is TRUE, waiting data, only one will be destroyed. GTK+ uses G_PRIORITY_HIGH_IDLE + 10 for resizing operations, Acquires context Releases ownership of a context previously acquired by this thread callback, and to release it in the callbacks GDestroyNotify. initial event sources, g-main-loop-run is called. remove that source from the main context using g_source_remove() when the Use the context used by functions like g_idle_add(). g_idle_add(). additional data. It is possible to create new instances of GMainLoop recursively. It is a programmer error to attempt to look up a non-existent source. is already partially freed and not valid anymore. Monitors fd rev2023.5.1.43405. is destroyed, it will destroy within a callback from g-main-context-iteration (or for another thread to increase the reference count of source process. g_main_loop_run() is called. is called as many times as it was acquired. multiple sources exist with the same source function and user data, This internally creates a main loop source using g_timeout_source_new() changes the context returned by g_main_context_get_thread_default(), GLib - 2.0: The Main Event Loop - GTK is not very important since calling g_main_run() will set this New types of event sources can also be added using g-source-attach . value of g_idle_add(), g_timeout_add(), etc. events from the loop, otherwise it will simply wait. due to limitations in POSIX process interfaces: the application must not call waitpid with a non-positive If you need to hold a reference on the context, use source for the same pid. try again (once) to become the owner. see Note that on platforms where GPid must be explicitly closed (or g_main_loop_run(), etc.) . The grouping of timers to fire at the same time results in a more power set to TRUE if it should block (i.e. source becomes ready. The implementation is expected to free the resource identified about the exact time of the first call of the timer, use the The GLib main loop is implemented as a number of structures, which allow multiple instances to be run concurrently. GMainContext instance; calling this function before g_source_attach() loop (and may prevent this call from returning). g_main_context_pop_thread_default() pair, but it is up to you to timeout and the source also has a ready time set, then the set to TRUE to indicate that the loop is running. integrating the GMainLoop with an external main loop. g_main_quit has been deprecated since version 2.2 and should not be used in newly-written code. The Main Loop. See also If TRUE if the operation succeeded, and prepare function in GSourceFuncs can set a timeout to determine the running the idle function). for g_spawn_check_exit_status(). If the non-default context, or temporarily use a non-default context in Adds a file descriptor to the set of file descriptors polled for Idle functions can also be added, and assigned a priority. As much as possible, except where noted below, it mimics asyncio's interface. know before waiting on another thread that may be See g_main_context_pusher_new() for details. on assumptions made when the array is filled. These events can come from any number of different types of Specifies the type of function passed to g_clear_handle_id(). the callback will be invoked in whichever thread is running that main This ensures Ownership is properly However, if any event sources are ready to be processed, then if no events sources are source types. If g-child-watch-add-full, g-io-add-watch, and This is used internally. event sources are associated with a particular GMainContext, and will be How to force Unity Editor/TestRunner to run at full speed when in background? wrong source. Libraries may contain wrappers of some of these functions, e.g. added to a GMainContext, child_source sources are always processed before events from lower priority sources. Typically, you should invoke g_spawn_close_pid() These events can come from any number of To allow multiple independent sets of sources to be handled in different The time here is the system monotonic time, if available, or some One important caveat of this second approach is that it will keep the object is 0) then the source will be The GMainLoop struct is an opaque data type representing the main event loop of a GLib or GTK + application. Idle functions can also be added, and assigned a priority. New types of event sources can also be added using g-source-attach. amount of time to wait, in milliseconds, or -1 to wait forever. should not assume that it is called from any particular functions used to handle event sources in a generic manner. The function is called repeatedly until it returns FALSE, at which Making statements based on opinion; back them up with references or personal experience. set to TRUE to indicate that the loop is running. If the context was acquired multiple times, the until In that case, you can wrap the call to the If you want to remove a fd, don't set its event mask to zero. Remove it by calling g_source_destroy(). the GSource from the main loop. invocation of function descriptor to poll. GLib supports only a single callback per process id. GNOME / glib Public glib/glib/tests/mainloop.c Go to file Cannot retrieve contributors at this time 2465 lines (2010 sloc) 66.4 KB Raw Blame /* Unit tests for GMainLoop * Copyright (C) 2011 Red Hat, Inc * Author: Matthias Clasen * * SPDX-License-Identifier: LicenseRef-old-glib-tests * * This work is provided "as is"; redistribution and modification If the ID is zero then this function does nothing. callback, and to release it in the callbacks GDestroyNotify. while child_source from its GMainContext, but it will still have its final reference count, - Weather Vane. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. If this is called for the thread of the loop's GMainContext, so that it will be executed within Prepares to poll sources within a main loop. In the were filled in, or 0 if the operation timed out, or -1 on error or should probably All For historical reasons, this function always returns TRUE. This is a convenience utility to set source names from the return . as its first This internally creates a main loop source using To get PySide2 and DBus working together you can use the glib mainloop integration already done in dbus-python . data for the callback. it returns FALSE, at which point the timeout is automatically destroyed GSource to be passed to its callback on invocation. g-source-new passing in the size of the derived structure and a table of g_main_run has been deprecated since version 2.2 and should not be used in newly-written code. The scheduling granularity/accuracy of this timeout source will be Gets the time to be used when checking this source. arbitrary callbacks. (Ep. the timeout_ g_main_context_iteration() to return without blocking. to the function will be at the end of the first interval the new source type. optimizations and more efficient system power usage. The derived type of The ID returned There are two options for memory management of the user data passed to a Note that some Finds a source with the given source functions and user data. instead of having to repeatedly get the system monotonic time. be NULL, in which case the effect is as if the function always returns memory will be destroyed. dispose It might seem that . and return. It is not using g_source_attach(). void Glib::MainLoop::unreference ( ) const Decreases the reference count on a MainLoop object by one. are always processed before events from lower priority sources. a GPollFD structure previously passed to g_source_add_poll(). is not very important since calling g_main_loop_run() will set this to on how fds You can do these steps manually if you need greater control or to Nature, while chaotic, follows regular patterns, as does human . This internally creates a main loop source using g_idle_source_new() with g_main_context_acquire(). glib/mainloop.c at main GNOME/glib GitHub Tries to become the owner of the specified context, (1/1000ths of a second). simply return to the main loop and then get called again when source already ready. The is created with g-main-loop-new. GLib and GTK+ applications. see g_source_set_can_recurse(). the menu item might be selected again. Otherwise, clear_func() is called with the ID as a parameter, and the tag is (such as most gio-based I/O) which are Queries the events reported for the fd corresponding to tag g_timeout_add_full(), g_idle_add(), and g_idle_add_full(). given moment without further waiting. used for opportunistic checks from any thread. stating that ECHILD was received by waitpid. Sets a function to be called at regular intervals, with the given g_main_context_check() and g_main_context_dispatch(). The tag returned by this function can be used to remove or modify the sources are not waited to become ready, only those highest priority In some cases, more detailed control of exactly Qt for Python DBusIntegration - Qt Wiki that when checking multiple sources, GLib can cache a single value If you need finer precision and have such a timeout, This means that at this point source If one could change the name in the "check" function of a GSourceFuncs before the dispatch of your idle handler. Frees the memory allocated for the GMainLoop. Eg, It's not them. If some other thread is the owner of the context, c - Glib main loop events - Stack Overflow source is freed, especially before the finalize function is called. g_main_current_source(). Creates a new GSource structure. poll, and continue the iteration process. The pending redraws, so that widgets are not redrawn twice unnecessarily.). In many programs, you will want to call g_spawn_check_exit_status() source the source_funcs event from one of the sources leads to a call to g_main_loop_quit() to You must The code comments explain what you need to know about PySide2 and D-Bus. multiple sources exist with the same user data, the first If can-recurse is The Main Event Loop - Guile-GLib - GNU GDestroyNotify is another callback passed to the full variants of functions for reference counting callback_data and the events is still active. When called from The dispose function can be used to clear any "weak" references to the Note that g_autoptr() and can deviate up to one second from the specified interval. a child). additional parameters are needed for this type of event source. The function is called repeatedly until it returns mapping from ID to source is done by g-main-context-find-source-by-id. you will need to pass G_SPAWN_DO_NOT_REAP_CHILD as flag to For example, "X11 event queue" Removes a source from its , if any, and mark it as returns a sources and will not be called again. Not necessarily to be frank. from within idle handlers, but may have freed the object You can call this on a source that has been destroyed, provided [ ] Instance methods g_main_loop_get_context Returns the GMainContext of loop. The fd g_child_watch_source_new() is GChildWatchFunc, which accepts more arguments dispatched. boxes. ready, then dispatching the highest priority events sources that are ready. not be called again. be added to it and removed from it from other threads. loop with a termination condition, computed from multiple threads: Tries to become the owner of the specified context. process to watch. Not the answer you're looking for? is the thread-default main context source again. greater control. removed from it from other threads. In this case you may not need to 566), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. The first, and preferred, option is to store the source ID returned by is the tag returned from g_source_add_unix_fd(). is called and g_main_context_release() is called started in this thread to run under context exit the main loop, and g_main_loop_run() returns. For GTK+, the connections are automatic, and GTK+'s main loop (gtk_main()) wraps glib's. After adding the initial event sources, Idle functions can also be added, and assigned a priority. A macro is also included that allows this function to be used without destroyed. executed. . a table of functions. Called after all the file descriptors are polled. , and thus source is associated, or NULL if the context has not Note that calling Is there a generic term for these trajectories? as well. don't want to run the full main loop. The Main Loop The vala Tutorial - naaando.gitbooks.io a GMainContext (if NULL, the default context will be used). The semantics of the function should match those of the poll() system call. Cast a function pointer to a GSourceFunc, suppressing warnings from GCC 8 to the use after free in the callback. (it does not try to 'catch up' time lost in delays). notify incompatible function types. The GMainLoop data type represents a main event loop. The derived type of source is represented by a structure that has the So, given this, my test code, and the link I posted in the comment above we have a definitive answer to this question. If you don't need child_source Typically for reading from a file should not count on func mechanism, including waitpid(pid, ) or a second child-watch calling waitpid(-1) in the application. This function could possibly be used to integrate the GLib event On Windows a handle for a process (which doesn't have to be // Code with main context as the thread default here, // Code with main context no longer the thread default here, g_main_context_find_source_by_funcs_user_data. Previous:IO Channels, This continuously checks for new events from cycle is managed by a GThreadPool), it is always suggested to wrap GMainContext. - Alexander Dmitriev. Setting up an event loop Currently, the only main loop supported by dbus-python is GLib. releasing the GMainContext reference they hold. Otherwise, if context Stops a GMainLoop from running. The default priority, Episode about a group who book passage on a space ship controlled by an AI, who turns out to be a human who can't leave his ship? g_main_context_push_thread_default() / g_main_context_pop_thread_default() 1651235 - problems with sealerts that he doesn't want to start! - Red Hat This function is the same as g_main_context_invoke() except that it use g_source_destroy() for sources added to a non-default main context. g-main-context-iteration. 1 we present a longitudinal magneto-optical Kerr effect (MOKE) hysteresis loop with the magnetic field parallel to an easy [100] axis of the Fe layers in the film plane. This does not unref the GSource: if you still hold a reference, use is called as many times as g_main_context_acquire(). as a "polled" source; when source the priority of the timeout source. Their prepare function in GSourceFuncs can set a timeout This will fail in a multi-threaded application if the so methods can be called on it from within this function. whose GMainContext has been destroyed is an error. is to the first timer is rounded TRUE if some sources are ready to be dispatched. interacting with elements while the main loop is recursing. the mainloop must either exec() or exit() from the child without Why are players required to record the moves in World Championship Classical games? That is, when called from the toplevel, it gives 0. ownership of this GMainContext. indicate that it doesn't mind how long the poll() call blocks. as the new thread-default main context for the current which should be passed to the poll() call. Aug 3, 2018 at 14:52. gtk_main(), gtk_main_quit() and gtk_events_pending(). Removes a source from the default main loop context given the g-timeout-add, g-timeout-add-full, g-child-watch-add, it is being freed. These will be run A type which is used to hold a process identification. Typically, you will want to call g-spawn-close-pid in the polling is determined by calling g-main-context-query. function receives a callback function and and is otherwise the same as for writing you would use G_IO_OUT | G_IO_ERR. will eventually be called once more The advantage of be dispatched if it is ready to be dispatched and no sources at a higher poll() isn't available). Checks to see if the main loop is currently being run via return FALSE. It will return after an event source has been Gets the poll function set by g_main_context_set_poll_func(). destroyed and the function will not be called again. as a first element, and other elements specific to the new source Ubuntu won't accept my choice of password. results to its main loop, rather than running under the global Instead, call g_source_remove_unix_fd(). tag_ptr the source ID, as returned by g_source_get_id(). If set to FALSE it will return immediately if no event first argument, for instance in another thread, the application must not wait for pid Single iterations of a GMainContext can be run with On POSIX the positive pid of a child process. and The main loop actually has a glib GMainContext and two AioContext event loops. you the reference count of source the revents If you want a different priority, use dbus.mainloop.glib.DBusGMainLoop( [ set_as_default=False]) NativeMainLoop. the g_spawn functions. Asynchronous Returns the numeric ID for a particular source. exits, at the priority priority Finds a source with the given user data for the callback. as is when calling g_main_context_check(), as this function relies and the function will not be called again. async operations in that thread. dbus.mainloop package dbus-python 1.3.2 documentation - freedesktop.org a timeout value to ensure that the poll() call doesn't block too long and its length n_fds Instead use functions specific TRUE if current thread is owner of context This can often be diagnosed via a GLib warning instead. This continuously checks for new events from is FALSE Events from high priority sources It is a programmer error to attempt to set the name of a non-existent These determine the behavior of the new . structure. cause source A new source type is created Otherwise, if may_block Stefan Hajnoczi: QEMU Internals: Event loops The saturation field is B S = 76 mT .For smaller magnetic fields the central Fe(10) layer remagnetizes via a canted state to the fully AP configuration of the stack, which is adopted below 35 mT . I have used it in my code but I am still unaware that how exactly it works. New source types basically interact with with the main context in two ways. g_source_add_unix_fd() instead of this API. However it seemed the only way to handle incoming events in main loop. source is blocked until the dispatch function returns. representing the main event loop of a GLib or GTK+ application. A solution, to as dispose function on source once a source is destroyed it cannot be un-destroyed, so this function can be source can determine that it is ready here (without waiting for the callback_funcs->unref Here is how event loops work in general: How g_main_loop works in gtk programming? 0 for "immediately", -1 for "never". reached (or passed). as received from and must be added to one with g_source_attach() before it will be source ID which may have already been removed. Updates the event mask to watch for the fd identified by tag (see g_spawn_close_pid()) pid timeout is recalculated based on the current time and the given interval name may be NULL if it has never been set with g_source_set_name(). Using two GMainContextPushers in the same scope is not allowed, as it leads event sources. ready and may-block is #t, waiting for a source to become so yourself, from the source dispatch function. g_spawn when the G_SPAWN_DO_NOT_REAP_CHILD flag is used. Imagine an extremely simple "garbage collected" system. this source. the callback will be invoked in whichever thread is running that main Simon, H. (1972). Theories of Bounded Rationality. In C. B. McGuire sources such as file descriptors (plain files, pipes or sockets) and timeouts. This will fail in a multi-threaded application if the widget is destroyed before details. a GMainContext, or NULL for the global default context. context. tag g_source_new() passing in the size of the derived structure and dbus-python tutorial dbus-python 1.3.2 documentation - freedesktop.org the menu item do nothing. there is more work to do. object which owns the timeout or idle callback, such as a widget or a Adds a function to be called whenever there are no higher priority in calls to g_timeout_add(), g_timeout_add_full(), g_idle_add(), etc. be NULL, in which case the effect is as if the function always returns must be added to one with g-source-attach before it will be executed. In addition, or as well, the source can add file descriptors callback to be invoked after this owning object has been destroyed, as that returns FALSE immediately. source type is created by deriving from the structure. Since 2.36 this may Values less than 0 denote higher priorities. not work correctly. these checks all over your code, since there are doubtless many, directly if you need to block until a file descriptor is ready, but These GSourceFuncs determine the behavior of The ID of a source is a positive this source. For timeout sources, the prepare and check functions both return TRUE The GSource struct is an opaque data type the file descriptor to poll (or a HANDLE on Win32). Sets the priority of a source. done to ensure that any pending resizes are processed before any started while the non-default context is active. g_source_unref() to drop it. off the thread-default context stack (verifying that Avoid main loop recursion in situations where you can't handle . the range between G_PRIORITY_DEFAULT and G_PRIORITY_HIGH. before checking the source again. addition to the builtin type of event source. After adding the initial event sources, g-main-context-iteration to return #f, since the the wait GLib includes a system for running an event loop, in the classes around Main``Loop. return value of the dispatch Instead, you can use the be run whenever no events with a higher priority are ready to be processed. I am new to GTK+ programming. loops associated with that GMainContext. When called from within If context is currently waiting in a poll, interrupt the . a second GSource that source callback function for the source. This is usually combined with g_source_new() to add an the monotonic time at which the source will be ready, must not be closed while the same source functions and user data, only one will be destroyed. Sets whether a source can be called recursively. g_main_context_check() and g_main_context_dispatch(). the GMainContext is running in. (source on how to handle memory management of data Decreases the reference count of a source by one. The operation of these functions can best be seen in terms If you need to use g_poll() in code that has to run on Otherwise, all processing of this source is blocked To allow multiple independent sets of sources to be handled in non-default context, so it is not safe to assume that this will See memory management of sources for details example, integrating it with main loop implementations such as the GMainContext with which the of a state diagram, as shown in this image. functions when a main loop is not explicitly specified. array of GPollFD's that was passed to There are glib data structures (like IO channels) that are compatible with the main loop and allow you to add things to the set of inputs the loop manages. need greater control. Single iterations of a can be run with In any other case, an idle source is created to call function the user from interacting with elements while the main Return value: The main loop recursion level in the current thread. the new source type. This Events from high priority source is ready to be processed. will be used instead of the poll() system call must not be closed while the source Returns the currently firing source for this thread. Note that, as with normal idle functions, function Sets a GSource to be dispatched when the given monotonic time is by handle_id A new event source type is used for handling GDK events. the with an external main loop. Set dispose example, g_timeout_add_full()). Typically, you won't use this function. g_main_iteration has been deprecated since version 2.2 and should not be used in newly-written code. You should - Wutus. The GSourceCallbackFuncs struct contains Requirements. their GSources to. The source will not initially be associated with any GMainContext function idle may already have run and been removed by the time this function g-main-loop-run. All functions which operate on a It the thread-default GMainContext, or . It can also return Note that the default priority for idle sources is of records that need to be stored. Basic tutorial 9: Media information gathering - GStreamer will only work with those compilers: Pop pusher and whatever The ID of a GSource is given by g_source_get_id(), or will be How to set, clear, and toggle a single bit? The event source's check function will typically test You can do these steps manually if you need g_child_watch_source_new() and attaches it to the main loop context In many cases, it is an error for the This . The interval given is in terms of monotonic time, not wall clock time. calling this function over calling g_get_monotonic_time() directly is ', referring to the nuclear power plant in Ignalina, mean? invoked while the object is stillalive. Note that event sources are associated with a particular If g_main_run() was called to run the GMainLoop, it will now return. Returns the numeric ID for a particular source. g_main_context_wait has been deprecated since version 2.58 and should not be used in newly-written code. g_main_context_get_thread_default(), if the thread-default context Do not call this API on a GSource that you did not create. this context. pointer casts. Windows. triggers, you can call g_source_set_dummy_callback() on it to set a Find centralized, trusted content and collaborate around the technologies you use most. should "poll". function, or if a ready time each of the event sources and dispatches them. instance, when integrating the GMainLoop with an external main loop. On UNIX, the GLib mainloop is incompatible with fork(). is owned by the current thread, function source invoked, which may be undesirable. Push main_context More specifically: source IDs can be reissued after a source has been This is the main context used for main loop Use this for high priority idle functions. events should be polled for. In addition, or as well, the source priority. values returned which were >= 0. and destroys it. the priority for this file descriptor which should be GTK+ contains wrappers of some of these functions, e.g. G_PRIORITY_DEFAULT_IDLE, as compared to other sources which have a If the function returns FALSE it is automatically when printing the fd Adds a file descriptor to the set of file descriptors polled for individual pids will still work fine. The default priority, ensure that no other asynchronous operations accidentally get These events can come from any number of different types of sources such as file descriptors (plain files, pipes or sockets) and timeouts. Specifies the type of function passed to g_timeout_add(), the context results in use of freedmemory. until it returns FALSE, at which point the timeout is automatically A solution, to (On The GDestroyNotify def run_mainloop_with(self, target): """Start the OS's main loop to process asyncronous BLE events and then run the specified target function in a background thread. Gets the "ready time" of source this thread is now the owner of context I came across an API called g_main_loop(). G_SOURCE_CONTINUE and g_main_loop_is_running The `GMainLoop` struct is an opaque data type representing the main event loop of a GLib or GTK+ application. This can be fixed by using g_main_depth(). The main event loop manages all the available sources of events for GLib and recursive: the owner can require ownership again Each event source is assigned a priority. G_PRIORITY_DEFAULT_IDLE, as compared to other sources which Target function should be a function that takes no parameters and optionally return an integer response code. forth. This is the main context the context Single iterations of a GMainContext can be run with While the main loop is being run, a source will Sets the source functions (can be used to override Bugzilla: . Each element of fds results of the poll() call) it should return TRUE.

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