/* key-gen.c --- manufacturing sequential keys for some db tables * * ==================================================================== * Copyright (c) 2000-2004 CollabNet. All rights reserved. * * This software is licensed as described in the file COPYING, which * you should have received as part of this distribution. The terms * are also available at http://subversion.tigris.org/license-1.html. * If newer versions of this license are posted there, you may use a * newer version instead, at your option. * * This software consists of voluntary contributions made by many * individuals. For exact contribution history, see the revision * history and logs, available at http://subversion.tigris.org/. * ==================================================================== */ #ifndef SVN_LIBSVN_FS_KEY_GEN_H #define SVN_LIBSVN_FS_KEY_GEN_H #include <apr.h> #include "svn_types.h" #include "private/svn_skel.h" /* ### for svn_fs_base__{get,put}size() */ #ifdef __cplusplus extern "C" { #endif /* __cplusplus */ /* The alphanumeric keys passed in and out of svn_fs_base__next_key are guaranteed never to be longer than this many bytes, *including* the trailing null byte. It is therefore safe to declare a key as "char key[MAX_KEY_SIZE]". Note that this limit will be a problem if the number of keys in a table ever exceeds 18217977168218728251394687124089371267338971528174 76066745969754933395997209053270030282678007662838 67331479599455916367452421574456059646801054954062 15017704234999886990788594743994796171248406730973 80736524850563115569208508785942830080999927310762 50733948404739350551934565743979678824151197232629 947748581376, but that's a risk we'll live with for now. */ #define MAX_KEY_SIZE 200 /* In many of the databases, the value at this key is the key to use when storing a new record. */ #define NEXT_KEY_KEY "next-key" /* Generate the next key after a given alphanumeric key. * * The first *LEN bytes of THIS are an ascii representation of a * number in base 36: digits 0-9 have their usual values, and a-z have * values 10-35. * * The new key is stored in NEXT, null-terminated. NEXT must be at * least *LEN + 2 bytes long -- one extra byte to hold a possible * overflow column, and one for null termination. On return, *LEN * will be set to the length of the new key, not counting the null * terminator. In other words, the outgoing *LEN will be either equal * to the incoming, or to the incoming + 1. * * If THIS contains anything other than digits and lower-case * alphabetic characters, or if it starts with `0' but is not the * string "0", then *LEN is set to zero and the effect on NEXT * is undefined. */ void svn_fs_base__next_key(const char *this, apr_size_t *len, char *next); /* Compare two strings A and B as base-36 alphanumeric keys. * * Return -1, 0, or 1 if A is less than, equal to, or greater than B, * respectively. */ int svn_fs_base__key_compare(const char *a, const char *b); /* Compare two strings A and B as base-36 alphanumber keys. * * Return TRUE iff both keys are NULL or both keys have the same * contents. */ svn_boolean_t svn_fs_base__same_keys(const char *a, const char *b); #ifdef __cplusplus } #endif /* __cplusplus */ #endif /* SVN_LIBSVN_FS_KEY_GEN_H */