jail: Make waiting loop more efficient

When the log file descriptors were closed, epoll() was returning an
event which has not been handled. That caused the loop to use 100% CPU.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

diff --git a/src/libpakfire/jail.c b/src/libpakfire/jail.c
index 15caedf092f859954e5ddf656d9c55692db986a9..c4b19833f91d250605fcbf77e5c27a1d4276ea6e 100644 (file)
--- a/src/libpakfire/jail.c
+++ b/src/libpakfire/jail.c
@@ -596,7 +596,7 @@ static int pakfire_jail_wait(struct pakfire_jail* jail, struct pakfire_jail_exec
                goto ERROR;
        }
 
-       ev.events = EPOLLIN;
+       ev.events = EPOLLIN|EPOLLHUP;
 
        // Turn file descriptors into non-blocking mode and add them to epoll()
        for (unsigned int i = 0; i < sizeof(fds) / sizeof(*fds); i++) {
@@ -632,6 +632,7 @@ static int pakfire_jail_wait(struct pakfire_jail* jail, struct pakfire_jail_exec
                }
 
                for (int i = 0; i < num; i++) {
+                       int e  = events[i].events;
                        int fd = events[i].data.fd;
 
                        struct pakfire_log_buffer* buffer = NULL;
@@ -639,63 +640,76 @@ static int pakfire_jail_wait(struct pakfire_jail* jail, struct pakfire_jail_exec
                        void* data = NULL;
                        int priority;
 
-                       // Handle any changes to the PIDFD
-                       if (fd == pidfd) {
-                               // Call waidid() and store the result
-                               r = waitid(P_PIDFD, ctx->pidfd, &ctx->status, WEXITED);
-                               if (r) {
-                                       ERROR(jail->pakfire, "waitid() failed: %m\n");
-                                       goto ERROR;
-                               }
+                       // Check if there is any data to be read
+                       if (e & EPOLLIN) {
+                               // Handle any changes to the PIDFD
+                               if (fd == pidfd) {
+                                       // Call waidid() and store the result
+                                       r = waitid(P_PIDFD, ctx->pidfd, &ctx->status, WEXITED);
+                                       if (r) {
+                                               ERROR(jail->pakfire, "waitid() failed: %m\n");
+                                               goto ERROR;
+                                       }
 
-                               // Mark that we have ended so that we will process the remaining
-                               // events from epoll() now, but won't restart the outer loop.
-                               ended = 1;
-                               continue;
+                                       // Mark that we have ended so that we will process the remaining
+                                       // events from epoll() now, but won't restart the outer loop.
+                                       ended = 1;
+                                       continue;
 
-                       // Handle logging messages
-                       } else if (fd == log_INFO) {
-                               buffer = &ctx->buffers.log_INFO;
-                               priority = LOG_INFO;
+                               // Handle logging messages
+                               } else if (fd == log_INFO) {
+                                       buffer = &ctx->buffers.log_INFO;
+                                       priority = LOG_INFO;
 
-                               callback = pakfire_jail_default_log_callback;
+                                       callback = pakfire_jail_default_log_callback;
 
-                       } else if (fd == log_ERROR) {
-                               buffer = &ctx->buffers.log_ERROR;
-                               priority = LOG_ERR;
+                               } else if (fd == log_ERROR) {
+                                       buffer = &ctx->buffers.log_ERROR;
+                                       priority = LOG_ERR;
 
-                               callback = pakfire_jail_default_log_callback;
+                                       callback = pakfire_jail_default_log_callback;
 
-                       } else if (fd == log_DEBUG) {
-                               buffer = &ctx->buffers.log_DEBUG;
-                               priority = LOG_DEBUG;
+                               } else if (fd == log_DEBUG) {
+                                       buffer = &ctx->buffers.log_DEBUG;
+                                       priority = LOG_DEBUG;
 
-                               callback = pakfire_jail_default_log_callback;
+                                       callback = pakfire_jail_default_log_callback;
 
-                       // Handle anything from the log pipes
-                       } else if (fd == stdout) {
-                               buffer = &ctx->buffers.stdout;
-                               priority = LOG_INFO;
+                               // Handle anything from the log pipes
+                               } else if (fd == stdout) {
+                                       buffer = &ctx->buffers.stdout;
+                                       priority = LOG_INFO;
 
-                               callback = jail->log_callback;
-                               data = jail->log_data;
+                                       callback = jail->log_callback;
+                                       data = jail->log_data;
 
-                       } else if (fd == stderr) {
-                               buffer = &ctx->buffers.stderr;
-                               priority = LOG_ERR;
+                               } else if (fd == stderr) {
+                                       buffer = &ctx->buffers.stderr;
+                                       priority = LOG_ERR;
 
-                               callback = jail->log_callback;
-                               data = jail->log_data;
+                                       callback = jail->log_callback;
+                                       data = jail->log_data;
 
-                       } else {
-                               DEBUG(jail->pakfire, "Received invalid file descriptor %d\n", fd);
-                               continue;
+                               } else {
+                                       DEBUG(jail->pakfire, "Received invalid file descriptor %d\n", fd);
+                                       continue;
+                               }
+
+                               // Handle log event
+                               r = pakfire_jail_handle_log(jail, ctx, priority, fd, buffer, callback, data);
+                               if (r)
+                                       goto ERROR;
                        }
 
-                       // Handle log event
-                       r = pakfire_jail_handle_log(jail, ctx, priority, fd, buffer, callback, data);
-                       if (r)
-                               goto ERROR;
+                       // Check if any file descriptors have been closed
+                       if (e & EPOLLHUP) {
+                               // Remove the file descriptor
+                               r = epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, NULL);
+                               if (r) {
+                                       ERROR(jail->pakfire, "Could not remove closed file-descriptor %d: %m\n", fd);
+                                       goto ERROR;
+                               }
+                       }
                }
        }