Add opt.experimental_infallible_new.

This allows a guarantee that operator new never throws.

Fix the .gitignore rules to include test/integration/cpp while we're here.

src/jemalloc.c

@@ -141,6 +141,7 @@ void (*junk_free_callback)(void *ptr, size_t size) = &default_junk_free;
 
 bool	opt_utrace = false;
 bool	opt_xmalloc = false;
+bool	opt_experimental_infallible_new = false;
 bool	opt_zero = false;
 unsigned	opt_narenas = 0;
 fxp_t		opt_narenas_ratio = FXP_INIT_INT(4);
@@ -1307,6 +1308,12 @@ malloc_conf_init_helper(sc_data_t *sc_data, unsigned bin_shard_sizes[SC_NBINS],
 			if (config_xmalloc) {
 				CONF_HANDLE_BOOL(opt_xmalloc, "xmalloc")
 			}
+			if (config_enable_cxx) {
+				CONF_HANDLE_BOOL(
+				    opt_experimental_infallible_new,
+				    "experimental_infallible_new")
+			}
+
 			CONF_HANDLE_BOOL(opt_tcache, "tcache")
 			CONF_HANDLE_SIZE_T(opt_tcache_max, "tcache_max",
 			    0, TCACHE_MAXCLASS_LIMIT, CONF_DONT_CHECK_MIN,

src/jemalloc_cpp.cpp

@@ -56,6 +56,12 @@ void	operator delete[](void* ptr, std::size_t size, std::align_val_t al) noexcep
 JEMALLOC_NOINLINE
 static void *
 handleOOM(std::size_t size, bool nothrow) {
+	if (opt_experimental_infallible_new) {
+		safety_check_fail("<jemalloc>: Allocation failed and "
+		    "opt.experimental_infallible_new is true. Aborting.\n");
+		return nullptr;
+	}
+
 	void *ptr = nullptr;
 
 	while (ptr == nullptr) {
@@ -93,7 +99,6 @@ fallback_impl(std::size_t size) noexcept(IsNoExcept) {
 	if (likely(ptr != nullptr)) {
 		return ptr;
 	}
-
 	return handleOOM(size, IsNoExcept);
 }
 

src/stats.c

@@ -1501,6 +1501,7 @@ stats_general_print(emitter_t *emitter) {
 	OPT_WRITE_BOOL("zero")
 	OPT_WRITE_BOOL("utrace")
 	OPT_WRITE_BOOL("xmalloc")
+	OPT_WRITE_BOOL("experimental_infallible_new")
 	OPT_WRITE_BOOL("tcache")
 	OPT_WRITE_SIZE_T("tcache_max")
 	OPT_WRITE_UNSIGNED("tcache_nslots_small_min")