From e912cfc19ddfa54d4aeb5eb5f2f99b728e0b418b Mon Sep 17 00:00:00 2001
From: Jonathan G Rennison <j.g.rennison@gmail.com>
Date: Sat, 19 Aug 2023 15:28:45 +0100
Subject: [PATCH] Ring buffer: Use as backing for std::queue uses

---
 src/core/CMakeLists.txt         |  1 +
 src/core/ring_buffer.hpp        |  5 +++++
 src/core/ring_buffer_queue.hpp  | 20 ++++++++++++++++++++
 src/linkgraph/demands.cpp       |  4 ++--
 src/network/core/http_curl.cpp  |  4 ++--
 src/script/api/script_event.cpp |  4 ++--
 src/worker_thread.h             |  4 ++--
 7 files changed, 34 insertions(+), 8 deletions(-)
 create mode 100644 src/core/ring_buffer_queue.hpp

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index ebb7efa509..d060255b96 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -29,6 +29,7 @@ add_files(
     random_func.cpp
     random_func.hpp
     ring_buffer.hpp
+    ring_buffer_queue.hpp
     serialisation.cpp
     serialisation.hpp
     smallstack_type.hpp
diff --git a/src/core/ring_buffer.hpp b/src/core/ring_buffer.hpp
index 01484f2cca..8ff914eb45 100644
--- a/src/core/ring_buffer.hpp
+++ b/src/core/ring_buffer.hpp
@@ -192,6 +192,11 @@ public:
 		}
 	};
 
+	using difference_type = std::ptrdiff_t;
+	using size_type = size_t;
+	using value_type = T;
+	using reference = T &;
+	using const_reference = const T &;
 	typedef ring_buffer_iterator<T, false> iterator;
 	typedef ring_buffer_iterator<const T, false> const_iterator;
 	typedef ring_buffer_iterator<T, true> reverse_iterator;
diff --git a/src/core/ring_buffer_queue.hpp b/src/core/ring_buffer_queue.hpp
new file mode 100644
index 0000000000..894cc8bdf2
--- /dev/null
+++ b/src/core/ring_buffer_queue.hpp
@@ -0,0 +1,20 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD 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, version 2.
+ * OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file ring_buffer_queue.hpp std::queue backed by a ring buffer. */
+
+#ifndef RING_BUFFER_QUEUE_HPP
+#define RING_BUFFER_QUEUE_HPP
+
+#include "ring_buffer.hpp"
+
+#include <queue>
+
+template<class T>
+using ring_buffer_queue = std::queue<T, ring_buffer<T>>;
+
+#endif /* RING_BUFFER_QUEUE_HPP */
diff --git a/src/linkgraph/demands.cpp b/src/linkgraph/demands.cpp
index 88128daced..4e7c71c309 100644
--- a/src/linkgraph/demands.cpp
+++ b/src/linkgraph/demands.cpp
@@ -2,13 +2,13 @@
 
 #include "../stdafx.h"
 #include "demands.h"
-#include <queue>
+#include "../core/ring_buffer_queue.hpp"
 #include <algorithm>
 #include <tuple>
 
 #include "../safeguards.h"
 
-typedef std::queue<NodeID> NodeList;
+typedef ring_buffer_queue<NodeID> NodeList;
 
 /**
  * Scale various things according to symmetric/asymmetric distribution.
diff --git a/src/network/core/http_curl.cpp b/src/network/core/http_curl.cpp
index c3422d0789..9368533fcf 100644
--- a/src/network/core/http_curl.cpp
+++ b/src/network/core/http_curl.cpp
@@ -14,6 +14,7 @@
 #include "../../fileio_func.h"
 #include "../../rev.h"
 #include "../../thread.h"
+#include "../../core/ring_buffer_queue.hpp"
 #include "../network_internal.h"
 
 #include "http.h"
@@ -23,7 +24,6 @@
 #include <curl/curl.h>
 #include <memory>
 #include <mutex>
-#include <queue>
 
 #include "../../safeguards.h"
 
@@ -69,7 +69,7 @@ public:
 
 static std::thread _http_thread;
 static std::atomic<bool> _http_thread_exit = false;
-static std::queue<std::unique_ptr<NetworkHTTPRequest>> _http_requests;
+static ring_buffer_queue<std::unique_ptr<NetworkHTTPRequest>> _http_requests;
 static std::mutex _http_mutex;
 static std::condition_variable _http_cv;
 #if defined(UNIX)
diff --git a/src/script/api/script_event.cpp b/src/script/api/script_event.cpp
index efdc720cf3..4f9cfcaaba 100644
--- a/src/script/api/script_event.cpp
+++ b/src/script/api/script_event.cpp
@@ -10,13 +10,13 @@
 #include "../../stdafx.h"
 #include "script_event_types.hpp"
 
-#include <queue>
+#include "../../core/ring_buffer_queue.hpp"
 
 #include "../../safeguards.h"
 
 /** The queue of events for a script. */
 struct ScriptEventData {
-	std::queue<ScriptEvent *> stack; ///< The actual queue.
+	ring_buffer_queue<ScriptEvent *> stack; ///< The actual queue.
 };
 
 /* static */ void ScriptEventController::CreateEventPointer()
diff --git a/src/worker_thread.h b/src/worker_thread.h
index 6000af3c78..82ae5b415a 100644
--- a/src/worker_thread.h
+++ b/src/worker_thread.h
@@ -10,7 +10,7 @@
 #ifndef WORKER_THREAD_H
 #define WORKER_THREAD_H
 
-#include <queue>
+#include "core/ring_buffer_queue.hpp"
 #include <mutex>
 #include <condition_variable>
 #if defined(__MINGW32__)
@@ -33,7 +33,7 @@ private:
 	uint workers_waiting = 0;
 	bool exit = false;
 	std::mutex lock;
-	std::queue<WorkerJob> jobs;
+	ring_buffer_queue<WorkerJob> jobs;
 	std::condition_variable worker_wait_cv;
 	std::condition_variable done_cv;