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4c86fa5 Create a generic cache for objects of same size
Trond Norbye authored Mar 27, 2009
1 /* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
2 #ifndef CACHE_H
3 #define CACHE_H
4 #include <pthread.h>
5
6 #ifdef HAVE_UMEM_H
7 #include <umem.h>
8 #define cache_t umem_cache_t
9 #define cache_alloc(a) umem_cache_alloc(a, UMEM_DEFAULT)
10 #define cache_free(a, b) umem_cache_free(a, b)
11 #define cache_create(a,b,c,d,e) umem_cache_create((char*)a, b, c, d, e, NULL, NULL, NULL, 0)
12 #define cache_destroy(a) umem_cache_destroy(a);
13
14 #else
15
16 #ifndef NDEBUG
17 /* may be used for debug purposes */
18 extern int cache_error;
19 #endif
20
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Trond Norbye authored Apr 17, 2009
21 /**
22 * Constructor used to initialize allocated objects
23 *
24 * @param obj pointer to the object to initialized.
25 * @param notused1 This parameter is currently not used.
26 * @param notused2 This parameter is currently not used.
27 * @return you should return 0, but currently this is not checked
28 */
29 typedef int cache_constructor_t(void* obj, void* notused1, int notused2);
30 /**
31 * Destructor used to clean up allocated objects before they are
32 * returned to the operating system.
33 *
34 * @param obj pointer to the object to initialized.
35 * @param notused1 This parameter is currently not used.
36 * @param notused2 This parameter is currently not used.
37 * @return you should return 0, but currently this is not checked
38 */
39 typedef void cache_destructor_t(void* obj, void* notused);
4c86fa5 Create a generic cache for objects of same size
Trond Norbye authored Mar 27, 2009
40
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41 /**
42 * Definition of the structure to keep track of the internal details of
43 * the cache allocator. Touching any of these variables results in
44 * undefined behavior.
45 */
4c86fa5 Create a generic cache for objects of same size
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46 typedef struct {
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47 /** Mutex to protect access to the structure */
4c86fa5 Create a generic cache for objects of same size
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48 pthread_mutex_t mutex;
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49 /** Name of the cache objects in this cache (provided by the caller) */
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50 char *name;
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51 /** List of pointers to available buffers in this cache */
4c86fa5 Create a generic cache for objects of same size
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52 void **ptr;
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53 /** The size of each element in this cache */
4c86fa5 Create a generic cache for objects of same size
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54 size_t bufsize;
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55 /** The capacity of the list of elements */
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56 int freetotal;
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57 /** The current number of free elements */
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58 int freecurr;
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59 /** The constructor to be called each time we allocate more memory */
4c86fa5 Create a generic cache for objects of same size
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60 cache_constructor_t* constructor;
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61 /** The destructor to be called each time before we release memory */
4c86fa5 Create a generic cache for objects of same size
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62 cache_destructor_t* destructor;
63 } cache_t;
64
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65 /**
66 * Create an object cache.
67 *
68 * The object cache will let you allocate objects of the same size. It is fully
69 * MT safe, so you may allocate objects from multiple threads without having to
70 * do any syncrhonization in the application code.
71 *
72 * @param name the name of the object cache. This name may be used for debug purposes
73 * and may help you track down what kind of object you have problems with
74 * (buffer overruns, leakage etc)
75 * @param bufsize the size of each object in the cache
76 * @param align the alignment requirements of the objects in the cache.
77 * @param constructor the function to be called to initialize memory when we need
78 * to allocate more memory from the os.
79 * @param destructor the function to be called before we release the memory back
80 * to the os.
81 * @return a handle to an object cache if successful, NULL otherwise.
82 */
83 cache_t* cache_create(const char* name, size_t bufsize, size_t align,
4c86fa5 Create a generic cache for objects of same size
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84 cache_constructor_t* constructor,
85 cache_destructor_t* destructor);
652884e Added documentation on the cache interface
Trond Norbye authored Apr 17, 2009
86 /**
87 * Destroy an object cache.
88 *
89 * Destroy and invalidate an object cache. You should return all buffers allocated
90 * with cache_alloc by using cache_free before calling this function. Not doing
91 * so results in undefined behavior (the buffers may or may not be invalidated)
92 *
93 * @param handle the handle to the object cache to destroy.
94 */
95 void cache_destroy(cache_t* handle);
96 /**
97 * Allocate an object from the cache.
98 *
99 * @param handle the handle to the object cache to allocate from
100 * @return a pointer to an initialized object from the cache, or NULL if
101 * the allocation cannot be satisfied.
102 */
103 void* cache_alloc(cache_t* handle);
104 /**
105 * Return an object back to the cache.
106 *
107 * The caller should return the object in an initialized state so that
108 * the object may be returned in an expected state from cache_alloc.
109 *
110 * @param handle handle to the object cache to return the object to
111 * @param ptr pointer to the object to return.
112 */
113 void cache_free(cache_t* handle, void* ptr);
4c86fa5 Create a generic cache for objects of same size
Trond Norbye authored Mar 27, 2009
114 #endif
115
116 #endif
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