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// Copyright © Tavian Barnes <tavianator@tavianator.com>
// SPDX-License-Identifier: 0BSD
/**
* Asynchronous I/O queues.
*/
#ifndef BFS_IOQ_H
#define BFS_IOQ_H
#include "prelude.h"
#include "dir.h"
#include "stat.h"
#include <stddef.h>
/**
* An queue of asynchronous I/O operations.
*/
struct ioq;
/**
* I/O queue operations.
*/
enum ioq_op {
/** ioq_close(). */
IOQ_CLOSE,
/** ioq_opendir(). */
IOQ_OPENDIR,
/** ioq_closedir(). */
IOQ_CLOSEDIR,
/** ioq_stat(). */
IOQ_STAT,
};
/**
* The I/O queue implementation needs two tag bits in each pointer to a struct
* ioq_ent, so we need to ensure at least 4-byte alignment. The natural
* alignment is enough on most architectures, but not m68k, so over-align it.
*/
#define IOQ_ENT_ALIGN alignas(4)
/**
* An I/O queue entry.
*/
struct ioq_ent {
/** The I/O operation. */
IOQ_ENT_ALIGN enum ioq_op op;
/** The return value (on success) or negative error code (on failure). */
int result;
/** Arbitrary user data. */
void *ptr;
/** Operation-specific arguments. */
union {
/** ioq_close() args. */
struct ioq_close {
int fd;
} close;
/** ioq_opendir() args. */
struct ioq_opendir {
struct bfs_dir *dir;
const char *path;
int dfd;
enum bfs_dir_flags flags;
} opendir;
/** ioq_closedir() args. */
struct ioq_closedir {
struct bfs_dir *dir;
} closedir;
/** ioq_stat() args. */
struct ioq_stat {
const char *path;
struct bfs_stat *buf;
void *xbuf;
int dfd;
enum bfs_stat_flags flags;
} stat;
};
};
/**
* Create an I/O queue.
*
* @param depth
* The maximum depth of the queue.
* @param nthreads
* The maximum number of background threads.
* @return
* The new I/O queue, or NULL on failure.
*/
struct ioq *ioq_create(size_t depth, size_t nthreads);
/**
* Check the remaining capacity of a queue.
*/
size_t ioq_capacity(const struct ioq *ioq);
/**
* Asynchronous close().
*
* @param ioq
* The I/O queue.
* @param fd
* The fd to close.
* @param ptr
* An arbitrary pointer to associate with the request.
* @return
* 0 on success, or -1 on failure.
*/
int ioq_close(struct ioq *ioq, int fd, void *ptr);
/**
* Asynchronous bfs_opendir().
*
* @param ioq
* The I/O queue.
* @param dir
* The allocated directory.
* @param dfd
* The base file descriptor.
* @param path
* The path to open, relative to dfd.
* @param flags
* Flags that control which directory entries are listed.
* @param ptr
* An arbitrary pointer to associate with the request.
* @return
* 0 on success, or -1 on failure.
*/
int ioq_opendir(struct ioq *ioq, struct bfs_dir *dir, int dfd, const char *path, enum bfs_dir_flags flags, void *ptr);
/**
* Asynchronous bfs_closedir().
*
* @param ioq
* The I/O queue.
* @param dir
* The directory to close.
* @param ptr
* An arbitrary pointer to associate with the request.
* @return
* 0 on success, or -1 on failure.
*/
int ioq_closedir(struct ioq *ioq, struct bfs_dir *dir, void *ptr);
/**
* Asynchronous bfs_stat().
*
* @param ioq
* The I/O queue.
* @param dfd
* The base file descriptor.
* @param path
* The path to stat, relative to dfd.
* @param flags
* Flags that affect the lookup.
* @param buf
* A place to store the stat buffer, if successful.
* @param ptr
* An arbitrary pointer to associate with the request.
* @return
* 0 on success, or -1 on failure.
*/
int ioq_stat(struct ioq *ioq, int dfd, const char *path, enum bfs_stat_flags flags, struct bfs_stat *buf, void *ptr);
/**
* Pop a response from the queue.
*
* @param ioq
* The I/O queue.
* @return
* The next response, or NULL.
*/
struct ioq_ent *ioq_pop(struct ioq *ioq, bool block);
/**
* Free a queue entry.
*
* @param ioq
* The I/O queue.
* @param ent
* The entry to free.
*/
void ioq_free(struct ioq *ioq, struct ioq_ent *ent);
/**
* Cancel any pending I/O operations.
*/
void ioq_cancel(struct ioq *ioq);
/**
* Stop and destroy an I/O queue.
*/
void ioq_destroy(struct ioq *ioq);
#endif // BFS_IOQ_H
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