alq.h revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
5 * Copyright (c) 2008-2009, Lawrence Stewart <lstewart@freebsd.org>
6 * Copyright (c) 2010, The FreeBSD Foundation
7 * All rights reserved.
8 *
9 * Portions of this software were developed at the Centre for Advanced
10 * Internet Architectures, Swinburne University of Technology, Melbourne,
11 * Australia by Lawrence Stewart under sponsorship from the FreeBSD Foundation.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 *    notice unmodified, this list of conditions, and the following
18 *    disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 *    notice, this list of conditions and the following disclaimer in the
21 *    documentation and/or other materials provided with the distribution.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 *
34 * $FreeBSD: stable/11/sys/sys/alq.h 330897 2018-03-14 03:19:51Z eadler $
35 *
36 */
37#ifndef _SYS_ALQ_H_
38#define	_SYS_ALQ_H_
39
40/*
41 * Opaque type for the Async. Logging Queue
42 */
43struct alq;
44
45/* The thread for the logging daemon */
46extern struct thread *ald_thread;
47
48/*
49 * Async. Logging Entry
50 */
51struct ale {
52	intptr_t	ae_bytesused;	/* # bytes written to ALE. */
53	char		*ae_data;	/* Write ptr. */
54	int		ae_pad;		/* Unused, compat. */
55};
56
57/* Flag options. */
58#define	ALQ_NOWAIT	0x0001	/* ALQ may not sleep. */
59#define	ALQ_WAITOK	0x0002	/* ALQ may sleep. */
60#define	ALQ_NOACTIVATE	0x0004	/* Don't activate ALQ after write. */
61#define	ALQ_ORDERED	0x0010	/* Maintain write ordering between threads. */
62
63/* Suggested mode for file creation. */
64#define	ALQ_DEFAULT_CMODE	0600
65
66/*
67 * alq_open_flags:  Creates a new queue
68 *
69 * Arguments:
70 *	alq	Storage for a pointer to the newly created queue.
71 *	file	The filename to open for logging.
72 *	cred	Credential to authorize open and I/O with.
73 *	cmode	Creation mode for file, if new.
74 *	size	The size of the queue in bytes.
75 *	flags	ALQ_ORDERED
76 * Returns:
77 *	error from open or 0 on success
78 */
79struct ucred;
80int alq_open_flags(struct alq **alqp, const char *file, struct ucred *cred, int cmode,
81	    int size, int flags);
82int alq_open(struct alq **alqp, const char *file, struct ucred *cred, int cmode,
83	    int size, int count);
84
85/*
86 * alq_writen:  Write data into the queue
87 *
88 * Arguments:
89 *	alq	The queue we're writing to
90 *	data	The entry to be recorded
91 *	len	The number of bytes to write from *data
92 *	flags	(ALQ_NOWAIT || ALQ_WAITOK), ALQ_NOACTIVATE
93 *
94 * Returns:
95 *	EWOULDBLOCK if:
96 *		Waitok is ALQ_NOWAIT and the queue is full.
97 *		The system is shutting down.
98 *	0 on success.
99 */
100int alq_writen(struct alq *alq, void *data, int len, int flags);
101int alq_write(struct alq *alq, void *data, int flags);
102
103/*
104 * alq_flush:  Flush the queue out to disk
105 */
106void alq_flush(struct alq *alq);
107
108/*
109 * alq_close:  Flush the queue and free all resources.
110 */
111void alq_close(struct alq *alq);
112
113/*
114 * alq_getn:  Return an entry for direct access
115 *
116 * Arguments:
117 *	alq	The queue to retrieve an entry from
118 *	len	Max number of bytes required
119 *	flags	(ALQ_NOWAIT || ALQ_WAITOK)
120 *
121 * Returns:
122 *	The next available ale on success.
123 *	NULL if:
124 *		flags is ALQ_NOWAIT and the queue is full.
125 *		The system is shutting down.
126 *
127 * This leaves the queue locked until a subsequent alq_post.
128 */
129struct ale *alq_getn(struct alq *alq, int len, int flags);
130struct ale *alq_get(struct alq *alq, int flags);
131
132/*
133 * alq_post_flags:  Schedule the ale retrieved by alq_get/alq_getn for writing.
134 *	alq	The queue to post the entry to.
135 *	ale	An asynch logging entry returned by alq_get.
136 *	flags	ALQ_NOACTIVATE
137 */
138void alq_post_flags(struct alq *alq, struct ale *ale, int flags);
139
140static __inline void
141alq_post(struct alq *alq, struct ale *ale)
142{
143	alq_post_flags(alq, ale, 0);
144}
145
146#endif	/* _SYS_ALQ_H_ */
147