mdw@git.distorted.org.uk Git - sgt/agedu/blob - index.h

   1 /*
   2  * index.h: Manage indexes for agedu.
   3  */
   4
   5 #include <sys/types.h>
   6
   7 /*
   8  * Given the size of an existing data file and the number of
   9  * entries required in the index, calculate and return an upper
  10  * bound on the required size of the index file after an index has
  11  * been written on to the end of it.
  12  */
  13 off_t index_compute_size(off_t currentsize, int nodecount);
  14
  15 /*
  16  * Build an index, given the address of a memory-mapped data file
  17  * and the starting offset within it.
  18  *
  19  * trie_file structures passed to tf must of course be within the
  20  * bounds of the memory-mapped file.
  21  *
  22  * indexbuild_realsize returns the total amount of data _actually_
  23  * written into the file, to allow it to be truncated afterwards.
  24  */
  25 typedef struct indexbuild indexbuild;
  26 indexbuild *indexbuild_new(void *t, off_t startoff, int nodecount);
  27 void indexbuild_add(indexbuild *ib, const struct trie_file *tf);
  28 off_t indexbuild_realsize(indexbuild *ib);
  29 void indexbuild_free(indexbuild *ib);
  30
  31 /*
  32  * Query an index to find the total size of records with name
  33  * index strictly less than n, with atime less than at.
  34  */
  35 unsigned long long index_query(const void *t, int n, unsigned long long at);
  36
  37 /*
  38  * Retrieve an order statistic from the index: given a fraction f,
  39  * return an atime such that (at most) the requested fraction of
  40  * the total data is older than it.
  41  */
  42 unsigned long long index_order_stat(const void *t, double f);