Introduce DefragAllocator

lib/base/CMakeLists.txt

@@ -14,7 +14,7 @@ mkclass_target(sysloglogger.ti sysloglogger-ti.cpp sysloglogger-ti.hpp)
 
 set(base_SOURCES
   i2-base.hpp
-  allocator.cpp
+  allocator.cpp allocator.hpp
   application.cpp application.hpp application-ti.hpp application-version.cpp application-environment.cpp
   array.cpp array.hpp array-script.cpp
   atomic.hpp

lib/base/allocator.cpp

@@ -2,19 +2,99 @@
 
 #ifndef _WIN32
 
+#include "base/allocator.hpp"
+#include <algorithm>
+#include <boost/config.hpp>
 #include <cstddef>
 #include <dlfcn.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+using namespace icinga;
+
+struct DAPage
+{
+	size_t TotalSize = sizeof(DAPage);
+	DAPage* Next = nullptr;
+	max_align_t* MemoryBegin = nullptr;
+	max_align_t* MemoryEnd = nullptr;
+	max_align_t Memory[1] = {};
+};
+
+static thread_local struct {
+	unsigned int InUse = 0;
+	DAPage* TopPage = nullptr;
+} l_DefragAllocator;
 
 extern "C" void* malloc(size_t bytes)
 {
 	static const auto libcMalloc = (void*(*)(size_t))dlsym(RTLD_NEXT, "malloc");
+	static const size_t pageSize = std::max(128L * 1024L, sysconf(_SC_PAGESIZE));
+
+	if (BOOST_LIKELY(!l_DefragAllocator.InUse)) {
 		return libcMalloc(bytes);
 	}
 
+	if (BOOST_UNLIKELY(!bytes)) {
+		return nullptr;
+	}
+
+	auto chunks ((bytes + sizeof(max_align_t) - 1u) / sizeof(max_align_t));
+
+	if (BOOST_UNLIKELY(!l_DefragAllocator.TopPage || l_DefragAllocator.TopPage->MemoryEnd - l_DefragAllocator.TopPage->MemoryBegin < chunks)) {
+		auto total ((sizeof(DAPage) + sizeof(max_align_t) * (chunks - 1u) + pageSize - 1u) / pageSize * pageSize);
+
+		auto nextPage (mmap(nullptr, total, PROT_READ | PROT_WRITE, MAP_ANONYMOUS
+#ifdef MAP_HASSEMAPHORE
+		| MAP_HASSEMAPHORE
+#endif
+		| MAP_PRIVATE, -1, 0));
+
+		if (BOOST_UNLIKELY(nextPage == MAP_FAILED)) {
+			return nullptr;
+		}
+
+		auto p ((DAPage*)nextPage);
+
+		p->TotalSize = total;
+		p->Next = l_DefragAllocator.TopPage;
+		p->MemoryBegin = p->Memory;
+		p->MemoryEnd = p->MemoryBegin + chunks;
+
+		l_DefragAllocator.TopPage = p;
+	}
+
+	auto memory ((void*)l_DefragAllocator.TopPage->MemoryBegin);
+
+	l_DefragAllocator.TopPage->MemoryBegin += chunks;
+
+	return memory;
+}
+
 extern "C" void free(void* memory)
 {
 	static const auto libcFree = (void(*)(void*))dlsym(RTLD_NEXT, "free");
+
+	if (BOOST_LIKELY(!l_DefragAllocator.InUse)) {
 		libcFree(memory);
 	}
+}
+
+DefragAllocator::DefragAllocator()
+{
+	++l_DefragAllocator.InUse;
+}
+
+DefragAllocator::~DefragAllocator()
+{
+	if (!--l_DefragAllocator.InUse) {
+		while (l_DefragAllocator.TopPage) {
+			auto next (l_DefragAllocator.TopPage->Next);
+
+			munmap(l_DefragAllocator.TopPage, l_DefragAllocator.TopPage->TotalSize);
+			l_DefragAllocator.TopPage = next;
+		}
+	}
+}
 
 #endif /* _WIN32 */

lib/base/allocator.hpp

@@ -0,0 +1,24 @@
+/* Icinga 2 | (c) 2023 Icinga GmbH | GPLv2+ */
+
+#pragma once
+
+namespace icinga
+{
+
+/**
+ * TODO
+ *
+ * @ingroup base
+ */
+class DefragAllocator
+{
+public:
+	DefragAllocator();
+	DefragAllocator(const DefragAllocator&) = delete;
+	DefragAllocator(DefragAllocator&&) = delete;
+	DefragAllocator& operator=(const DefragAllocator&) = delete;
+	DefragAllocator& operator=(DefragAllocator&&) = delete;
+	~DefragAllocator();
+};
+
+}