mirror of
https://gitlab.gnome.org/GNOME/glib.git
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305 lines
8.7 KiB
C
305 lines
8.7 KiB
C
/*******************************************************************************
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Copyright (c) 2011, 2012 Dmitry Matveev <me@dmitrymatveev.co.uk>
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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*******************************************************************************/
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#include "config.h"
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#include <sys/types.h>
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#include <sys/event.h>
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#include <sys/time.h>
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#include <unistd.h>
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#include <errno.h>
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#include <glib.h>
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#include "kqueue-thread.h"
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#include "kqueue-sub.h"
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#include "kqueue-utils.h"
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static gboolean kt_debug_enabled = FALSE;
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#define KT_W if (kt_debug_enabled) g_warning
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static GQueue pick_up_fds_queue = G_QUEUE_INIT;
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G_LOCK_DEFINE_STATIC (pick_up_lock);
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static GSList *remove_fds_list = NULL;
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G_LOCK_DEFINE_STATIC (remove_lock);
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/* GIO does not have analogues for NOTE_LINK and(?) NOTE_REVOKE, so
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* we do not ask kqueue() to watch for these events for now. */
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const uint32_t KQUEUE_VNODE_FLAGS =
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NOTE_DELETE | NOTE_WRITE | NOTE_EXTEND | NOTE_ATTRIB | NOTE_RENAME;
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extern int get_kqueue_descriptor(void);
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/**
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* _kqueue_thread_collect_fds:
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* @events: a #kevents - the list of events to monitor. Will be extended
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* with new items.
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*
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* Picks up new file descriptors for monitoring from a global queue.
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*
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* To add new items to the list, use _kqueue_thread_push_fd().
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*/
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static void
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_kqueue_thread_collect_fds (kevents *events)
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{
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g_assert (events != NULL);
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gint length = 0;
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G_LOCK (pick_up_lock);
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if ((length = g_queue_get_length (&pick_up_fds_queue)) != 0)
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{
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gpointer fdp = NULL;
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kevents_extend_sz (events, length);
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while ((fdp = g_queue_pop_head (&pick_up_fds_queue)) != NULL)
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{
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struct kevent *pevent = &events->memory[events->kq_size++];
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EV_SET (pevent,
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GPOINTER_TO_INT (fdp),
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EVFILT_VNODE,
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EV_ADD | EV_ENABLE | EV_ONESHOT,
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KQUEUE_VNODE_FLAGS,
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0,
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0);
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}
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}
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G_UNLOCK (pick_up_lock);
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}
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/**
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* _kqueue_thread_cleanup_fds:
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* @events: a #kevents -- list of events to monitor. Cancelled
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* subscriptions will be removed from it, and its size
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* probably will be reduced.
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*
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* Removes file descriptors from monitoring.
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*
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* This function will pick up file descriptors from a global list
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* to cancel monitoring on them. The list will be freed then.
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*
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* To add new items to the list, use _kqueue_thread_remove_fd().
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*/
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static void
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_kqueue_thread_cleanup_fds (kevents *events)
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{
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g_assert (events != NULL);
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G_LOCK (remove_lock);
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if (remove_fds_list)
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{
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size_t oldsize = events->kq_size;
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int i, j;
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for (i = 1, j = 1; i < oldsize; i++)
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{
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int fd = events->memory[i].ident;
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GSList *elem = g_slist_find (remove_fds_list, GINT_TO_POINTER (fd));
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if (elem == NULL)
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{
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if (i != j)
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events->memory[j] = events->memory[i];
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++j;
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}
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else if (close (fd) == -1)
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KT_W ("Failed to close fd %d, error %d", fd, errno);
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}
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KT_W ("FD Clean up complete, kq_size now %d\n", j);
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events->kq_size = j;
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kevents_reduce (events);
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g_slist_free (remove_fds_list);
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remove_fds_list = NULL;
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}
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G_UNLOCK (remove_lock);
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}
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/**
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* _kqueue_thread_drop_fd:
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* @events: a #kevents -- list of events to monitor. Cancelled
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* subscriptions will be removed from it, and its size
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* probably will be reduced.
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*
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* Removes a concrete file descriptor from monitoring.
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*/
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static void
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_kqueue_thread_drop_fd (kevents *events, int fd)
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{
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g_assert (events != NULL);
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int i;
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for (i = 1; i < events->kq_size; i++)
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{
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if (events->memory[i].ident == fd)
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{
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if (close (fd) == -1)
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KT_W ("Failed to close fd %d, error %d", fd, errno);
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events->memory[i] = events->memory[--events->kq_size];
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return;
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}
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}
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}
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/**
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* _kqueue_thread_func:
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* @arg: a pointer to int -- control file descriptor.
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*
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* The thread communicates with the outside world through a so-called
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* command file descriptor. The thread reads control commands from it
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* and writes the notifications into it.
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*
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* Control commands are single-byte characters:
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* - 'A' - pick up new file descriptors to monitor
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* - 'R' - remove some descriptors from monitoring.
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*
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* For details, see _kqueue_thread_collect_fds() and
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* _kqueue_thread_cleanup_fds().
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*
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* Notifications, that thread writes into the command file descriptor,
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* are represented with #kqueue_notification objects.
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*
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* Returns: %NULL
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*/
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void*
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_kqueue_thread_func (void *arg)
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{
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int fd, kqueue_descriptor;
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kevents waiting;
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g_assert (arg != NULL);
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kevents_init_sz (&waiting, 1);
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fd = *(int *) arg;
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kqueue_descriptor = get_kqueue_descriptor();
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if (kqueue_descriptor == -1)
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{
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KT_W ("fatal: kqueue is not initialized!\n");
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return NULL;
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}
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EV_SET (&waiting.memory[0],
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fd,
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EVFILT_READ,
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EV_ADD | EV_ENABLE | EV_ONESHOT,
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NOTE_LOWAT,
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1,
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0);
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waiting.kq_size = 1;
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for (;;)
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{
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/* TODO: Provide more items in the 'eventlist' to kqueue(2).
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* Currently the backend takes notifications from the kernel one
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* by one, i.e. there will be a lot of system calls and context
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* switches when the application will monitor a lot of files with
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* high filesystem activity on each. */
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struct kevent received;
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KT_W ("Watching for %zi items", waiting.kq_size);
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int ret = kevent (kqueue_descriptor, waiting.memory, waiting.kq_size, &received, 1, NULL);
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int kevent_errno = errno;
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KT_W ("Awoken.");
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if (ret == -1)
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{
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KT_W ("kevent failed: %d", kevent_errno);
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if (kevent_errno == EINTR)
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continue;
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else
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return NULL;
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}
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if (received.ident == fd)
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{
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char c;
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if (!_ku_read (fd, &c, 1))
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{
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KT_W ("Failed to read command, error %d", errno);
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continue;
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}
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if (c == 'A')
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_kqueue_thread_collect_fds (&waiting);
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else if (c == 'R')
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_kqueue_thread_cleanup_fds (&waiting);
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}
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else
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{
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struct kqueue_notification kn;
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kn.fd = received.ident;
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if (received.flags & EV_ERROR)
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{
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kn.flags = NOTE_REVOKE;
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_kqueue_thread_drop_fd (&waiting, received.ident);
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}
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else
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kn.flags = (received.fflags & ~NOTE_REVOKE);
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if (!_ku_write (fd, &kn, sizeof (struct kqueue_notification)))
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KT_W ("Failed to write a kqueue notification, error %d", errno);
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}
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}
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kevents_free (&waiting);
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return NULL;
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}
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/**
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* _kqueue_thread_push_fd:
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* @fd: a file descriptor
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*
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* Puts a new file descriptor into the pick up list for monitroing.
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*
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* The kqueue thread will not start monitoring on it immediately, it
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* should be bumped via its command file descriptor manually.
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* See kqueue_thread() and _kqueue_thread_collect_fds() for details.
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*/
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void
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_kqueue_thread_push_fd (int fd)
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{
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G_LOCK (pick_up_lock);
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g_queue_push_tail (&pick_up_fds_queue, GINT_TO_POINTER (fd));
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G_UNLOCK (pick_up_lock);
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}
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/**
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* _kqueue_thread_remove_fd:
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* @fd: a file descriptor
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*
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* Puts a new file descriptor into the remove list to cancel monitoring
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* on it.
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*
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* The kqueue thread will not stop monitoring on it immediately, it
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* should be bumped via its command file descriptor manually.
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* See kqueue_thread() and _kqueue_thread_collect_fds() for details.
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*/
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void
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_kqueue_thread_remove_fd (int fd)
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{
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G_LOCK (remove_lock);
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remove_fds_list = g_slist_prepend (remove_fds_list, GINT_TO_POINTER (fd));
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G_UNLOCK (remove_lock);
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}
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