filters/readahead/readahead.h

   1 /* nbdkit
   2  * Copyright Red Hat
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
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   8  * * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * * 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  * * Neither the name of Red Hat nor the names of its contributors may be
  16  * used to endorse or promote products derived from this software without
  17  * specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  22  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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  27  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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  29  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #ifndef NBDKIT_READAHEAD_H
  34 #define NBDKIT_READAHEAD_H
  35
  36 #include <pthread.h>
  37
  38 #include <nbdkit-filter.h>
  39
  40 #include "vector.h"
  41
  42 /* List of commands issued to the background thread. */
  43 struct command {
  44   enum { CMD_QUIT, CMD_CACHE } type;
  45   nbdkit_next *next;
  46   uint64_t offset;
  47   uint32_t count;
  48 };
  49 DEFINE_VECTOR_TYPE (command_queue, struct command);
  50
  51 struct bgthread_ctrl {
  52   command_queue cmds;           /* Command queue. */
  53   pthread_mutex_t lock;         /* Lock for queue. */
  54   pthread_cond_t cond;          /* Condition queue size 0 -> 1. */
  55 };
  56
  57 /* Start background thread (one per connection). */
  58 extern void *readahead_thread (void *vp);
  59
  60 #endif /* NBDKIT_READAHEAD_H */