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session: Unify handling of I/O and timer sources 

Handle I/O sources and timer ("dummy") sources within the same
polling loop, so that both may be used together. Slightly change
the API to improve consistency: a timeout value of -1 now disables
the timeout, and 0 makes the source always time out immediately.
The "dummy" sources already behaved that way, although it wasn't
documented as such.

Make sure that I/O events are processed preferentially: Skip any
timeout callbacks if an I/O event occurred within the same poll
iteration. This applies to both timer/idle sources and timeouts
of I/O sources.

Do not create dummy GPollFDs for timer/idle sources. Instead,
split the sources array into an I/O section and a timer section,
and create corresponding GPollFDs only for the I/O section. Use
GArray to simplify the handling of the dynamic arrays.
This commit is contained in:
Daniel Elstner 2015-08-31 02:35:57 +02:00
parent 62d7945f80
commit faa5d7d997
2 changed files with 137 additions and 114 deletions
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15
src/libsigrok-internal.h
View File

@ -721,16 +721,15 @@ struct sr_session {
gboolean running; gboolean running;
unsigned int num_sources;
/* /*
* Both "sources" and "pollfds" are of the same size and contain pairs * Each I/O source has an entry with the same index in both "sources"
* of descriptor and callback function. We can not embed the GPollFD * and "pollfds". The "sources" array may be larger than "pollfds",
* into the source struct since we want to be able to pass the array * in which case the excess sources are pure timer sources.
* of all poll descriptors to g_poll(). * We can not embed the GPollFD into the source struct since we want
* to be able to pass the array of all poll descriptors to g_poll().
*/ */
struct source *sources; GArray *sources;
GPollFD *pollfds; GArray *pollfds;
/* /*
* These are our synchronization primitives for stopping the session in * These are our synchronization primitives for stopping the session in

234
src/session.c
View File

@ -45,7 +45,8 @@
*/ */
struct source { struct source {
int64_t due; int64_t timeout; /* microseconds */
int64_t due; /* microseconds */
sr_receive_data_callback cb; sr_receive_data_callback cb;
void *cb_data; void *cb_data;
@ -54,8 +55,8 @@ struct source {
*/ */
gintptr poll_object; gintptr poll_object;
int timeout;
gboolean is_usb; gboolean is_usb;
gboolean triggered;
}; };
struct datafeed_callback { struct datafeed_callback {
@ -87,8 +88,10 @@ SR_API int sr_session_new(struct sr_context *ctx,
session = g_malloc0(sizeof(struct sr_session)); session = g_malloc0(sizeof(struct sr_session));
session->ctx = ctx; session->ctx = ctx;
session->running = FALSE;
session->abort_session = FALSE; session->sources = g_array_new(FALSE, FALSE, sizeof(struct source));
session->pollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
g_mutex_init(&session->stop_mutex); g_mutex_init(&session->stop_mutex);
*new_session = session; *new_session = session;
@ -121,6 +124,9 @@ SR_API int sr_session_destroy(struct sr_session *session)
g_slist_free_full(session->owned_devs, (GDestroyNotify)sr_dev_inst_free); g_slist_free_full(session->owned_devs, (GDestroyNotify)sr_dev_inst_free);
g_array_unref(session->pollfds);
g_array_unref(session->sources);
g_free(session); g_free(session);
return SR_OK; return SR_OK;
@ -377,12 +383,10 @@ static gboolean sr_session_check_aborted(struct sr_session *session)
return stop; return stop;
} }
static int _sr_session_source_remove(struct sr_session *session, gintptr poll_object);
/** /**
* Call every device in the current session's callback. * Poll the session's event sources.
*
* For sessions not driven by select loops such as sr_session_run(),
* but driven by another scheduler, this can be used to poll the devices
* from within that scheduler.
* *
* @param session The session to use. Must not be NULL. * @param session The session to use. Must not be NULL.
* @retval SR_OK Success. * @retval SR_OK Success.
@ -390,15 +394,13 @@ static gboolean sr_session_check_aborted(struct sr_session *session)
*/ */
static int sr_session_iteration(struct sr_session *session) static int sr_session_iteration(struct sr_session *session)
{ {
int64_t start_time; int64_t start_time, stop_time, min_due, due;
int64_t stop_time; int timeout_ms;
int64_t min_due;
int64_t due;
unsigned int i; unsigned int i;
int ret, timeout; int ret;
int fd;
int revents; int revents;
gboolean stop_checked; gboolean triggered, stopped;
gboolean stopped;
struct source *source; struct source *source;
GPollFD *pollfd; GPollFD *pollfd;
gintptr poll_object; gintptr poll_object;
@ -406,16 +408,18 @@ static int sr_session_iteration(struct sr_session *session)
int64_t usb_due; int64_t usb_due;
struct timeval tv; struct timeval tv;
#endif #endif
if (session->num_sources <= 0) { if (session->sources->len == 0) {
sr_session_check_aborted(session); sr_session_check_aborted(session);
return SR_OK; return SR_OK;
} }
start_time = g_get_monotonic_time(); start_time = g_get_monotonic_time();
min_due = INT64_MAX; min_due = INT64_MAX;
for (i = 0; i < session->num_sources; ++i) { for (i = 0; i < session->sources->len; ++i) {
if (session->sources[i].due < min_due) source = &g_array_index(session->sources, struct source, i);
min_due = session->sources[i].due; if (source->due < min_due)
min_due = source->due;
source->triggered = FALSE;
} }
#ifdef HAVE_LIBUSB_1_0 #ifdef HAVE_LIBUSB_1_0
usb_due = INT64_MAX; usb_due = INT64_MAX;
@ -433,13 +437,15 @@ static int sr_session_iteration(struct sr_session *session)
} }
} }
#endif #endif
if (min_due > start_time) if (min_due == INT64_MAX)
timeout = (min_due == INT64_MAX) ? -1 timeout_ms = -1;
: MIN((min_due - start_time + 999) / 1000, INT_MAX); else if (min_due > start_time)
timeout_ms = MIN((min_due - start_time + 999) / 1000, INT_MAX);
else else
timeout = 0; timeout_ms = 0;
ret = g_poll(session->pollfds, session->num_sources, timeout); ret = g_poll((GPollFD *)session->pollfds->data,
session->pollfds->len, timeout_ms);
#ifdef G_OS_UNIX #ifdef G_OS_UNIX
if (ret < 0 && errno != EINTR) { if (ret < 0 && errno != EINTR) {
sr_err("Error in poll: %s", g_strerror(errno)); sr_err("Error in poll: %s", g_strerror(errno));
@ -452,13 +458,27 @@ static int sr_session_iteration(struct sr_session *session)
} }
#endif #endif
stop_time = g_get_monotonic_time(); stop_time = g_get_monotonic_time();
stop_checked = FALSE; triggered = FALSE;
stopped = FALSE; stopped = FALSE;
for (i = 0; i < session->num_sources; i++) { for (i = 0; i < session->sources->len; ++i) {
source = &session->sources[i]; source = &g_array_index(session->sources, struct source, i);
pollfd = &session->pollfds[i]; if (source->triggered)
revents = (ret > 0) ? pollfd->revents : 0; continue; /* already handled */
poll_object = source->poll_object;
fd = (int)poll_object;
revents = 0;
if (i < session->pollfds->len) {
pollfd = &g_array_index(session->pollfds, GPollFD, i);
fd = pollfd->fd;
if (ret > 0)
revents = pollfd->revents;
}
if (ret > 0 && revents == 0)
continue; /* skip timeouts if any I/O event occurred */
due = source->due; due = source->due;
#ifdef HAVE_LIBUSB_1_0 #ifdef HAVE_LIBUSB_1_0
if (source->is_usb && usb_due < due) if (source->is_usb && usb_due < due)
@ -470,29 +490,30 @@ static int sr_session_iteration(struct sr_session *session)
* The source may be gone after the callback returns, * The source may be gone after the callback returns,
* so access any data now that needs accessing. * so access any data now that needs accessing.
*/ */
poll_object = source->poll_object; if (source->timeout >= 0)
if (source->timeout > 0) source->due = stop_time + source->timeout;
source->due = stop_time + INT64_C(1000) * source->timeout; source->triggered = TRUE;
pollfd->revents = 0; triggered = TRUE;
/* /*
* Invoke the source's callback on an event or timeout. * Invoke the source's callback on an event or timeout.
*/ */
if (!source->cb(pollfd->fd, revents, source->cb_data)) if (!source->cb(fd, revents, source->cb_data))
sr_session_source_remove(session, poll_object); _sr_session_source_remove(session, poll_object);
/* /*
* We want to take as little time as possible to stop * We want to take as little time as possible to stop
* the session if we have been told to do so. Therefore, * the session if we have been told to do so. Therefore,
* we check the flag after processing every source, not * we check the flag after processing every source, not
* just once per main event loop. * just once per main event loop.
*/ */
if (!stopped) { if (!stopped)
stopped = sr_session_check_aborted(session); stopped = sr_session_check_aborted(session);
stop_checked = TRUE;
}
/* Restart loop as the sources list may have changed. */ /* Restart loop as the sources list may have changed. */
i = 0; i = 0;
} }
if (!stop_checked)
/* Check for abort at least once per iteration. */
if (!triggered)
sr_session_check_aborted(session); sr_session_check_aborted(session);
return SR_OK; return SR_OK;
@ -609,11 +630,14 @@ SR_API int sr_session_start(struct sr_session *session)
* *
* @retval SR_OK Success. * @retval SR_OK Success.
* @retval SR_ERR_ARG Invalid session passed. * @retval SR_ERR_ARG Invalid session passed.
* @retval SR_ERR Error during event processing.
* *
* @since 0.4.0 * @since 0.4.0
*/ */
SR_API int sr_session_run(struct sr_session *session) SR_API int sr_session_run(struct sr_session *session)
{ {
int ret;
if (!session) { if (!session) {
sr_err("%s: session was NULL", __func__); sr_err("%s: session was NULL", __func__);
return SR_ERR_ARG; return SR_ERR_ARG;
@ -629,17 +653,12 @@ SR_API int sr_session_run(struct sr_session *session)
sr_info("Running."); sr_info("Running.");
/* Do we have real sources? */ /* Poll event sources until none are left. */
if (session->num_sources == 1 && session->pollfds[0].fd == -1) { while (session->sources->len > 0) {
/* Dummy source, freewheel over it. */ ret = sr_session_iteration(session);
while (session->num_sources) if (ret != SR_OK)
session->sources[0].cb(-1, 0, session->sources[0].cb_data); return ret;
} else {
/* Real sources, use g_poll() main loop. */
while (session->num_sources)
sr_session_iteration(session);
} }
return SR_OK; return SR_OK;
} }
@ -854,8 +873,8 @@ SR_PRIV int sr_session_send(const struct sr_dev_inst *sdi,
* *
* @param session The session to use. Must not be NULL. * @param session The session to use. Must not be NULL.
* @param pollfd The GPollFD. * @param pollfd The GPollFD.
* @param[in] timeout Max time to wait before the callback is called, * @param[in] timeout Max time in ms to wait before the callback is called,
* ignored if 0. * or -1 to wait indefinitely.
* @param cb Callback function to add. Must not be NULL. * @param cb Callback function to add. Must not be NULL.
* @param cb_data Data for the callback function. Can be NULL. * @param cb_data Data for the callback function. Can be NULL.
* @param poll_object Handle by which the source is identified * @param poll_object Handle by which the source is identified
@ -868,34 +887,36 @@ SR_PRIV int sr_session_source_add_internal(struct sr_session *session,
GPollFD *pollfd, int timeout, sr_receive_data_callback cb, GPollFD *pollfd, int timeout, sr_receive_data_callback cb,
void *cb_data, gintptr poll_object, gboolean is_usb) void *cb_data, gintptr poll_object, gboolean is_usb)
{ {
struct source *new_sources, *s; struct source src;
GPollFD *new_pollfds;
if (!cb) { if (!cb) {
sr_err("%s: cb was NULL", __func__); sr_err("%s: cb was NULL", __func__);
return SR_ERR_ARG; return SR_ERR_ARG;
} }
/* Note: cb_data can be NULL, that's not a bug. */ /* Note: cb_data can be NULL, that's not a bug. */
new_pollfds = g_realloc(session->pollfds, src.cb = cb;
sizeof(GPollFD) * (session->num_sources + 1)); src.cb_data = cb_data;
new_sources = g_realloc(session->sources, sizeof(struct source) * src.poll_object = poll_object;
(session->num_sources + 1)); src.is_usb = is_usb;
src.triggered = FALSE;
new_pollfds[session->num_sources] = *pollfd; if (timeout >= 0) {
s = &new_sources[session->num_sources++]; src.timeout = INT64_C(1000) * timeout;
if (timeout > 0) src.due = g_get_monotonic_time() + src.timeout;
s->due = g_get_monotonic_time() + INT64_C(1000) * timeout; } else {
else src.timeout = -1;
s->due = INT64_MAX; src.due = INT64_MAX;
s->cb = cb; }
s->cb_data = cb_data;
s->poll_object = poll_object; if (pollfd) {
s->timeout = timeout; /* I/O source */
s->is_usb = is_usb; g_array_insert_val(session->sources, session->pollfds->len, src);
session->pollfds = new_pollfds; g_array_append_vals(session->pollfds, pollfd, 1);
session->sources = new_sources; } else {
/* Timer source */
g_array_append_val(session->sources, src);
}
return SR_OK; return SR_OK;
} }
@ -906,7 +927,8 @@ SR_PRIV int sr_session_source_add_internal(struct sr_session *session,
* @param session The session to use. Must not be NULL. * @param session The session to use. Must not be NULL.
* @param fd The file descriptor. * @param fd The file descriptor.
* @param events Events to check for. * @param events Events to check for.
* @param timeout Max time to wait before the callback is called, ignored if 0. * @param timeout Max time in ms to wait before the callback is called,
* or -1 to wait indefinitely.
* @param cb Callback function to add. Must not be NULL. * @param cb Callback function to add. Must not be NULL.
* @param cb_data Data for the callback function. Can be NULL. * @param cb_data Data for the callback function. Can be NULL.
* *
@ -920,20 +942,25 @@ SR_API int sr_session_source_add(struct sr_session *session, int fd,
{ {
GPollFD p; GPollFD p;
if (fd < 0 && timeout < 0) {
sr_err("Timer source without timeout would block indefinitely");
return SR_ERR_ARG;
}
p.fd = fd; p.fd = fd;
p.events = events; p.events = events;
p.revents = 0; p.revents = 0;
return sr_session_source_add_internal(session, &p, timeout, return sr_session_source_add_internal(session,
cb, cb_data, fd, FALSE); (fd < 0) ? NULL : &p, timeout, cb, cb_data, fd, FALSE);
} }
/** /**
* Add an event source for a GPollFD. * Add an event source for a GPollFD.
* *
* @param session The session to use. Must not be NULL. * @param session The session to use. Must not be NULL.
* @param pollfd The GPollFD. * @param pollfd The GPollFD. Must not be NULL.
* @param timeout Max time to wait before the callback is called, ignored if 0. * @param timeout Max time in ms to wait before the callback is called,
* or -1 to wait indefinitely.
* @param cb Callback function to add. Must not be NULL. * @param cb Callback function to add. Must not be NULL.
* @param cb_data Data for the callback function. Can be NULL. * @param cb_data Data for the callback function. Can be NULL.
* *
@ -946,6 +973,10 @@ SR_API int sr_session_source_add_pollfd(struct sr_session *session,
GPollFD *pollfd, int timeout, sr_receive_data_callback cb, GPollFD *pollfd, int timeout, sr_receive_data_callback cb,
void *cb_data) void *cb_data)
{ {
if (!pollfd) {
sr_err("%s: pollfd was NULL", __func__);
return SR_ERR_ARG;
}
return sr_session_source_add_internal(session, pollfd, timeout, return sr_session_source_add_internal(session, pollfd, timeout,
cb, cb_data, (gintptr)pollfd, FALSE); cb, cb_data, (gintptr)pollfd, FALSE);
} }
@ -956,7 +987,8 @@ SR_API int sr_session_source_add_pollfd(struct sr_session *session,
* @param session The session to use. Must not be NULL. * @param session The session to use. Must not be NULL.
* @param channel The GIOChannel. * @param channel The GIOChannel.
* @param events Events to poll on. * @param events Events to poll on.
* @param timeout Max time to wait before the callback is called, ignored if 0. * @param timeout Max time in ms to wait before the callback is called,
* or -1 to wait indefinitely.
* @param cb Callback function to add. Must not be NULL. * @param cb Callback function to add. Must not be NULL.
* @param cb_data Data for the callback function. Can be NULL. * @param cb_data Data for the callback function. Can be NULL.
* *
@ -971,7 +1003,7 @@ SR_API int sr_session_source_add_channel(struct sr_session *session,
{ {
GPollFD p; GPollFD p;
#ifdef _WIN32 #ifdef G_OS_WIN32
g_io_channel_win32_make_pollfd(channel, events, &p); g_io_channel_win32_make_pollfd(channel, events, &p);
#else #else
p.fd = g_io_channel_unix_get_fd(channel); p.fd = g_io_channel_unix_get_fd(channel);
@ -994,34 +1026,18 @@ SR_API int sr_session_source_add_channel(struct sr_session *session,
*/ */
static int _sr_session_source_remove(struct sr_session *session, gintptr poll_object) static int _sr_session_source_remove(struct sr_session *session, gintptr poll_object)
{ {
unsigned int old; unsigned int i;
if (!session->sources || !session->num_sources) { for (i = 0; i < session->sources->len; ++i) {
sr_err("%s: sources was NULL", __func__); if (g_array_index(session->sources, struct source, i)
return SR_ERR_BUG; .poll_object == poll_object) {
}
for (old = 0; old < session->num_sources; old++) { g_array_remove_index(session->sources, i);
if (session->sources[old].poll_object == poll_object) if (i < session->pollfds->len)
g_array_remove_index(session->pollfds, i);
break; break;
} }
/* fd not found, nothing to do */
if (old == session->num_sources)
return SR_OK;
session->num_sources--;
if (old != session->num_sources) {
memmove(&session->pollfds[old], &session->pollfds[old + 1],
(session->num_sources - old) * sizeof(GPollFD));
memmove(&session->sources[old], &session->sources[old + 1],
(session->num_sources - old) * sizeof(struct source));
} }
session->pollfds = g_realloc(session->pollfds, sizeof(GPollFD) * session->num_sources);
session->sources = g_realloc(session->sources, sizeof(struct source) * session->num_sources);
return SR_OK; return SR_OK;
} }
@ -1039,7 +1055,7 @@ static int _sr_session_source_remove(struct sr_session *session, gintptr poll_ob
*/ */
SR_API int sr_session_source_remove(struct sr_session *session, int fd) SR_API int sr_session_source_remove(struct sr_session *session, int fd)
{ {
return _sr_session_source_remove(session, (gintptr)fd); return _sr_session_source_remove(session, fd);
} }
/** /**
@ -1047,7 +1063,7 @@ SR_API int sr_session_source_remove(struct sr_session *session, int fd)
* *
* @param session The session to use. Must not be NULL. * @param session The session to use. Must not be NULL.
* @param pollfd The poll descriptor for which the source should be removed. * @param pollfd The poll descriptor for which the source should be removed.
* * Must not be NULL.
* @return SR_OK upon success, SR_ERR_ARG upon invalid arguments, or * @return SR_OK upon success, SR_ERR_ARG upon invalid arguments, or
* SR_ERR_MALLOC upon memory allocation errors, SR_ERR_BUG upon * SR_ERR_MALLOC upon memory allocation errors, SR_ERR_BUG upon
* internal errors. * internal errors.
@ -1057,6 +1073,10 @@ SR_API int sr_session_source_remove(struct sr_session *session, int fd)
SR_API int sr_session_source_remove_pollfd(struct sr_session *session, SR_API int sr_session_source_remove_pollfd(struct sr_session *session,
GPollFD *pollfd) GPollFD *pollfd)
{ {
if (!pollfd) {
sr_err("%s: pollfd was NULL", __func__);
return SR_ERR_ARG;
}
return _sr_session_source_remove(session, (gintptr)pollfd); return _sr_session_source_remove(session, (gintptr)pollfd);
} }
@ -1065,7 +1085,7 @@ SR_API int sr_session_source_remove_pollfd(struct sr_session *session,
* *
* @param session The session to use. Must not be NULL. * @param session The session to use. Must not be NULL.
* @param channel The channel for which the source should be removed. * @param channel The channel for which the source should be removed.
* * Must not be NULL.
* @retval SR_OK Success. * @retval SR_OK Success.
* @retval SR_ERR_ARG Invalid argument. * @retval SR_ERR_ARG Invalid argument.
* @return SR_ERR_BUG Internal error. * @return SR_ERR_BUG Internal error.
@ -1075,6 +1095,10 @@ SR_API int sr_session_source_remove_pollfd(struct sr_session *session,
SR_API int sr_session_source_remove_channel(struct sr_session *session, SR_API int sr_session_source_remove_channel(struct sr_session *session,
GIOChannel *channel) GIOChannel *channel)
{ {
if (!channel) {
sr_err("%s: channel was NULL", __func__);
return SR_ERR_ARG;
}
return _sr_session_source_remove(session, (gintptr)channel); return _sr_session_source_remove(session, (gintptr)channel);
} }