ReplyList::end() {
+		return m_replies.end();
+	}
+
+	void ReplyList::clear() {
+		m_replies.clear();
+		m_next_iterator = m_replies.begin();
+		m_size = 0;
+	}
+} //namespace redis

src/reply_list.hpp

@@ -0,0 +1,47 @@
+/* Copyright 2016, Michele Santullo
+ * This file is part of "incredis".
+ *
+ * "incredis" 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.
+ *
+ * "incredis" 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 "incredis".  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef idF28625434960439DBB5B4F2A1E24CD60
+#define idF28625434960439DBB5B4F2A1E24CD60
+
+#include <forward_list>
+
+namespace redis {
+	class Reply;
+
+	class ReplyList {
+	public:
+		using ReplyPtr = std::forward_list<Reply>::iterator;
+
+		ReplyList ( void );
+		~ReplyList ( void ) noexcept;
+
+		ReplyPtr add ( void );
+		std::size_t size ( void ) const;
+		bool empty ( void ) const;
+		std::forward_list<Reply>::iterator begin ( void );
+		std::forward_list<Reply>::iterator end ( void );
+		void clear ( void );
+
+	private:
+		std::forward_list<Reply> m_replies;
+		std::forward_list<Reply>::iterator m_next_iterator;
+		std::size_t m_size;
+	};
+} //namespace redis
+
+#endif