alq.h revision 103785
1/* 2 * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD: head/sys/sys/alq.h 103785 2002-09-22 07:11:14Z jeff $ 27 * 28 */ 29#ifndef _SYS_ALD_H_ 30#define _SYS_ALD_H_ 31 32/* 33 * Opaque type for the Async. Logging Queue 34 */ 35struct alq; 36 37/* 38 * Async. Logging Entry 39 */ 40struct ale { 41 struct ale *ae_next; /* Next Entry */ 42 char *ae_data; /* Entry buffer */ 43 int ae_flags; /* Entry flags */ 44}; 45 46#define AE_VALID 0x0001 /* Entry has valid data */ 47 48 49/* waitok options */ 50#define ALQ_NOWAIT 0x0001 51#define ALQ_WAITOK 0x0002 52 53/* 54 * alq_open: Creates a new queue 55 * 56 * Arguments: 57 * alq Storage for a pointer to the newly created queue. 58 * file The filename to open for logging. 59 * size The size of each entry in the queue. 60 * count The number of items in the buffer, this should be large enough 61 * to store items over the period of a disk write. 62 * Returns: 63 * error from open or 0 on success 64 */ 65int alq_open(struct alq **, const char *file, int size, int count); 66 67/* 68 * alq_write: Write data into the queue 69 * 70 * Arguments: 71 * alq The queue we're writing to 72 * data The entry to be recorded 73 * waitok Are we permitted to wait? 74 * 75 * Returns: 76 * EWOULDBLOCK if: 77 * Waitok is ALQ_NOWAIT and the queue is full. 78 * The system is shutting down. 79 * 0 on success. 80 */ 81int alq_write(struct alq *alq, void *data, int waitok); 82 83/* 84 * alq_flush: Flush the queue out to disk 85 */ 86void alq_flush(struct alq *alq); 87 88/* 89 * alq_close: Flush the queue and free all resources. 90 */ 91void alq_close(struct alq *alq); 92 93/* 94 * alq_get: Return an entry for direct access 95 * 96 * Arguments: 97 * alq The queue to retrieve an entry from 98 * waitok Are we permitted to wait? 99 * 100 * Returns: 101 * The next available ale on success. 102 * NULL if: 103 * Waitok is ALQ_NOWAIT and the queue is full. 104 * The system is shutting down. 105 * 106 * This leaves the queue locked until a subsequent alq_post. 107 */ 108struct ale *alq_get(struct alq *alq, int waitok); 109 110/* 111 * alq_post: Schedule the ale retrieved by alq_get for writing. 112 * alq The queue to post the entry to. 113 * ale An asynch logging entry returned by alq_get. 114 */ 115void alq_post(struct alq *, struct ale *); 116 117#endif /* _SYS_ALD_H_ */ 118