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haiku/headers/private/kernel/event_queue.h

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kernel: Add event queue implementation to wait for objects efficiently. Based on hamishm's original patch from 2015, but heavily modified, refactored, and reworked. From the original commit message: > When an object is deleted, a B_EVENT_INVALID event is delivered, > and the object is unregistered from the queue. > > The special event flag B_EVENT_ONE_SHOT can be passed in when adding > an object so that the object is automatically unregistered when an > event is delivered. Modifications to the original change include: * Removed the public interface (syscalls remain private for the moment) * Event list queueing/dequeueing almost entirely rewritten, including: - Clear events field when dequeueing. - Have B_EVENT_QUEUED actually indicate whether the event has been appended to the linked list (or not), based around lock state. The previous logic was prone to races and double-insertions. - "Modify" is now just "Deselect + Select" performed at once; previously it could cause use-after-frees. - Unlock for deselect only once at the end of dequeue. - Handle INVALID events still in the queue upon destruction, fixing memory leaks. * Deduplified code with wait_for_objects. * Use of C++ virtual dispatch instead of C-style enum + function calls, and BReferenceable plus destructors for teardown. * Removed select/modify/delete flags. Select/Modify are now the same operation on the syscall interface, and "Delete" is done when 0 is passed for "events". Additionally, the events selected can be fetched by passing -1 for "events". * Implemented level-triggered mode. * Use of BStackOrHeapArray and other convenience routines in syscalls. Change-Id: I1d2f094fd981c95215a59adbc087523c7bbbe40b Reviewed-on: https://review.haiku-os.org/c/haiku/+/6745 Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org> Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>
2023-07-26 16:51:38 -04:00
/*
* Copyright 2015, Hamish Morrison, hamishm53@gmail.com.
* All rights reserved. Distributed under the terms of the MIT License.
*/
#ifndef _KERNEL_EVENT_QUEUE_H
#define _KERNEL_EVENT_QUEUE_H
#include <OS.h>
#include <event_queue_defs.h>
#ifdef __cplusplus
extern "C" {
#endif
extern int _user_event_queue_create(int openFlags);
extern status_t _user_event_queue_select(int queue, event_wait_info* userInfos,
int numInfos);
extern ssize_t _user_event_queue_wait(int queue, event_wait_info* infos,
int numInfos, uint32 flags, bigtime_t timeout);
#ifdef __cplusplus
}
#endif
#endif
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