add benchmark

src/benchmark/CMakeLists.txt

@@ -1,10 +1,11 @@
 set (BENCHMARK_SRCS
 	${CMAKE_CURRENT_SOURCE_DIR}/benchmark.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/benchmark_activeobjectmgr.cpp
+	${CMAKE_CURRENT_SOURCE_DIR}/benchmark_ipc_channel.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/benchmark_lighting.cpp
-	${CMAKE_CURRENT_SOURCE_DIR}/benchmark_serialize.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/benchmark_mapblock.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/benchmark_mapmodify.cpp
+	${CMAKE_CURRENT_SOURCE_DIR}/benchmark_serialize.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/benchmark_sha.cpp
 	PARENT_SCOPE)
 

src/benchmark/benchmark_ipc_channel.cpp

@@ -0,0 +1,95 @@
+/*
+Minetest
+Copyright (C) 2024 DS
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program 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 Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "benchmark_setup.h"
+#include "threading/ipc_channel.h"
+#include <thread>
+
+#include "log.h"
+
+TEST_CASE("benchmark_ipc_channel")
+{
+	// same as in test_threading.cpp (TODO: remove duplication)
+	struct IPCChannelResourcesSingleProcess final : public IPCChannelResources
+	{
+		void cleanupLast() noexcept override
+		{
+			delete data.shared;
+#ifdef IPC_CHANNEL_IMPLEMENTATION_WIN32
+			CloseHandle(data.sem_b);
+			CloseHandle(data.sem_a);
+#endif
+		}
+
+		void cleanupNotLast() noexcept override
+		{
+			// nothing to do (i.e. no unmapping needed)
+		}
+
+		~IPCChannelResourcesSingleProcess() override { cleanup(); }
+	};
+
+	auto resource_data = [] {
+		auto shared = new IPCChannelShared();
+
+#ifdef IPC_CHANNEL_IMPLEMENTATION_WIN32
+		HANDLE sem_a = CreateSemaphoreA(nullptr, 0, 1, nullptr);
+		REQUIRE(sem_a != INVALID_HANDLE_VALUE);
+
+		HANDLE sem_b = CreateSemaphoreA(nullptr, 0, 1, nullptr);
+		REQUIRE(sem_b != INVALID_HANDLE_VALUE);
+
+		return IPCChannelResources::Data{shared, sem_a, sem_b};
+#else
+		return IPCChannelResources::Data{shared};
+#endif
+	}();
+
+	auto resources_first = std::make_unique<IPCChannelResourcesSingleProcess>();
+	resources_first->setFirst(resource_data);
+
+	IPCChannelEnd end_a = IPCChannelEnd::makeA(std::move(resources_first));
+
+	// echos back messages. stops if "" is sent
+	std::thread thread_b([=] {
+		auto resources_second = std::make_unique<IPCChannelResourcesSingleProcess>();
+		resources_second->setSecond(resource_data);
+		IPCChannelEnd end_b = IPCChannelEnd::makeB(std::move(resources_second));
+
+		for (;;) {
+			end_b.recv();
+			end_b.send(end_b.getRecvData(), end_b.getRecvSize());
+			if (end_b.getRecvSize() == 0)
+				break;
+		}
+	});
+
+	BENCHMARK("simple_call", i) {
+		char buf[16] = {};
+		buf[i & 0xf] = i;
+		end_a.exchange(buf, 16);
+		return reinterpret_cast<const u8 *>(end_a.getRecvData())[i & 0xf];
+	};
+
+	// stop thread_b
+	end_a.exchange(nullptr, 0);
+	REQUIRE(end_a.getRecvSize() == 0);
+
+	thread_b.join();
+}

src/threading/ipc_channel.cpp

@@ -242,6 +242,7 @@ IPCChannelEnd IPCChannelEnd::makeB(std::unique_ptr<IPCChannelResources> resource
 void IPCChannelEnd::sendSmall(const void *data, size_t size) noexcept
 {
 	write_once(&m_out->size, size);
+	if (size != 0)
 		memcpy(m_out->data, data, size);
 #if defined(IPC_CHANNEL_IMPLEMENTATION_WIN32)
 	post(m_sem_out);
@@ -275,6 +276,7 @@ bool IPCChannelEnd::sendLarge(const void *data, size_t size, int timeout_ms) noe
 		size -= IPC_CHANNEL_MSG_SIZE;
 		data = (u8 *)data + IPC_CHANNEL_MSG_SIZE;
 	} while (size > IPC_CHANNEL_MSG_SIZE);
+	if (size != 0)
 		memcpy(m_out->data, data, size);
 #if defined(IPC_CHANNEL_IMPLEMENTATION_WIN32)
 	post(m_sem_out);

src/unittest/test_threading.cpp

@@ -276,6 +276,7 @@ void TestThreading::testIPCChannel()
 
 	IPCChannelEnd end_a = IPCChannelEnd::makeA(std::move(resources_first));
 
+	// echos back messages. stops if "" is sent
 	std::thread thread_b([=] {
 		auto resources_second = std::make_unique<IPCChannelResourcesSingleProcess>();
 		resources_second->setSecond(resource_data);
@@ -297,6 +298,7 @@ void TestThreading::testIPCChannel()
 		UASSERTEQ(int, ((const char *)end_a.getRecvData())[i - 1], 123);
 	}
 
+	// stop thread_b
 	UASSERT(end_a.exchangeWithTimeout(buf, 0, -1));
 	UASSERTEQ(int, end_a.getRecvSize(), 0);