Print jemalloc default config on startup

Since jemalloc config can be changed via 'MALLOC_CONF' env variable,
printing on startup ensures that we can check in the error log if the
default config has been overridden.

src/Makefile

@@ -149,11 +149,18 @@ ifeq ($(TEST_WITHASAN),1)
 	WASAN += -DTEST_WITHASAN
 endif
 
+NOJEMALLOC := $(shell echo $(NOJEMALLOC))
+ifeq ($(NOJEMALLOC),1)
+NOJEM=-DNOJEM
+else
+NOJEM=
+endif
+
 MYCXXFLAGS := $(STDCPP)
 ifeq ($(CXX),clang++)
 	MYCXXFLAGS += -fuse-ld=lld
 endif
-MYCXXFLAGS += $(IDIRS) $(OPTZ) $(DEBUG) $(PSQLCH) -DGITVERSION=\"$(GIT_VERSION)\" $(WGCOV) $(WASAN)
+MYCXXFLAGS += $(IDIRS) $(OPTZ) $(DEBUG) $(PSQLCH) -DGITVERSION=\"$(GIT_VERSION)\" $(NOJEM) $(WGCOV) $(WASAN)
 
 
 STATICMYLIBS := -Wl,-Bstatic -lconfig -lproxysql -ldaemon -lconfig++ -lre2 -lpcrecpp -lpcre -lmariadbclient -lhttpserver -lmicrohttpd -linjection -lcurl -lssl -lcrypto -lev

src/main.cpp

@@ -1902,7 +1902,61 @@ void handleProcessRestart() {
 	} while (pid > 0);
 }
 
+#ifndef NOJEM
+int print_jemalloc_conf() {
+	int rc = 0;
+
+	bool xmalloc = 0;
+	bool prof_accum = 0;
+	bool prof_leak = 0;
+
+	size_t lg_cache_max = 0;
+	size_t lg_prof_sample = 0;
+	size_t lg_prof_interval = 0;
+
+	size_t bool_sz = sizeof(bool);
+	size_t size_sz = sizeof(size_t);
+	size_t ssize_sz = sizeof(ssize_t);
+
+	rc = mallctl("config.xmalloc", &xmalloc, &bool_sz, NULL, 0);
+	if (rc) { proxy_error("Failed to fetch 'config.xmalloc' with error %d", rc); return rc; }
+
+	rc = mallctl("opt.lg_tcache_max", &lg_cache_max, &size_sz, NULL, 0);
+	if (rc) { proxy_error("Failed to fetch 'opt.lg_tcache_max' with error %d", rc);  return rc; }
+
+	rc = mallctl("opt.prof_accum", &prof_accum, &bool_sz, NULL, 0);
+	if (rc) { proxy_error("Failed to fetch 'opt.prof_accum' with error %d", rc); return rc; }
+
+	rc = mallctl("opt.prof_leak", &prof_leak, &bool_sz, NULL, 0);
+	if (rc) { proxy_error("Failed to fetch 'opt.prof_leak' with error %d", rc);  return rc; }
+
+	rc = mallctl("opt.lg_prof_sample", &lg_prof_sample, &size_sz, NULL, 0);
+	if (rc) { proxy_error("Failed to fetch 'opt.lg_prof_sample' with error %d", rc);  return rc; }
+
+	rc = mallctl("opt.lg_prof_interval", &lg_prof_interval, &ssize_sz, NULL, 0);
+	if (rc) { proxy_error("Failed to fetch 'opt.lg_prof_interval' with error %d", rc);  return rc; }
+
+	proxy_info(
+		"Using jemalloc with MALLOC_CONF:"
+			" config.xmalloc:%d, lg_tcache_max:%lu, opt.prof_accum:%d, opt.prof_leak:%d,"
+			" opt.lg_prof_sample:%lu, opt.lg_prof_interval:%lu, rc:%d\n",
+		xmalloc, lg_cache_max, prof_accum, prof_leak, lg_prof_sample, lg_prof_interval, rc
+	);
+
+	return 0;
+}
+#else
+int print_jemalloc_conf() {
+	return 0;
+}
+#endif
+
 int main(int argc, const char * argv[]) {
+	// Output current jemalloc conf; no action taken when disabled
+	{
+		int rc = print_jemalloc_conf();
+		if (rc) { exit(EXIT_FAILURE); }
+	}
 
 	{
 		MYSQL *my = mysql_init(NULL);