FreeBSD/Linux Kernel Cross Reference
sys/sys/alq.h

     /*-
      * SPDX-License-Identifier: BSD-2-Clause
      *
      * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
      * Copyright (c) 2008-2009, Lawrence Stewart <lstewart@freebsd.org>
      * Copyright (c) 2010, The FreeBSD Foundation
      * All rights reserved.
      *
      * Portions of this software were developed at the Centre for Advanced
     * Internet Architectures, Swinburne University of Technology, Melbourne,
     * Australia by Lawrence Stewart under sponsorship from the FreeBSD Foundation.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice unmodified, this list of conditions, and the following
     *    disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     *
     * $FreeBSD: releng/12.0/sys/sys/alq.h 326256 2017-11-27 15:01:59Z pfg $
     *
     */
    #ifndef _SYS_ALQ_H_
    #define _SYS_ALQ_H_
    
    /*
     * Opaque type for the Async. Logging Queue
     */
    struct alq;
    
    /* The thread for the logging daemon */
    extern struct thread *ald_thread;
    
    /*
     * Async. Logging Entry
     */
    struct ale {
            intptr_t        ae_bytesused;   /* # bytes written to ALE. */
            char            *ae_data;       /* Write ptr. */
            int             ae_pad;         /* Unused, compat. */
    };
    
    /* Flag options. */
    #define ALQ_NOWAIT      0x0001  /* ALQ may not sleep. */
    #define ALQ_WAITOK      0x0002  /* ALQ may sleep. */
    #define ALQ_NOACTIVATE  0x0004  /* Don't activate ALQ after write. */
    #define ALQ_ORDERED     0x0010  /* Maintain write ordering between threads. */
    
    /* Suggested mode for file creation. */
    #define ALQ_DEFAULT_CMODE       0600
    
    /*
     * alq_open_flags:  Creates a new queue
     *
     * Arguments:
     *      alq     Storage for a pointer to the newly created queue.
     *      file    The filename to open for logging.
     *      cred    Credential to authorize open and I/O with.
     *      cmode   Creation mode for file, if new.
     *      size    The size of the queue in bytes.
     *      flags   ALQ_ORDERED
     * Returns:
     *      error from open or 0 on success
     */
    struct ucred;
    int alq_open_flags(struct alq **alqp, const char *file, struct ucred *cred, int cmode,
                int size, int flags);
    int alq_open(struct alq **alqp, const char *file, struct ucred *cred, int cmode,
                int size, int count);
    
    /*
     * alq_writen:  Write data into the queue
     *
     * Arguments:
     *      alq     The queue we're writing to
     *      data    The entry to be recorded
     *      len     The number of bytes to write from *data
     *      flags   (ALQ_NOWAIT || ALQ_WAITOK), ALQ_NOACTIVATE
     *
     * Returns:
     *      EWOULDBLOCK if:
     *              Waitok is ALQ_NOWAIT and the queue is full.
     *              The system is shutting down.
     *      0 on success.
     */
   int alq_writen(struct alq *alq, void *data, int len, int flags);
   int alq_write(struct alq *alq, void *data, int flags);
   
   /*
    * alq_flush:  Flush the queue out to disk
    */
   void alq_flush(struct alq *alq);
   
   /*
    * alq_close:  Flush the queue and free all resources.
    */
   void alq_close(struct alq *alq);
   
   /*
    * alq_getn:  Return an entry for direct access
    *
    * Arguments:
    *      alq     The queue to retrieve an entry from
    *      len     Max number of bytes required
    *      flags   (ALQ_NOWAIT || ALQ_WAITOK)
    *
    * Returns:
    *      The next available ale on success.
    *      NULL if:
    *              flags is ALQ_NOWAIT and the queue is full.
    *              The system is shutting down.
    *
    * This leaves the queue locked until a subsequent alq_post.
    */
   struct ale *alq_getn(struct alq *alq, int len, int flags);
   struct ale *alq_get(struct alq *alq, int flags);
   
   /*
    * alq_post_flags:  Schedule the ale retrieved by alq_get/alq_getn for writing.
    *      alq     The queue to post the entry to.
    *      ale     An asynch logging entry returned by alq_get.
    *      flags   ALQ_NOACTIVATE
    */
   void alq_post_flags(struct alq *alq, struct ale *ale, int flags);
   
   static __inline void
   alq_post(struct alq *alq, struct ale *ale)
   {
           alq_post_flags(alq, ale, 0);
   }
   
   #endif  /* _SYS_ALQ_H_ */

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