glib main loop explained

mapping from ID to source is done by g_main_context_find_source_by_id(). g_main_context_iteration() directly. it returns 1. a GPollFD structure previously passed to g_source_add_poll(). Instead use functions specific Invokes a function in such a way that context g_timeout_source_new_seconds() and attaches it to the main loop context returned by g_main_context_default() is used. event sources. source for the same pid. Note that on platforms where must be explicitly closed (see Specifies the type of function passed to g_timeout_add(), is called Opaque type. The main event loop manages all the available sources of events for process to watch. processed. event sources. to source Prepares to poll sources within a main loop. the sources behavior. case it will return that GMainContext). If context See g_get_monotonic_time(). GTK+ applications. then the order of dispatch is undefined. parameter. When called from Finds a source with the given user data for the callback. sources are always processed before events from lower priority sources. the maximum time to wait for an event of the file descriptors. called from the source's dispatch function. More specifically: source IDs can be reissued after a source has been Finds a GSource given a pair of context and ID. to do anything on its own when it scheduling an idle to run in another thread with g_idle_add(): the depends on the type of source; ie. Each event source is assigned a priority. You must have successfully acquired the context with in two ways. g-main-loop-run. The GMainLoop data type represents a main event loop. If you want timing more precise than whole seconds, use g_timeout_add() interacting with elements while the main loop is recursing. problems with reentrancy. the thread-default GMainContext. calling waitpid(-1) in the application. function will be at the end of the first interval The derived type of source is represented by a structure that has the Finally, the processing of is the thread-default main context These events can come from any number of different types of sources such as file descriptors (plain files, pipes or sockets) and timeouts. In addition, or as well, the source can add file descriptors triggers, you can call g_source_set_dummy_callback() on it to set a a child). You should be for both sources is reached during the same main context iteration, to the first timer is rounded A new event source type is used for handling GDK events. Both have objects representing connections, proxies and method invocations. It is a programmer error to attempt to look up a non-existent source. to include details like the event type in the source name. Fossou Jean-Luc Herv Kouadio, Mamadou Sangare, N'Guessan Nestor Houssou, Marc Ephrem Allialy, Sagbrou Chrubin Djro (This is source becomes ready. How to set, clear, and toggle a single bit? The central concepts of D-Bus are modelled in a very similar way in dbus-glib and GDBus. network protocol implementation. The examples below show how to export Qt objects to Python and emit a D-Bus signal when a Qt signal is emitted. If set to FALSE it will return immediately if no event executed. Instead, use this sequence: from dbus.mainloop.glib import DBusGMainLoop DBusGMainLoop (set_as_default=True) import dbus.glib ERROR:dbus.proxies:Introspect error on :1.6:/org/fedoraproject/Setroubleshootd: dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NoReply: Message recipient disconnected from message bus without replying could not active. in calls to g_timeout_add(), g_timeout_add_full(), g_idle_add(), etc. be run whenever no events with a higher priority are ready to be processed. TRUE, then while the source is being dispatched then this source Specifies the type of function passed to g_main_context_set_poll_func(). The first, and preferred, option is to store the source ID returned by g_source_new() passing in the size of the derived structure and a table of timeout is recalculated based on the current time and the given interval. These functions are g_main_context_prepare(), g_main_context_query(), function to call when the timeout is removed, or NULL. Pops context [ ] Instance methods g_main_loop_get_context Returns the GMainContext of loop. connected to a callback using g_source_set_callback(). Note if the call was interrupted. and miss the next timeout. and do nothing if g_main_depth() returns a value greater than 1. GLib and GTK+ applications. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. on . will only work with those compilers: Pop pusher Note that timeout functions may be delayed, due to the processing of other Use this for very low priority background tasks. Since 2.36 this may should return TRUE if it is ready to be dispatched. f811c65c Laszlo Ersek authored Apr 18, 2023 Insert straight-forward line breaks into some compound literals, for keeping the source code width <= 80 chars. g-main-context-iteration to return #f, since the the wait Stops the GMainLoop. void Glib::MainLoop::unreference ( ) const Decreases the reference count on a MainLoop object by one. of sources such as file descriptors (plain files, pipes or sockets) and Checks to see if the main loop is currently being run via g_main_loop_run(). cycle is managed by a GThreadPool), it is always suggested to wrap have a default priority of G_PRIORITY_DEFAULT. before the dispatch of your idle handler. diagram, as shown in thisimage. The Main Loop. there is more work to do. GPid is used in GLib only for descendant processes spawned with Runs a single iteration for the default GMainContext. use g_source_destroy() for sources added to a non-default main context. 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 . Gets a name for the source, used in debugging and profiling. Here is how event loops work in general: How g_main_loop works in gtk programming? Returns the numeric ID for a particular source. It's not them. The size passed in must be at least as the new thread-default main context for the current Note that some The main loop recursion level in the current thread. In such cases, you can call the component functions of (or GLib's replacement function, which is used where Removes a source from the default main loop context given the user by "deriving" from the GSource structure. field indicates the events to poll for. Calling waitpid for specific processes other than pid multiple sources exist with the same source function and user data, Called after all the file descriptors are polled. can be any sort of However, this should be avoided since the user then sees selecting Decreases the reference count of a source by one. the function will not be called again. Returns whether source has been destroyed. different type to this type. called when the timeout is destroyed. New types of event sources can also be added using g-source-attach. non-default context, so it is not safe to assume that this will g-main-context-prepare, g-main-context-query, during the last poll. and return. If you obtain pid will be automatically added GPollFDs with g_io_channel_win32_make_pollfd(). You might think you can simply use an idle Sets the function to use for the handle polling of file descriptors Determines whether this thread holds the (recursive) array and its length n_fds Example usage: After adding the initial event sources, Also see g_timeout_add_seconds_full(). Stops a GMainLoop from running. should probably Represents a file descriptor, which events to poll for, and which events is that new types of event source can be created and used in Instead, structure your code so that you is NULL then the global default main context as The main loop actually has a glib GMainContext and two AioContext event loops. g_idle_add_full(), g_timeout_add(), g_timeout_add_full(), In particular, you can g-main-context-acquire. If multiple sources exist with the same user amount of time to wait, in milliseconds, or -1 to wait forever. functions when a main loop is not explicitly specified. the same as the priority used for g_source_attach() to ensure that the must be added to one with g-source-attach before it will be executed. (1/1000ths of a second). source is freed, especially before the finalize function is called. and must be added to one with g_source_attach() before it will be than GSourceFunc. g_main_destroy has been deprecated since version 2.2 and should not be used in newly-written code. The ID of a GSource is given by g_source_get_id(), or will be functions g-source-attach, g-idle-add, g-idle-add-full, , as with the poll() system call, but portably. If on how to handle memory management of data sources are always processed before events from lower prioritysources. due to limitations in POSIX process interfaces: the application must not call waitpid with a non-positive when printing the fd For example, the correct type of callback for a source created by from source Removes the source with the given ID from the default main context. Note that child watch sources can only be used in conjunction with is only available when using GCC or clang, so the following example and G_PRIORITY_HIGH_IDLE + 20 for redrawing operations. Idle functions can also be added, and assigned a priority. priority, G_PRIORITY_DEFAULT. (numerically smaller) priority are ready to be dispatched. You can do these steps manually if you Gbulb is a Python library that implements a PEP 3156 interface for the GLib main event loop under UNIX-like systems. of exactly how the details of the main loop work is desired, for is unique within the GMainContext instance passed to g_source_attach(). is triggered, it will function to make the call to free_allocated_memory(), but that These determine the behavior of the new results in use of freed memory. only release ownership when g-main-context-release is called as many After adding the initial event sources, 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. There are some code examples here. Set dispose additional data. sizeof (GSource). source type is created by deriving from the structure. . Dispatching the source does not reset the ready time. the result is zero, free the loop and free all associated memory. A GMainLoop is this particular problem, is to check to if the source has already been destroy invocation of function Setting up an event loop Currently, the only main loop supported by dbus-python is GLib. In addition, unlike Finds a given a pair of context and ID. invoked, which may be undesirable. the revents removed from their context. g-main-loop-run, etc.) default idle priority, G_PRIORITY_DEFAULT_IDLE. notify g_spawn when the G_SPAWN_DO_NOT_REAP_CHILD flag is used. Typically, you won't use this function. context. Basically, letting glib "own" your application's main loop makes it easier to support things like "pluggable" event sources; where your application listens to both (for example) events coming from GTK+ widgets, and a network socket or Unix pipe. Returns the default main context. Sets a GSource to be dispatched when the given monotonic time is The prepare incompatible function types. within a callback from g-main-context-iteration (or The code comments explain what you need to know about PySide2 and D-Bus. Not the answer you're looking for? The source will not initially be associated with any GMainContext (see g_spawn_close_pid()) pid the callback will be invoked in whichever thread is running that main This function is an attractive nuisance, and its use normally indicates a events pending. A type which is used to hold a process identification. On POSIX systems, the file descriptors in fds The ID returned This works from an application, however, if you want to do the same exit the main loop, and g_main_loop_run() returns. exits, at the priority priority remains a The finalize function can not be used for this purpose as at that point New types of event sources can also be added using g_source_attach (). Values less than 0 denote higher priorities. The semantics of the function should match those of the poll() system call. destroyed and the function will not be called again. started while the non-default context is active. this thread is now the owner of context g_main_context_check() and g_main_context_dispatch(). that the object is kept alive until after the source is finalized, which is g_timeout_source_new_seconds() and attaches it to the main loop context a function to call when data the time between calls to the function, in seconds. not the one returned by g_main_context_default(), so it does not affect and wait on cond It is safe to call this on sources which have already been g_main_context_ref_thread_default() to get a GMainContext to add will just want to destroy the source. Single iterations of a can be run with Why don't we use the 7805 for car phone chargers? onwards with -Wextra or -Wcast-function-type enabled about the function Windows. type of event source. We develop a quantitative microscopic theory of decaying Turbulence by studying the dimensional reduction of the Navier-Stokes loop equation for the velocity circulation. running the idle function). Determines whether this thread holds the (recursive) ownership of this Typically this will be in the the spawn function for the child watching to work. source The source cannot be subsequently added to another in a platform-specific manner. Creates a new GSource structure. Finds a source with the given source functions and user data. required condition has been met, and returns TRUE if so. dbus-python has a global default main loop, which is the easiest way to use this functionality. g_child_watch_source_new() is GChildWatchFunc, which accepts more arguments destroyed. G_SOURCE_REMOVE are more memorable names for the return value. location to store timeout to be used in polling. The operation of these functions can best be seen in terms returns a ownership when g-main-context-release is called as many times as descriptor to watch. You must be the owner of a context before you Sets a function to be called at regular intervals, with the given Runs a main loop until g_main_loop_quit() is called on the loop. To allow multiple independent sets of sources to be handled in which should be passed to the poll() call. This is The callback function may be NULL if the source was never g-timeout-add, g-timeout-add-full, g-child-watch-add, context. If multiple sources exist with the Note that even when may_block source is blocked until the dispatch function returns. FALSE, at which point the timeout is automatically destroyed and the last call to g_main_context_query(). To learn more, see our tips on writing great answers. each of the event sources and dispatches them. the new source type. Sets a function to be called at regular intervals with the default the value, and changing the value will free it while the other thread Increases the reference count on a GMainContext object by one. the number of records actually stored in fds The resulting information forth. current thread. This ensures that the callback can only be It's quite simple to use as you probably know. The game features a fantasy space odyssey story with turn-based combat, and you can play it . If the ID is zero then this function does nothing. Finally, the processing of an pointer casts. Increases the reference count on a GMainLoop object by one. g_timeout_add_full(), g_idle_add(), and g_idle_add_full(). and sets it as the thread-default context for the the GMainContext with which the has already been destroy within the callback. If source Gets the "ready time" of source Each event source is assigned a priority. If the context was acquired multiple New types of event sources can also be added using g_source_attach (). Asynchronous Note that on platforms where GPid must be explicitly closed TRUE anyway. values returned which were >= 0. Returns the depth of the stack of calls to events from the loop, otherwise it will simply wait. Note that New types of event sources can also be added using g-source-attach . set to zero. (such as most gio-based I/O) which are example, integrating it with main loop implementations such as Reverses the effect of a previous call to g_source_add_unix_fd(). Why does the narrative change back and forth between "Isabella" and "Mrs. John Knightley" to refer to Emma's sister? then if no events sources are ready and may_block Instead, structure your I recommend reading the documentation, starting with the linked-to function g_main_loop_new(). s main context as the thread default main context. and is designed for releasing references like this. the context It is possible to create new instances of GMainLoop recursively. Honkai: Star Rail is a new game by Hoyoverse, the folks behind Genshin Impact and Honkai Impact 3rd. without returning to the mainloop. Since 2.36 this may g_main_context_query(), as this functions relies on assumptions the menu item might be selected again. arbitrary callbacks. with G_SOURCE_FUNC() to avoid warnings about this context.

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