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samba-mirror/source3/lib/tevent_glib_glue.c
Ralph Boehme fa39a7b2e6 s3/lib: new tevent_glib_glue subsystem
tevent_glib_glue_create() takes glib GMainContext and adds its event
sources to a tevent context. tevent will poll the sources and run
handlers for pending events as detailed in the glib documentation:

https://developer.gnome.org/glib/stable/glib-The-Main-Event-Loop.html

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Noel Power <npower@samba.org>
2019-04-24 18:32:14 +00:00

884 lines
20 KiB
C

/*
Unix SMB/CIFS implementation.
Integration of a glib g_main_context into a tevent_context
Copyright (C) Stefan Metzmacher 2016
Copyright (C) Ralph Boehme 2016
** NOTE! The following LGPL license applies to the tevent
** library. This does NOT imply that all of Samba is released
** under the LGPL
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "replace.h"
#include "system/filesys.h"
#include "lib/util/debug.h"
#include "lib/util/select.h"
#include <tevent.h>
#undef DBGC_CLASS
#define DBGC_CLASS DBGC_TEVENT
#ifdef HAVE_GLIB
#include <glib.h>
#include "tevent_glib_glue.h"
struct fd_map {
struct tevent_glib_glue *glue;
int fd;
struct tevent_fd *fd_event;
};
struct tevent_glib_glue {
/*
* The tevent context we're feeding.
*/
struct tevent_context *ev;
/*
* The glib gmain context we're polling and whether we're currently
* owning it by virtue of g_main_context_acquire().
*/
GMainContext *gmain_ctx;
bool gmain_owner;
/*
* Set by samba_tevent_glib_glue_quit().
*/
bool quit;
/*
* tevent trace callback and data we got from tevent_get_trace_callback()
* before installing our own trace callback.
*/
tevent_trace_callback_t prev_tevent_trace_cb;
void *prev_tevent_trace_data;
/*
* Don't call tevent_glib_prepare() in the tevent tracepoint handler if
* explicity told so. This is an optimisation for the case that glib
* event sources are created from glib event callbacks.
*/
bool skip_glib_refresh;
/*
* Used when acquiring the glib gmain context failed.
*/
struct tevent_timer *acquire_retry_timer;
/*
* glib gmain context timeout and priority for the current event look
* iteration. gtimeout is translated to a tevent timer event, unless it
* is 0 which signals some event source is pending. In that case we
* dispatch an immediate event. gpriority is ignored by us, just passed
* to the glib relevant functions.
*/
gint gtimeout;
gint gpriority;
struct tevent_timer *timer;
struct tevent_immediate *im;
bool scheduled_im;
/*
* glib gmain context fds returned from g_main_context_query(). These
* get translated to tevent fd events.
*/
GPollFD *gpollfds;
gint num_gpollfds;
/*
* A copy of gpollfds and num_gpollfds from the previous event loop
* iteration, used to detect changes in the set of fds.
*/
GPollFD *prev_gpollfds;
gint num_prev_gpollfds;
/*
* An array of pointers to fd_map's. The fd_map'd contain the tevent
* event fd as well as a pointer to the corresponding glib GPollFD.
*/
struct fd_map **fd_map;
size_t num_maps;
};
static bool tevent_glib_prepare(struct tevent_glib_glue *glue);
static bool tevent_glib_process(struct tevent_glib_glue *glue);
static bool tevent_glib_glue_reinit(struct tevent_glib_glue *glue);
static void tevent_glib_fd_handler(struct tevent_context *ev,
struct tevent_fd *fde,
uint16_t flags,
void *private_data);
typedef int (*gfds_cmp_cb)(const void *fd1, const void *fd2);
typedef bool (*gfds_found_cb)(struct tevent_glib_glue *glue,
const GPollFD *new,
const GPollFD *old);
typedef bool (*gfds_new_cb)(struct tevent_glib_glue *glue,
const GPollFD *fd);
typedef bool (*gfds_removed_cb)(struct tevent_glib_glue *glue,
const GPollFD *fd);
/**
* Compare two sorted GPollFD arrays
*
* For every element that exists in gfds and prev_gfds found_fn() is called.
* For every element in gfds but not in prev_gfds, new_fn() is called.
* For every element in prev_gfds but not in gfds removed_fn() is called.
**/
static bool cmp_gfds(struct tevent_glib_glue *glue,
GPollFD *gfds,
GPollFD *prev_gfds,
size_t num_gfds,
size_t num_prev_gfds,
gfds_cmp_cb cmp_cb,
gfds_found_cb found_cb,
gfds_new_cb new_cb,
gfds_removed_cb removed_cb)
{
bool ok;
size_t i = 0, j = 0;
int cmp;
while (i < num_gfds && j < num_prev_gfds) {
cmp = cmp_cb(&gfds[i], &prev_gfds[j]);
if (cmp == 0) {
ok = found_cb(glue, &gfds[i], &prev_gfds[j]);
if (!ok) {
return false;
}
i++;
j++;
} else if (cmp < 0) {
ok = new_cb(glue, &gfds[i]);
if (!ok) {
return false;
}
i++;
} else {
ok = removed_cb(glue, &prev_gfds[j]);
if (!ok) {
return false;
}
j++;
}
}
while (i < num_gfds) {
ok = new_cb(glue, &gfds[i++]);
if (!ok) {
return false;
}
}
while (j < num_prev_gfds) {
ok = removed_cb(glue, &prev_gfds[j++]);
if (!ok) {
return false;
}
}
return true;
}
static int glib_fd_cmp_func(const void *p1, const void *p2)
{
const GPollFD *lhs = p1;
const GPollFD *rhs = p2;
if (lhs->fd < rhs->fd) {
return -1;
} else if (lhs->fd > rhs->fd) {
return 1;
}
return 0;
}
/*
* We already have a tevent fd event for the glib GPollFD, but we may have to
* update flags.
*/
static bool match_gfd_cb(struct tevent_glib_glue *glue,
const GPollFD *new_gfd,
const GPollFD *old_gfd)
{
size_t i;
struct fd_map *fd_map = NULL;
struct tevent_fd *fd_event = NULL;
if (new_gfd->events == old_gfd->events) {
return true;
}
for (i = 0; i < glue->num_maps; i++) {
if (glue->fd_map[i]->fd == new_gfd->fd) {
break;
}
}
if (i == glue->num_maps) {
DBG_ERR("match_gfd_cb: glib fd %d not in map\n", new_gfd->fd);
return false;
}
fd_map = glue->fd_map[i];
if (fd_map == NULL) {
DBG_ERR("fd_map for fd %d is NULL\n", new_gfd->fd);
return false;
}
fd_event = fd_map->fd_event;
if (fd_event == NULL) {
DBG_ERR("fd_event for fd %d is NULL\n", new_gfd->fd);
return false;
}
tevent_fd_set_flags(fd_event, 0);
if (new_gfd->events & (G_IO_IN | G_IO_HUP | G_IO_ERR)) {
TEVENT_FD_READABLE(fd_event);
}
if (new_gfd->events & G_IO_OUT) {
TEVENT_FD_WRITEABLE(fd_event);
}
return true;
}
static bool new_gfd_cb(struct tevent_glib_glue *glue, const GPollFD *gfd)
{
struct tevent_fd *fd_event = NULL;
struct fd_map *fd_map = NULL;
uint16_t events = 0;
bool revent;
bool wevent;
revent = (gfd->events & (G_IO_IN | G_IO_HUP | G_IO_ERR));
wevent = (gfd->events & G_IO_OUT);
if (revent) {
events |= TEVENT_FD_READ;
}
if (wevent) {
events |= TEVENT_FD_WRITE;
}
glue->fd_map = talloc_realloc(glue,
glue->fd_map,
struct fd_map *,
glue->num_maps + 1);
if (glue->fd_map == NULL) {
DBG_ERR("talloc_realloc failed\n");
return false;
}
fd_map = talloc_zero(glue->fd_map, struct fd_map);
if (fd_map == NULL) {
DBG_ERR("talloc_realloc failed\n");
return false;
}
glue->fd_map[glue->num_maps] = fd_map;
glue->num_maps++;
fd_event = tevent_add_fd(glue->ev,
glue->fd_map,
gfd->fd,
events,
tevent_glib_fd_handler,
fd_map);
if (fd_event == NULL) {
DBG_ERR("tevent_add_fd failed\n");
return false;
}
*fd_map = (struct fd_map) {
.glue = glue,
.fd = gfd->fd,
.fd_event = fd_event,
};
DBG_DEBUG("added tevent_fd for glib fd %d\n", gfd->fd);
return true;
}
static bool remove_gfd_cb(struct tevent_glib_glue *glue, const GPollFD *gfd)
{
size_t i;
for (i = 0; i < glue->num_maps; i++) {
if (glue->fd_map[i]->fd == gfd->fd) {
break;
}
}
if (i == glue->num_maps) {
DBG_ERR("remove_gfd_cb: glib fd %d not in map\n", gfd->fd);
return false;
}
TALLOC_FREE(glue->fd_map[i]->fd_event);
TALLOC_FREE(glue->fd_map[i]);
if (i + 1 < glue->num_maps) {
memmove(&glue->fd_map[i],
&glue->fd_map[i+1],
(glue->num_maps - (i + 1)) * sizeof(struct fd_map *));
}
glue->fd_map = talloc_realloc(glue,
glue->fd_map,
struct fd_map *,
glue->num_maps - 1);
if (glue->num_maps > 0 && glue->fd_map == NULL) {
DBG_ERR("talloc_realloc failed\n");
return false;
}
glue->num_maps--;
return true;
}
static short gpoll_to_poll_event(gushort gevent)
{
short pevent = 0;
if (gevent & G_IO_IN) {
pevent |= POLLIN;
}
if (gevent & G_IO_OUT) {
pevent |= POLLOUT;
}
if (gevent & G_IO_HUP) {
pevent |= POLLHUP;
}
if (gevent & G_IO_ERR) {
pevent |= POLLERR;
}
return pevent;
}
static gushort poll_to_gpoll_event(short pevent)
{
gushort gevent = 0;
if (pevent & POLLIN) {
gevent |= G_IO_IN;
}
if (pevent & POLLOUT) {
gevent |= G_IO_OUT;
}
if (pevent & POLLHUP) {
gevent |= G_IO_HUP;
}
if (pevent & POLLERR) {
gevent |= G_IO_ERR;
}
return gevent;
}
static void tevent_glib_fd_handler(struct tevent_context *ev,
struct tevent_fd *fde,
uint16_t flags,
void *private_data)
{
struct fd_map *fd_map = talloc_get_type_abort(
private_data, struct fd_map);
struct tevent_glib_glue *glue = NULL;
GPollFD *gpollfd = NULL;
struct pollfd fd;
int ret;
int i;
glue = fd_map->glue;
for (i = 0; i < glue->num_gpollfds; i++) {
if (glue->gpollfds[i].fd != fd_map->fd) {
continue;
}
gpollfd = &glue->gpollfds[i];
break;
}
if (gpollfd == NULL) {
DBG_ERR("No gpollfd for fd_map [%p] fd [%d]\n",
fd_map, fd_map->fd);
return;
}
/*
* We have to poll() the fd to get the correct fd event for glib. tevent
* only tells us about readable/writable in flags, but we need the full
* glory for glib.
*/
fd = (struct pollfd) {
.fd = gpollfd->fd,
.events = gpoll_to_poll_event(gpollfd->events),
};
ret = sys_poll_intr(&fd, 1, 0);
if (ret == -1) {
DBG_ERR("poll: %s\n", strerror(errno));
return;
}
if (ret == 0) {
return;
}
gpollfd->revents = poll_to_gpoll_event(fd.revents);
tevent_glib_process(glue);
return;
}
static void tevent_glib_timer_handler(struct tevent_context *ev,
struct tevent_timer *te,
struct timeval current_time,
void *private_data)
{
struct tevent_glib_glue *glue = talloc_get_type_abort(
private_data, struct tevent_glib_glue);
glue->timer = NULL;
tevent_glib_process(glue);
return;
}
static void tevent_glib_im_handler(struct tevent_context *ev,
struct tevent_immediate *im,
void *private_data)
{
struct tevent_glib_glue *glue = talloc_get_type_abort(
private_data, struct tevent_glib_glue);
glue->scheduled_im = false;
tevent_glib_process(glue);
return;
}
static bool save_current_fdset(struct tevent_glib_glue *glue)
{
/*
* Save old glib fds. We only grow the prev array.
*/
if (glue->num_prev_gpollfds < glue->num_gpollfds) {
glue->prev_gpollfds = talloc_realloc(glue,
glue->prev_gpollfds,
GPollFD,
glue->num_gpollfds);
if (glue->prev_gpollfds == NULL) {
DBG_ERR("talloc_realloc failed\n");
return false;
}
}
glue->num_prev_gpollfds = glue->num_gpollfds;
if (glue->num_gpollfds > 0) {
memcpy(glue->prev_gpollfds, glue->gpollfds,
sizeof(GPollFD) * glue->num_gpollfds);
memset(glue->gpollfds, 0, sizeof(GPollFD) * glue->num_gpollfds);
}
return true;
}
static bool get_glib_fds_and_timeout(struct tevent_glib_glue *glue)
{
bool ok;
gint num_fds;
ok = save_current_fdset(glue);
if (!ok) {
return false;
}
while (true) {
num_fds = g_main_context_query(glue->gmain_ctx,
glue->gpriority,
&glue->gtimeout,
glue->gpollfds,
glue->num_gpollfds);
if (num_fds == glue->num_gpollfds) {
break;
}
glue->gpollfds = talloc_realloc(glue,
glue->gpollfds,
GPollFD,
num_fds);
if (num_fds > 0 && glue->gpollfds == NULL) {
DBG_ERR("talloc_realloc failed\n");
return false;
}
glue->num_gpollfds = num_fds;
};
if (glue->num_gpollfds > 0) {
qsort(glue->gpollfds,
num_fds,
sizeof(GPollFD),
glib_fd_cmp_func);
}
DBG_DEBUG("num fds: %d, timeout: %d ms\n",
num_fds, glue->gtimeout);
return true;
}
static bool tevent_glib_update_events(struct tevent_glib_glue *glue)
{
uint64_t microsec;
struct timeval tv;
bool ok;
ok = cmp_gfds(glue,
glue->gpollfds,
glue->prev_gpollfds,
glue->num_gpollfds,
glue->num_prev_gpollfds,
glib_fd_cmp_func,
match_gfd_cb,
new_gfd_cb,
remove_gfd_cb);
if (!ok) {
return false;
}
TALLOC_FREE(glue->timer);
if (glue->gtimeout == -1) {
return true;
}
if (glue->gtimeout == 0) {
/*
* glue->gtimeout is 0 if g_main_context_query() returned
* timeout=0. That means there are pending events ready to be
* dispatched. We only want to run one event handler per loop
* iteration, so we schedule an immediate event to run it in the
* next iteration.
*/
if (glue->scheduled_im) {
return true;
}
tevent_schedule_immediate(glue->im,
glue->ev,
tevent_glib_im_handler,
glue);
glue->scheduled_im = true;
return true;
}
microsec = glue->gtimeout * 1000;
tv = tevent_timeval_current_ofs(microsec / 1000000,
microsec % 1000000);
glue->timer = tevent_add_timer(glue->ev,
glue,
tv,
tevent_glib_timer_handler,
glue);
if (glue->timer == NULL) {
DBG_ERR("tevent_add_timer failed\n");
return false;
}
return true;
}
static void tevent_glib_retry_timer(struct tevent_context *ev,
struct tevent_timer *te,
struct timeval current_time,
void *private_data)
{
struct tevent_glib_glue *glue = talloc_get_type_abort(
private_data, struct tevent_glib_glue);
glue->acquire_retry_timer = NULL;
(void)tevent_glib_prepare(glue);
}
/**
* Fetch glib event sources and add them to tevent
*
* Fetch glib event sources and attach corresponding tevent events to our tevent
* context. get_glib_fds_and_timeout() gets the relevant glib event sources: the
* set of active fds and the next timer. tevent_glib_update_events() then
* translates those to tevent and creates tevent events.
*
* When called, the thread must NOT be the owner to the glib main
* context. tevent_glib_prepare() is either the first function when the
* tevent_glib_glue is created, or after tevent_glib_process() has been called
* to process pending event, which will have ceased ownership.
**/
static bool tevent_glib_prepare(struct tevent_glib_glue *glue)
{
bool ok;
gboolean gok;
if (glue->quit) {
/* Set via samba_tevent_glib_glue_quit() */
return true;
}
if (glue->acquire_retry_timer != NULL) {
/*
* We're still waiting on the below g_main_context_acquire() to
* succeed, just return.
*/
return true;
}
if (glue->gmain_owner) {
g_main_context_release(glue->gmain_ctx);
glue->gmain_owner = false;
}
gok = g_main_context_acquire(glue->gmain_ctx);
if (!gok) {
DBG_ERR("couldn't acquire g_main_context\n");
/*
* Ensure no tevent event fires while we're not the gmain
* context owner. The event handler would call
* tevent_glib_process() and that expects being the owner of the
* context.
*/
ok = tevent_glib_glue_reinit(glue);
if (!ok) {
DBG_ERR("tevent_glib_glue_reinit failed\n");
samba_tevent_glib_glue_quit(glue);
return false;
}
glue->acquire_retry_timer = tevent_add_timer(
glue->ev,
glue,
tevent_timeval_current_ofs(0, 1000),
tevent_glib_retry_timer,
glue);
if (glue->acquire_retry_timer == NULL) {
DBG_ERR("tevent_add_timer failed\n");
samba_tevent_glib_glue_quit(glue);
return false;
}
return true;
}
glue->gmain_owner = true;
/*
* Discard "ready" return value from g_main_context_prepare(). We don't
* want to dispatch events here, thats only done in from the tevent loop.
*/
(void)g_main_context_prepare(glue->gmain_ctx, &glue->gpriority);
ok = get_glib_fds_and_timeout(glue);
if (!ok) {
DBG_ERR("get_glib_fds_and_timeout failed\n");
samba_tevent_glib_glue_quit(glue);
return false;
}
ok = tevent_glib_update_events(glue);
if (!ok) {
DBG_ERR("tevent_glib_update_events failed\n");
samba_tevent_glib_glue_quit(glue);
return false;
}
return true;
}
/**
* Process pending glib events
*
* tevent_glib_process() gets called to process pending glib events via
* g_main_context_check() and then g_main_context_dispatch().
*
* After pending event handlers are dispatched, we rearm the glib glue event
* handlers in tevent by calling tevent_glib_prepare().
*
* When tevent_glib_process() is called the thread must own the glib
* gmain_ctx. That is achieved by tevent_glib_prepare() being the only function
* that acuires context ownership.
*
* To give other threads that are blocked on g_main_context_acquire(gmain_ctx) a
* chance to acquire context ownership (eg needed to attach event sources), we
* release context ownership before calling tevent_glib_prepare() which will
* acquire it again.
*/
static bool tevent_glib_process(struct tevent_glib_glue *glue)
{
bool ok;
DBG_DEBUG("tevent_glib_process\n");
/*
* Ignore the "sources_ready" return from g_main_context_check(). glib
* itself also ignores it in g_main_context_iterate(). In theory only
* calling g_main_context_dispatch() if g_main_context_check() returns
* true should work, but older glib versions had a bug where
* g_main_context_check() returns false even though events are pending.
*
* https://bugzilla.gnome.org/show_bug.cgi?id=11059
*/
(void)g_main_context_check(glue->gmain_ctx,
glue->gpriority,
glue->gpollfds,
glue->num_gpollfds);
g_main_context_dispatch(glue->gmain_ctx);
ok = tevent_glib_prepare(glue);
if (!ok) {
return false;
}
glue->skip_glib_refresh = true;
return true;
}
static void tevent_glib_glue_trace_callback(enum tevent_trace_point point,
void *private_data)
{
struct tevent_glib_glue *glue = talloc_get_type_abort(
private_data, struct tevent_glib_glue);
if (point == TEVENT_TRACE_AFTER_LOOP_ONCE) {
if (!glue->skip_glib_refresh) {
tevent_glib_prepare(glue);
}
glue->skip_glib_refresh = false;
}
/* chain previous handler */
if (glue->prev_tevent_trace_cb != NULL) {
glue->prev_tevent_trace_cb(point, glue->prev_tevent_trace_data);
}
}
static void tevent_glib_glue_cleanup(struct tevent_glib_glue *glue)
{
size_t n = talloc_array_length(glue->fd_map);
size_t i;
for (i = 0; i < n; i++) {
TALLOC_FREE(glue->fd_map[i]->fd_event);
TALLOC_FREE(glue->fd_map[i]);
}
tevent_set_trace_callback(glue->ev,
glue->prev_tevent_trace_cb,
glue->prev_tevent_trace_data);
glue->prev_tevent_trace_cb = NULL;
glue->prev_tevent_trace_data = NULL;
TALLOC_FREE(glue->fd_map);
glue->num_maps = 0;
TALLOC_FREE(glue->gpollfds);
glue->num_gpollfds = 0;
TALLOC_FREE(glue->prev_gpollfds);
glue->num_prev_gpollfds = 0;
TALLOC_FREE(glue->timer);
TALLOC_FREE(glue->acquire_retry_timer);
TALLOC_FREE(glue->im);
/*
* These are not really needed, but let's wipe the slate clean.
*/
glue->skip_glib_refresh = false;
glue->gtimeout = 0;
glue->gpriority = 0;
}
static bool tevent_glib_glue_reinit(struct tevent_glib_glue *glue)
{
tevent_glib_glue_cleanup(glue);
glue->im = tevent_create_immediate(glue);
if (glue->im == NULL) {
return false;
}
tevent_get_trace_callback(glue->ev,
&glue->prev_tevent_trace_cb,
&glue->prev_tevent_trace_data);
tevent_set_trace_callback(glue->ev,
tevent_glib_glue_trace_callback,
glue);
return true;
}
void samba_tevent_glib_glue_quit(struct tevent_glib_glue *glue)
{
tevent_glib_glue_cleanup(glue);
glue->quit = true;
return;
}
struct tevent_glib_glue *samba_tevent_glib_glue_create(TALLOC_CTX *mem_ctx,
struct tevent_context *ev,
GMainContext *gmain_ctx)
{
bool ok;
struct tevent_glib_glue *glue = NULL;
glue = talloc_zero(mem_ctx, struct tevent_glib_glue);
if (glue == NULL) {
DBG_ERR("talloc_zero failed\n");
return NULL;
}
*glue = (struct tevent_glib_glue) {
.ev = ev,
.gmain_ctx = gmain_ctx,
};
glue->im = tevent_create_immediate(glue);
tevent_get_trace_callback(glue->ev,
&glue->prev_tevent_trace_cb,
&glue->prev_tevent_trace_data);
tevent_set_trace_callback(glue->ev,
tevent_glib_glue_trace_callback,
glue);
ok = tevent_glib_prepare(glue);
if (!ok) {
TALLOC_FREE(glue);
return NULL;
}
return glue;
}
#else /* HAVE_GLIB */
struct tevent_glib_glue *samba_tevent_glib_glue_create(TALLOC_CTX *mem_ctx,
struct tevent_context *ev,
GMainContext *gmain_ctx)
{
errno = ENOSYS;
return NULL;
}
void samba_tevent_glib_glue_quit(struct tevent_glib_glue *glue)
{
return;
}
#endif /* HAVE_GLIB */