From 48ce9170b057ddd2165b0239a92aede15849f7a3 Mon Sep 17 00:00:00 2001 From: Egor Tensin Date: Mon, 12 Jun 2023 01:42:08 +0200 Subject: use signalfd to stop on SIGTERM Is this an overkill? I don't know. The thing is, correctly intercepting SIGTERM (also SIGINT, etc.) is incredibly tricky. For example, before this commit, my I/O loops in server.c and worker.c were inherently racy. This was immediately obvious if you tried to run the tests. The tests (especially the Valgrind flavour) would run a worker, wait until it prints a "Waiting for a new command" line, and try to kill it using SIGTERM. The problem is, the global_stop_flag check could have already been executed by the worker, and it would hang forever in recv(). The solution seems to be to use signalfd and select()/poll(). I've never used either before, but it seems to work well enough - at least the very same tests pass and don't hang now. --- src/event_loop.h | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) create mode 100644 src/event_loop.h (limited to 'src/event_loop.h') diff --git a/src/event_loop.h b/src/event_loop.h new file mode 100644 index 0000000..eb5ff05 --- /dev/null +++ b/src/event_loop.h @@ -0,0 +1,36 @@ +/* + * Copyright (c) 2023 Egor Tensin + * This file is part of the "cimple" project. + * For details, see https://github.com/egor-tensin/cimple. + * Distributed under the MIT License. + */ + +#ifndef __EVENT_LOOP_H__ +#define __EVENT_LOOP_H__ + +#include +#include + +struct event_loop; + +int event_loop_create(struct event_loop **); +void event_loop_destroy(struct event_loop *); + +int event_loop_run(struct event_loop *); + +#define EVENT_LOOP_REMOVE 1 + +typedef int (*event_loop_handler)(struct event_loop *, int fd, short revents, void *arg); + +struct event_fd { + int fd; + short events; + event_loop_handler handler; + void *arg; + + SIMPLEQ_ENTRY(event_fd) entries; +}; + +int event_loop_add(struct event_loop *, const struct event_fd *); + +#endif -- cgit v1.2.3