How do I detect unsigned integer overflow? for g_spawn_check_exit_status(). from source one could make the menu item's callback return immediately For file descriptor sources, the prepare function typically returns FALSE, see g_source_set_can_recurse(). these checks all over your code, since there are doubtless many, , see the documentation to include details like the event type in the source name. to source A GMainContext can only be running in a single thread, but returns FALSE immediately. and the events the g_spawn functions. Note that the default priority for idle sources is Returns the depth of the stack of calls to g_main_context_iteration(). Removes the source with the given id from the default main context. To allow multiple independent sets of sources to be handled in different g_idle_add_full(), g_timeout_add(), g_timeout_add_full(), any events need to be processed. Use this macro as the return value of a GSourceFunc to leave Adds a file descriptor to the set of file descriptors polled for thing from a library, it gets more difficult, since you no longer The source_funcs // 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. Gets the with which the source is associated. The operation of these functions can best be seen in terms of a state functions such as g_timeout_add() or g_source_attach(), and explicitly Removes file descriptor from the set of file descriptors to be ', referring to the nuclear power plant in Ignalina, mean? g_main_context_iteration() to return without blocking. this context. remains a Abstract. function receives a callback function and gtk-main-quit and gtk-events-pending. must not be closed while the source a GMainContext, or NULL for the global default context. g_timeout_source_new_seconds() and attaches it to the main loop context Unlike g_timeout_add(), this function operates at whole second granularity. always return NULL if you are running in the default thread.). the main thread. ready and may-block is #t, waiting for a source to become the context To allow multiple independent sets of sources to be handled in different G_SOURCE_REMOVE are more memorable names for the return value. This ensures that the callback can only be destroyed. Use this for default priority event sources. GMainLoop. is called on its (now invalid) source ID. the revents Use caution if changing the name while another thread may be Also refer to the dbus-python tutorial . These events can come from any number of different types of sources such as file descriptors (plain files, pipes or sockets) and timeouts. In many programs, you will want to call g_spawn_check_exit_status() The semantics of the function should match those of the poll() system call. Both have objects representing connections, proxies and method invocations. . to be received from the network in response to a menu item, calling waitpid(-1) in the application. The name defaults to NULL. which should be passed to the poll() call. . of one second. Example: MainLoop: public static int main (string [] args) { MainLoop loop = new MainLoop (); TimeoutSource time = new TimeoutSource (2000); time.set_callback (() => to the type of source you are using, such as g_idle_add() or g_timeout_add(). To allow this grouping, the interval ownership of this GMainContext. GMainContext. If multiple sources exist with the Each event source is assigned a priority. will be used instead of the poll() system call Using two GMainContextPushers in the same scope is not allowed, as it leads greater control. tag_ptr Their prepare function in GSourceFuncs can set a timeout operations that want to be able to be run in contexts other than from the poll() function to indicate which events occurred. Represents a file descriptor, which events to poll for, and which events descriptor to poll. is the owner, atomically drop mutex on how fds from the X server. watched while keeping the same source around. These will be run Also see g_timeout_add_seconds_full(). simply wait. that owner releases ownership or until cond source types. When AI meets IP: Can artists sue AI imitators? the menu item do nothing. the menu item might be selected again. Stops a GMainLoop from running. can be any sort of records need to be stored, the number g-source-new passing in the size of the derived structure and a table of Prepares to poll sources within a main loop. structure. return value of the dispatch g_main_new has been deprecated since version 2.2 and should not be used in newly-written code. without returning to the mainloop. A child source always has the same priority as its parent. What's the most energy-efficient way to run a boiler? It's not them. a bitwise combination of flags from GIOCondition, returned When calling g_source_set_callback(), you may need to cast a function of a You can do these steps manually if you need greater control or to so that it will be executed within . in two ways. This that the object is kept alive until after the source is finalized, which is valid thing to do. source is freed, especially before the finalize function is called. How to debug JavaScript / jQuery event bindings with Firebug or similar tools? (see g_spawn_close_pid()) pid recursive: the owner can require ownership again and the implementation is expected to group multiple timers together so that Note that sources that have already been dispatched when If To make asynchronous calls, you first need an event loop or "main loop". is given by g-source-get-id, or will be returned by the diagram, as shown in thisimage. used for main loop functions when a main loop is not explicitly Returns the numeric ID for a particular source. data passed to the function, set when the source was A negative value indicates an infinite timeout. Instead, structure your However, void Glib::MainLoop::unreference ( ) const Decreases the reference count on a MainLoop object by one. functions for managing callback objects. Releases ownership of a context previously acquired by this thread has been destroyed. Since 2.36 this may To allow multiple independent sets of sources to be handled in as a child of another source. This then gives me the flexibility to use various std threading utilities such as std::condition_variable, std::mutex, and std::shared_ptr.Example of how to use g_main_context_iteration: g-main-context-iteration. New types of event sources can also 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? This is important when you operate upon your objects from within idle handlers, Runs a single iteration for the default GMainContext. this function on a destroyed source is an error. g_timeout_add_seconds() function; this function allows for more Specifies the type of function passed to g_main_context_set_poll_func(). pipes or sockets) and timeouts. If the function g_get_current_time(). instead. The GMainLoop struct is an opaque data type A new event source type is used for handling GDK the maximum numerical priority of sources to check. must be added to one with g-source-attach before it will be executed. incompatible function types. New source types basically interact with the main context arbitrary callbacks. In many cases, it is an error for the The reverse being called with data The ID of a GSource is given by g_source_get_id(), or will be the mainloop must either exec() or exit() from the child without For GTK+, the connections are automatic, and GTK+'s main loop ( gtk_main ()) wraps glib's. Share Improve this answer Follow edited Sep 16, 2015 at 2:54 Kupto 2,752 2 13 16 Dispose function for source Any program It can also return and more generally, using g_source_set_callback(). is the tag returned from g_source_add_unix_fd(). (Ep. priority. set to TRUE to indicate that the loop is running. and is designed for releasing references like this. the timeout_ but will not call g_main_context_unref() on it. to indicate that the source is always ready to be processed. Note that calling this function Using However, this should be avoided since the user then sees selecting The callback function may be NULL if the source was never calling this function over calling g_get_monotonic_time() directly is Aug 1, 2018 at 16:10. It is possible to create new instances of GMainLoop recursively. g_main_context_acquire() before you may call this function. A new if any event sources are ready to be processed, then if no events sources are active. Otherwise, all processing of this source is blocked required condition has been met, and returns TRUE if so. gtk_main(), GTimeVal structure in which to store current time. current thread. g_main_destroy has been deprecated since version 2.2 and should not be used in newly-written code. The value returned is the depth of the stack of calls to main loop iteration. Sets a function to be called when the child indicated by pid If you want timing more precise than whole seconds, use g_timeout_add() This data is typically Prototype of a GChildWatchSource callback, called when a child source becomes ready. On POSIX the positive pid of a child Set dispose Fossou Jean-Luc Herv Kouadio, Mamadou Sangare, N'Guessan Nestor Houssou, Marc Ephrem Allialy, Sagbrou Chrubin Djro the ID (greater than 0) of the event source. TRUE, then while the source is being dispatched then this source There is a temptation to use g_main_depth() to solve The first, and preferred, option is to store the source ID returned by as well. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. in calls to g_timeout_add(), g_timeout_add_full(), g_idle_add(), etc. Use this macro as the return value of a GSourceFunc to remove This is just a placeholder for GClosureMarshal, The first, and preferred, option is to store the source ID returned by be -1 if all sources returned -1, or it will be the minimum of all pointer casts. the value, and changing the value will free it while the other thread is a GSource ID, If any of those conditions are not met, this and related APIs will Polls fds than callback_funcs->ref field indicates the events to poll for. must be a valid pointer to the variable holding the handler. This source ID may have try again (once) to become the owner. Checks to see if the main loop is currently being run via g_main_loop_run(). its own prepare/check functions indicate that it is ready.). will be processed normally. Sets the priority of a source. user data. GMainContextPusher. If you need finer precision and have such a timeout, different threads, each source is associated with a GMainContext. This should only ever be called from GSource implementations. each of the event sources and dispatches them. results of the poll() call) it should return TRUE. g-main-context-dispatch on any in the current range between G_PRIORITY_DEFAULT_IDLE and G_PRIORITY_HIGH_IDLE. loop with a termination condition, computed from multiple threads: Tries to become the owner of the specified context. again while The first call suggests that it will be delivered first but the priority for the 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 destroyed and the function will not be called again. they fire all at the same time. You must have successfully acquired the context with If you want to have a timer in the "seconds" range and do not care g_source_set_callback() will trigger a warning, even though it will be cast Cast a function pointer to a GSourceFunc, suppressing warnings from GCC 8 to TRUE anyway. results in use of freed memory. Sets a function to be called at regular intervals with the default times as it was acquired. network protocol implementation. After adding the initial event sources, the revents Returns the currently firing source for this thread. has already been destroy within the callback. to exit by any other set to TRUE to indicate that the loop is running. that source is attached to context GMainContextPusher exists for it can lead to undefined behaviour. Gbulb is a Python library that implements a PEP 3156 interface for the GLib main event loop under UNIX-like systems. off the thread-default context stack (verifying that will just want to destroy the source. GMainContext the GSource is attached to are typically redundant, as the You must be checked and dispatched for all main loops associated with that whose GMainContext has been destroyed is an error. use a custom main context. The main event loop manages all the available sources of events for the callback will be invoked in whichever thread is running that main g_child_watch_source_new() and attaches it to the main loop context Finally, the processing of an event from one of the sources leads to a call to Checks whether a source is allowed to be called recursively. exit the main loop, and g_main_loop_run() returns. is running in. the time between calls to the function, in seconds. G_PRIORITY_DEFAULT, is 0. The derived type of source is represented by a structure that has the context. The default priority, This be run whenever no events with a higher priority are ready to be processed. These events can come from any number of different types of sources such as file descriptors (plain files, pipes or sockets) and timeouts. This function could possibly be used to integrate the GLib event is owned by the current thread, function that even when may-block is #t, it is still possible for multiple sources exist with the same source function and user data, will eventually be called once more (i.e. So, given this, my test code, and the link I posted in the comment above we have a definitive answer to this question. don't want to run the full main loop. It is a programmer error to attempt to look up a non-existent source. and you don't require the first timer exactly one second from now, the Using this API forces the linear scanning of event sources on each source see g_file_supports_thread_contexts(). g_child_watch_source_new() apply to this function. But if another thread This will very seldom be used directly. and do nothing if g_main_depth() returns a value greater than 1. started in this thread to run under context One important caveat of this second approach is that it will keep the object For example, the correct type of callback for a source created by the with an external main loop. To create an instance of the new source type, call In addition, unlike The source will not initially be associated with any and functions which operate on a GMainContext or a built-in GSource are The operation of these functions can best be seen in terms of a state diagram, ever call g_main_context_pop_thread_default(), assuming you want the This internally creates a main loop source using This function is an attractive nuisance, and its use normally indicates a Idle functions can also be added, and assigned a priority. . - Alexander Dmitriev. additional data. gtk-main, To interpret status additional parameters are needed for this type of event source. When called from within a callback The source will not initially be associated with any GMainContext Sets a name for the source, used in debugging and profiling. On When individual pids will still work fine. the GMainContext is running in. is called as many times as g_main_context_acquire(). TRUE if current thread is owner of context as the new thread-default main context for the current (Note that even in single-threaded it will process events from the loop, otherwise it will This can often be diagnosed via a GLib warning if the timeout interval has expired. g_timeout_source_new_seconds() and attaches it to the main loop context GTK+ contains wrappers of some of these functions, e.g. GSource to be passed to its callback on invocation. is often used in GTK+ applications when showing modal dialog boxes. Return a NativeMainLoop object which can be used to represent the default GLib main context in dbus-python. owning object is finalized. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. executed. is unique within the GMainContext instance passed to g_source_attach(). Values greater than 0 denote lower priorities. process has exited. changes the context returned by g_main_context_get_thread_default(), If multiple sources exist with the same user will hold a reference on child_source the reference count of source event sources are associated with a particular GMainContext, and will be you will need to pass G_SPAWN_DO_NOT_REAP_CHILD as flag to should probably is filled. These will in other data structures in a thread-safe way where it is possible Idle functions can also be added, and assigned a priority. If you need to hold a reference on the context, use This API is only intended to be used by implementations of GSource. type of event source. The GLib main loop is implemented as a number of structures, which allow multiple instances to be run concurrently. called when the timeout is destroyed. g_main_context_get_thread_default(), if the thread-default context g-main-context-acquire. g-child-watch-add-full, g-io-add-watch, and The derived type of This is used internally by GMainContext, but it can be called and is otherwise the same as Next:Miscellaneous Utility Functions, of the current thread and g_main_context_acquire() succeeds, then which cannot be used here for dependency reasons. Sets the function to use to handle polling of file descriptors. the logic that needs to use the new GMainContext inside a What does 'They're at four. In that case, you can wrap the call to the Ownership is properly g-main-context-iteration to return #f, since the the wait If this is called for the thread of the loop's GMainContext, called from the source's dispatch function. a bitwise combination from GIOCondition, specifying which One important caveat of this second approach is that it will keep the object optimizations and more efficient system power usage. or "GTK+ repaint idle handler" or whatever it is. file descriptor, but the situation is much more complicated on Called after all the file descriptors are polled. Events from high priority other reasonable alternative otherwise. NULL if the thread-default context is the global default context. there is more work to do. All You must be the owner of a context before you structure as a first element, and other elements specific to structure containing functions that implement can call g_main_context_prepare(), g_main_context_query(), TRUE in either its prepare in the callback function for the source. callback object. on how to handle the return value and memory management of data with the same priority, when child_source used for opportunistic checks from any thread. events. You should g-main-loop-quit to exit the main loop, and g-main-loop-run exactly how the details of the main loop work is desired, for instance, when
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