#pragma once #include #include #include #include #include #include #include #include #if defined(BOOST_USE_VALGRIND) #include #endif namespace DB::ErrorCodes { extern const int CANNOT_ALLOCATE_MEMORY; } /// This is an implementation of allocator for fiber stack. /// The reference implementation is protected_fixedsize_stack from boost::context. /// This implementation additionally track memory usage. It is the main reason why it is needed. class FiberStack { private: size_t stack_size; size_t page_size = 0; public: /// NOTE: If you see random segfaults in CI and stack starts from boost::context::...fiber... /// probably it worth to try to increase stack size for coroutines. /// /// Current value is just enough for all tests in our CI. It's not selected in some special /// way. We will have 40 pages with 4KB page size. static constexpr size_t default_stack_size = 192 * 1024; /// 64KB was not enough for tests explicit FiberStack(size_t stack_size_ = default_stack_size) : stack_size(stack_size_) { page_size = ::sysconf(_SC_PAGESIZE); } boost::context::stack_context allocate() { size_t num_pages = 1 + (stack_size - 1) / page_size; size_t num_bytes = (num_pages + 1) * page_size; /// Add one page at bottom that will be used as guard-page void * vp = ::mmap(nullptr, num_bytes, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (MAP_FAILED == vp) DB::throwFromErrno(fmt::format("FiberStack: Cannot mmap {}.", ReadableSize(num_bytes)), DB::ErrorCodes::CANNOT_ALLOCATE_MEMORY); /// TODO: make reports on illegal guard page access more clear. /// Currently we will see segfault and almost random stacktrace. if (-1 == ::mprotect(vp, page_size, PROT_NONE)) { ::munmap(vp, num_bytes); DB::throwFromErrno("FiberStack: cannot protect guard page", DB::ErrorCodes::CANNOT_ALLOCATE_MEMORY); } /// Do not count guard page in memory usage. CurrentMemoryTracker::alloc(num_pages * page_size); boost::context::stack_context sctx; sctx.size = num_bytes; sctx.sp = static_cast< char * >(vp) + sctx.size; #if defined(BOOST_USE_VALGRIND) sctx.valgrind_stack_id = VALGRIND_STACK_REGISTER(sctx.sp, vp); #endif return sctx; } void deallocate(boost::context::stack_context & sctx) { #if defined(BOOST_USE_VALGRIND) VALGRIND_STACK_DEREGISTER(sctx.valgrind_stack_id); #endif void * vp = static_cast< char * >(sctx.sp) - sctx.size; ::munmap(vp, sctx.size); /// Do not count guard page in memory usage. CurrentMemoryTracker::free(sctx.size - page_size); } };