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81 lines
2.8 KiB
C
81 lines
2.8 KiB
C
#include "pma.h"
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struct pma_cursor {
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PMA pma;
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int position; /* -1 if the position is undefined. */
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struct list next;
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void *skey, *sval; /* used in dbts. */
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};
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struct pma {
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enum typ_tag tag;
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int N; /* How long is the array? Always a power of two >= 4. */
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int n_pairs_present; /* How many array elements are non-null. */
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struct kv_pair **pairs;
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int uplgN; /* The smallest power of two >= lg(N) */
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double udt_step; /* upper density threshold step */
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/* Each doubling decreases the density by density step.
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* For example if array_len=256 and uplgN=8 then there are 5 doublings.
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* Regions of size 8 are full. Regions of size 16 are 90% full.
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* Regions of size 32 are 80% full. Regions of size 64 are 70% full.
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* Regions of size 128 are 60% full. Regions of size 256 are 50% full.
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* The density step is 0.10. */
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double ldt_step; /* lower density threshold step */
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struct list cursors;
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int (*compare_fun)(DB*,const DBT*,const DBT*);
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void *skey, *sval; /* used in dbts */
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};
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int pmainternal_count_region (struct kv_pair *pairs[], int lo, int hi);
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void pmainternal_calculate_parameters (PMA pma);
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int pmainternal_smooth_region (struct kv_pair *pairs[], int n, int idx, int base, PMA pma);
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int pmainternal_printpairs (struct kv_pair *pairs[], int N);
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int pmainternal_make_space_at (PMA pma, int idx);
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int pmainternal_find (PMA pma, DBT *, DB*); // The DB is so the comparison fuction can be called.
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void print_pma (PMA pma); /* useful for debugging, so keep the name short. I.e., not pmainternal_print_pma() */
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/*
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* resize the pma array to asksize. zero all array entries starting from startx.
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*/
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int __pma_resize_array(PMA pma, int asksize, int startx);
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/*
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* extract pairs from the pma in the window delimited by lo and hi.
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*/
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struct kv_pair_tag *__pma_extract_pairs(PMA pma, int count, int lo, int hi);
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/*
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* update the cursors in a cursor set given a set of tagged pairs.
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*/
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void __pma_update_cursors(PMA pma, struct list *cursorset, struct kv_pair_tag *tpairs, int n);
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/*
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* update this pma's cursors given a set of tagged pairs.
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*/
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void __pma_update_my_cursors(PMA pma, struct kv_pair_tag *tpairs, int n);
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/*
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* a deletion occured at index "here" in the pma. rebalance the windows around "here". if
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* necessary, shrink the pma.
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*/
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void __pma_delete_at(PMA pma, int here);
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/*
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* finish a deletion from the pma. called when there are no cursor references
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* to the kv pair.
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*/
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void __pma_delete_finish(PMA pma, int here);
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/*
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* count the number of cursors that reference a pma pair
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*/
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int __pma_count_cursor_refs(PMA pma, int here);
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/* density thresholds */
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#define PMA_LDT_HIGH 0.25
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#define PMA_LDT_LOW 0.40
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#define PMA_UDT_HIGH 1.00
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#define PMA_UDT_LOW 0.50
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/* minimum array size */
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#define PMA_MIN_ARRAY_SIZE 4
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