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git.ipfire.org Git - thirdparty/squid.git/blob - include/heap.h
2 * AUTHOR: John Dilley, Hewlett Packard
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32 /****************************************************************************
33 * Copyright (C) 1999 by Hewlett Packard
35 * Heap data structure. Used to store objects for cache replacement. The
36 * heap is implemented as a contiguous array in memory. Heap sort and heap
37 * update are done in-place. The heap is ordered with the smallest value at
38 * the top of the heap (as in the smallest object key value). Child nodes
39 * are larger than their parent.
40 ****************************************************************************/
45 * Function for generating heap keys. The first argument will typically be
46 * a dws_md_p passed in as a void *. Should find a way to get type safety
47 * without having heap know all about metadata objects... The second arg is
48 * the current aging factor for the heap.
50 typedef unsigned long heap_mutex_t
;
51 typedef void * heap_t
;
52 typedef double heap_key
;
53 typedef heap_key
heap_key_func(heap_t
, heap_key
);
56 * Heap node. Has a key value generated by a key_func, id (array index) so
57 * it can be quickly found in its heap, and a pointer to a data object that
58 * key_func can generate a key from.
60 typedef struct _heap_node
{
67 * Heap object. Holds an array of heap_node objects along with a heap size
68 * (array length), the index of the last heap element, and a key generation
69 * function. Also stores aging factor for this heap.
71 typedef struct _heap
{
75 heap_key_func
*gen_key
; /* key generator for heap */
76 heap_key age
; /* aging factor for heap */
80 /****************************************************************************
82 ****************************************************************************/
85 * Create and initialize a new heap.
87 SQUIDCEXTERN heap
*new_heap(int init_size
, heap_key_func gen_key
);
90 * Delete a heap and clean up its memory. Does not delete what the heap
91 * nodes are pointing to!
93 SQUIDCEXTERN
void delete_heap(heap
*);
96 * Insert a new node into a heap, returning a pointer to it. The heap_node
97 * object returned is used to update or delete a heap object. Nothing else
98 * should be done with this data structure (especially modifying it!) The
99 * heap does not assume ownership of the data passed to it.
101 SQUIDCEXTERN heap_node
*heap_insert(heap
*hp
, heap_t dat
);
104 * Delete a node out of a heap. Returns the heap data from the deleted
105 * node. The caller is responsible for freeing this data.
107 SQUIDCEXTERN heap_t
heap_delete(heap
*, heap_node
* elm
);
110 * The semantics of this routine is the same as the followings:
111 * heap_delete(hp, elm);
112 * heap_insert(hp, dat);
113 * Returns the old data object from elm (the one being replaced). The
114 * caller must free this as necessary.
116 SQUIDCEXTERN heap_t
heap_update(heap
*, heap_node
* elm
, heap_t dat
);
119 * Generate a heap key for a given data object. Alternative macro form:
122 SQUIDCEXTERN heap_key
heap_gen_key(heap
* hp
, heap_t dat
);
124 #define heap_gen_key(hp,md) ((hp)->gen_key((md),(hp)->age))
125 #endif /* MACRO_DEBUG */
128 * Extract the minimum (root) element and maintain the heap property.
129 * Returns the data pointed to by the root node, which the caller must
132 SQUIDCEXTERN heap_t
heap_extractmin(heap
*);
135 * Extract the last leaf node (does not change the heap property).
136 * Returns the data that had been in the heap which the caller must free if
137 * necessary. Note that the last node is guaranteed to be less than its
138 * parent, but may not be less than any of the other (leaf or parent) notes
139 * in the tree. This operation is fast but imprecise.
141 SQUIDCEXTERN heap_t
heap_extractlast(heap
* hp
);
144 * Get the root key, the nth key, the root (smallest) element, or the nth
145 * element. None of these operations modify the heap.
147 SQUIDCEXTERN heap_key
heap_peepminkey(heap
*);
148 SQUIDCEXTERN heap_key
heap_peepkey(heap
*, int n
);
150 SQUIDCEXTERN heap_t
heap_peepmin(heap
*);
151 SQUIDCEXTERN heap_t
heap_peep(heap
*, int n
);
154 * Is the heap empty? How many nodes (data objects) are in it?
157 SQUIDCEXTERN
int heap_empty(heap
*);
158 SQUIDCEXTERN
int heap_nodes(heap
*);
159 #else /* MACRO_DEBUG */
160 #define heap_nodes(heap) ((heap)->last)
161 #define heap_empty(heap) ((heap)->last <= 0 ? 1 : 0)
162 #endif /* MACRO_DEBUG */
165 * Print the heap or a node in the heap.
167 SQUIDCEXTERN
void heap_print(heap
*);
168 SQUIDCEXTERN
void heap_printnode(char *msg
, heap_node
* elm
);
170 SQUIDCEXTERN
int verify_heap_property(heap
*);
172 #endif /* SQUID_HEAP_H */