Manipulate lists of records the Redis way via Tokyo Cabinet B+ Tree database

list.c

#include <stdio.h>
#include <tcbdb.h>
#include <tcutil.h>

int main(int argc, char *argv[]) {
  TCBDB *db = tcbdbnew();
  tcbdbopen(db, "list.db", BDBOWRITER | BDBOCREAT | BDBOTRUNC);
  
  /* The B+ Tree database features record duplication for a given key
     (see `tcbdbputdup`) which means we can easily append data for a
     given key a-la Redis RPUSH.
     In addition we use (on purpose) integer like primary keys and
     not directly list names, e.g. FRUITS, etc, to illustrate the
     key ordering (see below)
  */
  
  /* This is equivalent with Redis to:
     RPUSH FRUITS "orange"
     RPUSH FRUITS "pear"
     RPUSH FRUITS "kiwi"
  */
  tcbdbputdup2(db, "1", "FRUITS");
  tcbdbputdup2(db, "1", "orange");
  tcbdbputdup2(db, "1", "pear");
  tcbdbputdup2(db, "1", "kiwi");
  
  /* This is equivalent with Redis to:
     RPUSH BRANDS "Coca Cola"
     RPUSH BRANDS "evian"
  */
  tcbdbputdup2(db, "2", "BRANDS");
  tcbdbputdup2(db, "2", "Coca Cola");
  tcbdbputdup2(db, "2", "evian");
  
  BDBCUR *cur = tcbdbcurnew(db);
  
  /* The B+ Tree database also features key ordering which allows to retrieve
     the last (e.g. the most recent) record */
  if (tcbdbcurlast(cur)) {
    TCMAP *uniq = tcmapnew();
    for (;;) {
      int ksiz;
      const char *kbuf = tcbdbcurkey3(cur, &ksiz);
      /* WARNING: with record duplication the cursor traverses *all* records
                  Make sure to skip the keys already seen */
      if (tcmapputkeep(uniq, kbuf, ksiz, "", 0)) {
        TCLIST *vals = tcbdbget4(db, kbuf, ksiz);
        char *head = tclistshift2(vals);
        char *tail = tcstrjoin(vals, ',');
        printf("%s -> [%s]\n", head, tail);
        free(head);
        free(tail);
        tclistdel(vals);
      }
      if (!tcbdbcurprev(cur)) break;
    }
    tcmapdel(uniq);
  }
  tcbdbcurdel(cur);
  tcbdbdel(db);
  
  /* Output should be:
     BRANDS -> [Coca Cola,evian]
     FRUITS -> [orange,pear,kiwi]
   */
    
  return 0;
}