Publican was generating a subtle error during a build:
Error: no ID for constraint linkend: Server-wayland-server-core_8h.
This was caused by doxygen applying the doc comment at the top of
wayland-server.h as the documentation for struct wl_object. As such, the
generated documentation for wl_object was also very incorrect.
Make the file doc comments in wayland-client.h and wayland-server.h real
doxygen file doc comments with the \file command, add a \brief, make the
inclusion warning a \warning, correct the language of the comment in
wayland-server.h, and remove one unnecessary line break.
This squelches the publican error, removes the bad wl_object documentation,
and makes the comment appear in the generated html documentation.
References: d74a9c079b
Signed-off-by: Yong Bakos <ybakos@humanoriented.com>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>
wayland-client.h and wayland-server.h include the protocol headers generated
at build time. This means that a libwayland user cannot generate and use
protocol code created from a wayland.xml newer than the installed libwayland,
because it is not possible to only include the API header.
Another use case is language bindings, which would generate their own protocol
code and which only need to use the library ABI, not the generated C code.
This commit adds wayland-client-core.h and wayland-server-core.h which do not
include the protocol headers or any deprecated code.
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
1) there is nothing like main thread since
3c7e8bfbb4 anymore, so remove
it from documentation and update the doc accordingly.
2) use calling 'default queue' instead of 'main queue'. In the code
we use display->default_queue, so it'll be easier the understand.
3) update some obsolete or unprecise pieces of documentation
v2. Not only remove out-of-date comment, but fix/remove more
things across the wayland-client.[ch]
v3. fixes (rephrasing unclear paragraphs etc.)
according to Pakka Paalanen notes (thanks)
Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Daniel Stone <daniel@fooishbar.org>
This does not make a difference to doxygen output but may help other
document generators not make redundant links.
Reviewed-by: Bryce Harrington <b.harrington@samsung.com>
wl_display_roundtrip() works on the default queue. Add a parallel
wl_display_roundtrip_queue().
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
When an error occurs, wl_display_get_error() does not
provide any way of getting know if it was a local error or if it was
an error event, respectively what object caused the error and what
the error was.
This patch introduces a new function wl_display_get_protocol_error()
which will return error code, interface and id of the object that
generated the error.
wl_display_get_error() will work the same way as before.
wl_display_get_protocol_error() DOES NOT indicate that a non-protocol
error happened. It returns valid information only in that case that
(protocol) error occurred, so it should be used after calling
wl_display_get_error() with positive result.
[Pekka Paalanen] Applied another hunk of Bryce's comments to docs,
added libtool version bump.
Reviewed-by: Pekka Paalanen <ppaalanen@gmail.com>
Reviewed-by: Bryce Harrington <b.harrington@samsung.com>
The server requires clients to only allocate one ID ahead of the previously
highest ID in order to keep the ID range tight. Failure to do so will
make the server close the client connection. However, the way we allocate
new IDs is racy. The generated code looks like:
new_proxy = wl_proxy_create(...);
wl_proxy_marshal(proxy, ... new_proxy, ...);
If two threads do this at the same time, there's a chance that thread A
will allocate a proxy, then get pre-empted by thread B which then allocates
a proxy and then passes it to wl_proxy_marshal(). The ID for thread As
proxy will be one higher that the currently highest ID, but the ID for
thread Bs proxy will be two higher. But since thread B prempted thread A
before it could send its new ID, B will send its new ID first, the server
will see the ID from thread Bs proxy first, and will reject it.
We fix this by introducing wl_proxy_marshal_constructor(). This
function is identical to wl_proxy_marshal(), except that it will
allocate a wl_proxy for NEW_ID arguments and send it, all under the
display mutex. By introducing a new function, we maintain backwards
compatibility with older code from the generator, and make sure that
the new generated code has an explicit dependency on a new enough
libwayland-client.so.
A virtual Wayland merit badge goes to Kalle Vahlman, who tracked this
down and analyzed the issue.
Reported-by: Kalle Vahlman <kalle.vahlman@movial.com>
This commit adds support for language bindings on the client half of the
library. The idea is the same as for server-side dispatchers.
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
This is the mirror function to wl_proxy_add_listener and is useful
inside client libraries to differentiate events on listeners for which
multiple proxies have been created.
The current thread model assumes that the application or toolkit will have
one thread that either polls the display fd and dispatches events or just
dispatches in a loop. Only this main thread will read from the fd while
all other threads will block on a pthread condition and expect the main
thread to deliver events to them.
This turns out to be too restrictive. We can't assume that there
always will be a thread like that. Qt QML threaded rendering will
block the main thread on a condition that's signaled by a rendering
thread after it finishes rendering. This leads to a deadlock when the
rendering threads blocks in eglSwapBuffers(), and the main thread is
waiting on the condition. Another problematic use case is with games
that has a rendering thread for a splash screen while the main thread
is busy loading game data or compiling shaders. The main thread isn't
responsive and ends up blocking eglSwapBuffers() in the rendering thread.
We also can't assume that there will be only one thread polling on the
file descriptor. A valid use case is a thread receiving data from a
custom wayland interface as well as a device fd or network socket.
The thread may want to wait on either events from the wayland
interface or data from the fd, in which case it needs to poll on both
the wayland display fd and the device/network fd.
The solution seems pretty straightforward: just let all threads read
from the fd. However, the main-thread restriction was introduced to
avoid a race. Simplified, main loops will do something like this:
wl_display_dispatch_pending(display);
/* Race here if other thread reads from fd and places events
* in main eent queue. We go to sleep in poll while sitting on
* events that may stall the application if not dispatched. */
poll(fds, nfds, -1);
/* Race here if other thread reads and doesn't queue any
* events for main queue. wl_display_dispatch() below will block
* trying to read from the fd, while other fds in the mainloop
* are ignored. */
wl_display_dispatch(display);
The restriction that only the main thread can read from the fd avoids
these races, but has the problems described above.
This patch introduces new API to solve both problems. We add
int wl_display_prepare_read(struct wl_display *display);
and
int wl_display_read_events(struct wl_display *display);
wl_display_prepare_read() registers the calling thread as a potential
reader of events. Once data is available on the fd, all reader
threads must call wl_display_read_events(), at which point one of the
threads will read from the fd and distribute the events to event
queues. When that is done, all threads return from
wl_display_read_events().
From the point of view of a single thread, this ensures that between
calling wl_display_prepare_read() and wl_display_read_events(), no
other thread will read from the fd and queue events in its event
queue. This avoids the race conditions described above, and we avoid
relying on any one thread to be available to read events.
This is a useful shorthand for client application debugging macros,
since you can ask the object class from the object itself.
Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>
The need for wl_display_update_func_t was removed in
commit 53d24713a3
Author: Kristian Høgsberg <krh@bitplanet.net>
Date: Thu Oct 4 16:54:22 2012 -0400
Change filedescriptor API to be thread safe
and wl_callback_func_t does not seem to have ever been used in the first place.
Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>
On the client side EGL, all the wl_buffer.release events need to be
processed before buffer allocation, otherwise a third buffer might
be allocated unnecessarily. However, the buffer allocation should
not block in the case no event was received. In order to do that, a
non-blocking queue dispatch function is needed.
If any callback or helper function fails with a fatal error, we now
set the last_error flag and prevent all further I/O on the wl_display. We
wake up all sleeping event-queues and notify the caller that they
should shutdown wl_display.
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
A server may asynchronously send errors via wl_display.error() events.
Instead of aborting we now the a "last_error" flag inside of wl_display
objects. The user can retrieve these via wl_display_get_error().
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Add some brief documentation for the public libwayland-client entry
points. This is by no means complete, some functions are still
undocumented and some might need extra information.
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
If the main thread ends up dispatching a non-main queue, and not in
a wl_display_dispatch() callback, we may queue up main queue events and read
all data from the socket fd. When we get back to the main loop, the
socket fd is no longer readable and nothing will trigger dispatching of
the queued up events.
The new function wl_display_dispatch_pending() will dispatch any pending
events, but not attempt to read from the socket. Clients that integrate
the wayland socket fd into a main loop should call
wl_display_dispatch_pending() and then wl_display_flush()
before going back to blocking in poll(2) or similar mechanism.
The function wl_proxy_create_for_id() would try to acquire the display
lock, but the only call path leading to it would call it with the lock
already acquired.
This patch removes the attempt to acquire the lock and makes the
function static. It was exported before because client had to create
proxy's manually when the server sent a new object id, but since commit
9de9e39f [1] this is no longer necessary.
[1] commit 9de9e39f87
Author: Kristian Høgsberg <krh@bitplanet.net>
Date: Thu Jun 28 22:01:58 2012 -0400
Allocate client proxy automatically for new objects
v2: Change the right function. Previous patch changed wl_proxy_create()
instead of wl_proxy_create_for_id().
The only way to make the global object listener interface thread safe is to
make it its own interface and make different listeners different wl_proxies.
The core of the problem is the callback we do when a global show up or
disappears, which we can't do with a lock held. On the other hand we can't
iterate the global list or the listener list without a lock held as new
globals or listeners may come and go during the iteration.
Making a copy of the list under the lock and then iterating after dropping
the lock wont work either. In case of the listener list, once we drop the
lock another thread may unregister a listener and destroy the callbackk
data, which means that when we eventually call that listener we'll pass it
free memory and break everything.
We did already solve the thread-safe callback problem, however. It's what
we do for all protocol events. So we can just make the global registry
functionality its own new interface and give each thread its own proxy.
That way, the thread will do its own callbacks (with no locks held) and
destroy the proxy when it's no longer interested in wl_registry events.
We used to special case this because of the untyped new-id argument in
the bind request. Now that the scanner can handle that, we can
remove the special case.
Switching to the generated stubs does bring an API change since we now
also take the interface version that the client expects as an argument.
Previously we would take this from the interface struct, but the
application may implement a lower version than what the interface struct
provides. To make sure we don't try to dispatch event the client
doesn't implement handlers for, we have to use a client supplied version
number.
This introduces wl_event_queue, which is what will make multi-threaded
wayland clients possible and useful. The driving use case is that of a
GL rendering thread that renders and calls eglSwapBuffer independently of
a "main thread" that owns the wl_display and handles input events and
everything else. In general, the EGL and GL APIs have a threading model
that requires the wayland client library to be usable from several threads.
Finally, the current callback model gets into trouble even in a single
threaded scenario: if we have to block in eglSwapBuffers, we may end up
doing unrelated callbacks from within EGL.
The wl_event_queue mechanism lets the application (or middleware such as
EGL or toolkits) assign a proxy to an event queue. Only events from objects
associated with the queue will be put in the queue, and conversely,
events from objects associated with the queue will not be queue up anywhere
else. The wl_display struct has a built-in event queue, which is considered
the main and default event queue. New proxies are associated with the
same queue as the object that created them (either the object that a
request with a new-id argument was sent to or the object that sent an
event with a new-id argument). A proxy can be moved to a different event
queue by calling wl_proxy_set_queue().
A subsystem, such as EGL, will then create its own event queue and associate
the objects it expects to receive events from with that queue. If EGL
needs to block and wait for a certain event, it can keep dispatching event
from its queue until that events comes in. This wont call out to unrelated
code with an EGL lock held. Similarly, we don't risk the main thread
handling an event from an EGL object and then calling into EGL from a
different thread without the lock held.
The update callback for the file descriptors was always a bit awkward and
un-intuitive. The idea was that whenever the protocol code needed to
write data to the fd it would call the 'update' function. This function
would adjust the mainloop so that it polls for POLLOUT on the fd so we
can eventually flush the data to the socket.
The problem is that in multi-threaded applications, any thread can issue
a request, which writes data to the output buffer and thus triggers the
update callback. Thus, we'll be calling out with the display mutex
held and may call from any thread.
The solution is to eliminate the udpate callback and just require that
the application or server flushes all connection buffers before blocking.
This turns out to be a simpler API, although we now require clients to
deal with EAGAIN and non-blocking writes. It also saves a few syscalls,
since the socket will be writable most of the time and most writes will
complete, so we avoid changing epoll to poll for POLLOUT, then write and
then change it back for each write.
The core libwayland libraries should not handle logging, only passing
the error messages to subscribed functions.
An application linked to libwayland-server or libwayland-client
will be able to set own functions (one per library) to handle error
messages.
Change in this series: make the wl_log return int, because
of compatibility with printf. It will return the number of bytes logged.
This adds a public header so that applications can get the Wayland
version number at compile time. This can be used to make applications
that support compiling against multiple versions of Wayland.
There is a separate installed header called cogl-version.h which gets
included by both wayland-client.h and wayland-server.h
The canonical place for the version number is the configure.ac script
which splits it into three separate m4 defines for the major, minor
and micro version. These are copied into the generated
wayland-version.h header using AC_SUBST. There is also a string form
of the complete version number.
The version number is now also automatically copied into the two .pc
files.
Because the major, minor and micro parts are required it is no longer
possible to leave the version number as 'master' when building from
git. Most projects seem to immediately bump the git repo to a fake
version number (usually odd) after making a release so that there is
always a relative number that can be used for comparison. This patch
sets the git version to 0.99.0 under the assumption that the next
release will be 1.0.0.
This avoids the clash with the wayland-server version with the same
name, and allows linking against both wayland-client and wayland-server
at the same time, which can be useful for unit testing purposes as
well as for nested compositing.
Without this there will be crashes as the wrong wl_display_destroy()
is called.
We set aside a range of the object ID space for use by the server. This
allows the server to bind an object to an ID for a client and pass that
object to the client. The client can use the object immediately and the
server can emit events to the object immdiately.
So obvious in retrospect. The object system can do all the work for us
and keep track of pending calls as regular objects and we don't need to
abuse the resource system to get them cleaned up on client exit. We
don't need the custom key management or (broken) lookup, we just sue
object IDs. And last but not least, anybody can receive the callback,
not just display listeners.
