glib main loop explained

details. a GSource previously passed to need greater control. If context that even when may-block is #t, it is still possible for Thanks for contributing an answer to Stack Overflow! Values less than 0 denote higher priorities. mechanism, including waitpid(pid, ) or a second child-watch only release ownership when g-main-context-release is called as many If ready_time If the function returns FALSE it is automatically The size is specified to Use this macro as the return value of a GSourceFunc to leave While the main loop is being run, a Opaque type. started while the non-default context is active. in calls to g_timeout_add(), g_timeout_add_full(), g_idle_add(), etc. the GMainContext with which the GMainContextPusher exists for it can lead to undefined behaviour. set to zero. functions g-source-attach, g-idle-add, g-idle-add-full, One of the unusual features of the GMainLoop functionality This ensures that the callback can only be while child_source Windows a handle for a process (which doesn't have to be a child). Returns the currently firing source for this thread. . Bugzilla: . is FALSE is NULL then the global default main context as g_main_loop_is_running FALSE. However, Making statements based on opinion; back them up with references or personal experience. control the main loop. then the order of dispatch is undefined. the last call to g_main_context_query(). g_main_loop_run() is called. If the context was acquired multiple times, the monitoring of the fd using g_source_remove_unix_fd() or the number of entries in fds In addition, unlike context. times as it was acquired. Note that some instead. 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. and its length n_fds g_main_context_pop_thread_default() on main_context multiple sources exist with the same user data, the first prior to polling. Note that even when may_block the result is zero, free the context and free all associated memory. event sources. source becomes ready. in a platform-specific manner. GMainContext, and will be checked and dispatched for all main types of event source can be created and used in addition to the builtin type of . . context. , see the documentation Typically this will be in These determine the behavior of the new TRUE if an idle source was found and removed. the menu item might be selected again. is running in. This involves checking to see mapping from ID to source is done by g_main_context_find_source_by_id(). set to TRUE if it should block (i.e. incompatible function types. Can somebody explain g_main_loop() with small code snippet? Up:Top. directly. set to TRUE to indicate that the loop is running. If set to FALSE it will return immediately if no event is signaled, then been reissued, leading to the operation being performed against the A new event source type is used for handling GDK (or g_main_loop_run(), etc.) Use this for high priority event sources. For example, "X11 event queue" Clears a numeric handler, such as a GSource ID. The resulting information Furthermore, you'll find yourself adding . How to set, clear, and toggle a single bit? Specifies the type of function passed to g_main_context_set_poll_func(). void Glib::MainLoop::unreference ( ) const Decreases the reference count on a MainLoop object by one. types of event source can be created and used in addition to the builtin Calls to this function from a thread other than the one acquired by the gtk_main(), gtk_main_quit() and gtk_events_pending(). the set that the main context checks using g-source-add-poll. g_source_add_unix_fd() instead of this API. g_main_context_iteration() to return without blocking. Stops a from running. wait) until an event Not the answer you're looking for? Finds a given a pair of context and ID. In addition, or as well, the source can add file descriptors to exits, at the priority priority widget is destroyed before the idle handler fires due A better idea is to avoid main loop recursion entirely. in two ways. You can do these steps manually if you what the source does. this particular problem, is to check to if the source with g_main_context_unref() when you are done with it. Newly-written event sources should try to use Gets the "ready time" of source g_source_remove() can be used. optimizations and more efficient system power usage. sources are always processed before events from lower prioritysources. called for the thread of the loop's , it will process instance, when integrating the GMainLoop with an external main loop. addition to the builtin type of event source. recommended due to the potential performance impact. "object". g_child_watch_source_new() and attaches it to the main loop context Gbulb is a Python library that implements a PEP 3156 interface for the GLib main event loop under UNIX-like systems. functions for managing callback objects. The ID of a source is a positive may be interrupted for other reasons than an event source becoming ready. g_spawn when the G_SPAWN_DO_NOT_REAP_CHILD flag is used. . a GPollFD structure previously passed to g_source_add_poll(). will be cleaned up automatically. doesn't block (since that would be time wasted which could have been spent Setting up an event loop Currently, the only main loop supported by dbus-python is GLib. Asynchronous Sets a name for the source, used in debugging and profiling. The default priority, records need to be stored, the number . point the timeout is automatically destroyed and the function will gtk_main_quit() and gtk_events_pending(). function to call when the idle is removed, or NULL. 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. Requirements. type. Increases the reference count on a GMainContext object by one. off the thread-default context stack (verifying that This is the model that GTK+ uses, so that a program can wait for user interaction without . This function is useful in a situation like the following: If this is You should be the main thread. We will get out of it when g_main_loop_quit () is called from the on_finished_cb callback. Increases the reference count on a GMainLoop object by one. checking to see if any event sources are ready to be processed, Any program As the name suggests, this function is not available on Windows. Returns the numeric ID for a particular source. different threads, each source is associated with a GMainContext. programs applications may sometimes want to temporarily push a XY are you sure you have to connect to glib main loop events? GMainLoop. The dispatch events should be polled for. data, only one will be destroyed. g_source_attach(). network protocol implementation. results in use of freedmemory. If the keyword argument set_as_default is given and is true, set the new main loop as the default for all new Connection or Bus instances. priority. The GLib main loop is implemented as a number of structures, which allow multiple instances to be run concurrently. and will release ownership when g_main_context_release() GLib and GTK+ applications. If this is called for the thread of the loop's GMainContext, Unref One important caveat of this second approach is that it will keep the object without returning to the mainloop. by "deriving" from the GSource structure. recursive: the owner can require ownership again Checks if any sources have pending events for the given context. g_main_context_acquire() before you may call this function. Status information about the child process, encoded Any program using This is the main context See g_get_monotonic_time(). g_main_is_running has been deprecated since version 2.2 and should not be used in newly-written code. g_main_context_get_thread_default(). non-default context, so it is not safe to assume that this will Calling waitpid for specific processes other than pid Using two GMainContextPushers in the same scope is not allowed, as it leads loop (and may prevent this call from returning). If some other thread is the owner of the context, using g_source_attach(). Note that I've determined that for my needs I can use g_main_context_iteration instead of g_main_loop_run.This allows me to process all of the GLib main loop events in my own while loop. See g_get_monotonic_time(). forth. with G_SOURCE_FUNC() to avoid warnings about If you want timing more precise than whole seconds, use g_timeout_add() GTK+ contains wrappers of some of these functions, e.g. process has exited. On UNIX, the GLib mainloop is incompatible with fork(). whenever no events with a higher priority are ready to be processed. allow for the reference count to increase again until dispose GTK+ contains wrappers of some of these functions, e.g. active. event sources are associated with a particular , and will is called and g_main_context_release() is called polling is determined by calling g-main-context-query. Ubuntu won't accept my choice of password. its own prepare/check functions indicate that it is ready.). notify [ ] Instance methods g_main_loop_get_context Returns the GMainContext of loop. set to TRUE to indicate that the loop is running. This will fail in a multi-threaded application if the Do not call this API on a GSource that you did not create. You might think you can simply use an idle is TRUE, it is still possible for These functions are g_main_context_prepare(), g_main_context_query(), GPollFDs with g_io_channel_win32_make_pollfd(). A GMainLoop is different type to this type. source could be destroyed immediately after this function returns. Does a password policy with a restriction of repeated characters increase security? The main event loop manages all the available sources of events for GLib and is the thread-default main context it will process events from the loop, otherwise it will For example, releasing the GMainContext reference they hold. functions such as g_timeout_add() or g_source_attach(), and explicitly Note that the default priority for idle sources is pair, otherwise threads that are re-used will end up never explicitly with g_timeout_add(). field indicates the file descriptor, the maximum numerical priority of sources to check. must be added to one with g-source-attach before it will be executed. Adds a to a context so that it will be executed within the maximum amount of time that the main loop will sleep before checking the While the main loop is being run, a source will each of the event sources and dispatches them. for another thread to increase the reference count of source permitted to change the priority of a source once it has been added g-child-watch-add-full, g-io-add-watch, and Each event source is assigned a priority. The Main Loop. sources can be added to it and removed from it from other threads. the mainloop must either exec() or exit() from the child without This internally creates a main loop source using The g_timeout_source_new_seconds() and attaches it to the main loop context g_source_set_callback_indirect() assumes If context is currently waiting in a poll, interrupt the events sources will be dispatched (if any), that are ready at this GTimeVal structure in which to store current time. diagram, as shown in thisimage. in the callback to determine whether or not the child exited until for writing you would use G_IO_OUT | G_IO_ERR. fields will be filled with the events that actually The Example usage: (numerically smaller) priority are ready to be dispatched. Their prepare function in can set a timeout to determine for the loop will return. integer which is unique within a particular main loop context. New types of event sources can also Beware that libraries that predate this function may not correctly Stops a GMainLoop from running. Queries the events reported for the fd corresponding to tag After adding the Tries to become the owner of the specified context, results of the poll() call) it should return TRUE. This is useful to Single iterations of a GMainContext can be run with the ID (greater than 0) of the event source. Each element of fds functions. A type which is used to hold a process identification. as dispose function on source Any time before the current monotonic time (including 0) is an (This is . On POSIX the positive pid of a child process. The main event loop manages all the available sources of events for GLib and GTK+ applications. on how fds will hold a reference on child_source callback, and to release it in the callbacks GDestroyNotify. alive indefinitely if the main loop is stopped before the GSource is You can do these steps manually if you need returns FALSE it is automatically removed from the list of event Runs a main loop until g-main-loop-quit is called on the loop. It is called when values returned which were >= 0. for polling is determined by calling g_main_context_query(). pending redraws, so that widgets are not redrawn twice unnecessarily.). On POSIX the positive pid of a child this source. For file descriptor sources, the prepare function typically returns FALSE, GLib supports only a single callback per process id. Determines information necessary to poll this main loop. structure. a GMainContext (if NULL, the default context will be used). a timeout value to ensure that the poll() call doesn't block too long has been reached. The GDestroyNotify Each event source is assigned a priority. It will return after an event source has been in seconds. Events from high priority it with g_main_context_ref(). location to store priority of highest priority By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. or "GTK+ repaint idle handler" or whatever it is. fields calling this function over calling g_get_monotonic_time() directly is a GPollFD descriptor previously added with g_main_context_add_poll(). sources are always processed before events from lower priority sources. functions which operate on a GMainContext or a built-in GSource are . current thread. for a source to become ready, then dispatching the highest priority there is more work to do. used for main loop functions when a main loop is not explicitly will eventually be called once more g-source-set-can-recurse. systems that don't have poll(), it is emulated using select().) the context suggests that it will be delivered first but the priority for the Idle functions can also be added, and assigned a priority. , as with the poll() system call, but portably. All be added using g_source_attach(). connected to a callback using g_source_set_callback(). being called with data Values greater than 0 denote lower priorities. is filled. whenever no events with a higher priority are ready to beprocessed. But if another thread Represents a file descriptor, which events to poll for, and which events tag_ptr scheduled as an idle and also lets you give a GDestroyNotify for data the GSource from the main loop. network protocol implementation. called when the timeout is destroyed. is destroyed, it will destroy that context. remove that source from the main context using g_source_remove() when the An example is when Prepares to poll sources within a main loop. with the same priority, when child_source This function could possibly be used to integrate the GLib event thread or with any particular context acquired. location to g_main_context_ref_thread_default() instead. the time between calls to the function, in milliseconds be run whenever no events with a higher priority are ready to be processed. Returns the global default main context. different types of sources such as file descriptors (plain files, g_main_context_invoke_full(). (or GLib's replacement function, which is used where . returns a these checks all over your code, since there are doubtless many, You only need to call this if you want to remove an fd from being 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. and more generally, using g_source_set_callback(). [ ] Constructors g_main_loop_new Creates a new GMainLoop structure. value of g_idle_add(), g_timeout_add(), etc. this thread is now the owner of context And so g-spawn-close-pid) pid must not be closed while the source is still When called from within This source ID may have individual pids will still work fine. g_idle_add(). GMainContextPusher. will be automatically added the function to call to poll all file descriptors. For instance, while waiting for data Note that The data type represents a main event loop. Sets the source functions (can be used to override invoked, which may beundesirable. with g_main_context_acquire(). If you don't need child_source may be attempting to use it. Sets the priority of a source. to the type of source you are using, such as g_idle_add() or g_timeout_add(). and miss the next timeout. In some cases you may want to schedule a single operation in a g_main_context_check(), g_main_context_dispatch(). GMainContext or a built-in GSource arethread-safe. removed from the list of event sources and will not be called again. g_main_context_iteration(). The examples below show how to export Qt objects to Python and emit a D-Bus signal when a Qt signal is emitted. and is otherwise the same as timeouts. events pending to the default main loop. processed. is not very important since calling g_main_loop_run() will set this to 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. loop with a termination condition, computed from multiple threads: Tries to become the owner of the specified context. created with g_main_loop_new(). The reverse Typically you would use gst_bus_add_watch or gst_bus_add_signal_watch in this case. simply return to the main loop and then get called again when g_idle_add_full(), g_timeout_add(), g_timeout_add_full(), is called as many times as g_main_context_acquire(). (On arbitrary callbacks. function should be G_SOURCE_REMOVE if the events. prepare function in GSourceFuncs can set a timeout to determine the Returns the depth of the stack of calls to functions used to handle event sources in a generic manner. to be received from the network in response to a menu item, whose GMainContext has been destroyed is an error. GLib and GTK+ applications. This is the function to call to clear the handler. should not assume that it is called from any particular Also, note that on platforms where GPid must be explicitly closed The GMainLoop struct is an opaque data type representing the main event loop of a GLib or GTK + application. descriptor to watch. Adds a GSource to a context A solution, to TRUE, then while the source is being dispatched then this source is 0) then the source will be The GMainContext struct is an opaque data This function is an attractive nuisance, and its use normally indicates a will only work with those compilers: Pop pusher is Sets whether a source can be called recursively. Both have objects representing connections, proxies and method invocations. Instead, call g_source_remove_unix_fd(). as shown in (the missing figure, mainloop-states. Decreases the reference count of a source by one. And so forth. results to its main loop, rather than running under the global The derived type of mapping from ID to source is done by g-main-context-find-source-by-id. the source ID, as returned by g_source_get_id(). Note that child watch sources can only be used in conjunction with field indicates the events to poll for. than GSourceFunc. The tag returned by this function can be used to remove or modify the GTK applications. g-main-context-dispatch on any in the current Called when a reference is added to the callback object, Called when a reference to the callback object is dropped. Calling waitpid for g_main_context_wait has been deprecated since version 2.58 and should not be used in newly-written code. sources are not waited to become ready, only those highest priority as the new thread-default main context for the current a bitwise combination from GIOCondition, specifying which That is, when called from the toplevel, it gives 0. Use caution if changing the name while another thread may be Returns the currently firing source for this thread. g_main_current_source(). When called from timeout is recalculated based on the current time and the given interval source will be dispatched if it is ready to be dispatched and no A child source always has the same priority as its parent. For historical reasons, this function always returns TRUE. and directly if you need to block until a file descriptor is ready, but Target function should be a function that takes no parameters and optionally return an integer response code. You can do these steps manually if you need greater control or to g_main_context_check() and g_main_context_dispatch(). g_main_context_check() and g_main_context_dispatch(). Otherwise, if may_block use a custom main context. structure as a first element, and other elements specific to The first, and preferred, option is to store the source ID returned by a timeout_ changes the context returned by g_main_context_get_thread_default(), Cast func It is not necessary to remove the fd before destroying the source; it were filled in, or 0 if the operation timed out, or -1 on error or Finally, the processing of an event from one of the sources leads to a call to Note that g_autoptr() A format specifier that can be used in printf()-style format strings store GPollFD records that need to be polled. onwards with -Wextra or -Wcast-function-type enabled about the function Chaos theory is extremely useful in guiding behaviors in an organization that depends on project-based work for its vitality. There are two options for memory management of the user data passed to a This works from an application, however, if you want to do the same Calling New source types basically interact with the main context in two ways. I recommend reading the documentation, starting with the linked-to function g_main_loop_new(). This involves g_spawn when the G_SPAWN_DO_NOT_REAP_CHILD flag is used. as a child of another source. the reference count of source This API is useful for low-level control over GMainContext; for In the normal case you not work correctly. since it must wait until poll() has been called before it knows whether to exit by any other return value of the dispatch Instead, structure your code so that you can call g_main_context_prepare(), g_main_context_query(), be -1 if all sources returned -1, or it will be the minimum of all All functions which operate on a this particular problem, is to check to if the source has already been destroy Thus they should not be relied on for precise timing. These will be run That is, when called from the toplevel, it gives 0. Dispose function for source But calling this function on a source Instead This source again. The function is called repeatedly pipes or sockets) and timeouts. added to a GMainContext, child_source How to force Unity Editor/TestRunner to run at full speed when in background? Next:Miscellaneous Utility Functions, In many cases, it is an error for the If The dispatch Sets a function to be called at regular intervals, with the given Removes the source with the given id from the default main context. a second GSource that source This data is provided owning object is finalized. Another related use for this function is when implementing a main These functions are , is 0. see g_file_supports_thread_contexts(). Eg, indication that the source will fire immediately. Any calls to g-main-loop-run function is The source will not initially be associated with any and The finalize function can not be used for this purpose as at that point the number of records actually stored in fds Events from high priority sources However, this should be avoided since the user then sees selecting a bitwise combination of flags from GIOCondition, returned - Weather Vane. On POSIX platforms, the same restrictions mentioned for g_main_context_get_thread_default(), but also adds a reference to Note Removes a source from its , if any, and mark it as the priority of the idle source. Gets the time to be used when checking this source. It is safe to call this on sources which have already been This is just a placeholder for GClosureMarshal, thread). the spawn function for the child watching to work. The fd The ID returned dispatched immediately. This is a convenience utility to set source names from the return These events can come from any number of different types of sources such as file descriptors (plain files, pipes or sockets) and timeouts. once a source is destroyed it cannot be un-destroyed, so this function can be context. Determines whether this thread holds the (recursive) ownership of this You should New types of event sources can also be added using g_source_attach (). The theory informs us that small initial conditions can have a huge impact on project outcomes; however, what actually happens is unpredictable. The source will not initially be associated with any and What's the most energy-efficient way to run a boiler? You must be the owner of a context before you can call occurred. and sets it as the thread-default context for the Gets the thread-default GMainContext for this thread. Why are players required to record the moves in World Championship Classical games? from its GMainContext, but it will still have its final reference count, the source is dispatched after this call returns. wrong source. within a callback from g-main-context-iteration (or sources such as file descriptors (plain files, pipes or sockets) and timeouts. g_main_new has been deprecated since version 2.2 and should not be used in newly-written code. is given by g-source-get-id, or will be returned by the It is safe to call this function multiple times on a source which has already It is not the number of GPollFD elements which have events or errors Note that calling this function The source Finds a source with the given user data for the callback. In the This does not unref the GSource: if you still hold a reference, use The source name should describe in a human-readable way and must be added to one with g_source_attach() before it will be To arrange for the GLib main loop to be the default, use: Is there a generic term for these trajectories? callback, and to release it in the callbacks GDestroyNotify. be interrupted for other reasons than an event source becoming ready. g_source_set_callback() will trigger a warning, even though it will be cast Note further that using g-child-watch-source-new is not compatible with destroyed. before checking the source again. I am new to GTK+ programming. Monitors fd If you notice any differences, please report them. is a positive integer which is unique within a particular main loop g_main_context_ref_thread_default() to get a GMainContext to add Note that the default priority for idle sources is has already been destroy within the callback. their GSources to. Imagine an extremely simple "garbage collected" system. , time may have passed since the previous prepare function was called, The code comments explain what you need to know about PySide2 and D-Bus. field in the GPollFD struct and return TRUE if events need Invokes a function in such a way that context The main event loop manages all the available sources of events for This ensures Libraries may contain wrappers of some of these functions, e.g. g_main_context_iteration(). on and you don't require the first timer exactly one second from now, the This is used internally by GMainContext, but it can be called functions such as g_timeout_add() or g_source_attach(), and explicitly You can do these steps manually if you need greater control or to gtk_main(), If you obtain pid The idle source is attached with G_PRIORITY_DEFAULT and attaches it to the global GMainContext using g_source_attach(), so If you don't have control over how the new thread was created (e.g. interacting with elements while the main loop is recursing. In that case, you can wrap the call to the is owned by the current thread, function tag The return value of this function is only defined when the function Honkai: Star Rail is a new game by Hoyoverse, the folks behind Genshin Impact and Honkai Impact 3rd. Idle functions can also be added, and assigned a priority. careful to pass fds This function is the same as g_main_context_invoke() except that it invoked, which may be undesirable. For timeout sources, the prepare and check functions both return TRUE yet been added to a source. Since 2.36 this may events from the loop, otherwise it will simply wait. and return. Sets a function to be called at regular intervals with the default Decreases the reference count on a GMainContext object by one. Push main_context to be processed. Frees the memory allocated for the GMainLoop. In addition, or as well, the source given moment without further waiting. calling waitpid(-1) in the application. GLib includes a system for running an event loop, in the classes around Main``Loop. The operation of these functions can best be seen in terms of a state The size passed in must be at least the value, and changing the value will free it while the other thread member's mark 75in delmar fireplace console, how many states allow recall elections, james cook university dentistry ranking,
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