Convert data reading into event based system

[log-plotter] / event.c

diff --git a/event.c b/event.c
new file mode 100644 (file)
index 0000000..b3cbaf2
--- /dev/null
+++ b/event.c
@@ -0,0 +1,98 @@
+#include <errno.h>
+#include <sys/epoll.h>
+
+#include "event.h"
+#include "trace.h"
+
+static int epoll_fd = -1;
+
+static int init_event_handler(void)
+{
+       epoll_fd = epoll_create(1);
+       if (epoll_fd < 0) {
+               pr_err("Failed to create epoll socket: %m\n");
+               return -1;
+       }
+
+       return 0;
+}
+
+int register_event_handler(struct eventhandler_entry *handler)
+{
+       struct epoll_event ev;
+       int ret = 0;
+
+       if (epoll_fd < 0)
+               ret = init_event_handler();
+
+       if (ret < 0)
+               return ret;
+
+       if (handler->fd < 0) {
+               pr_err("Invalid file descriptor of %d for handler %s\n",
+                       handler->fd, handler->name);
+               return -1;
+       }
+
+       if (!handler->handle_event) {
+               pr_err("Handler %s missing callback function\n", handler->name);
+               return -1;
+       }
+
+       pr_debug("Registering handler for \"%s\", fd=%d\n",
+               handler->name, handler->fd);
+
+       ev.data.fd = handler->fd;
+       ev.data.ptr = handler;
+       ev.events = handler->events;
+       ret = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, handler->fd, &ev);
+       if (ret) {
+               pr_err("Failed to add epoll_fd: %m\n");
+               return -1;
+       }
+
+       return 0;
+}
+
+int poll_events(int timeout_ms)
+{
+       struct epoll_event event;
+       struct eventhandler_entry *handler;
+       int ret;
+
+       ret = epoll_wait(epoll_fd, &event, 1, timeout_ms);
+
+       if (ret == -1) {
+               if (errno != EINTR) {
+                       pr_err("epoll_wait: %m\n");
+                       return -1;
+               }
+
+               /*
+                * If epoll_wait() was interrupted, better start
+                * everything again from the beginning
+                */
+               return 0;
+       }
+
+       if (ret == 0) {
+               pr_info("Timed out\n");
+               goto out;
+       }
+
+       handler = event.data.ptr;
+
+       if (!handler || !handler->handle_event) {
+               pr_err("Corrupted event handler for fd %d\n",
+                       event.data.fd);
+               goto out;
+       }
+
+       pr_debug("Running handler %s to handle events from fd %d\n",
+               handler->name, handler->fd);
+       handler->handle_event(handler);
+
+out:
+       return ret;
+}
+