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