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include/linux/prio_heap.h 1.76 KB
8707d8b8c   Paul Menage   Fix cpusets updat...
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  #ifndef _LINUX_PRIO_HEAP_H
  #define _LINUX_PRIO_HEAP_H
  
  /*
   * Simple insertion-only static-sized priority heap containing
   * pointers, based on CLR, chapter 7
   */
  
  #include <linux/gfp.h>
  
  /**
   * struct ptr_heap - simple static-sized priority heap
   * @ptrs - pointer to data area
   * @max - max number of elements that can be stored in @ptrs
   * @size - current number of valid elements in @ptrs (in the range 0..@size-1
   * @gt: comparison operator, which should implement "greater than"
   */
  struct ptr_heap {
  	void **ptrs;
  	int max;
  	int size;
  	int (*gt)(void *, void *);
  };
  
  /**
   * heap_init - initialize an empty heap with a given memory size
   * @heap: the heap structure to be initialized
   * @size: amount of memory to use in bytes
   * @gfp_mask: mask to pass to kmalloc()
   * @gt: comparison operator, which should implement "greater than"
   */
  extern int heap_init(struct ptr_heap *heap, size_t size, gfp_t gfp_mask,
  		     int (*gt)(void *, void *));
  
  /**
   * heap_free - release a heap's storage
   * @heap: the heap structure whose data should be released
   */
  void heap_free(struct ptr_heap *heap);
  
  /**
   * heap_insert - insert a value into the heap and return any overflowed value
   * @heap: the heap to be operated on
   * @p: the pointer to be inserted
   *
   * Attempts to insert the given value into the priority heap. If the
   * heap is full prior to the insertion, then the resulting heap will
   * consist of the smallest @max elements of the original heap and the
   * new element; the greatest element will be removed from the heap and
   * returned. Note that the returned element will be the new element
   * (i.e. no change to the heap) if the new element is greater than all
   * elements currently in the heap.
   */
  extern void *heap_insert(struct ptr_heap *heap, void *p);
  
  
  
  #endif /* _LINUX_PRIO_HEAP_H */