Waiting queue. More...

Collaboration diagram for Waitqueue:

Data Structures
struct	waitqueue
	Waiting Queue. More...

Macros
#define	__WAITQUEUE_INIT(_queue)
	Default init value.

#define	__INIT_WAITQUEUE(_queue) _queue = __WAITQUEUE_INIT(_queue)
	Initialize a waitqueue.

#define	DECLARE_WAITQUEUE(_queue) struct waitqueue INIT_WAITQUEUE(_queue)
	Declare and initialize a waitqueue.

#define	waitqueue_enqueue(waitqueue, thread)
	Mark a thread as waiting for the event to finish.

Functions
bool	waitqueue_is_empty (struct waitqueue *)
	Check whether anyone is waiting for this event to finish.

void	waitqueue_enqueue_locked (struct waitqueue , struct thread )
	Mark a thread as waiting for the event to finish. More...

const struct thread *	waitqueue_peek (struct waitqueue *)

struct thread *	waitqueue_dequeue (struct waitqueue *)
	Wakeup the first thread inside the queue. More...

size_t	waitqueue_dequeue_all (struct waitqueue *)
	Wakeup all the threads inside the queue. More...

Detailed Description

A waitqueue is used to list threads that are waiting for a ressource before being rescheduled.

Some examples are:

A mutex must wakeup all thread that tried to take the lock when the owner eventually releases it
An IP packet may need to wait for an ARP request to complete for it to retreive the destination's MAC address

All accesses to a waitqueue are placed behind a lock to make this API thread safe.

Usage

A waitqueue is used exactly as you would a regular queue. The only difference is that when a thread is queued it is automatically marked as waiting, and resumes running once dequeued.

Function Documentation

◆ waitqueue_dequeue()

struct thread * waitqueue_dequeue ( struct waitqueue * queue )

Returns: The thread that was waken up

◆ waitqueue_dequeue_all()

size_t waitqueue_dequeue_all ( struct waitqueue * queue )

Returns: The number of threads that were waken up

◆ waitqueue_enqueue_locked()

void waitqueue_enqueue_locked	(	struct waitqueue *	queue,
		struct thread *	thread
	)

This function is equivalent to waitqueue_enqueue. It should be called when holding the queue's lock.

NOTE: This function releases the lock held by the caller

◆ waitqueue_peek()

const struct thread * waitqueue_peek ( struct waitqueue * queue )

Returns: The first thread inside the waitqueue

Data Structures

Macros