mirror of https://gitee.com/openkylin/qemu.git
329 lines
10 KiB
C
329 lines
10 KiB
C
/*
|
|
* QEMU aio implementation
|
|
*
|
|
* Copyright IBM, Corp. 2008
|
|
*
|
|
* Authors:
|
|
* Anthony Liguori <aliguori@us.ibm.com>
|
|
*
|
|
* This work is licensed under the terms of the GNU GPL, version 2. See
|
|
* the COPYING file in the top-level directory.
|
|
*
|
|
*/
|
|
|
|
#ifndef QEMU_AIO_H
|
|
#define QEMU_AIO_H
|
|
|
|
#include "qemu/typedefs.h"
|
|
#include "qemu-common.h"
|
|
#include "qemu/queue.h"
|
|
#include "qemu/event_notifier.h"
|
|
#include "qemu/thread.h"
|
|
#include "qemu/rfifolock.h"
|
|
#include "qemu/timer.h"
|
|
|
|
typedef struct BlockDriverAIOCB BlockDriverAIOCB;
|
|
typedef void BlockDriverCompletionFunc(void *opaque, int ret);
|
|
|
|
typedef struct AIOCBInfo {
|
|
void (*cancel_async)(BlockDriverAIOCB *acb);
|
|
AioContext *(*get_aio_context)(BlockDriverAIOCB *acb);
|
|
size_t aiocb_size;
|
|
} AIOCBInfo;
|
|
|
|
struct BlockDriverAIOCB {
|
|
const AIOCBInfo *aiocb_info;
|
|
BlockDriverState *bs;
|
|
BlockDriverCompletionFunc *cb;
|
|
void *opaque;
|
|
int refcnt;
|
|
};
|
|
|
|
void *qemu_aio_get(const AIOCBInfo *aiocb_info, BlockDriverState *bs,
|
|
BlockDriverCompletionFunc *cb, void *opaque);
|
|
void qemu_aio_unref(void *p);
|
|
void qemu_aio_ref(void *p);
|
|
|
|
typedef struct AioHandler AioHandler;
|
|
typedef void QEMUBHFunc(void *opaque);
|
|
typedef void IOHandler(void *opaque);
|
|
|
|
struct AioContext {
|
|
GSource source;
|
|
|
|
/* Protects all fields from multi-threaded access */
|
|
RFifoLock lock;
|
|
|
|
/* The list of registered AIO handlers */
|
|
QLIST_HEAD(, AioHandler) aio_handlers;
|
|
|
|
/* This is a simple lock used to protect the aio_handlers list.
|
|
* Specifically, it's used to ensure that no callbacks are removed while
|
|
* we're walking and dispatching callbacks.
|
|
*/
|
|
int walking_handlers;
|
|
|
|
/* Used to avoid unnecessary event_notifier_set calls in aio_notify.
|
|
* Writes protected by lock or BQL, reads are lockless.
|
|
*/
|
|
bool dispatching;
|
|
|
|
/* lock to protect between bh's adders and deleter */
|
|
QemuMutex bh_lock;
|
|
|
|
/* Anchor of the list of Bottom Halves belonging to the context */
|
|
struct QEMUBH *first_bh;
|
|
|
|
/* A simple lock used to protect the first_bh list, and ensure that
|
|
* no callbacks are removed while we're walking and dispatching callbacks.
|
|
*/
|
|
int walking_bh;
|
|
|
|
/* Used for aio_notify. */
|
|
EventNotifier notifier;
|
|
|
|
/* GPollFDs for aio_poll() */
|
|
GArray *pollfds;
|
|
|
|
/* Thread pool for performing work and receiving completion callbacks */
|
|
struct ThreadPool *thread_pool;
|
|
|
|
/* TimerLists for calling timers - one per clock type */
|
|
QEMUTimerListGroup tlg;
|
|
};
|
|
|
|
/* Used internally to synchronize aio_poll against qemu_bh_schedule. */
|
|
void aio_set_dispatching(AioContext *ctx, bool dispatching);
|
|
|
|
/**
|
|
* aio_context_new: Allocate a new AioContext.
|
|
*
|
|
* AioContext provide a mini event-loop that can be waited on synchronously.
|
|
* They also provide bottom halves, a service to execute a piece of code
|
|
* as soon as possible.
|
|
*/
|
|
AioContext *aio_context_new(void);
|
|
|
|
/**
|
|
* aio_context_ref:
|
|
* @ctx: The AioContext to operate on.
|
|
*
|
|
* Add a reference to an AioContext.
|
|
*/
|
|
void aio_context_ref(AioContext *ctx);
|
|
|
|
/**
|
|
* aio_context_unref:
|
|
* @ctx: The AioContext to operate on.
|
|
*
|
|
* Drop a reference to an AioContext.
|
|
*/
|
|
void aio_context_unref(AioContext *ctx);
|
|
|
|
/* Take ownership of the AioContext. If the AioContext will be shared between
|
|
* threads, a thread must have ownership when calling aio_poll().
|
|
*
|
|
* Note that multiple threads calling aio_poll() means timers, BHs, and
|
|
* callbacks may be invoked from a different thread than they were registered
|
|
* from. Therefore, code must use AioContext acquire/release or use
|
|
* fine-grained synchronization to protect shared state if other threads will
|
|
* be accessing it simultaneously.
|
|
*/
|
|
void aio_context_acquire(AioContext *ctx);
|
|
|
|
/* Relinquish ownership of the AioContext. */
|
|
void aio_context_release(AioContext *ctx);
|
|
|
|
/**
|
|
* aio_bh_new: Allocate a new bottom half structure.
|
|
*
|
|
* Bottom halves are lightweight callbacks whose invocation is guaranteed
|
|
* to be wait-free, thread-safe and signal-safe. The #QEMUBH structure
|
|
* is opaque and must be allocated prior to its use.
|
|
*/
|
|
QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque);
|
|
|
|
/**
|
|
* aio_notify: Force processing of pending events.
|
|
*
|
|
* Similar to signaling a condition variable, aio_notify forces
|
|
* aio_wait to exit, so that the next call will re-examine pending events.
|
|
* The caller of aio_notify will usually call aio_wait again very soon,
|
|
* or go through another iteration of the GLib main loop. Hence, aio_notify
|
|
* also has the side effect of recalculating the sets of file descriptors
|
|
* that the main loop waits for.
|
|
*
|
|
* Calling aio_notify is rarely necessary, because for example scheduling
|
|
* a bottom half calls it already.
|
|
*/
|
|
void aio_notify(AioContext *ctx);
|
|
|
|
/**
|
|
* aio_bh_poll: Poll bottom halves for an AioContext.
|
|
*
|
|
* These are internal functions used by the QEMU main loop.
|
|
* And notice that multiple occurrences of aio_bh_poll cannot
|
|
* be called concurrently
|
|
*/
|
|
int aio_bh_poll(AioContext *ctx);
|
|
|
|
/**
|
|
* qemu_bh_schedule: Schedule a bottom half.
|
|
*
|
|
* Scheduling a bottom half interrupts the main loop and causes the
|
|
* execution of the callback that was passed to qemu_bh_new.
|
|
*
|
|
* Bottom halves that are scheduled from a bottom half handler are instantly
|
|
* invoked. This can create an infinite loop if a bottom half handler
|
|
* schedules itself.
|
|
*
|
|
* @bh: The bottom half to be scheduled.
|
|
*/
|
|
void qemu_bh_schedule(QEMUBH *bh);
|
|
|
|
/**
|
|
* qemu_bh_cancel: Cancel execution of a bottom half.
|
|
*
|
|
* Canceling execution of a bottom half undoes the effect of calls to
|
|
* qemu_bh_schedule without freeing its resources yet. While cancellation
|
|
* itself is also wait-free and thread-safe, it can of course race with the
|
|
* loop that executes bottom halves unless you are holding the iothread
|
|
* mutex. This makes it mostly useless if you are not holding the mutex.
|
|
*
|
|
* @bh: The bottom half to be canceled.
|
|
*/
|
|
void qemu_bh_cancel(QEMUBH *bh);
|
|
|
|
/**
|
|
*qemu_bh_delete: Cancel execution of a bottom half and free its resources.
|
|
*
|
|
* Deleting a bottom half frees the memory that was allocated for it by
|
|
* qemu_bh_new. It also implies canceling the bottom half if it was
|
|
* scheduled.
|
|
* This func is async. The bottom half will do the delete action at the finial
|
|
* end.
|
|
*
|
|
* @bh: The bottom half to be deleted.
|
|
*/
|
|
void qemu_bh_delete(QEMUBH *bh);
|
|
|
|
/* Return whether there are any pending callbacks from the GSource
|
|
* attached to the AioContext, before g_poll is invoked.
|
|
*
|
|
* This is used internally in the implementation of the GSource.
|
|
*/
|
|
bool aio_prepare(AioContext *ctx);
|
|
|
|
/* Return whether there are any pending callbacks from the GSource
|
|
* attached to the AioContext, after g_poll is invoked.
|
|
*
|
|
* This is used internally in the implementation of the GSource.
|
|
*/
|
|
bool aio_pending(AioContext *ctx);
|
|
|
|
/* Dispatch any pending callbacks from the GSource attached to the AioContext.
|
|
*
|
|
* This is used internally in the implementation of the GSource.
|
|
*/
|
|
bool aio_dispatch(AioContext *ctx);
|
|
|
|
/* Progress in completing AIO work to occur. This can issue new pending
|
|
* aio as a result of executing I/O completion or bh callbacks.
|
|
*
|
|
* Return whether any progress was made by executing AIO or bottom half
|
|
* handlers. If @blocking == true, this should always be true except
|
|
* if someone called aio_notify.
|
|
*
|
|
* If there are no pending bottom halves, but there are pending AIO
|
|
* operations, it may not be possible to make any progress without
|
|
* blocking. If @blocking is true, this function will wait until one
|
|
* or more AIO events have completed, to ensure something has moved
|
|
* before returning.
|
|
*/
|
|
bool aio_poll(AioContext *ctx, bool blocking);
|
|
|
|
/* Register a file descriptor and associated callbacks. Behaves very similarly
|
|
* to qemu_set_fd_handler2. Unlike qemu_set_fd_handler2, these callbacks will
|
|
* be invoked when using aio_poll().
|
|
*
|
|
* Code that invokes AIO completion functions should rely on this function
|
|
* instead of qemu_set_fd_handler[2].
|
|
*/
|
|
void aio_set_fd_handler(AioContext *ctx,
|
|
int fd,
|
|
IOHandler *io_read,
|
|
IOHandler *io_write,
|
|
void *opaque);
|
|
|
|
/* Register an event notifier and associated callbacks. Behaves very similarly
|
|
* to event_notifier_set_handler. Unlike event_notifier_set_handler, these callbacks
|
|
* will be invoked when using aio_poll().
|
|
*
|
|
* Code that invokes AIO completion functions should rely on this function
|
|
* instead of event_notifier_set_handler.
|
|
*/
|
|
void aio_set_event_notifier(AioContext *ctx,
|
|
EventNotifier *notifier,
|
|
EventNotifierHandler *io_read);
|
|
|
|
/* Return a GSource that lets the main loop poll the file descriptors attached
|
|
* to this AioContext.
|
|
*/
|
|
GSource *aio_get_g_source(AioContext *ctx);
|
|
|
|
/* Return the ThreadPool bound to this AioContext */
|
|
struct ThreadPool *aio_get_thread_pool(AioContext *ctx);
|
|
|
|
/**
|
|
* aio_timer_new:
|
|
* @ctx: the aio context
|
|
* @type: the clock type
|
|
* @scale: the scale
|
|
* @cb: the callback to call on timer expiry
|
|
* @opaque: the opaque pointer to pass to the callback
|
|
*
|
|
* Allocate a new timer attached to the context @ctx.
|
|
* The function is responsible for memory allocation.
|
|
*
|
|
* The preferred interface is aio_timer_init. Use that
|
|
* unless you really need dynamic memory allocation.
|
|
*
|
|
* Returns: a pointer to the new timer
|
|
*/
|
|
static inline QEMUTimer *aio_timer_new(AioContext *ctx, QEMUClockType type,
|
|
int scale,
|
|
QEMUTimerCB *cb, void *opaque)
|
|
{
|
|
return timer_new_tl(ctx->tlg.tl[type], scale, cb, opaque);
|
|
}
|
|
|
|
/**
|
|
* aio_timer_init:
|
|
* @ctx: the aio context
|
|
* @ts: the timer
|
|
* @type: the clock type
|
|
* @scale: the scale
|
|
* @cb: the callback to call on timer expiry
|
|
* @opaque: the opaque pointer to pass to the callback
|
|
*
|
|
* Initialise a new timer attached to the context @ctx.
|
|
* The caller is responsible for memory allocation.
|
|
*/
|
|
static inline void aio_timer_init(AioContext *ctx,
|
|
QEMUTimer *ts, QEMUClockType type,
|
|
int scale,
|
|
QEMUTimerCB *cb, void *opaque)
|
|
{
|
|
timer_init(ts, ctx->tlg.tl[type], scale, cb, opaque);
|
|
}
|
|
|
|
/**
|
|
* aio_compute_timeout:
|
|
* @ctx: the aio context
|
|
*
|
|
* Compute the timeout that a blocking aio_poll should use.
|
|
*/
|
|
int64_t aio_compute_timeout(AioContext *ctx);
|
|
|
|
#endif
|