7d11e744c1
things allows variable length messages to be easily supported. - Extend KPI with alq_writen() and alq_getn() to support variable length messages, which is enabled at ALQ creation time depending on the arguments passed to alq_open(). Also add variants of alq_open() and alq_post() that accept a flags argument. The KPI is still fully backwards compatible and shouldn't require any change in ALQ consumers unless they wish to utilise the new features. - Introduce the ALQ_NOACTIVATE and ALQ_ORDERED flags to allow ALQ consumers to have more control over IO scheduling and resource acquisition respectively. - Strengthen invariants checking. - Document ALQ changes in ALQ(9) man page. Sponsored by: FreeBSD Foundation Reviewed by: gnn, jeff, rpaulo, rwatson MFC after: 1 month
145 lines
4.5 KiB
C
145 lines
4.5 KiB
C
/*-
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* Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
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* Copyright (c) 2008-2009, Lawrence Stewart <lstewart@freebsd.org>
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* Copyright (c) 2010, The FreeBSD Foundation
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* All rights reserved.
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*
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* Portions of this software were developed at the Centre for Advanced
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* Internet Architectures, Swinburne University of Technology, Melbourne,
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* Australia by Lawrence Stewart under sponsorship from the FreeBSD Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*
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*/
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#ifndef _SYS_ALQ_H_
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#define _SYS_ALQ_H_
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/*
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* Opaque type for the Async. Logging Queue
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*/
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struct alq;
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/* The thread for the logging daemon */
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extern struct thread *ald_thread;
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/*
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* Async. Logging Entry
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*/
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struct ale {
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intptr_t ae_bytesused; /* # bytes written to ALE. */
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char *ae_data; /* Write ptr. */
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int ae_pad; /* Unused, compat. */
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};
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/* Flag options. */
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#define ALQ_NOWAIT 0x0001 /* ALQ may not sleep. */
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#define ALQ_WAITOK 0x0002 /* ALQ may sleep. */
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#define ALQ_NOACTIVATE 0x0004 /* Don't activate ALQ after write. */
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#define ALQ_ORDERED 0x0010 /* Maintain write ordering between threads. */
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/* Suggested mode for file creation. */
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#define ALQ_DEFAULT_CMODE 0600
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/*
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* alq_open_flags: Creates a new queue
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*
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* Arguments:
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* alq Storage for a pointer to the newly created queue.
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* file The filename to open for logging.
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* cred Credential to authorize open and I/O with.
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* cmode Creation mode for file, if new.
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* size The size of the queue in bytes.
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* flags ALQ_ORDERED
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* Returns:
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* error from open or 0 on success
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*/
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struct ucred;
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int alq_open_flags(struct alq **alqp, const char *file, struct ucred *cred, int cmode,
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int size, int flags);
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int alq_open(struct alq **alqp, const char *file, struct ucred *cred, int cmode,
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int size, int count);
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/*
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* alq_writen: Write data into the queue
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*
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* Arguments:
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* alq The queue we're writing to
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* data The entry to be recorded
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* len The number of bytes to write from *data
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* flags (ALQ_NOWAIT || ALQ_WAITOK), ALQ_NOACTIVATE
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*
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* Returns:
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* EWOULDBLOCK if:
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* Waitok is ALQ_NOWAIT and the queue is full.
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* The system is shutting down.
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* 0 on success.
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*/
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int alq_writen(struct alq *alq, void *data, int len, int flags);
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int alq_write(struct alq *alq, void *data, int flags);
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/*
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* alq_flush: Flush the queue out to disk
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*/
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void alq_flush(struct alq *alq);
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/*
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* alq_close: Flush the queue and free all resources.
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*/
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void alq_close(struct alq *alq);
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/*
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* alq_getn: Return an entry for direct access
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*
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* Arguments:
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* alq The queue to retrieve an entry from
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* len Max number of bytes required
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* flags (ALQ_NOWAIT || ALQ_WAITOK)
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*
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* Returns:
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* The next available ale on success.
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* NULL if:
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* flags is ALQ_NOWAIT and the queue is full.
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* The system is shutting down.
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*
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* This leaves the queue locked until a subsequent alq_post.
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*/
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struct ale *alq_getn(struct alq *alq, int len, int flags);
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struct ale *alq_get(struct alq *alq, int flags);
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/*
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* alq_post_flags: Schedule the ale retrieved by alq_get/alq_getn for writing.
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* alq The queue to post the entry to.
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* ale An asynch logging entry returned by alq_get.
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* flags ALQ_NOACTIVATE
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*/
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void alq_post_flags(struct alq *alq, struct ale *ale, int flags);
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static __inline void
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alq_post(struct alq *alq, struct ale *ale)
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{
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alq_post_flags(alq, ale, 0);
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}
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#endif /* _SYS_ALQ_H_ */
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