git.m6w6.name Git - m6w6/libmemcached/blob - src/libmemcachedprotocol/cache.h

   1 /*
   2     +--------------------------------------------------------------------+
   3     | libmemcached - C/C++ Client Library for memcached                  |
   4     +--------------------------------------------------------------------+
   5     | Redistribution and use in source and binary forms, with or without |
   6     | modification, are permitted under the terms of the BSD license.    |
   7     | You should have received a copy of the license in a bundled file   |
   8     | named LICENSE; in case you did not receive a copy you can review   |
   9     | the terms online at: https://opensource.org/licenses/BSD-3-Clause  |
  10     +--------------------------------------------------------------------+
  11     | Copyright (c) 2006-2014 Brian Aker   https://datadifferential.com/ |
  12     | Copyright (c) 2020 Michael Wallner   <mike@php.net>                |
  13     +--------------------------------------------------------------------+
  14 */
  15
  16 #pragma once
  17
  18 #include <pthread.h>
  19
  20 #ifdef HAVE_UMEM_H
  21 #  include <umem.h>
  22 #  define cache_t                     umem_cache_t
  23 #  define cache_alloc(a)              umem_cache_alloc(a, UMEM_DEFAULT)
  24 #  define cache_free(a, b)            umem_cache_free(a, b)
  25 #  define cache_create(a, b, c, d, e) umem_cache_create((char *) a, b, c, d, e, NULL, NULL, NULL, 0)
  26 #  define cache_destroy(a)            umem_cache_destroy(a);
  27 #else
  28 #  ifndef NDEBUG
  29 /* may be used for debug purposes */
  30 extern int cache_error;
  31 #  endif
  32
  33 /**
  34  * Constructor used to initialize allocated objects
  35  *
  36  * @param obj pointer to the object to initialized.
  37  * @param notused1 This parameter is currently not used.
  38  * @param notused2 This parameter is currently not used.
  39  * @return you should return 0, but currently this is not checked
  40  */
  41 typedef int cache_constructor_t(void *obj, void *notused1, int notused2);
  42 /**
  43  * Destructor used to clean up allocated objects before they are
  44  * returned to the operating system.
  45  *
  46  * @param obj pointer to the object to initialized.
  47  * @param notused1 This parameter is currently not used.
  48  * @param notused2 This parameter is currently not used.
  49  * @return you should return 0, but currently this is not checked
  50  */
  51 typedef void cache_destructor_t(void *obj, void *notused);
  52
  53 /**
  54  * Definition of the structure to keep track of the internal details of
  55  * the cache allocator. Touching any of these variables results in
  56  * undefined behavior.
  57  */
  58 typedef struct {
  59   /** Mutex to protect access to the structure */
  60   pthread_mutex_t mutex;
  61   /** Name of the cache objects in this cache (provided by the caller) */
  62   char *name;
  63   /** List of pointers to available buffers in this cache */
  64   void **ptr;
  65   /** The size of each element in this cache */
  66   size_t bufsize;
  67   /** The capacity of the list of elements */
  68   size_t freetotal;
  69   /** The current number of free elements */
  70   size_t freecurr;
  71   /** The constructor to be called each time we allocate more memory */
  72   cache_constructor_t *constructor;
  73   /** The destructor to be called each time before we release memory */
  74   cache_destructor_t *destructor;
  75 } cache_t;
  76
  77 /**
  78  * Create an object cache.
  79  *
  80  * The object cache will let you allocate objects of the same size. It is fully
  81  * MT safe, so you may allocate objects from multiple threads without having to
  82  * do any syncrhonization in the application code.
  83  *
  84  * @param name the name of the object cache. This name may be used for debug purposes
  85  *             and may help you track down what kind of object you have problems with
  86  *             (buffer overruns, leakage etc)
  87  * @param bufsize the size of each object in the cache
  88  * @param align the alignment requirements of the objects in the cache.
  89  * @param constructor the function to be called to initialize memory when we need
  90  *                    to allocate more memory from the os.
  91  * @param destructor the function to be called before we release the memory back
  92  *                   to the os.
  93  * @return a handle to an object cache if successful, NULL otherwise.
  94  */
  95 cache_t *cache_create(const char *name, size_t bufsize, size_t align,
  96                       cache_constructor_t *constructor, cache_destructor_t *destructor);
  97 /**
  98  * Destroy an object cache.
  99  *
 100  * Destroy and invalidate an object cache. You should return all buffers allocated
 101  * with cache_alloc by using cache_free before calling this function. Not doing
 102  * so results in undefined behavior (the buffers may or may not be invalidated)
 103  *
 104  * @param handle the handle to the object cache to destroy.
 105  */
 106 void cache_destroy(cache_t *handle);
 107 /**
 108  * Allocate an object from the cache.
 109  *
 110  * @param handle the handle to the object cache to allocate from
 111  * @return a pointer to an initialized object from the cache, or NULL if
 112  *         the allocation cannot be satisfied.
 113  */
 114 void *cache_alloc(cache_t *handle);
 115 /**
 116  * Return an object back to the cache.
 117  *
 118  * The caller should return the object in an initialized state so that
 119  * the object may be returned in an expected state from cache_alloc.
 120  *
 121  * @param handle handle to the object cache to return the object to
 122  * @param ptr pointer to the object to return.
 123  */
 124 void cache_free(cache_t *handle, void *ptr);
 125 #endif //  HAVE_UMEM_H