Use the lua script to save new pasties.

I had to add a {store:} prefix, see this:
https://stackoverflow.com/questions/38720084/generate-new-key-inside-evalsha

src/kamokan_impl/CMakeLists.txt

@@ -8,7 +8,6 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 add_library(${PROJECT_NAME} STATIC
 	response.cpp
 	submit_paste_response.cpp
-	num_to_token.cpp
 	index_response.cpp
 	pastie_response.cpp
 	ini_file.cpp

src/kamokan_impl/retrieve_pastie.lua

@@ -1,5 +1,7 @@
 local token = KEYS[1]
-local result = redis.call("HMGET", token, "pastie", "selfdes", "lang")
+local token_prefix = ARGV[1]
+local full_token = token_prefix .. token
+local result = redis.call("HMGET", full_token, "pastie", "selfdes", "lang")
 if false == result[1] then
 	return redis.error_reply("PastieNotFound")
 end
@@ -7,7 +9,7 @@ end
 local selfdes = 0
 local deleted = 0
 if result[2] == 1 then
-	deleted = redis.call("DEL", token)
+	deleted = redis.call("DEL", full_token)
 	selfdes = 1
 end
 

src/kamokan_impl/save_pastie.lua

@@ -1,4 +1,4 @@
-function num_to_value (num)
+local function num_to_token (num)
   local retval = ""
   local running = true
 
@@ -12,18 +12,34 @@ function num_to_value (num)
   return retval
 end
 
-paste_counter = KEYS[1]
-next_id = redis.call("INCR", paste_counter) - 1
-token = num_to_token(next_id)
-text = ARGV[1]
-ttl = ARGV[2]
-lang = ARGV[3]
-selfdestruct = ARGV[4]
-redis.call("HMSET", token,
+local paste_counter_token = KEYS[1]
+local flooding_token = KEYS[2]
+
+local flooding_result = redis.call("GET", flooding_token)
+if flooding_result then
+  return redis.error_reply("UserFlooding")
+end
+
+local token_prefix = ARGV[1]
+local text = ARGV[2]
+local ttl = ARGV[3]
+local lang = ARGV[4]
+local selfdestruct = ARGV[5]
+local flood_wait = ARGV[6]
+
+local next_id = redis.call("INCR", paste_counter_token) - 1
+local token = num_to_token(next_id)
+local saved = redis.call("HMSET", token_prefix .. token,
   "pastie", text,
   "max_ttl", ttl,
   "lang", lang,
   "selfdes", selfdestruct
 )
+if saved then
+  redis.call("SET", flooding_token, "")
+  redis.call("EXPIRE", flooding_token, flood_wait)
+else
+  return redis.error_reply("PastieNotSaved")
+end
 
 return token

src/kamokan_impl/storage.cpp

@@ -18,12 +18,12 @@
 #include "storage.hpp"
 #include "settings_bag.hpp"
 #include "incredis/incredis.hpp"
-#include "num_to_token.hpp"
 #include "duckhandy/stringize.h"
 #include "spdlog.hpp"
 #include "truncated_string.hpp"
 #include "string_conv.hpp"
 #include "lua_scripts_for_redis.hpp"
+#include "redis_to_error_reason.hpp"
 #include <cassert>
 #include <ciso646>
 #include <string>
@@ -32,6 +32,8 @@
 
 namespace kamokan {
 	namespace {
+		const char g_token_prefix[] = "kamokan:{store:}";
+
 		redis::IncRedis make_incredis (const SettingsBag& parSettings) {
 			using redis::IncRedis;
 
@@ -130,54 +132,64 @@ namespace kamokan {
 		const std::string& parRemoteIP
 	) const {
 		using tawashi::ErrorReasons;
-		using redis::RedisInt;
+		using boost::string_view;
+		using dhandy::lexical_cast;
 
 		if (not is_connected())
 			return make_submission_result(ErrorReasons::RedisDisconnected);
 
 		assert(m_redis);
 		auto& redis = *m_redis;
-		if (redis.get(parRemoteIP)) {
-			//please wait and submit again
-			return make_submission_result(ErrorReasons::UserFlooding);
+
+		redis::Script retrieve = m_redis->command().make_script(string_view(g_save_script, g_save_script_size));
+		auto batch = m_redis->command().make_batch();
+		{
+			string_view paste_counter_token("{store:}paste_counter");
+			std::string prefix(g_token_prefix);
+			const auto expiry = lexical_cast<std::string>(parExpiry);
+			const auto self_des = string_view(parSelfDestruct ? "1" : "0");
+			const auto flood_wait = m_settings->as<string_view>("resubmit_wait");
+			retrieve.run(batch,
+				std::make_tuple(paste_counter_token, prefix + parRemoteIP),
+				std::make_tuple(prefix, parText, expiry, parLang, self_des, flood_wait)
+			);
+		}
+		auto raw_replies = batch.replies();
+		auto statuslog = spdlog::get("statuslog");
+		if (raw_replies.empty()) {
+			statuslog->error("Received empty reply from redis");
+			return make_submission_result(ErrorReasons::UnknownReason);
 		}
 
-		auto statuslog = spdlog::get("statuslog");
+		if (raw_replies.front().is_error()) {
+			statuslog->error("Received error reply from redis");
+			return make_submission_result(redis_to_error_reason(get_error_string(raw_replies.front())));
+		}
+
+		std::string token = get_string(raw_replies.front());
+
 		if (statuslog->should_log(spdlog::level::info)) {
 			statuslog->info(
-				"Submitting pastie of size {} to redis -> \"{}\"",
+				"Saved pastie of size {} to redis token \"{}\" -> \"{}\"",
 				parText.size(),
+				token,
 				tawashi::truncated_string(parText, 30)
 			);
 		}
-
-		const auto next_id = redis.incr("paste_counter");
-		std::string token = num_to_token(next_id);
-		assert(not token.empty());
-		if (redis.hmset(token,
-			"pastie", parText,
-			"max_ttl", dhandy::lexical_cast<std::string>(parExpiry),
-			"lang", parLang,
-			"selfdes", static_cast<RedisInt>(parSelfDestruct ? 1 : 0))
-		) {
-			redis.set(parRemoteIP, "");
-			redis.expire(parRemoteIP, m_settings->as<uint32_t>("resubmit_wait"));
-			if (redis.expire(token, parExpiry))
 		return make_submission_result(std::move(token));
 	}
 
-		return make_submission_result(ErrorReasons::PastieNotSaved);
-	}
-
 	auto Storage::retrieve_pastie (const boost::string_view& parToken, uint32_t parMaxTokenLen) const -> RetrievedPastie {
+		using boost::string_view;
+
 		RetrievedPastie retval;
 		retval.valid_token = is_valid_token(parToken, parMaxTokenLen);
 		if (not retval.valid_token)
 			return retval;
 
-		redis::Script retrieve = m_redis->command().make_script(boost::string_view(g_load_script, g_load_script_size));
+		redis::Script retrieve = m_redis->command().make_script(string_view(g_load_script, g_load_script_size));
 		auto batch = m_redis->command().make_batch();
-		retrieve.run(batch, std::make_tuple(parToken), std::make_tuple());
+		retrieve.run(batch, std::make_tuple(parToken), std::make_tuple(string_view(g_token_prefix)));
 		auto raw_replies = batch.replies();
 		if (raw_replies.empty())
 			return retval;

src/kamokan_impl/string_conv.hpp

@@ -50,6 +50,12 @@ namespace kamokan {
 		return dhandy::lexical_cast<uint32_t>(parStr);
 	}
 
+	template <>
+	[[gnu::pure,gnu::always_inline]] inline
+	long long string_conv (boost::string_view parStr) {
+		return dhandy::lexical_cast<long long>(parStr);
+	}
+
 	template <>
 	inline
 	std::string string_conv (boost::string_view parStr) {

test/simulation/CMakeLists.txt

@@ -11,6 +11,7 @@ add_executable(${PROJECT_NAME}
 	test_index_response.cpp
 	test_submit_pastie.cpp
 	fake_storage.cpp
+	num_to_token.cpp
 )
 
 target_include_directories(${PROJECT_NAME}